tag:theconversation.com,2011:/africa/topics/particle-accelerators-13348/articlesParticle accelerators – The Conversation2023-10-17T19:03:53Ztag:theconversation.com,2011:article/2056282023-10-17T19:03:53Z2023-10-17T19:03:53ZNew technique uses near-miss particle physics to peer into quantum world − two physicists explain how they are measuring wobbling tau particles<figure><img src="https://images.theconversation.com/files/532985/original/file-20230620-21-sf8wvl.jpg?ixlib=rb-1.1.0&rect=464%2C501%2C4206%2C3241&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Large Hadron Collider at CERN can be used to study many kinds of fundamental particles, including mysterious and rare tau particles.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/abstract-neon-circles-digital-fractal-black-royalty-free-image/1191907046?phrase=particle+physics&adppopup=true">Oxygen/Moment via Getty Images</a></span></figcaption></figure><p>One way physicists seek clues to unravel the mysteries of the universe is by smashing matter together and inspecting the debris. But these types of destructive experiments, while incredibly informative, have limits. </p>
<p>We are two scientists who <a href="https://www.colorado.edu/physics/dennis-perepelitsa">study nuclear</a> and <a href="https://www.phy.cam.ac.uk/staff/dr-jesse-liu">particle physics</a> using CERN’s Large Hadron Collider near Geneva, Switzerland. Working with an international group of nuclear and particle physicists, our team realized that hidden in the data from previous studies was a remarkable and innovative experiment. </p>
<p>In a new paper published in Physical Review Letters, we developed a new method with our colleagues for measuring <a href="https://doi.org/10.1103/PhysRevLett.131.151802">how fast a particle called the tau wobbles</a>.</p>
<p>Our novel approach looks at the times incoming particles in the accelerator whiz by each other rather than the times they smash together in head-on collisions. Surprisingly, this approach enables far more accurate measurements of the tau particle’s wobble than previous techniques. This is the first time in nearly 20 years scientists have measured this wobble, known as the <a href="https://doi.org/10.1088/1742-6596/912/1/012001">tau magnetic moment</a>, and it may help illuminate tantalizing cracks <a href="https://theconversation.com/the-standard-model-of-particle-physics-may-be-broken-an-expert-explains-182081">emerging in the known laws of physics</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/531776/original/file-20230613-26-1ofchy.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing a particle wobbling off of a vertical axis." src="https://images.theconversation.com/files/531776/original/file-20230613-26-1ofchy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531776/original/file-20230613-26-1ofchy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=319&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531776/original/file-20230613-26-1ofchy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=319&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531776/original/file-20230613-26-1ofchy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=319&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531776/original/file-20230613-26-1ofchy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=401&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531776/original/file-20230613-26-1ofchy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=401&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531776/original/file-20230613-26-1ofchy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=401&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Electrons, muons and taus all wobble in a magnetic field like a spinning top. Measuring the wobbling speed can provide clues into quantum physics.</span>
<span class="attribution"><span class="source">Jesse Liu</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Why measure a wobble?</h2>
<p>Electrons, the building blocks of atoms, have two heavier cousins called the <a href="https://www.britannica.com/science/subatomic-particle/Charged-leptons-electron-muon-tau">muon and the tau</a>. Taus are the heaviest in this family of three and the most mysterious, as they exist only for minuscule amounts of time.</p>
<p>Interestingly, when you place an electron, muon or tau inside a magnetic field, these particles wobble in a manner similar to how a spinning top wobbles on a table. This wobble is called a particle’s magnetic moment. It is possible to predict how fast these particles should wobble using the <a href="https://home.cern/science/physics/standard-model">Standard Model of particle physics</a> – scientists’ best theory of how particles interact.</p>
<p>Since the 1940s, physicists have been interested in measuring magnetic moments to reveal intriguing <a href="https://doi.org/10.1103/PhysRev.74.250">effects in the quantum world</a>. According to quantum physics, clouds of particles and antiparticles are constantly <a href="https://www.symmetrymagazine.org/article/july-2009/virtual-particles">popping in and out of existence</a>. These fleeting fluctuations slightly alter how fast electrons, muons and taus wobble inside a magnetic field. By measuring this wobble very precisely, physicists can peer into this cloud to uncover possible hints of undiscovered particles. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/531789/original/file-20230613-15-4hjd2s.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart showing the basic particles." src="https://images.theconversation.com/files/531789/original/file-20230613-15-4hjd2s.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531789/original/file-20230613-15-4hjd2s.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=574&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531789/original/file-20230613-15-4hjd2s.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=574&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531789/original/file-20230613-15-4hjd2s.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=574&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531789/original/file-20230613-15-4hjd2s.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=722&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531789/original/file-20230613-15-4hjd2s.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=722&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531789/original/file-20230613-15-4hjd2s.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=722&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Electrons, muons and taus are three closely related particles in the Standard Model of particle physics – scientists’ current best description of the fundamental laws of nature.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Standard_Model_of_Elementary_Particles.svg#/media/File:Standard_Model_of_Elementary_Particles.svg">MissMJ, Cush/Wikimedia Commons</a></span>
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</figure>
<h2>Testing electrons, muons and taus</h2>
<p>In 1948, theoretical physicist Julian Schwinger first calculated how the quantum cloud <a href="https://doi.org/10.1103/PhysRev.73.416">alters the electron’s magnetic moment</a>. Since then, experimental physicists have measured the speed of the electron’s wobble to an extraordinary <a href="https://doi.org/10.1038/s41586-020-2964-7">13 decimal places</a>. </p>
<p>The heavier the particle, the more its wobble will change because of undiscovered new particles lurking in its quantum cloud. Since electrons are so light, this limits their sensitivity to new particles.</p>
<p>Muons and taus are much heavier but also far shorter-lived than electrons. While muons exist only for mere microseconds, scientists at Fermilab near Chicago measured the muon’s magnetic moment to <a href="https://news.fnal.gov/2021/04/first-results-from-fermilabs-muon-g-2-experiment-strengthen-evidence-of-new-physics/">10 decimal places</a> in 2021. They found that muons wobbled noticeably faster than Standard Model predictions, suggesting unknown particles may be appearing in the muon’s quantum cloud.</p>
<p>Taus are the heaviest particle of the family – 17 times more massive than a muon and 3,500 times heavier than an electron. This makes them much more <a href="https://doi.org/10.1103/PhysRevD.64.035003">sensitive to potentially undiscovered particles</a> in the quantum clouds. But taus are also the hardest to see, since they live for just a millionth of the time a muon exists.</p>
<p>To date, the best measurement of the tau’s magnetic moment was made in 2004 using <a href="https://home.cern/science/accelerators/large-electron-positron-collider">a now-retired electron collider</a> at CERN. Though an incredible scientific feat, after multiple years of collecting data that experiment could measure the speed of the tau’s wobble to only <a href="https://doi.org/10.1140/epjc/s2004-01852-y">two decimal places</a>. Unfortunately, to test the Standard Model, physicists would need a measurement <a href="https://doi.org/10.1142/S0217732307022694">10 times as precise</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/531773/original/file-20230613-29-zwf5pp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing two particles nearly colliding." src="https://images.theconversation.com/files/531773/original/file-20230613-29-zwf5pp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531773/original/file-20230613-29-zwf5pp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=319&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531773/original/file-20230613-29-zwf5pp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=319&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531773/original/file-20230613-29-zwf5pp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=319&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531773/original/file-20230613-29-zwf5pp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=401&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531773/original/file-20230613-29-zwf5pp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=401&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531773/original/file-20230613-29-zwf5pp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=401&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Instead of colliding two nuclei head-on to create tau particles, two lead ions can whiz past each other in a near miss and still produce taus.</span>
<span class="attribution"><span class="source">Jesse Liu</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Lead ions for near-miss physics</h2>
<p>Since the 2004 measurement of the tau’s magenetic moment, physicists have been seeking new ways to measure the tau wobble.</p>
<p>The Large Hadron Collider usually smashes the nuclei of two atoms together – that is why it is called a collider. These head-on collisions create a <a href="https://cds.cern.ch/record/2841509">fireworks display of debris</a> that can include taus, but the noisy conditions preclude careful measurements of the tau’s magnetic moment.</p>
<p>From 2015 to 2018, there was an experiment at CERN that was designed primarily to allow nuclear physicists to study <a href="https://home.cern/science/physics/heavy-ions-and-quark-gluon-plasma">exotic hot matter</a> created in head-on collisions. The particles used in this experiment were lead nuclei that had been stripped of their electrons – called lead ions. Lead ions are electrically charged and produce <a href="https://doi.org/10.1038/nphys4208">strong electromagnetic fields</a>. </p>
<p>The electromagnetic fields of lead ions contain particles of light called photons. When two lead ions collide, their photons can also collide and convert all their energy into a single pair of particles. It was these photon collisions that scientists used to <a href="https://doi.org/10.1103/PhysRevLett.121.212301">measure muons</a>.</p>
<p>These lead ion experiments ended in 2018, but it wasn’t until 2019 that one of us, Jesse Liu, teamed up with particle physicist Lydia Beresford in Oxford, England, and realized the data from the same lead ion experiments could potentially be used to do something new: measure the tau’s magnetic moment. </p>
<p><a href="https://doi.org/10.1103/PhysRevD.102.113008">This discovery was a total surprise</a>. It goes like this: Lead ions are so small that they often miss each other in collision experiments. But occasionally, the ions pass very close to each other without touching. When this happens, their accompanying photons can still smash together while the ions continue flying on their merry way. </p>
<p>These photon collisions can create a variety of particles – like the muons in the previous experiment, and also taus. But without the chaotic fireworks produced by head-on collisions, these near-miss events are far quieter and ideal for measuring traits of the elusive tau.</p>
<p>Much to our excitement, when the team looked back at data from 2018, indeed these lead ion near misses were creating tau particles. There was a new experiment hidden in plain sight!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532999/original/file-20230620-8426-na9es5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A long tube in an underground tunnel." src="https://images.theconversation.com/files/532999/original/file-20230620-8426-na9es5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532999/original/file-20230620-8426-na9es5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532999/original/file-20230620-8426-na9es5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532999/original/file-20230620-8426-na9es5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532999/original/file-20230620-8426-na9es5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532999/original/file-20230620-8426-na9es5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532999/original/file-20230620-8426-na9es5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Large Hadron Collider accelerates particles to incredibly high speeds before trying to smash particles together, but not all attempts result in successful collisions.</span>
<span class="attribution"><a class="source" href="http://cds.cern.ch/record/1211045">Maximilien Brice/CERN</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>First measurement of tau wobble in two decades</h2>
<p>In April 2022, the CERN team announced that we had found <a href="https://atlas.cern/updates/briefing/observation-taupair-heavy-ions">direct evidence of tau particles created</a> during lead ion near misses. Using that data, the team was also able to measure the tau magnetic moment – the first time such a measurement had been done since 2004. The final results were published on Oct. 12, 2023.</p>
<p>This landmark result measured the tau wobble to two decimal places. Much to our astonishment, this method tied the previous best measurement using only one month of data recorded in 2018.</p>
<p>After no experimental progress for nearly 20 years, this result opens an entirely new and important path toward the tenfold improvement in precision needed to test Standard Model predictions. Excitingly, more data is on the horizon. </p>
<p>The Large Hadron Collider just restarted <a href="https://home.cern/news/news/experiments/lhc-lead-ion-collision-run-starts">lead ion data collection on Sept. 28, 2023</a>, after routine maintenance and upgrades. Our team plans to quadruple the sample size of lead ion near-miss data by 2025. This increase in data will double the accuracy of the measurement of the tau magnetic moment, and improvements to analysis methods may go even further.</p>
<p>Tau particles are one of physicists’ best windows to the enigmatic quantum world, and we are excited for surprises that upcoming results may reveal about the fundamental nature of the universe.</p><img src="https://counter.theconversation.com/content/205628/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jesse Liu is supported by a Junior Research Fellowship at Trinity College, University of Cambridge. </span></em></p><p class="fine-print"><em><span>Dennis V. Perepelitsa receives research funding from the U.S. Department of Energy, Office of Science.</span></em></p>Physicists uncovered a new experiment hidden in old data from the Large Hadron Collider. Using this innovative approach, the team has unlocked an entirely new way to study quantum physics.Jesse Liu, Research Fellow in Physics, University of CambridgeDennis V. Perepelitsa, Associate Professor of Physics, University of Colorado BoulderLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1857542022-11-14T22:12:12Z2022-11-14T22:12:12ZPowerful linear accelerator begins smashing atoms – 2 scientists on the team explain how it could reveal rare forms of matter<figure><img src="https://images.theconversation.com/files/484140/original/file-20220912-16-rp5qhi.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3000%2C1199&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A new particle accelerator at Michigan State University is set to discover thousands of never-before-seen isotopes. </span> <span class="attribution"><span class="source">Facility for Rare Isotope Beams</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Just a few hundred feet from where we are sitting is a large metal chamber devoid of air and draped with the wires needed to control the instruments inside. A beam of particles passes through the interior of the chamber silently at around half the speed of light until it smashes into a solid piece of material, resulting in a burst of rare isotopes.</p>
<p>This is all taking place in the <a href="https://frib.msu.edu/">Facility for Rare Isotope Beams</a>, or FRIB, which is operated by Michigan State University for the U.S. Department of Energy Office of Science. Starting in May 2022, national and international teams of scientists converged at Michigan State University and began running scientific experiments at FRIB with the goal of creating, isolating and studying new isotopes. The experiments promised to provide new insights into the fundamental nature of the universe.</p>
<p>We are two professors in <a href="https://www.chemistry.msu.edu/faculty-research/faculty-members/liddick-sean.aspx">nuclear chemistry</a> and <a href="https://scholar.google.com/citations?user=vlmJRrsAAAAJ&hl=en&oi=sra">nuclear physics</a> who study rare isotopes. Isotopes are, in a sense, different flavors of an element with the same number of protons in their nucleus but different numbers of neutrons. </p>
<p>The accelerator at FRIB started working at low power, but when it finishes ramping up to full strength, it will be the most powerful heavy-ion accelerator on Earth. By accelerating heavy ions – electrically charged atoms of elements – FRIB will allow scientists like us to create and study thousands of never-before-seen isotopes. A community of roughly <a href="https://fribusers.org/">1,600 nuclear scientists from all over the world</a> has been waiting for a decade to begin doing science enabled by the new particle accelerator.</p>
<p>The <a href="https://newscenter.lbl.gov/2022/11/14/frib-experiment-pushes-elements-to-the-limit/">first experiments at FRIB</a> were completed over the summer of 2022. Even though the facility is currently running at only a fraction of its full power, multiple scientific collaborations working at FRIB have already produced and <a href="https://doi.org/10.1103/PhysRevLett.129.212501">detected about 100 rare isotopes</a>. These early results are helping researchers learn about some of the rarest physics in the universe.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/yGHuZnfnUtI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Rare isotopes are radioactive and decay over time as they emit radiation – visible here as the streaks coming from the small piece of uranium in the center.</span></figcaption>
</figure>
<h2>What is a rare isotope?</h2>
<p>It takes incredibly high amounts of energy to produce most isotopes. In nature, heavy rare isotopes are produced during the cataclysmic deaths of massive stars called <a href="https://physicstoday.scitation.org/doi/10.1063/1.1825268">supernovas</a> or during the <a href="https://doi.org/10.1038/s41586-019-1676-3">merging of two neutron stars</a>.</p>
<p>To the naked eye, two isotopes of any element look and behave the same way – all isotopes of the element mercury would look just like the liquid metal used in old thermometers. However, because the nuclei of isotopes of the same element have different numbers of neutrons, they differ in how long they live, what type of radioactivity they emit and in many other ways.</p>
<p>For example, some isotopes are stable and do not decay or emit radiation, so they are common in the universe. Other isotopes of the very same element can be radioactive so they inevitably decay away as they turn into other elements. Since radioactive isotopes disappear over time, they are relatively rarer. </p>
<p>Not all decay happens at the same rate though. Some radioactive elements – like potassium-40 – emit particles through decay at such a low rate that a small amount of the isotope can <a href="https://www.nndc.bnl.gov/nudat3/">last for billions of years</a>. Other, more highly radioactive isotopes like magnesium-38 exist for only a fraction of a second before decaying away into other elements. Short-lived isotopes, by definition, do not survive long and are rare in the universe. So if you want to study them, you have to make them yourself.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/480464/original/file-20220822-77906-xtxwle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram of a large facility." src="https://images.theconversation.com/files/480464/original/file-20220822-77906-xtxwle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480464/original/file-20220822-77906-xtxwle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=463&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480464/original/file-20220822-77906-xtxwle.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=463&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480464/original/file-20220822-77906-xtxwle.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=463&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480464/original/file-20220822-77906-xtxwle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=582&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480464/original/file-20220822-77906-xtxwle.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=582&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480464/original/file-20220822-77906-xtxwle.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=582&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Facility for Rare Isotope Beams was designed to allow researchers to create rare isotopes and measure them before they decay.</span>
<span class="attribution"><a class="source" href="https://frib.zenfolio.com/p798584095">Facility for Rare Isotope Beams</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Creating isotopes in a lab</h2>
<p>While only about <a href="https://doi.org/10.1038/nature11188">250 isotopes naturally occur on Earth</a>, theoretical models predict that about <a href="https://doi.org/10.1038/nature11188">7,000 isotopes should exist in nature</a>. Scientists have used particle accelerators to produce around <a href="http://www.nndc.bnl.gov/ensdf/">3,000 of these rare isotopes</a>.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/480463/original/file-20220822-76734-8linop.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A hallway with dozens of large chambers on either side extending into the distance." src="https://images.theconversation.com/files/480463/original/file-20220822-76734-8linop.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/480463/original/file-20220822-76734-8linop.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480463/original/file-20220822-76734-8linop.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480463/original/file-20220822-76734-8linop.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480463/original/file-20220822-76734-8linop.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=507&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480463/original/file-20220822-76734-8linop.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=507&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480463/original/file-20220822-76734-8linop.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=507&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The green-colored chambers use electromagnetic waves to accelerate charged ions to nearly half the speed of light.</span>
<span class="attribution"><a class="source" href="https://frib.zenfolio.com/p798584095">Facility for Rare Isotope Beams</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The FRIB accelerator is 1,600 feet long and made of three segments folded in roughly the shape of a paperclip. Within these segments are numerous, extremely cold vacuum chambers that alternatively pull and push the ions using powerful electromagnetic pulses. FRIB can accelerate any naturally occurring isotope – whether it is as light as oxygen or as heavy as uranium – to approximately <a href="https://frib.msu.edu/science/nuclearphysics/index.html">half the speed of light</a>.</p>
<p>To create radioactive isotopes, you only need to smash this beam of ions into a solid target like a piece of beryllium metal or a rotating disk of carbon.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/480466/original/file-20220822-38135-yurmqa.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A complicated machine in a large tube." src="https://images.theconversation.com/files/480466/original/file-20220822-38135-yurmqa.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/480466/original/file-20220822-38135-yurmqa.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480466/original/file-20220822-38135-yurmqa.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480466/original/file-20220822-38135-yurmqa.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480466/original/file-20220822-38135-yurmqa.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480466/original/file-20220822-38135-yurmqa.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480466/original/file-20220822-38135-yurmqa.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">There are many different instruments designed to measure specific attributes of the particles created during experiments at FRIB – like this instrument called FDSi, which is built to measure charged particles, neutrons and photons.</span>
<span class="attribution"><span class="source">Facility for Rare Isotope Beams</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The impact of the ion beam on the fragmentation target <a href="https://doi.org/10.1098/rsta.1998.0260">breaks the nucleus of the stable isotope apart</a> and produces many hundreds of rare isotopes simultaneously. To isolate the interesting or new isotopes from the rest, a separator sits between the target and the sensors. Particles with the right momentum and electrical charge will be passed through the separator while the rest are absorbed. Only a <a href="https://frib.msu.edu/users/instruments/operation.html">subset of the desired isotopes will reach the many instruments</a> built to observe the nature of the particles. </p>
<p>The probability of creating any specific isotope during a single collision can be very small. The odds of creating some of the rarer exotic isotopes can be on the order of <a href="https://doi.org/10.1088/0031-8949/91/5/053003">1 in a quadrillion</a> – roughly the same odds as winning back-to-back Mega Millions jackpots. But the powerful beams of ions used by FRIB contain so many ions and produce so many collisions in a single experiment that the team can reasonably expect to <a href="https://groups.nscl.msu.edu/frib/rates/fribrates.html">find even the rarest of isotopes</a>. According to calculations, FRIB’s accelerator should be able to <a href="https://msu.edu/discoverfrib">produce approximately 80% of all theorized isotopes</a>.</p>
<h2>The first two FRIB scientific experiments</h2>
<p>A multi-institution team led by researchers at Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory (ORNL), University of Tennessee, Knoxville (UTK), Mississippi State University and Florida State University, together with researchers at MSU, began running the first experiment at FRIB on May 9, 2022. The group directed a beam of calcium-48 – a calcium nucleus with 28 neutrons instead of the usual 20 – into a beryllium target at 1 kW of power. Even at one quarter of a percent of the facility’s 400-kW maximum power, approximately 40 different isotopes passed through the separator to the <a href="https://fds.ornl.gov/initiator/">instruments</a>.</p>
<p>The FDSi device recorded the time each ion arrived, what isotope it was and when it decayed away. Using this information, the collaboration deduced the half-lives of the isotopes; the team has already <a href="https://doi.org/10.1103/PhysRevLett.129.212501">reported on five previously unknown half-lives</a>.</p>
<p>The second FRIB experiment began on June 15, 2022, led by a collaboration of researchers from Lawrence Livermore National Laboratory, ORNL, UTK and MSU. The facility accelerated a beam of selenium-82 and used it to produce rare isotopes of the elements scandium, calcium and potassium. These isotopes are commonly found in neutron stars, and the goal of the experiment was to better understand what type of radioactivity these isotopes emit as they decay. Understanding this process could shed light on <a href="https://doi.org/10.1038/nature12757">how neutron stars lose energy</a>.</p>
<p>The first two FRIB experiments were just the tip of the iceberg of this new facility’s capabilities. Over the coming years, FRIB is set to explore four big questions in nuclear physics: First, what are the properties of atomic nuclei with a large difference between the numbers of protons and neutrons? Second, how are elements formed in the cosmos? Third, do physicists understand the fundamental symmetries of the universe, like why there is more matter than antimatter in the universe? Finally, how can the information from rare isotopes be applied in medicine, industry and national security? </p>
<p><em>This story was updated to correctly represent the number of neutrons in the nucleus of calcium-48.</em></p><img src="https://counter.theconversation.com/content/185754/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sean Liddick receives funding from the Department of Energy . </span></em></p><p class="fine-print"><em><span>Artemis Spyrou receives funding from the National Science Foundation in the U.S.</span></em></p>A new particle accelerator has just begun operation. It is the most powerful accelerator of its kind on Earth and will allow physicists to study some of the rarest matter in the universe.Sean Liddick, Associate Professor of Chemistry, Michigan State UniversityArtemis Spyrou, Professor of Nuclear Physics, Michigan State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1695632021-10-11T21:05:29Z2021-10-11T21:05:29ZThe Electron-Ion Collider: new accelerator could solve the mystery of how matter holds together<figure><img src="https://images.theconversation.com/files/425743/original/file-20211011-19-vu81yy.jpg?ixlib=rb-1.1.0&rect=13%2C60%2C1500%2C929&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Brookhaven National Laboratory in the US.</span> <span class="attribution"><span class="source">Credit: Brookhaven National Laboratory</span></span></figcaption></figure><p>When the Nobel Prize-winning US physicist <a href="https://www.nobelprize.org/prizes/physics/1961/hofstadter/biographical/">Robert Hofstadter</a> and his team fired highly energetic electrons at a small vial of hydrogen at the <a href="https://www.slac.stanford.edu/gen/grad/GradHandbook/slac.html">Stanford Linear Accelerator Center</a> in 1956, they opened the door to a new era of physics. Until then, it was thought that protons and neutrons, which make up an atom’s nucleus, were the most fundamental particles in nature. They were considered to be “dots” in space, lacking physical dimensions. Now it suddenly became clear that these particles were not fundamental at all, and had a size and complex internal structure as well. </p>
<p>What Hofstadter and his team saw was a small deviation in how electrons “scattered”, or bounced, when hitting the hydrogen. This suggested there was more to a nucleus than the dot-like protons and neutrons they had imagined. The experiments that followed around the world at accelerators – machines that propel particles to very high energies – heralded a paradigm shift in our understanding of matter. </p>
<p>Yet there is a lot we still don’t know about the atomic nucleus – as well as the “strong force”, one of four <a href="https://www.space.com/four-fundamental-forces.html">fundamental forces</a> of nature, that holds it together. Now a brand-new accelerator, the <a href="http://eicug.org">Electron-Ion Collider</a>, to be built within the decade at the Brookhaven National Laboratory in Long Island, US, with the help of <a href="https://www.ukri.org/news/uk-to-lead-detector-development-for-powerful-particle-collider/">1,300 scientists</a> from around the world, could help take our understanding of the nucleus to a new level. </p>
<h2>Strong but strange force</h2>
<p>After the revelations of the 1950s, it <a href="https://www.science.org/doi/pdf/10.1126/science.256.5061.1287">soon became clear</a> that particles called quarks and gluons are the <a href="https://theconversation.com/explainer-what-are-fundamental-particles-38339">fundamental building blocks</a> of matter. They are the constituents of hadrons, which is the collective name for protons and other particles. Sometimes people imagine that these kinds of particles fit together like Lego, with quarks in a certain configuration making up protons, and then protons and neutrons coupling up to create a nucleus, and the nucleus attracting electrons to build an atom. But quarks and gluons are anything but static building blocks.</p>
<p>A theory called <a href="https://cerncourier.com/a/the-history-of-qcd/">quantum chromodynamics</a> describes how the strong force works between quarks, mediated by gluons, which are force carriers. Yet it cannot help us to analytically calculate the proton’s properties. This isn’t some fault of our theorists or computers — the equations themselves are simply not solvable. </p>
<p>This is why the experimental study of the proton and other hadrons is so crucial: to understand the proton and the force that binds it, one must study it from every angle. For this, the accelerator is our most powerful tool. </p>
<p>Yet when you look at the proton with a collider (a type of accelerator which uses two beams), what we see depends on how deep — and with what — we look: sometimes it appears as three constituent quarks, at other times as an ocean of gluons, or a teeming sea of pairs of quarks and their antiparticles (antiparticles are near identical to particles, but have the opposite charge or other quantum properties).</p>
<figure class="align-center ">
<img alt="Drawing of how an electron colliding with a charged atom can reveal its nuclear structure." src="https://images.theconversation.com/files/425745/original/file-20211011-15-d4amgd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/425745/original/file-20211011-15-d4amgd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/425745/original/file-20211011-15-d4amgd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/425745/original/file-20211011-15-d4amgd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/425745/original/file-20211011-15-d4amgd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=551&fit=crop&dpr=1 754w, https://images.theconversation.com/files/425745/original/file-20211011-15-d4amgd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=551&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/425745/original/file-20211011-15-d4amgd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=551&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">How an electron colliding with a charged atom can reveal its nuclear structure.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/brookhavenlab/49898747421/in/album-72157714316624996/">Brookhaven National Lab/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>So while our understanding of matter at this tiniest of scales has made great progress in the past 60 years, many mysteries remain which the tools of today cannot fully address. What is the nature of the confinement of quarks within a hadron? How does the mass of the proton arise from the almost massless quarks, 1,000 times lighter? </p>
<p>To answer such questions, we need a microscope that can image the structure of the proton and nucleus across the widest range of magnifications in exquisite detail, and build 3D images of their structure and dynamics. That’s exactly what the new collider will do.</p>
<h2>Experimental set up</h2>
<p>The Electron-Ion Collider (EIC) will use a very intense beam of electrons as its probe, with which it will be possible to slice the proton or nucleus open and look at the structure inside it. It will do that by colliding a beam of electrons with a beam of protons or ions (charged atoms) and look at how the electrons scatter. The ion beam is the first of its kind in the world.</p>
<p>Effects which are barely perceptible, such as scattering processes which are so rare you only observe them once in a billion collisions, will become visible. By studying these processes, myself and other scientists will be able to reveal the structure of protons and neutrons, how it is modified when they are bound by the strong force, and how new hadrons are created. We could also uncover what sort of matter is made up of pure gluons — something which has never been seen.</p>
<figure class="align-center ">
<img alt="Drawing of the experimental setup." src="https://images.theconversation.com/files/425744/original/file-20211011-16-p3n4ju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/425744/original/file-20211011-16-p3n4ju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/425744/original/file-20211011-16-p3n4ju.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/425744/original/file-20211011-16-p3n4ju.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/425744/original/file-20211011-16-p3n4ju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=512&fit=crop&dpr=1 754w, https://images.theconversation.com/files/425744/original/file-20211011-16-p3n4ju.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=512&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/425744/original/file-20211011-16-p3n4ju.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=512&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Experiment scheme.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/brookhavenlab/49898746221/in/album-72157714316624996/">Brookhaven National Lab/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>The collider will be tuneable to a wide range of energies: this is like turning the magnification dial on a microscope, the higher the energy, the deeper inside the proton or nucleus one can look and the finer the features one can resolve.</p>
<p>Newly formed collaborations of scientists across the world, which are part of the EIC team, are also designing detectors, which will be placed at two different collision points in the collider. Aspects of this effort are led by UK teams, which have just been awarded <a href="https://www.ukri.org/news/uk-to-lead-detector-development-for-powerful-particle-collider/">a grant</a> to lead the design of three key components of the detectors and develop the technologies needed to realise them: sensors for precision tracking of charged particles, sensors for the detection of electrons scattered extremely closely to the beam line and detectors to measure the polarisation (direction of spin) of the particles scattered in the collisions.</p>
<p>While it may take another ten years before the collider is fully designed and built, it is likely to be well worth the effort. Understanding the structure of the proton and, through it, the fundamental force that gives rise to over 99% of the visible mass in the universe, is one of the greatest challenges in physics today.</p><img src="https://counter.theconversation.com/content/169563/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daria Sokhan receives funding from UKRI, STFC, EU Commission, Ile-de-France region.
Daria Sokhan is currently on leave at CEA Saclay, France, where she holds the Blaise Pascal Chair.</span></em></p>The force of nature that holds the atomic nucleus together is poorly understood, but that may be about to change.Daria Sokhan, Blaise Pascal Chair, CEA Saclay, France / Senior Lecturer, School of Physics and Astronomy, University of GlasgowLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1593072021-04-22T15:51:44Z2021-04-22T15:51:44ZAntimatter: scientists find way to trap elusive material by blasting it with lasers<figure><img src="https://images.theconversation.com/files/396533/original/file-20210422-20-ujnwp3.jpeg?ixlib=rb-1.1.0&rect=105%2C2%2C1211%2C752&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cern scientists have successfully cooled antimatter with a laser for the first time.</span> <span class="attribution"><span class="source">Chukman So</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Antimatter is believed to play a huge part in the story of our universe. It’s the counterpart to matter: identical in every way – with protons, neutrons and electrons – but with an opposite electric charge. According to our best understanding of the <a href="https://www.newscientist.com/article/dn17111-how-dirac-predicted-antimatter/">laws of physics</a>, the universe of today should be equally populated by both matter and antimatter.</p>
<p>Yet, as far as we can tell, <a href="https://home.cern/science/physics/matter-antimatter-asymmetry-problem">it’s not</a>. Antimatter is elusive, and one of the major conundrums in modern physics is how we can explain a “<a href="https://www.symmetrymagazine.org/article/october-2005/explain-it-in-60-seconds">symmetrical</a>” universe of equal parts matter and antimatter when, after decades of searching, the universe appears to be almost entirely void of antimatter.</p>
<p>To try to unravel this cosmic mystery, physicists are studying <a href="https://theconversation.com/cern-discovery-sheds-light-on-the-great-mystery-of-why-the-universe-has-less-antimatter-than-matter-147226">various features</a> of antimatter. In particular, we’re interested in small differences between matter and antimatter that could explain the asymmetry we observe – in turn validating existing laws of physics.</p>
<p>But studying antimatter is incredibly difficult. It takes huge amounts of energy to create it, and even then it’s liable to disappear: annihilating itself when it comes into contact with the matter that surrounds us. </p>
<p><a href="https://www.nature.com/articles/s41586-021-03289-6">Research by</a> my colleagues at Cern and I has produced a way to create, trap and laser-cool antimatter for long enough for us to target a whole new set of more accurate measurements. Our experiments could be a significant step in solving the mystery of the missing antimatter in our universe.</p>
<h2>Making antimatter</h2>
<p>Just as matter is made up of atoms, antimatter is made up of antiatoms. The easiest antiatom to make is antihydrogen, <a href="https://home.cern/news/press-release/cern/first-atoms-antimatter-produced-cern">first created</a> by Cern in 1995 and <a href="https://theconversation.com/antimatter-measured-for-the-first-time-5782">first measured</a> in 2012. Consisting of just one antielectron (called a positron) orbiting around a one antiproton nucleus, antihydrogen (and hydrogen, its counterpart in matter) has the simplest atomic structure in the universe.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-is-antimatter-53414">Explainer: what is antimatter?</a>
</strong>
</em>
</p>
<hr>
<p>But making antihydrogen isn’t easy. The classical high-energy physics approach to the problem uses a particle collider – like the <a href="https://theconversation.com/explainer-how-does-an-experiment-at-the-large-hadron-collider-work-42846">LHC at Cern</a> – to convert enormous amounts of kinetic energy into a plethora of sub-atomic shrapnel for us to study.</p>
<p>Particle accelerators can be used to create antiprotons. To make a single usable antiproton, though, we need 1 million protons and at least 26 million times the energy that’s eventually “stored” in an antiproton. This makes each antiproton we make incredibly precious.</p>
<p>Once we’d created enough antiprotons, we needed antielectrons (positrons) in order to build our antiatoms. Happily, positrons can be quite easily gathered from a <a href="https://www.sciencedirect.com/topics/engineering/positron-emitting-radionuclides">radioactive source</a>. With our core ingredients collected, we just needed to combine them.</p>
<p>This we achieved by forcing the antiprotons and positrons into contact within an electromagnetic trap. Crucially, this had to happen in a vacuum, because if the antiparticles were to make contact with any parts of the apparatus – which was of course made of matter – they’d simply annihilate on contact, disappearing altogether. Only after all of these steps could we form usable antihydrogen atoms, pinned in a vacuum by a combination of magnetic fields. </p>
<figure class="align-center ">
<img alt="Four electrodes around a laser" src="https://images.theconversation.com/files/396572/original/file-20210422-13-va7eme.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/396572/original/file-20210422-13-va7eme.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=348&fit=crop&dpr=1 600w, https://images.theconversation.com/files/396572/original/file-20210422-13-va7eme.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=348&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/396572/original/file-20210422-13-va7eme.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=348&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/396572/original/file-20210422-13-va7eme.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=438&fit=crop&dpr=1 754w, https://images.theconversation.com/files/396572/original/file-20210422-13-va7eme.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=438&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/396572/original/file-20210422-13-va7eme.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=438&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This demonstration of our electromagnetic trap shows how the forces it creates can hold charged particles in space.</span>
<span class="attribution"><a class="source" href="https://alpha.web.cern.ch/gallery-images/paul-trap-action">Niels Madsen</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Measuring antihydrogen</h2>
<p>In this state, it’s possible to take measurements of the antihydrogen. What we’re looking to measure here is a key atomic transition between two energy states of the antihydrogen atom. This transition is particularly suitable for precise measurements, and the equivalent one in hydrogen has been measured with a staggering 15 decimal places of precision.</p>
<p>We took our antihydrogen measurement to 12 decimal places of precision. This is worse than the most precise measurement of ordinary hydrogen by a factor of 1,000, but it’s currently the best measure of antihydrogen anyone has done.</p>
<p>But one key limitation of our measurement is the movement of the antiatoms in the trap itself, due to their kinetic energy. By reducing this movement further, our measurements would be far more accurate. Our experiment achieved this, for the first time, by blasting the antiatoms with laser light.</p>
<figure class="align-center ">
<img alt="A man inserts a rod into a container of liquid hydrogen in a lab" src="https://images.theconversation.com/files/396574/original/file-20210422-20-1nlyyzd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/396574/original/file-20210422-20-1nlyyzd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/396574/original/file-20210422-20-1nlyyzd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/396574/original/file-20210422-20-1nlyyzd.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/396574/original/file-20210422-20-1nlyyzd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/396574/original/file-20210422-20-1nlyyzd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/396574/original/file-20210422-20-1nlyyzd.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Liquid helium helps cool antihydrogen in our trap – but lasers help reduce the temperature further.</span>
<span class="attribution"><a class="source" href="https://alpha.web.cern.ch/gallery-images/alpha-uk-work">Niels Madsen</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Laser cooling</h2>
<p>The light in a laser is made up of photons, which <a href="https://www.britannica.com/science/photon">carry a momentum</a> of their own. When an atom absorbs a photon, the atom’s velocity changes slightly. By following this basic principle, we knew we could use the momentum contained in our laser beam to reduce the kinetic energy of the trapped antiatoms – cooling them closer to absolute zero.</p>
<p>That required us to only hit the antiatoms with photons when they were moving towards the laser, as this would in effect cancel out some of the velocity of the antiatom: a bit like how you’d apply force to slow a child on a swing.</p>
<p>By using this targeted <a href="https://www.sciencedirect.com/topics/chemical-engineering/laser-cooling">laser-cooling</a>, we managed to reduce the temperature of our stored antihydrogen by a factor of ten, which has the potential to improve future measurement precision by a factor of four. </p>
<p>We’ve not yet made enough measurements to publish new, more precise data on antihydrogen – but that’s coming very soon. Beyond that, our laser-cooling technique has put us on a firm path towards higher precision in many measurements of both matter and antimatter, and takes us a step closer to making an even more precise measurement of hydrogen itself.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/cern-discovery-sheds-light-on-the-great-mystery-of-why-the-universe-has-less-antimatter-than-matter-147226">CERN: discovery sheds light on the great mystery of why the universe has less 'antimatter' than matter</a>
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</em>
</p>
<hr>
<p>Laser-cooling opens up exciting possibilities for measuring antihydrogen. Combined with existing techniques that allow us to accumulate relatively large amounts of antihydrogen (thousands of antiatoms per day) we will soon know even more about the nature of antihydrogen – and that extra knowledge could help us understand why matter is everywhere in our universe, while antimatter is so elusive.</p><img src="https://counter.theconversation.com/content/159307/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Niels Madsen receives (or has received) funding from the EPSRC, The Royal Society and the Leverhulm Trust. He is professor of experimental physics at Swansea University. </span></em></p>Laser-cooling enables new measurements that could explain why antimatter is so scarce in our universe.Niels Madsen, Professor of Physics, Swansea UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1554332021-02-18T17:31:37Z2021-02-18T17:31:37ZIt’s no Large Hadron Collider, but our new particle accelerator is the size of a large room<figure><img src="https://images.theconversation.com/files/385027/original/file-20210218-20-1451rd2.png?ixlib=rb-1.1.0&rect=7%2C0%2C1552%2C1031&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A prototype of our novel plasma-based particle accelerator</span> <span class="attribution"><span class="source">EuPRAXIA Conceptual Design Report</span></span></figcaption></figure><p>In 2010, when scientists were preparing to smash the first particles together within the Large Hadron Collider (LHC), sections of the media fantasised that the EU-wide experiment might <a href="https://www.forbes.com/sites/startswithabang/2016/03/11/could-the-lhc-make-an-earth-killing-black-hole/">create a black hole</a> that could swallow and destroy our planet. How on Earth, columnists fumed, could scientists justify such a dangerous indulgence in the pursuit of abstract, theoretical knowledge?</p>
<p>But particle accelerators are much more than enormous toys for scientists to play with. They have practical uses too, though their sheer size has, so far, prevented their widespread use. Now, as part of a large-scale European collaboration, my team has <a href="https://doi.org/10.1140/epjst/e2020-000127-8">published a report</a> that explains in detail how a far smaller particle accelerator could be built – closer to the size of a large room, rather than a large city. </p>
<p>Inspired by the technological and scientific know-how of machines like the LHC, our particle accelerator is designed to be as small as possible so it can be put to immediate practical use in industry, in healthcare and in universities.</p>
<h2>Collider scope</h2>
<p>The biggest collider in the world, the LHC, uses particle acceleration to achieve the astonishing speeds at which it collides particles. This system was used to measure the sought-after <a href="https://www.sciencedirect.com/science/article/pii/S037026931200857X">Higgs boson particle</a> – one of the most elusive particles predicted by the Standard Model, which is our current model to describe the structure and operation of the universe.</p>
<p>Less giant and glamorous particle accelerators have been around since the early 1930s, performing useful jobs as well as causing collisions to help our understanding of fundamental science. Accelerated particles are used to generate radioactive materials and strong bursts of radiation, which are crucial for healthcare processes such as radiotherapy, nuclear medicine and CT scans.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/five-ways-particle-accelerators-have-changed-the-world-without-a-higgs-boson-in-sight-54187">Five ways particle accelerators have changed the world (without a Higgs boson in sight)</a>
</strong>
</em>
</p>
<hr>
<p>The typical downside to accelerators is that they tend to be bulky, complex to run and often prohibitively expensive. The LHC represents a pinnacle of experimental physics, but it is 27 kilometres (17 miles) in circumference and cost <a href="https://home.cern/sites/home.web.cern.ch/files/2018-07/factsandfigures-en_0.pdf">6.5 billion Swiss francs (£5.2 billion)</a> to build and test. The accelerators currently installed in select hospitals are smaller and cheaper, but they still cost tens of millions of pounds, and require 400x400m of space for installation. As such, only large regional hospitals can afford the money and the space to host a radiotherapy department.</p>
<p>Why exactly do accelerators need to be so big? The simple answer is that if they were any smaller, they’d break. Since they’re based on solid materials, ramping up the power too much would tear the system apart, creating a very expensive mess.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/385016/original/file-20210218-12-19epl5i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large yellow circle drawn over an aerial view of fields" src="https://images.theconversation.com/files/385016/original/file-20210218-12-19epl5i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385016/original/file-20210218-12-19epl5i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385016/original/file-20210218-12-19epl5i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385016/original/file-20210218-12-19epl5i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385016/original/file-20210218-12-19epl5i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385016/original/file-20210218-12-19epl5i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385016/original/file-20210218-12-19epl5i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Large Hadron Collider is a vast looped system on the France-Switzerland border.</span>
<span class="attribution"><span class="source">Cern</span></span>
</figcaption>
</figure>
<h2>Need for speed</h2>
<p>We set out to find a way to make smaller, cheaper particle accelerators for use in a wider range of hospitals – from the large and regional to the small and provincial.</p>
<p>Our team worked on the premise that to accelerate particles you actually have two options: either give them a strong boost over a short distance, or lots of small nudges over a long one – which is how the LHC works.</p>
<p>It’s a bit like reaching 100mph in a vehicle: you can either slowly accelerate in a truck over a long period of time, or you can put your foot down in a sports car and get there in a matter of seconds. Conventional accelerators are a bit like trucks: reliable and docile, but slow. We’ve been searching for the sports car alternative.</p>
<p>We found that alternative in plasma. The beauty of plasma is that it’s just composed of an ionised gas: a gas that’s been broken down to its tiniest components. As such, it doesn’t have the same limit on the power that can be applied to it as a solid system. In effect, you can’t break something that is already broken.</p>
<figure class="align-center ">
<img alt="A man holds a clear component in front of his eye. Behind him is a large yellow pipe" src="https://images.theconversation.com/files/385020/original/file-20210218-28-aii8mb.png?ixlib=rb-1.1.0&rect=8%2C5%2C1830%2C1196&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385020/original/file-20210218-28-aii8mb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=393&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385020/original/file-20210218-28-aii8mb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=393&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385020/original/file-20210218-28-aii8mb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=393&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385020/original/file-20210218-28-aii8mb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=494&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385020/original/file-20210218-28-aii8mb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=494&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385020/original/file-20210218-28-aii8mb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=494&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A researcher holding a section of our novel particle accelerator. Behind is the corresponding section in a traditional accelerator.</span>
<span class="attribution"><span class="source">EuPRAXIA Conceptual Design Report</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>It’s in this sense that plasmas can sustain much higher accelerating powers – up to a thousand times larger than a solid-state accelerator. The higher the power, the shorter time and distance it takes to accelerate particles, and this leads to smaller, cheaper accelerators. </p>
<p>Our accelerator uses powerful lasers to “shake” the plasmas it contains, moving their particles about in a way that creates waves. It’s a little like the wake left behind by a boat (the laser) on a lake (the plasma). Like a surfer, a beam placed on one of these waves can then be pushed forward by it, constantly accelerating. These waves within plasmas are very small (sub-millimetre) and very powerful, which is what allows the overall accelerator to be extremely small.</p>
<h2>Plasma perks</h2>
<p>Plasma-based particle accelerators like ours will need 100 times less space than existing designs, reducing the space required for installation from 400x400m to just 40x40m. The hardware needed to build our accelerator is cheaper to install, run and maintain. Overall, we expect our plasma accelerator to reduce the cost of installing an accelerator in a hospital by a factor of ten.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/385089/original/file-20210218-28-1ia04lk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Four different scanned images of a mouse" src="https://images.theconversation.com/files/385089/original/file-20210218-28-1ia04lk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/385089/original/file-20210218-28-1ia04lk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=909&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385089/original/file-20210218-28-1ia04lk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=909&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385089/original/file-20210218-28-1ia04lk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=909&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385089/original/file-20210218-28-1ia04lk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1142&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385089/original/file-20210218-28-1ia04lk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1142&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385089/original/file-20210218-28-1ia04lk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1142&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A mouse embryo scanned with our machine (left column) and traditional scans (right column).</span>
</figcaption>
</figure>
<p>Besides these two advantages, our accelerator can perform certain new functions that existing accelerators cannot. For instance, plasma-based accelerators can provide <a href="https://www.youtube.com/watch?v=a8ueGqLPy1I">detailed X-rays of biological samples</a> with <a href="https://www.pnas.org/content/115/25/6335/tab-figures-data">far greater clarity</a> than those that exist today. By providing a better image of the inside of a human body, this could help doctors find cancer at a much earlier stage, dramatically increasing the chance of successfully treating the illness. </p>
<p>The same ultra-high resolution imaging can also help spot the early signs of cracks and defects on machinery, at nanometer scale. Faults related to such defects are regarded as one of the “six big losses” well known to manufacturers. Their early detection by our accelerator could help extend the lifetime of high-precision, high-quality components in heavy industry and manufacturing.</p>
<h2>Accelerator rollout</h2>
<p>The European Strategy Forum on Research Infrastructures is assessing the design report, with a decision expected in summer 2021. If successful, construction of the first two prototypes is expected to be completed by 2030, with access to external users to be granted immediately after.</p>
<p>Several years of interdisciplinary research were needed for us to form the first detailed and realistic design of a machine of this kind. Our plasma accelerator is the most recent example of how obscure, abstract, fundamental physics can enter into our everyday lives – cutting research costs, improving manufacturing and helping to save lives.</p>
<p><em>This article was updated on February 23 2021 to clarify that the EuPRAXIA particle accelerator is designed to perform a different set of tasks than those performed by the Large Hadron Collider.</em></p><img src="https://counter.theconversation.com/content/155433/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gianluca Sarri receives funding from the Engineering and Physical Sciences Research Council (EPSRC) and the Science and Technology Facility Council (STFC). </span></em></p>The compact accelerators are 100 times smaller than traditional ones, and could easily fit inside hospitals and laboratories.Gianluca Sarri, Reader (Associate Professor) at the School of Mathematics and Physics, Queen's University BelfastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1314152020-02-11T17:58:12Z2020-02-11T17:58:12ZHow a ‘muon accelerator’ could unravel some of the universe’s greatest mysteries<figure><img src="https://images.theconversation.com/files/314757/original/file-20200211-146674-fyj6w5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The supernova remnant Cassiopeia A.</span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure><p>The fact that we are here at all is one of the greatest puzzles of physics. We are made from normal particles such as electrons, but every such particle also has an antimatter companion that is virtually identical to itself, but with the opposite charge. When matter and antimatter come into contact, they annihilate each other in a flash of light.</p>
<p>Physics suggests that matter and antimatter <a href="https://theconversation.com/cern-study-sheds-light-on-one-of-physics-biggest-mysteries-why-theres-more-matter-than-antimatter-113947">were created in almost equal quantities</a> in the Big Bang. So how come there’s almost only matter left today – why didn’t the matter and antimatter annihilate each other to render the universe lifeless? Our new research has enabled scientists <a href="http://www.natureasia.com/en/research/highlight/13209">to build a new type of accelerator</a>, based on particles called muons, that could help us find out.</p>
<p>A muon <a href="https://theconversation.com/explainer-what-are-fundamental-particles-38339">is almost identical</a> to an electron, except that it is 207 times heavier. What’s more, it decays into other particles in two millionths of a second. This lifetime, although short for us, is quite a long time for an unstable fundamental particle, and this explains why muons make up almost all the charged cosmic rays which reach the Earth’s surface.</p>
<p>Much of our ability to investigate the structure of matter at the shortest distances depends on creating beams of particles and accelerate them to high energies. However there are only four stable particles which can be used in this way, the electron and its anti-particle (positron), and the proton and its antiparticle (antiproton).</p>
<p>Particle beams consisting of those have been used for many years, yet both of these pairs have drawbacks. The electron and its partner are very light – when we try to accelerate them, they radiate electromagnetic energy. This is can be useful for applications such as TV but makes it hard to reach the sort of energies which we need to improve our understanding of the universe. </p>
<p>Unlike electrons, the proton and the anti-proton are made up of more fundamental particles – quarks and gluons. In a collision between a proton and anti-proton it is these fundamental particles which actually collide, resulting in a lower energy crash than you would have got if protons had been truly fundamental particles.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/314754/original/file-20200211-146686-rytr8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/314754/original/file-20200211-146686-rytr8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/314754/original/file-20200211-146686-rytr8t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/314754/original/file-20200211-146686-rytr8t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/314754/original/file-20200211-146686-rytr8t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=557&fit=crop&dpr=1 754w, https://images.theconversation.com/files/314754/original/file-20200211-146686-rytr8t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=557&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/314754/original/file-20200211-146686-rytr8t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=557&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Each particle also has an antiparticle, not included here.</span>
<span class="attribution"><a class="source" href="https://www.publicdomainpictures.net/en/view-image.php?image=35144&picture=fundamental-particles">Publicdomainpictures.net</a></span>
</figcaption>
</figure>
<p>The muons are heavy enough that they radiate much less energy,
but fundamental (not made up of smaller particles) so that all their energy is available for the investigation. When scientists created the <a href="https://theconversation.com/could-the-higgs-nobel-be-the-end-of-particle-physics-18978">Nobel-prize winning Higgs particle</a> with protons, they needed a machine 10km in diameter: the <a href="https://theconversation.com/explainer-how-does-an-experiment-at-the-large-hadron-collider-work-42846">Large Hadron Collider</a>. A muon machine, however, could achieve this with a circumference of just 200 metres.</p>
<p>The disadvantage of muons is that, unlike electrons and protons, they are unstable and need to be produced and then rapidly used before they all decay. We can produce muons by taking a narrow, high-intensity beam of protons and running it into a target made of a metal, such as titanium. This produces a beam of another fundamental particle called the pion. </p>
<p><a href="http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html">Pions</a> form a beam which fans out. If the original proton beam looks like a laser pointer, the pion beam looks more like a torch beam – with intensity dropping rapidly with distance. The pions then decay to produce the muons, meaning the beam spreads even more – resembling a light bulb. </p>
<p>We cannot accelerate such a beam in a machine like the LHC, so we need to create a beam which spreads out much less. This is challenging given that we have only have two millionths of a second to produce, accelerate and collide it.</p>
<p>But our team of physicists and engineers, from around the world – known as the <a href="http://mice.iit.edu/">Muon Ionisation Cooling Experiment</a> (MICE) – has now shown that it is possible. We used a process known as cooling to help compress the beam. This involves passing the muons through a container with liquid hydrogen at -250°C, slowing the particles down. We then passed them through an electromagnetic cavity, which caused the beam to accelerate in the required direction.</p>
<p>By repeating this several times it is possible to create a beam which spreads out much less and has a dense core. This beam can be injected into a particle accelerator to produce a high-energy muon beam. Such a beam can either be collided or left to circulate until the muons decay into an intense beam of neutrinos – far in excess of any neutrino beam which can currently be produced. </p>
<h2>Probing the universe</h2>
<p>In fact, a neutrino beam created from muons is part of a planned <a href="https://stfc.ukri.org/research/accelerator-science/neutrino-factory/">Neutrino Factory</a>, which would allow us to answer many questions related to the origin and evolution of the universe – such as the mysterious imbalance between matter and antimatter. </p>
<p>Neutrinos could also help us understand the details of how life-essential elements such as oxygen, carbon and silicon, which are formed in stars, spread across universe. These heavier elements were not produced in the Big Bang and yet are responsible for the planet we live on and all the life around us. We know that bursts of neutrinos, which are released in star explosions (supernovas), are responsible. </p>
<p>We could also collide two beams of muons in the same way as we collide protons at the LHC. The muons, being simpler than the protons, would allow for more precise determination of the properties of the Higgs particle, for example.</p>
<p>The properties of the muon also makes it an invaluable tool in the field of material physics. The ability to create more closely focused beams may improve the current measurements and open up new diagnostic methods.</p>
<p>Our method may also be used to help increase the intensity of any other charged particle beams. It has been a long project lasting over a dozen years, but it has been worth the effort when we consider what a powerful tool we have created.</p><img src="https://counter.theconversation.com/content/131415/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Kyberd receives funding from STFC.</span></em></p>When scientists created the Higgs particle with protons, they needed the 10km-wide Large Hadron Collider. A muon machine could achieve it with a diameter of just 200 metres.Paul Kyberd, Senior Lecturer in Particle Physics Informatics, Brunel University LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1288222019-12-18T12:20:35Z2019-12-18T12:20:35ZStar Wars: from The Force to R2D2, does the science hold up?<figure><img src="https://images.theconversation.com/files/306971/original/file-20191215-85417-1exvdqs.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C5152%2C3422&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Nope, it's not controlled by The Force.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p><a href="https://www.imdb.com/title/tt2527338/">Star Wars: The Rise Of Skywalker</a>, the final film in the epic <a href="https://theconversation.com/star-wars-a-new-hope-for-franchise-longevity-51775">Star Wars series</a>, will hit the big screens on December 19. Science fiction in general – and Star Wars in particular – is a hugely popular genre, much because of the titillating possibility that the mind-blowing technology we see on screen could one day work.</p>
<p>But what is science and what is fiction in Star Wars? Could the technology be ahead of actual science?</p>
<h2>The Force(s)</h2>
<p>The Force is at the heart of the Star Wars universe. It “gives the Jedi his powers. It’s an energy field created by all living things. It surrounds us, it penetrates us, it binds the galaxy together” as Obi Wan Kenobi <a href="https://en.wikiquote.org/wiki/The_Force">once explained</a> to Luke Skywalker. But is there any science to back this up?</p>
<p>Our current understanding is that there are <a href="https://www.space.com/four-fundamental-forces.html">four fundamental forces</a> in the universe: the electromagnetic force, the gravitational force and two different forces that control the atomic nucleus and its particles. </p>
<p>But you need different theories of physics to describe these forces. Quantum mechanics, which explains the nuclear forces, is <a href="https://theconversation.com/will-we-have-to-rewrite-einsteins-theory-of-general-relativity-50057">notoriously incompatible</a> with general relativity, which describes gravity. It is the holy grail of physics to try to <a href="https://theconversation.com/stephen-hawking-had-pinned-his-hopes-on-m-theory-to-fully-explain-the-universe-heres-what-it-is-93440">combine these theories</a> and unify all the forces into one “The Force”.</p>
<p>Science does however support the idea of an <a href="https://theconversation.com/what-is-nothing-martin-rees-qanda-101498">energy field that “surrounds everything”</a>. In fact, if you take out all the stuff in the universe – the galaxies, planets and people – you are left with an exotic kind of energy in empty space itself. Curiously, this kind of energy of nothingness can actually give rise to forces, as implied in Star Wars. That said, its effect is tiny and it certainly can’t give anyone special powers.</p>
<p>To explore the forces of the universe, physicists use accelerators to create and study particles associated with forces that – in some cases – have not been produced since the Big Bang itself. One example was the <a href="https://theconversation.com/could-the-higgs-nobel-be-the-end-of-particle-physics-18978">Higgs Boson</a> that was discovered in 2012 by the Large Hadron Collider (LHC) at CERN in Switzerland. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/306972/original/file-20191215-85417-10k6ufx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306972/original/file-20191215-85417-10k6ufx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306972/original/file-20191215-85417-10k6ufx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306972/original/file-20191215-85417-10k6ufx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306972/original/file-20191215-85417-10k6ufx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306972/original/file-20191215-85417-10k6ufx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306972/original/file-20191215-85417-10k6ufx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A lot of science in Star Wars doesn’t hold up.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The LHC is world’s largest and highest energy accelerator and will soon <a href="https://theconversation.com/how-an-army-of-engineers-battles-contamination-and-sleep-deprivation-to-take-hadron-collider-to-new-heights-67073">receive an upgrade</a>, further increasing its discovery potential.</p>
<h2>Light sabres</h2>
<p>Light sabres are one of the most famous weapon in film history. They are used by the Jedi and Sith and require knowledge of the Force so they can be controlled. Unfortunately, a real-world light sabre cannot currently be manufactured. One problem is that there is no way to make light emanate from a source and stop after only a metre – light will go on to infinity unless it hits something. Also, two intense light beams would cross each other.</p>
<p>However, the name “light sabre” could be misleading. There is a way to make something similar to this awesome weapon using plasma – a fourth state of matter consisting of highly charged particles. The blade could be made of plasma and be confined with an electromagnetic magnetic field. Theoretically, such a plasma sabre <a href="https://theconversation.com/how-to-build-a-real-lightsaber-51000">should be able to do many of the things</a> the light sabres in Star Wars do. They <a href="https://theconversation.com/why-lightsabers-would-be-far-more-lethal-than-george-lucas-envisioned-55726">may be more deadly</a> though.</p>
<p>We are still far from having such a technology available though. One much less glamorous use of plasmas is to <a href="https://www.open.edu/openlearn/science-maths-technology/engineering-technology/manupedia/plasma-arc-welding">melt and weld metal</a>. There are more exciting innovations using high-energy plasmas in the works though. For example, plasmas are now used to propel charged particles to high velocities over extremely short distances. This is helping scientists to design and build ever more compact particle accelerators, potentially up to 1,000 times smaller – and considerably less expensive – than current radiofrequency-based accelerators such as the LHC. </p>
<p>In this approach, a high intensity laser or particle beam is directed through a plasma medium. This creates a wake in the plasma, very much like the wake created by a boat running at speed along a river or lake. This allows the creation of a strong electric field which can be used for accelerating a beam of charged particles that is injected into this wake at the right time.</p>
<p>The hope is that plasma accelerators will pave the way for compact facilities being used for anything from imaging ultra-fast phenomena to testing innovative materials for industry.</p>
<h2>Proton torpedoes</h2>
<p>In the very first Star Wars movie, Luke Skywalker uses “<a href="https://starwars.fandom.com/wiki/Proton_torpedo/Legends">proton torpedoes</a>” to destroy the Death Star – the giant space station that obliterates planets. According to the Star Wars canon, these are a type of explosive warhead which releases clouds of high-energy proton particles (protons make up the atomic nucleus with neutrons). In Star Wars, these weapons are exceptionally manoeuvrable so they can be used against a variety of targets. This isn’t the case for actual torpedoes though.</p>
<p>More than 40 years on, protons are instead used in a different kind of war – that against cancer. Proton beams <a href="https://theconversation.com/explainer-what-is-proton-therapy-16100">can penetrate tissue</a> for a specific distance determined by their energy. They can deposit most of this energy at a specific location, destroying a target tumour but sparing healthy tissue. This is becoming a rapidly developing method of cancer treatment. </p>
<p>To further improve the technology, particle accelerator and clinical experts have been exploring ways to better control proton beams through online beam monitoring. Among others, instruments originally developed for the LHC are used to measure the detailed properties of the treatment beam without touching it. This helps target tumours with more precision and also helps reduce machine set-up times, allowing the treatment of more patients.</p>
<h2>Droids</h2>
<p>While we cannot currently build droids such as R2D2 or C3PO, research into Big Data Science, machine learning and artificial intelligence brings these technologies ever closer. So far, AI can already sort things, <a href="https://theconversation.com/an-ai-taught-itself-to-play-a-video-game-for-the-first-time-its-beating-humans-118028">play games</a>, <a href="https://theconversation.com/breast-cancer-diagnosis-by-ai-now-as-good-as-human-experts-115487">diagnose disease</a> and <a href="https://theconversation.com/how-an-ai-trained-to-read-scientific-papers-could-predict-future-discoveries-122353">predict scientific discoveries</a>. But it is still <a href="https://theconversation.com/worried-about-ai-taking-over-the-world-you-may-be-making-some-rather-unscientific-assumptions-103561">a long way</a> from being able from developing general intelligence – and it is <a href="https://theconversation.com/ai-theres-a-reason-its-so-bad-at-conversation-103249">notoriously bad at conversation</a>.</p>
<p>As the voiceover of Luke Skywalker says in the latest film trailer: “We’ve passed on all we know.” And that’s exactly what I and other researchers are trying to do. So let’s hope this article can inspire some readers who dream about what science could achieve in the next 40 years to become the next generation of scientists.</p><img src="https://counter.theconversation.com/content/128822/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Carsten Welsch receives funding from STFC and the European Union. He works for the University of Liverpool/Cockcroft Institute of Accelerator Science and Technology.</span></em></p>There are many forces in nature, but they may one day be united into The Force.Carsten Welsch, Professor of Physics, University of LiverpoolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1222302019-08-23T10:37:26Z2019-08-23T10:37:26ZGhost particles: how galaxies helped us weigh the lightest neutrino – and why it matters<figure><img src="https://images.theconversation.com/files/289201/original/file-20190823-170931-99idv2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Crab Nebula is a remnant of a supernova, a source of neutrinos.</span> <span class="attribution"><span class="source">NASA, ESA, J. Hester and A. Loll (Arizona State University)</span></span></figcaption></figure><p>Even when you close your eyes at night, 100 billion neutrinos produced in the sun will pass through them – <a href="https://theconversation.com/benefits-of-knowing-more-about-neutrinos-which-pass-through-our-bodies-unnoticed-49025">travelling close to the speed of light, but never hitting anything</a>. Neutrinos are extremely elusive and only weakly interact with matter around them: nature’s true ghosts. Until very recently, these tiny particles were believed to be massless.</p>
<p>In the late 1990s, <a href="https://theconversation.com/how-the-neutrino-could-solve-great-cosmic-mysteries-and-win-its-next-nobel-prize-48789">researchers demonstrated</a> that neutrinos constantly change between three different types (flavours or species), which affects how they interact with matter. This is something they can only do if they have mass – a discovery that was <a href="https://theconversation.com/physics-duo-wins-the-nobel-prize-for-solving-longstanding-neutrino-puzzle-48702">granted the Nobel Prize in 2015</a>. From these particle physics experiments, we know that at least two of the three neutrino species have mass. </p>
<p>Yet little has been known about the mass of the lightest species – until now. Our new study, <a href="https://www.ucl.ac.uk/news/2019/aug/maximum-mass-lightest-neutrino-revealed-using-astronomical-big-data">published in Physical Review Letters</a>, shows that the lightest neutrino is at least 6m times lighter than the mass of an electron, at 0.086 electron volts (a unit of energy). Our technique may give exact masses for each neutrino in the future.</p>
<p>Neutrinos are peculiar. Thanks to the <a href="https://theconversation.com/physicists-prove-quantum-spookiness-and-start-chasing-schrodingers-cat-48190">strange rules of quantum mechanics</a>, the relationships between the flavours and their masses are complicated. In any beam of neutrinos, the three masses are always present but in different ratios. Each flavour of neutrino has a combination of the three masses and each neutrino mass has a combination of the three flavours.</p>
<h2>Massive significance</h2>
<p>Neutrinos matter to understanding space. Back to the 1940s, <a href="https://journals.aps.org/pr/pdf/10.1103/PhysRev.58.1117">a letter to Physical Review</a> by physicists <a href="https://cosmosmagazine.com/space/this-week-in-science-history-big-bang-theorist-george-gamow-dies">George Gamow</a> and <a href="https://en.wikipedia.org/wiki/M%C3%A1rio_Schenberg">Mario Schoenberg</a> (a personal hero of mine) suggested that neutrinos played a major role in stellar evolution and supernovas (exploding stars). This <a href="https://www.nasa.gov/feature/goddard/2017/the-dawn-of-a-new-era-for-supernova-1987a/">was confirmed</a> when scientists detected the first neutrinos from a supernova in 1987, providing a better understanding of supernovas and neutrinos alike.</p>
<p>On a cosmological scale, however, because these ghostly particles have mass, they tend to drag a little bit of matter with them thanks to gravity. And so the more massive the neutrinos are, the “fuzzier” the distribution of galaxies around us will be. This means that by observing galaxies around us, we can infer the mass of neutrinos. It is amazing to think that the largest structures of galaxies in the universe are sensitive to the tiniest particles known by physics. </p>
<p>The reason scientists are so keen to find out their mass, is that it matters to our ultimate understanding of reality. <a href="https://theconversation.com/the-standard-model-of-particle-physics-the-absolutely-amazing-theory-of-almost-everything-94700">The Standard Model of Particle Physics</a> is one of the most precise theories of fundamental particles that we have so far. However, this theory predicts that neutrinos should be massless.</p>
<p>Understanding neutrino masses is a key point to move ahead towards a new and improved theory of particle physics. It is quite possible that by doing so, other mysteries in physics, which also cannot be explained by the standard model, such as the nature of <a href="https://theconversation.com/the-experiments-trying-to-crack-physics-biggest-question-what-is-dark-energy-52917">dark energy</a> and <a href="https://theconversation.com/from-machos-to-wimps-meet-the-top-five-candidates-for-dark-matter-51516">dark matter</a>, would also be solved.</p>
<h2>Two camps</h2>
<p>The way we made our discovery matters, too. Our international team of researchers from the UK and Brazil combined cosmological data and particle physics experiments.</p>
<p>Each approach has its limitations. When cosmologists determine neutrino masses from observations of galaxy distributions, they can only determine a maximum mass for the sum of the three neutrinos. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/289196/original/file-20190823-170906-1wxxyui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289196/original/file-20190823-170906-1wxxyui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=415&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289196/original/file-20190823-170906-1wxxyui.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=415&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289196/original/file-20190823-170906-1wxxyui.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=415&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289196/original/file-20190823-170906-1wxxyui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=522&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289196/original/file-20190823-170906-1wxxyui.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=522&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289196/original/file-20190823-170906-1wxxyui.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=522&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hercules galaxy cluster.</span>
<span class="attribution"><span class="source">ESO/INAF-VST/OmegaCAM</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Particle physics experiments can directly study neutrinos, for example by <a href="https://www.symmetrymagazine.org/article/november-2012/how-to-make-a-neutrino-beam">creating a beam</a> of them in the lab or detecting neutrinos from space underground. But most of them are based on detecting how neutrino flavours mix. This doesn’t tell you the absolute mass for each particle, but only <a href="https://www.sciencedirect.com/science/article/pii/S0550321316000602?via%3Dihub">the difference in mass</a> for two out of three neutrino species. It also doesn’t tell us which of the two is the heaviest neutrino.</p>
<p>Sadly, many cosmologists often ignore results from particle physics. And some particle physicists are sceptical of cosmologists’ statistical techniques, claiming their way of using prior knowledge, such as estimating that the mass cannot be negative, influences their results.</p>
<p>We combined the two by creating a mathematical model to calculate the sum of the neutrino masses by studying the large scale structure of more than a million galaxies from the <a href="http://www.sdss3.org/surveys/boss.php">Baryon Oscillation Spectroscopic Survey (BOSS)</a>. We also had to include many other parameters that affect galaxy distribution such as dark matter and dark energy. We then fed in what we know from particle physics experiments, which told us in very exact terms what the relationships between the masses of the neutrinos should be. This allowed us to calculate an upper limit of the mass of the lightest particle.</p>
<p>In order to achieve these results, we had to push the boundaries of big data analysis in cosmology to their limits, using more than half a million computing hours to process the data. Luckily, we had a <a href="https://www.ucl.ac.uk/research-it-services/grace-launch">super computer</a> to help us. </p>
<p>Although current available data is not powerful enough to detect a lower-bound for the mass of the lightest neutrino – it could still be massless– this work demonstrates that applying a combined methodology is the way forward. </p>
<p><a href="https://www.desi.lbl.gov">The Dark Energy Spectroscopic Instrument (DESI)</a>, which will analyse ten times more galaxies than we had access to, will give a much more reliable estimate of the total mass for all the neutrinos – and that may make it possible to work out a minimum mass. Excitingly, this might just launch a new era in neutrino physics.</p><img src="https://counter.theconversation.com/content/122230/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arthur Loureiro received funding from the National Council for Science and Technology (CNPq), Brazil.</span></em></p>If we want an improved theory of particle physics, understanding neutrino masses is key.Arthur Loureiro, Research Assistant in Cosmology and Astroparticle Physics, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1023312018-09-07T17:50:42Z2018-09-07T17:50:42ZTen years of Large Hadron Collider discoveries are just the start of decoding the universe<figure><img src="https://images.theconversation.com/files/235276/original/file-20180906-190642-1uweigo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The activity during a high-energy collision at the CMS control room of the European Organization for Nuclear Research, CERN, at their headquarters outside Geneva, Switzerland. </span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Switzerland-Retooled-Collider/7d495c0dc5a54744b645c260a1017822/9/0">AP Photo</a></span></figcaption></figure><p>Ten years! Ten years since the start of operations for <a href="https://home.cern/topics/large-hadron-collider">the Large Hadron Collider (LHC)</a>, one of the most complex machines ever created. The LHC is the world’s largest particle accelerator, buried 100 meters under the French and Swiss countryside with a 17-mile circumference.</p>
<p>On Sept. 10, 2008, protons, the center of a hydrogen atom, were circulated around the LHC accelerator for the first time. However, the excitement was short-lived because on Sept. 22 an incident occurred that damaged more than 50 of the LHC’s more than 6,000 magnets – which are critical for keeping the protons traveling on their circular path. Repairs took more than a year, but in March 2010 the LHC began colliding protons. The LHC is the crown jewel of <a href="https://home.cern">CERN, the European particle physics laboratory</a> that was founded after World War II as a way to reunite and rebuild science in war-torn Europe. Now <a href="https://voisins.cern/en/cern">scientists from six continents and 100 countries</a> conduct experiments there.</p>
<p>You might be wondering what the LHC does and why it is a big deal. Great questions. The LHC collides two beams of protons together at the highest energies ever achieved in a laboratory. Six experiments located around the 17-mile ring study the results of these collisions with massive detectors built in underground caverns. That’s the what, but why? The goal is to understand the nature of the most basic building blocks of universe and how they interact with each other. This is fundamental science at its most basic.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/235269/original/file-20180906-190647-fzqzvs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/235269/original/file-20180906-190647-fzqzvs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/235269/original/file-20180906-190647-fzqzvs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/235269/original/file-20180906-190647-fzqzvs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/235269/original/file-20180906-190647-fzqzvs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/235269/original/file-20180906-190647-fzqzvs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/235269/original/file-20180906-190647-fzqzvs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">View of the LHC in its tunnel at CERN (European particle physics laboratory) near Geneva, Switzerland. The LHC is a 27-kilometer-long underground ring of superconducting magnets housed in this pipe-like structure, or cryostat. The cryostat is cooled by liquid helium to keep it at an operating temperature just above absolute zero. It will accelerate two counterrotating beam of protons to an energy of 7 tera-electron volts (TeV) and then bring them to collide head-on. Several detectors are being built around the LHC to detect the various particles produced by the collision.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/SWITZERLAND-CERN-LHC-CRYOGENIC-SYSTEM/b3aef1c7c68a4092a95939b1ca9d36ec/139/0">Martial Trezzini/KEYSTONE/AP Photo</a></span>
</figcaption>
</figure>
<p>The LHC has not disappointed. One of the discoveries made with the LHC includes <a href="https://home.cern/topics/higgs-boson">the long sought-after Higgs boson</a>, predicted in 1964 by scientists working to combine theories of two of the fundamental forces of nature.</p>
<p>I work on one of the six LHC experiments – the <a href="https://cms.cern">Compact Muon Solenoid experiment</a> designed to <a href="https://doi.org/10.1088/0954-3899/34/6/S01">discover the Higgs boson and search for signs of previously unknown particles or forces</a>. My institution, <a href="http://www.fsu.edu">Florida State University</a>, joined the Compact Muon Solenoid collaboration in 1994 when I was a young graduate student at another school working on a different experiment at a different laboratory. Planning for the LHC dates back to 1984. The LHC was hard to build and expensive – 10 billion euros – and took 24 years to come to fruition. Now we are celebrating 10 years since the LHC began operating. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/235273/original/file-20180906-190659-o99p2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/235273/original/file-20180906-190659-o99p2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/235273/original/file-20180906-190659-o99p2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=849&fit=crop&dpr=1 600w, https://images.theconversation.com/files/235273/original/file-20180906-190659-o99p2y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=849&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/235273/original/file-20180906-190659-o99p2y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=849&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/235273/original/file-20180906-190659-o99p2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1067&fit=crop&dpr=1 754w, https://images.theconversation.com/files/235273/original/file-20180906-190659-o99p2y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1067&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/235273/original/file-20180906-190659-o99p2y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1067&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A view of the Compact Muon Solenoid detector at the European Organization for Nuclear Research (CERN)‘s Large Hadron Collider (LHC) particle accelerator. The core of the Compact Muon Solenoid is the world’s largest superconducting solenoid magnet.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Doomsday-Collider-/628e4c09cab04dafa48ef7d0e870d339/156/0">Martial Trezzini/KEYSTONE/AP Photo</a></span>
</figcaption>
</figure>
<h2>Discoveries from the LHC</h2>
<p>The most significant discovery to come from the LHC so far is <a href="https://doi.org/10.1016/j.physletb.2012.08.021">the discovery of the Higgs boson</a> on July 4, 2012. The announcement was made at CERN and <a href="http://www.fnal.gov/pub/today/Higgs_Media_Highlights/">captivated a worldwide audience</a>. In fact, my wife and I watched it via webcast on our big screen TV in our living room. Since the announcement was at 3 a.m. Florida time, we went for pancakes at IHOP to celebrate afterwards.</p>
<p>The Higgs boson was the last remaining piece of what we call <a href="https://doi.org/10.1103/RevModPhys.71.S96">the standard model of particle physics</a>. This theory covers all of the known fundamental particles – 17 of them – and three of the four forces through which they interact, although gravity is not yet included. The standard model is an incredibly well-tested theory. Two of the six scientists who developed the part of the standard model that predicts the Higgs boson <a href="https://www.nobelprize.org/prizes/physics/2013/summary/">won the Nobel Prize in 2013</a>.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/235262/original/file-20180906-190659-1kijrb0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/235262/original/file-20180906-190659-1kijrb0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/235262/original/file-20180906-190659-1kijrb0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=682&fit=crop&dpr=1 600w, https://images.theconversation.com/files/235262/original/file-20180906-190659-1kijrb0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=682&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/235262/original/file-20180906-190659-1kijrb0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=682&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/235262/original/file-20180906-190659-1kijrb0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=857&fit=crop&dpr=1 754w, https://images.theconversation.com/files/235262/original/file-20180906-190659-1kijrb0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=857&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/235262/original/file-20180906-190659-1kijrb0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=857&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Higgs boson, sometimes refered to as the ‘God particle,’ was first seen during by experiments at the Large Hadron Collider.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/higgs-boson-what-god-particle-part-171639761?src=gOrKO--a6FdCpbVa-e2fTg-1-27">Designua/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>I am often asked, why do we continue to run experiments, smashing together protons, if we’ve already discovered the Higgs boson? Aren’t we done? Well, there is still lots to be understood. There are a number of questions that the standard model does not answer. For example, studies of galaxies and other large-scale structures in the universe indicate that there is a lot more matter out there than we observe. We call this dark matter since we can’t see it. The most common explanation to date is that <a href="https://doi.org/10.1146/annurev-astro-082708-101659">dark matter is made of an unknown particle</a>. Physicists hope that the LHC may be able to produce this mystery particle and study it. That would be an amazing discovery.</p>
<p>Just last week, the ATLAS and Compact Muon Solenoid collaborations announced <a href="https://arxiv.org/abs/1808.08242">the first observation of the Higgs boson decaying, or breaking apart, into bottom quarks</a>. The Higgs boson decays in many different ways – some rare, some common. The standard model makes predictions about how often each type of decay happens. To fully test the model, we need to observe all of the predicted decays. Our recent observation is in agreement with the standard model – another success.</p>
<h2>More questions, more answers to come</h2>
<p>There are lots of other puzzles in the universe and we may require new theories of physics to explain such phenomena – such as <a href="https://doi.org/10.1103/RevModPhys.76.1">matter/anti-matter asymmetry</a> to explain why the universe has more matter than anti-matter, or the <a href="http://dx.doi.org/10.1590/S0103-97332007000400006">hierarchy problem</a> to understand why gravity is so much weaker than the other forces.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/235265/original/file-20180906-190650-10btvtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/235265/original/file-20180906-190650-10btvtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/235265/original/file-20180906-190650-10btvtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=421&fit=crop&dpr=1 600w, https://images.theconversation.com/files/235265/original/file-20180906-190650-10btvtr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=421&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/235265/original/file-20180906-190650-10btvtr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=421&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/235265/original/file-20180906-190650-10btvtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=529&fit=crop&dpr=1 754w, https://images.theconversation.com/files/235265/original/file-20180906-190650-10btvtr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=529&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/235265/original/file-20180906-190650-10btvtr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=529&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diagram of the standard model of particle physics. There are 13 fundamental particles that make up matter that have now been discovered and four fundamental force carriers.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/diagram-standard-model-particle-physics-12-170480570">Designua/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>But for me, the quest for new, unexplained data is important because every time that physicists think we have it all figured out, nature provides a surprise that leads to a deeper understanding of our world.</p>
<p>The LHC continues to test the standard model of particle physics. Scientists love when theory matches data. But we usually learn more when they don’t. This means we don’t fully understand what is happening. And that, for many of us, is the future goal of the LHC: to discover evidence of something we don’t understand. There are thousands of theories that predict new physics that we have not observed. Which are right? We need a discovery to learn if any are correct.</p>
<p>CERN plans to continue LHC operations for a long time. We are planning <a href="http://dx.doi.org/10.23731/CYRM-2017-004">upgrades to the accelerator and detectors</a> to allow it to run through 2035. It is not clear who will retire first, me or the LHC. Ten years ago, we anxiously awaited the first beams of protons. Now we are busy studying a wealth of data and hope for a surprise that leads us down a new path. Here’s to looking forward to the next 20 years.</p><img src="https://counter.theconversation.com/content/102331/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Todd Adams receives funding from US Department of Energy. </span></em></p>The Large Hadron Collider has generated mind-blowing science in the last decade – including the Higgs boson particle. Why is the LHC so important, and how will physicists use it in the years to come?Todd Adams, Professor of Physics, Florida State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/541872016-02-08T14:11:04Z2016-02-08T14:11:04ZFive ways particle accelerators have changed the world (without a Higgs boson in sight)<figure><img src="https://images.theconversation.com/files/110621/original/image-20160208-2608-14wrw0u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Collision course</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/losalamosnatlab/7944152554/in/photolist-bPMwDn-bPMK5M-bATwEq-bPMYb2-bPNeYM-bPMRRg-bPMvZR-bATsJY-bATnbQ-bASTMQ-bATq5E-bPN8Gr-8nuxVG-C3ncbw-m9hxzi-bUnyq9-a375Tj-dWGGaC-d6ZRMu-5RXsXk-9y3eZi-5WhPRd-8tfRob-5svVGs-ehTFV9-ypfh2-7k1Qjt-bhV6oV-aox8xG-bBBhxA-5oH88Q-aiMCe8-9MpCoe-dUtdGT-e3kkGk-apotRr-bWivbZ-aprbVq-aprbWJ-apotEZ-aprbWf-82Ur7X-82Uqgk-aprbY9-uggkkC-aiMC96-5ywu9v-dFcxxd-9SxkNc-6Vj6Kw">Los Alamos National Laboratory/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>The <a href="https://theconversation.com/explainer-how-does-an-experiment-at-the-large-hadron-collider-work-42846">Large Hadron Collider</a> is probably the world’s most famous science experiment. The 27km-long ring-shaped particle accelerator beneath the edge of the Alps grabbed the world’s attention in 2013 when it proved the existence of the Higgs boson particle. This helped <a href="https://theconversation.com/higgs-bosons-decay-confirms-physics-model-works-20882">physicists confirm</a> that one of their key theories about the way the universe worked was correct – a huge step for science. But particle accelerators also have a big impact on our real lives. Even Christmas wouldn’t be the same without them.</p>
<p>Particle accelerators accelerate the tiny building blocks of matter by using electric fields to speed them up to high velocity/energy. These electric fields are the invisible force field created by charged objects, like static electricity or high voltage equipment.</p>
<p>These devices were initially invented to study what happens when particles collide with each other or with targets. These experiments allowed us to understand the particles themselves, the world around us, and nuclear physics (the study of the atomic nucleus). In itself this knowledge has been vital to the development of many technologies such as MRI scanners in hospitals and nuclear power stations.</p>
<p>There are also medium-sized accelerators that produce intense light or neutrons to allow physicists, biologists and pharmacologists to study materials, viruses, proteins and medicines, leading to countless Nobel prizes and new drugs and vaccines. They are even used by chocolate and <a href="http://www.foodonline.com/doc/how-x-ray-inspection-helped-an-ice-cream-maker-improve-food-safety-and-quality-0001">ice cream makers</a> to study how to make the tastiest products by using X-rays to look at the formation of different crystal structures and how to avoiding icy or chalky parts. </p>
<p>However, the most common type of particle accelerators are not the big 27km giants but the small industrial and medical accelerators that are all around us.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/110617/original/image-20160208-2625-1yimal3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/110617/original/image-20160208-2625-1yimal3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=434&fit=crop&dpr=1 600w, https://images.theconversation.com/files/110617/original/image-20160208-2625-1yimal3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=434&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/110617/original/image-20160208-2625-1yimal3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=434&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/110617/original/image-20160208-2625-1yimal3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=545&fit=crop&dpr=1 754w, https://images.theconversation.com/files/110617/original/image-20160208-2625-1yimal3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=545&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/110617/original/image-20160208-2625-1yimal3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=545&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Radiotherapy.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&search_tracking_id=Bwlb8vrRoZc3hvzKpAiy_g&searchterm=radiotherapy&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=228667765">Shutterstock</a></span>
</figcaption>
</figure>
<h2>1. Treating cancer</h2>
<p>Particle accelerators play a vital role in modern healthcare. The isotopes used in <a href="https://theconversation.com/the-science-of-medical-imaging-spect-and-pet-14086">PET scanners</a> are normally produced in a particle accelerator, and accelerated electrons are fired onto targets to produce X-rays for radiotherapy and imaging. In the UK, the NHS is constructing two special radiotherapy centres at Manchester Christie and the University College London hospitals that <a href="https://theconversation.com/cutting-edge-particle-physics-could-bring-cancer-therapy-home-13765">use protons</a> rather than electrons for radiotherapy, which allow more targeted doses of radiation with less risk to surrounding tissue.</p>
<h2>2. Preventing terrorist attacks</h2>
<p>The same X-ray sources as used in radiotherapy are also commonly used to boost security at ports and airports. The technology can be used to scan cargo, to ensure that nothing is being smuggled into the country. Due to the size of most cargo, a particle accelerator is needed to produce the high energy X-rays that are required. By using two different X-ray energies, we can even distinguish between different materials (similar scanning can also be done using neutrons). A <a href="http://www.dailymail.co.uk/sciencetech/article-3327008/New-scanner-uses-3D-imaging-tubular-X-rays-spot-bombs-drugs.html">new generation</a> of these scanners may also be able to identify emissions from drugs, or explosives when treated with X-rays. </p>
<h2>3. Protecting the environment</h2>
<p>The X-rays from particle accelerators also have the handy side effect of killing bacteria and insects and this has led to them being used for <a href="http://www.emdt.co.uk/article/x-ray-sterilisation-technology-future">sterilising equipment</a> and for treating tobacco, grain or spices to kill any insects, so reducing waste. They can also be used for breaking down nasty elements in <a href="http://www.symmetrymagazine.org/article/october-2009/cleaner-living-through-electrons">waste water</a> or flue gases to protect the environment.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/110627/original/image-20160208-2625-1amqf2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/110627/original/image-20160208-2625-1amqf2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/110627/original/image-20160208-2625-1amqf2u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/110627/original/image-20160208-2625-1amqf2u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/110627/original/image-20160208-2625-1amqf2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/110627/original/image-20160208-2625-1amqf2u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/110627/original/image-20160208-2625-1amqf2u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Blue topaz.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/kohtz/4301851749/in/photolist-7y97DK-cjHsJ-8v6SJ7-8dMiFX-i5y7Ca-6nHpVJ-7aLwtr-6NHX66-7aLwG4-6nHo4q-6S6N7m-6S6NqQ-e3Qps-6nDdVD-6nHpgC-7hHznq-6NN9SA-6NN9iY-7hDBnR-7hDBED-7hHzxd-7eRFPS-7aQmAu-hqvSS-7d9Czz-74uzqF-2HoNxj-2HoPRA-2HjABF-6PvqGA-hqwpa-hqw3a-7fuPh9-hqw6x-hqvZf-hqvWE-hqwhP-hqwej-hqw9h-hqwsb-hqwbL-hqwjW-hqw4w-hqvPW-hqwg2-hqw7Q-hqvVN-hqwnZ-dJzAJd-oX4Xtb">Craig Kohtz/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>4. Making mobile phones</h2>
<p>Electrons or X-rays generated from particle accelerators also have a lot of <a href="http://www.accelerators-for-society.org/industry/index.php?id=8">industrial uses</a>. They can be used to activate certain molecules in paint or composite fibres to make it dry faster, this process – <a href="http://www.sciencedirect.com/science/article/pii/S0168583X05013364">called curing</a> – is commonly used in cereal box printing or making aircraft parts. Without curing, companies would need huge warehouses just for storing things while they dried out. They can also be used to change the <a href="http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/irradiated-gemstones.html">colour of gemstones</a>, for example an accelerator turns the naturally colourless or brown topaz into the nice blue colour normally associated with it. Particle accelerators are also used to implant ions in semiconductors to tailor their behaviour in electronics, such as mobile phone chips.</p>
<h2>5. Saving Christmas</h2>
<p>One common use for particle accelerators is cross-linking, where the particles are used to break polymer chains in a material so they recombine in a stronger configuration. This is commonly used to make the plastic in electrical cables heat-resistant or to make <a href="http://www.symmetrymagazine.org/article/october-2009/accelerator-application-shrink-wrap">shrink wrap </a>for keeping your Christmas turkey fresh. The plastic is stretched and then placed in an electron beam so that when it is heated it shrinks back to its original size. This provides a strong and tight wrapping, protecting your turkey from nasty bacteria.</p><img src="https://counter.theconversation.com/content/54187/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Graeme Burt receives funding from STFC. He works for the Cockcroft Institute of Accelerator Science and Technology and Lancaster University.</span></em></p>Particle accelerators are helping to push forward the frontiers of theoretical physics but they’ve also had more impact on your everyday life than you realise.Graeme Burt, Senior lecturer in engineering, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/458912015-08-12T05:36:32Z2015-08-12T05:36:32ZWorld’s most powerful laser is 2,000 trillion watts – but what’s it for?<figure><img src="https://images.theconversation.com/files/91442/original/image-20150811-11077-jx555l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lasers, going where no one has gone before.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Preamplifier_at_the_National_Ignition_Facility.jpg">Damien Jemison/LLNL</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The most powerful laser beam ever created has been recently fired at Osaka University in Japan, where the <a href="http://www.eurekalert.org/pub_releases/2015-08/ou-wpl080615.php">Laser for Fast Ignition Experiments</a> (LFEX) has been boosted to produce a beam with a peak power of 2,000 trillion watts – two petawatts – for an incredibly short duration, approximately a trillionth of a second or one picosecond.</p>
<p>Values this large are difficult to grasp, but we can think of it as a billion times more powerful than a typical stadium floodlight or as the overall power of all of the sun’s solar energy that falls on London. Imagine focusing all that solar power onto a surface as wide as a human hair for the duration of a trillionth of a second: that’s essentially the LFEX laser. </p>
<p>LFEX is only one of a series of ultra-high power lasers that are being built across the world, ranging from the gigantic 192-beam <a href="https://lasers.llnl.gov/">National Ignition Facility</a> in California, to the <a href="http://www.ibs.re.kr/eng/sub02_03_05.do?gubunCode=corels_en">CoReLS laser</a> in South Korea, and the <a href="http://www.clf.stfc.ac.uk/CLF/">Vulcan laser</a> at the Rutherford Appleton Laboratory outside Oxford, UK, to mention but a few. </p>
<p>There are other projects in design stages – of which the most ambitious is probably the <a href="http://www.eli-beams.eu/">Extreme Light Infrastructure</a>, an international collaboration based in Eastern Europe devoted to building a laser 10 times more powerful even than the LFEX. </p>
<p>So what is driving scientists all over the world to build these jewels of optical and electronic technology? What is enough to convince politicians to allocate such significant research funds to back these enormous projects?</p>
<h2>Recreating the early universe</h2>
<p>Well, the first reason that comes to mind is because <a href="https://theconversation.com/weve-just-started-work-on-the-technology-to-power-a-star-trek-style-replicator-43373">the “wow factor” that is associated with lasers</a>. But there’s a whole lot more than just exciting scientists’ and enthusiasts’ imagination. </p>
<p>Lasers this powerful are the only means we have to recreate the extreme environments found in space, such as in the atmosphere of stars – including our Sun – or in the core of giant planets such as Jupiter. When these ultra-powerful lasers are fired at ordinary matter it is instantaneously vaporised, leading to an extremely hot and dense ionised gas, which scientists call a plasma. This extreme state of matter is extremely rare on Earth, but very common in space – almost 99% of ordinary matter in the universe is believed to be in a plasma state.</p>
<p>Ultra-powerful lasers allow us to create a small replica of these extreme states and objects from the universe in such a way that they can be studied in a controlled manner in the laboratory. In a way, they allow us to travel back in time, since they can recreate the conditions found in the early universe, moments after the Big Bang. These extremely dense and hot environments, which only ultra-powerful lasers can create, have already taught us a lot about the <a href="https://theconversation.com/how-we-recreated-the-early-universe-in-the-laboratory-41399">evolution of our universe and its current state</a>.</p>
<h2>Uses closer to home</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/91441/original/image-20150811-11059-1xrmmia.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91441/original/image-20150811-11059-1xrmmia.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/91441/original/image-20150811-11059-1xrmmia.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91441/original/image-20150811-11059-1xrmmia.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91441/original/image-20150811-11059-1xrmmia.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91441/original/image-20150811-11059-1xrmmia.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91441/original/image-20150811-11059-1xrmmia.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91441/original/image-20150811-11059-1xrmmia.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One of the acceleration beams of the LFEX laser in Osaka.</span>
<span class="attribution"><a class="source" href="https://www.phys.sci.osaka-u.ac.jp/en/research_groups/group/13-0_azechi/azechi/index.html">Osaka University</a></span>
</figcaption>
</figure>
<p>On a more practical note, laser facilities are not only interesting for their input into theoretical research, they’re also at the core of crucial practical applications. For example, current research into alternative and clean energy generation or healthcare. The LFEX is mainly applies to the former, since it is built to study nuclear fusion research. </p>
<p>Unlike nuclear fission, nuclear fusion does not generate radioactive waste. This means fusion fuels are much easier to store and handle – we can use seawater and lithium, somewhat handier and easier to come by than uranium. </p>
<p>Nuclear fusion is what creates and sustains the immense energy of stars, but it requires a significant input of power to initiate the chain reaction. High-powered lasers such as LFEX are the best candidates for the job. In fact preliminary results are encouraging, with a test at the US National Ignition Facility managing to <a href="http://www.nature.com/news/laser-fusion-experiment-extracts-net-energy-from-fuel-1.14710">generate more energy than it expended</a> on one occasion last year.</p>
<h2>Inexpensive particle research</h2>
<p>This class of ultra-powerful lasers is also extremely appealing because they represent a much more compact and inexpensive (by comparison) alternative to the huge particle accelerators such as at CERN – which measure many kilometres in length. High-powered, laser-driven particle accelerators can generate ultra-high quality x-rays without the need to use radioisotope particles which need careful handling. These laser-driven x-rays can then be used for taking high-resolution images of biological tissues in a really compact and inexpensive system. For example, this laser-driven tomography <a href="http://www.nature.com/ncomms/2015/150720/ncomms8568/abs/ncomms8568.html">of an insect</a>.</p>
<p>Researchers are also now working on using laser-driven ion beams for cancer therapy. This technique has so far been restricted due to the cost and size of conventional accelerators. Laser-based cancer therapy would be affordable to a much larger number of hospitals, bringing this effective cancer therapy technique to a much larger number of patients.</p>
<p>So the ultra-high power that LFEX can deliver, if only for the briefest of moments, is not just a fancy new toy but an exciting step forward in applying laser technology to a wider range of disciplines – from the the seemingly abstract world of the early universe, to the very real uses providing the tools to diagnose disease or fight cancer.</p><img src="https://counter.theconversation.com/content/45891/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gianluca Sarri receives funding from EPSRC (grant no. EP/L013975/1)</span></em></p>Ultra-high powered lasers are the best and even cheapest approach to uncovering the secrets of physics, but with uses closer to home too.Gianluca Sarri, Lecturer at the School of Mathematics and Physics , Queen's University BelfastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/457902015-08-07T16:27:03Z2015-08-07T16:27:03ZWhat has nuclear physics ever given us?<figure><img src="https://images.theconversation.com/files/91172/original/image-20150807-27590-1vvbaay.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/75001512@N00/3242522688/in/photostream/">Joel Kramer</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>This year marks the 103rd anniversary of the birth of nuclear physics, when Ernest Rutherford, Hans Geiger and Ernest Marsden’s experiments at the University of Manchester led them to conclude that atoms consist of tiny, positively-charged nuclei orbited by negatively-charged electrons.</p>
<p>This year is also the 70th anniversary of the first nuclear bomb, dropped on Hiroshima. Though their discoveries led to the harnessing of nuclear energy as a weapon, it should not be forgotten that the purpose of Rutherford, Geiger and Marsden’s experiments, as with much of scientific research, was simply to understand nature. And in this they succeeded, handing us an understanding that has changed forever how we see the fabric of the world, and one which had led to much good, too.</p>
<h2>Nuclear physics, a window on the world</h2>
<p>So much science and technology has followed from the nuclear model of the atom. It spurred Danish physicist <a href="http://www.britannica.com/biography/Niels-Bohr">Niels Bohr</a> to develop the nascent quantum theory into a fully-fledged quantum mechanics that could describe the way atoms worked. That in turn has paved the way for so much of modern technology, not the least of which of course is the silicon chip and computerisation. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/91173/original/image-20150807-27582-tukotb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91173/original/image-20150807-27582-tukotb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/91173/original/image-20150807-27582-tukotb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91173/original/image-20150807-27582-tukotb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91173/original/image-20150807-27582-tukotb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91173/original/image-20150807-27582-tukotb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91173/original/image-20150807-27582-tukotb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91173/original/image-20150807-27582-tukotb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Of particle accelerators, big…</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:View_inside_detector_at_the_CMS_cavern_LHC_CERN.jpg">Tighef</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Rutherford’s experiments fired the nuclei of helium atoms at other nuclei, making use of the fact that radioactive decay generates fast <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html">alpha particles</a> to emerge from the nucleus. </p>
<p>To provide much more control, particle accelerators were developed in order to fire the basic building blocks of matter such as alpha particles, protons, or electrons at other objects. They didn’t know it at the time, but this set in motion the entire field of research now known as particle physics. The grandchildren of those first accelerators are devices such as the CERN Large Hadron Collider, at which the Higgs boson was discovered last year, inching us closer to understanding the universe. </p>
<h2>Nuclear understanding permeates everything</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/91174/original/image-20150807-27590-1s6fm9t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91174/original/image-20150807-27590-1s6fm9t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/91174/original/image-20150807-27590-1s6fm9t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91174/original/image-20150807-27590-1s6fm9t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91174/original/image-20150807-27590-1s6fm9t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91174/original/image-20150807-27590-1s6fm9t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91174/original/image-20150807-27590-1s6fm9t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91174/original/image-20150807-27590-1s6fm9t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">…and small particle accelerators too.</span>
<span class="attribution"><span class="source">TV by Sergio Stakhnyk/shutterstock.com</span></span>
</figcaption>
</figure>
<p>A century is a long time in science, and things move quickly. It wasn’t long ago that we all had particle accelerators in our homes – the cathode ray tubes in our televisions. These have been superseded by LCD, LED and plasma displays, which are founded on our development of <a href="https://theconversation.com/the-future-is-bright-the-future-is-quantum-dot-televisions-35765">quantum technologies</a>.<br>
Perhaps the most prevalent application of particle accelerators today is in hospitals in the form of radiotherapy machines for the treatment of cancer. </p>
<p>In addition, Nuclear physics is the key to more or less all diagnostic imaging such as such X-ray, PET, CT, MRI, NMR, SPECT and other techniques that allow us to look inside the body without resorting to the knife. </p>
<p>If you’ve ever benefitted from one of these, thanks are due to many people, not least the nuclear physics pioneers who just wondered “what is this stuff?” and “what if…?”.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/91177/original/image-20150807-27612-7h8cmh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/91177/original/image-20150807-27612-7h8cmh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91177/original/image-20150807-27612-7h8cmh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91177/original/image-20150807-27612-7h8cmh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91177/original/image-20150807-27612-7h8cmh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91177/original/image-20150807-27612-7h8cmh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91177/original/image-20150807-27612-7h8cmh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91177/original/image-20150807-27612-7h8cmh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nuclear science gives us a different view.</span>
<span class="attribution"><span class="source">scan by T-Photo/shutterstock.com</span></span>
</figcaption>
</figure>
<h2>From power stations to carbon dating</h2>
<p>The Hiroshima and Nagasaki bombs, those most infamous uses of nuclear physics, shocked the world 70 years ago. Nuclear processes are extremely energetic and can be manipulated to generate devastating explosive power. Yet the atomic bombs of World War II pale in comparison to the destructive force of modern thermonuclear weapons, which mimic the nuclear reactions taking place in the stars.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/91176/original/image-20150807-27573-zak3g4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91176/original/image-20150807-27573-zak3g4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=425&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91176/original/image-20150807-27573-zak3g4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=425&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91176/original/image-20150807-27573-zak3g4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=425&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91176/original/image-20150807-27573-zak3g4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=534&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91176/original/image-20150807-27573-zak3g4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=534&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91176/original/image-20150807-27573-zak3g4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=534&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Nuclear power comes in all shapes.</span>
<span class="attribution"><a class="source" href="http://www.geograph.org.uk/photo/1396226">Dave Croker</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Less well-known are the applications of nuclear physics in earth sciences. It’s our grasp of nuclear physics that helps us understand the Earth’s historical temperature record, through studying the ratio of oxygen isotopes in ice cores from Greenland and the Antarctic. Isotope tracking helps us understand the flow of ocean currents, the nature of aquifers in parts of the world where water is scarce, the migration of long-dead human populations, and the geological evolution of the earth as well as what is happening in stars. </p>
<p>It’s hard to disentangle one field of scientific research and place it in isolation. The words we use to isolate one from another are only to help humans categorise them – nature does not see it that way. Nuclear physics is so closely interwoven with so much of science and technology, and the social, cultural impact it has had in the last century, that it is interwoven with everything we know and use – we should be thankful for it, not fear it.</p><img src="https://counter.theconversation.com/content/45790/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Stevenson receives funding from the UK Science and Technology Facilities Council. He is a member of the Green Party.</span></em></p>It’s not just about weapons, nuclear science has changed practically everything around us – for the better.Paul Stevenson, Reader, University of SurreyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/447212015-07-15T12:57:00Z2015-07-15T12:57:00ZHere’s what you need to know about the Large Hadron Collider’s latest discovery: pentaquarks<figure><img src="https://images.theconversation.com/files/88494/original/image-20150715-17815-1pe2ckw.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">CERN</span></span></figcaption></figure><p>The Large Hadron Collider, famous for finding the Higgs boson, has now revealed another new and rather unusual particle. Teams at the LHC, the world’s largest particle accelerator, <a href="https://theconversation.com/large-hadron-collider-is-back-to-change-our-understanding-of-the-universe-again-42775">recently began</a> a second <a href="https://theconversation.com/explainer-how-does-an-experiment-at-the-large-hadron-collider-work-42846">run of experiments</a> using far more energy than the ones that found the Higgs particle <a href="https://theconversation.com/cern-discovers-a-higgs-like-particle-let-the-party-and-head-scratching-begin-8036">back in 2012</a>. But another of the groups, LHCb, have also been sifting through its data from the billions of particle collisions of the first run of the LHC, and now think they’ve <a href="http://arxiv.org/abs/1507.03414">spotted something new</a>: pentaquarks.</p>
<p>Pentaquarks are an exotic form of matter first predicted <a href="http://journals.aps.org/prd/abstract/10.1103/PhysRevD.20.748">back in 1979</a>. Everything around us is made of atoms, which are mode of a cloud of electrons orbiting a heavy nucleus made of protons and neutrons. But <a href="http://www.sciencedirect.com/science/article/pii/S0031916364920013">since the 1960s</a>, we’ve also known that protons and neutrons are made up of even smaller <a href="https://theconversation.com/explainer-quarks-12003">particles named “quarks</a>”, held together by something called the “strong force”, the strongest known force in nature in fact.</p>
<p><a href="http://wwwphy.princeton.edu/%7Ekirkmcd/examples/EP/breidenbach_prl_23_935_69.pdf">Experiments in 1968</a> provided the evidence for the quark model. If protons are hit hard enough, the strong force can be overcome and the proton smashed apart. The quark model actually explains the existence of more than 100 particles, all known as “hadrons” (as in Large Hadron Collider) and made up of different combinations of quarks. For example the proton is made of three quarks.</p>
<p>All hadrons seem to be made up of combinations of either two or three quarks, but there is no obvious reason more quarks could not stick together to form other types of hadron. <a href="https://inis.iaea.org/search/search.aspx?orig_q=RN:190196">Enter the pentaquark</a>: five quarks bound together to form a new type of particle. But until now, nobody knew for sure if pentaquarks actually existed – and, although there have been several discoveries claimed in the last 20 years, none has stood the test of time.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/88496/original/image-20150715-17785-klc9jf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/88496/original/image-20150715-17785-klc9jf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/88496/original/image-20150715-17785-klc9jf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/88496/original/image-20150715-17785-klc9jf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/88496/original/image-20150715-17785-klc9jf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/88496/original/image-20150715-17785-klc9jf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/88496/original/image-20150715-17785-klc9jf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The intricate dance of the J/psi and the proton.</span>
<span class="attribution"><span class="source">CERN</span></span>
</figcaption>
</figure>
<p>Pentaquarks are incredibly difficult to see; they are very rare and very unstable. This means that if it is possible to stick five quarks together, they won’t stay together for very long. The team on the LHCb experiment made their discovery by looking in detail at other exotic hadrons produced in the collisions and they way these break apart. In particular, they looked for the Lambda<sub>b</sub> particle, which can decay into thee other hadrons: a Kaon, a J/psi, and a proton.</p>
<p>The J/psi is made of two quarks and the proton is made of three. The scientists discovered that for a short period of time these five quarks were bound together in a single particle: a pentaquark. In fact, through detailed analysis of the data, they actually discovered two pentaquarks and have given them the catchy names Pc(4450)+ and Pc(4380)+.</p>
<h2>Why is this important?</h2>
<p>The discovery answers a decades-old question in particle physics and highlights another part of the mission of the LHC. Discoveries of new fundamental particles such as the Higgs boson tell us something completely new about the universe. But discoveries like pentaquarks give us a more complete understanding of the rich possibilities that lie in the universe we already know.</p>
<p>By developing this understanding, we may get some hints about how the universe developed after the Big Bang and how we’ve ended up with protons and neutrons instead of pentaquarks making up everyday matter. </p>
<p>With the LHC now colliding protons at almost twice the energy, scientists are ready to tackle some of the <a href="https://theconversation.com/large-hadron-collider-is-back-to-change-our-understanding-of-the-universe-again-42775">other open questions</a> in <a href="https://theconversation.com/beyond-the-higgs-boson-five-reasons-physics-is-still-interesting-20380">particle physics</a>. One of the main targets with the new data is <a href="https://theconversation.com/shedding-new-light-on-the-search-for-the-invisible-dark-matter-40083">Dark Matter</a>, a strange particle which seems to be all around the universe, but has never been seen. Testing the current understanding of quarks, the strong force and all the known particles at this new energy is an essential step towards making such discoveries.</p><img src="https://counter.theconversation.com/content/44721/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gavin Hesketh is a lecturer in particle physics at University College London, and a member of the ATLAS Collaboration at CERN. He receives funding from the Science and Technology Facilities Council, and the Royal Society.</span></em></p>The latest data from the particle accelerator that found the Higgs Boson has confirmed another of our theories about how the universe works.Gavin Hesketh, Lecturer in Particle Physics, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/428462015-06-05T15:34:31Z2015-06-05T15:34:31ZExplainer: how does an experiment at the Large Hadron Collider work?<figure><img src="https://images.theconversation.com/files/84113/original/image-20150605-8677-1ykfc31.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Supersize symmetry</span> <span class="attribution"><span class="source">Maximilien Brice/CERN</span></span></figcaption></figure><p>It’s not every day my Twitter feed is full of people talking about flat-tops, squeezing and injections, but then Wednesday 3 June was not an average day for the Large Hadron Collider.</p>
<p>The LHC is the world’s largest particle accelerator and lies in a tunnel below <a href="http://home.web.cern.ch">CERN</a>, the European physics lab just outside Geneva. And on Wednesday it was restarted after two year break for repairs and upgrades, ready to push our understanding of the universe to new limits. </p>
<p>As my fellow physicists crowded into the control rooms and waited for things to get underway, I was at a workshop in France. But I was able to follow the <a href="http://run2-13tev.web.cern.ch">switch-on online</a>. Here’s how things went down.</p>
<p><strong>8.09am. Injection: Billions of protons are loaded into the LHC.</strong></p>
<p>The LHC is a ring roughly 28km around that accelerates protons almost to the speed of light before colliding them head on. Protons are particles found in the atomic nucleus, roughly one thousand-million-millionth of a metre in size.</p>
<p>They are easiest to get from hydrogen, the simplest atom with just one electron orbiting one proton. The LHC starts with a bottle of hydrogen gas, which is sent through an electric field to strip away the electrons, leaving just the protons. Electric and magnetic fields are the key to a particle accelerator: because protons are positively charged, they accelerate when in an electric field and bend in a circle in a magnetic field. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/84109/original/image-20150605-8725-9xav1g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/84109/original/image-20150605-8725-9xav1g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/84109/original/image-20150605-8725-9xav1g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/84109/original/image-20150605-8725-9xav1g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/84109/original/image-20150605-8725-9xav1g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/84109/original/image-20150605-8725-9xav1g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/84109/original/image-20150605-8725-9xav1g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Big data.</span>
<span class="attribution"><span class="source">M.Brice/CERN</span></span>
</figcaption>
</figure>
<p><strong>9.45am. Ramp: Once the LHC is fully loaded, its two proton beams are slowly accelerated up to collision energy, now a world-record 6.5TeV per beam.</strong></p>
<p>Accelerating billions of protons to close to the speed of light, directing them all the way around the LHC, and then colliding them head-on, is a delicate balancing act performed by high voltage equipment and giant magnets. This is an amazing technical achievement. Indeed one of the main applications of particle physics research is in the industrial applications of the technology it develops along the way, from proton therapy cancer treatment to the <a href="http://home.web.cern.ch/topics/birth-web">world wide web</a>.</p>
<p>But for me, the excitement is in the science: the LHC is exploring the universe at the smallest scales. Everything we have learned so far is formulated in the <a href="http://home.web.cern.ch/about/physics/standard-model">Standard Model</a>, a theory which describes the universe made of tiny particles, and gives the rules for how these particles behave. By smashing some of these particles together at high energy, we are able to test these rules and make new discoveries.</p>
<p>The LHC “Run 1” (2010-2013) provided enough data to test the Standard Model to new levels of precision and discover the <a href="https://theconversation.com/definitely-maybe-evidence-grows-for-positive-id-of-higgs-boson-12790">Higgs boson</a>. This particle was predicted in the 1960s and plays a central role in the Standard Model. But it was almost 50 years before we had a machine powerful enough to discover it. As well as high energy, it needed lots of data: the Higgs boson is a rare thing, and fewer than one in a billion collisions at the LHC produce one.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/84110/original/image-20150605-8697-1094eps.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/84110/original/image-20150605-8697-1094eps.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/84110/original/image-20150605-8697-1094eps.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/84110/original/image-20150605-8697-1094eps.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/84110/original/image-20150605-8697-1094eps.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/84110/original/image-20150605-8697-1094eps.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/84110/original/image-20150605-8697-1094eps.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tense moments.</span>
<span class="attribution"><span class="source">Laurent Egli/CERN</span></span>
</figcaption>
</figure>
<p><strong>10.12am. Flat top: Beam energy levels off after reaching the target.</strong></p>
<p>These were tense moments for the CERN team on Wednesday. The LHC was operating at the <a href="https://theconversation.com/large-hadron-collider-is-back-to-change-our-understanding-of-the-universe-again-42775">highest energy ever</a> achieved in a particle accelerator. “Run 2” will collide protons at 60% higher energies than Run 1 by pushing the magnets and accelerators to the limit. We hope this extra reach will allow us to tackle some of the big questions in particle physics.</p>
<p>One of the main topics is <a href="http://home.web.cern.ch/about/physics/dark-matter">dark matter</a>. This seems to be a new type of particle spread through the entire universe. And with the LHC Run 2 we hope to make it in the lab for the first time. But if the Higgs boson is rare, dark matter is even rarer, and we will need to sort through a lot of collisions before having a hope of finding it.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/84111/original/image-20150605-8725-szj84l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/84111/original/image-20150605-8725-szj84l.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=309&fit=crop&dpr=1 600w, https://images.theconversation.com/files/84111/original/image-20150605-8725-szj84l.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=309&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/84111/original/image-20150605-8725-szj84l.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=309&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/84111/original/image-20150605-8725-szj84l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=388&fit=crop&dpr=1 754w, https://images.theconversation.com/files/84111/original/image-20150605-8725-szj84l.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=388&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/84111/original/image-20150605-8725-szj84l.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=388&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Worlds collide.</span>
<span class="attribution"><span class="source">CMS/CERN</span></span>
</figcaption>
</figure>
<p><strong>10.17am. Squeeze: The beams are fine-tuned, and focused at the four points around the LHC where they cross, and the experiments will record the collisions</strong></p>
<p>Almost there. The experiments now need to wait for the all-clear before they can start recording, and we begin studying things that have never been seen before. Still, many of the collisions will not be interesting, as the protons just smash apart without doing anything exciting.</p>
<p>To make matters worse, the rare new particles we are looking for also tend to be very unstable, and decay too quickly to be seen directly. So the job of the experiments is to measure whatever particles do come out of a collision and try to reconstruct what happened, looking for evidence of something unusual.</p>
<p>As well as dark matter, there are many other ideas to test, such as <a href="http://home.web.cern.ch/about/physics/supersymmetry">supersymmetry</a>, new gauge bosons, quantum black holes and heavy neutrinos, all of which we could reconstruct from the LHC collisions. Part of the joy and pain of science is that a <a href="https://theconversation.com/is-this-the-end-of-particle-physics-as-we-know-it-lets-hope-not-42849">new discovery</a> could come in a matter of days, or a matter of years.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/84107/original/image-20150605-8674-1xscz2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/84107/original/image-20150605-8674-1xscz2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/84107/original/image-20150605-8674-1xscz2w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/84107/original/image-20150605-8674-1xscz2w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/84107/original/image-20150605-8674-1xscz2w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/84107/original/image-20150605-8674-1xscz2w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/84107/original/image-20150605-8674-1xscz2w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Champagne flowing.</span>
<span class="attribution"><span class="source">Mike Struik/CERN</span></span>
</figcaption>
</figure>
<p><strong>10.43am. Stable beams: The LHC is now running smoothly, the beams are behaving as expected, and the experiments can start recording data.</strong></p>
<p>Run 2 has begun! Champagne is flowing at CERN. Now the attention moves to analysing the new data, and it’s time for the rest of us to get back to work.</p><img src="https://counter.theconversation.com/content/42846/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gavin Hesketh receives funding from The Royal Society and STFC.</span></em></p>Running the world’s largest particle accelerator requires a lot of energy, but it could reveal the secrets of the universe.Gavin Hesketh, Lecturer in Particle Physics, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/428492015-06-05T05:12:41Z2015-06-05T05:12:41ZIs this the end of particle physics as we know it? Let’s hope not<figure><img src="https://images.theconversation.com/files/83988/original/image-20150604-3374-4ampxo.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An artist's impression of the much-searched for magnetic monopole</span> <span class="attribution"><span class="source">Heikka Valja/MoEDAL Collaboration</span></span></figcaption></figure><p>Physicists around the world (myself included) are hoping that this week will mark the beginning of a new era of discovery. And not, as some fear, the end of particle physics as we know it.</p>
<p>After 27 months of shutdown and re-commissioning, the Large Hadron Collider has begun its <a href="http://home.web.cern.ch/about/updates/2015/06/lhc-experiments-back-business-record-energy">much-anticipated</a> “Season 2”. Deep beneath the Franco-Swiss border, the first physics data is now being collected in CERN’s freshly upgraded detector-temples at the record-breaking collision energy of 13 teraelectonvolts (TeV).</p>
<p>Much has been written about the <a href="http://home.web.cern.ch/about/updates/2015/04/proton-beams-are-back-lhc">upgrade to the accelerator</a>, <a href="https://theconversation.com/large-hadron-collider-is-back-to-change-our-understanding-of-the-universe-again-42775">the experiments</a>, and the <a href="https://theconversation.com/number-crunching-higgs-boson-meet-the-worlds-largest-distributed-computer-grid-38696">computing infrastructure</a> required to handle the fresh deluge of data from the new energy frontier. There has also – quite rightly – been a lot of attention paid to the crowning achievement of Run 1: the discovery of the <a href="http://home.web.cern.ch/topics/higgs-boson">Higgs boson</a>.</p>
<p>But the “<a href="http://arxiv.org/abs/1303.7367">elephant in the collider</a>” is this: we knew that Run 1 had to <a href="http://www.theguardian.com/science/life-and-physics/2014/aug/04/bosons-that-demanded-a-higgs">find the Higgs boson</a> – or something like it, and it did. With Run 2, we don’t know what we’re looking for.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/OMc6OCTxIEM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>OK, so maybe that’s bit of an over-simplification. We certainly have a good few guesses as to what’s beyond the Standard Model of particle physics, our current best understanding of matter and forces at the fundamental level that was essentially completed in July 2012.</p>
<p>One of the leading contenders is supersymmetry, a theory that provides a candidate for the dark matter that supposedly makes up some 23% of our universe. As it happens, my PhD was based on the first results from the LHC Run 1 that said we <a href="http://dx.doi.org/10.1016/j.physletb.2011.03.021">hadn’t found evidence</a> for supersymmetry.</p>
<p>To date, I have not had to write an embarrassing addendum to my thesis. But, while there are many <a href="http://www.theguardian.com/science/life-and-physics/2010/aug/21/susy-supersymmetry-higgs-boson">compelling arguments</a> for supersymmetry, it is not <em>required</em> in the same way the Higgs boson was. The Higgs was a missing piece in our current physics jigsaw; supersymmetry would represent a new puzzle entirely.</p>
<h2>Scientific wild-goose chase?</h2>
<p>Does that make Run 2 a waste of time? Are we pouring money into an extra-dimensional wild-goose chase? Are we, in fact, staring down the barrel of the end of collider-based particle physics?</p>
<p>You’d be forgiven for thinking so, if you had no knowledge or understanding of the history of particle physics (or how science works, for that matter). After all, science is arguably at its most boring when you 1) know exactly what you’re looking for, and 2) find it.</p>
<p>It’s much more fun to consider physics in the middle of the 20th century. You could pretty much describe all of known physics, chemistry, materials science, and biology with electrons, protons, neutrons and photons. Yet advances in particle detector technology – <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/1927/">Wilson’s cloud chamber</a>, <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/1948/">Blackett’s triggers</a>, <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/1950/">Powell’s photographic emulsions</a> – led to the discovery of completely new particles outside of this comfortable model of nature.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/83990/original/image-20150604-3371-lchj3j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83990/original/image-20150604-3371-lchj3j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=279&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83990/original/image-20150604-3371-lchj3j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=279&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83990/original/image-20150604-3371-lchj3j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=279&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83990/original/image-20150604-3371-lchj3j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=351&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83990/original/image-20150604-3371-lchj3j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=351&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83990/original/image-20150604-3371-lchj3j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=351&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Vehicle of discovery.</span>
<span class="attribution"><span class="source">Daniel Dominguez, Maximilien Brice/CERN</span></span>
</figcaption>
</figure>
<p>At the time, <a href="http://home.web.cern.ch/about/physics/cosmic-rays-particles-outer-space">cosmic rays</a> – particles bombarding our atmosphere from outer space – had far greater energies than the particles laboratory-based accelerators could produce. They represented a new energy frontier for physics, explored by the heroic particle hunters of the 1930s and ‘40s who trekked up mountains, launched high-altitude balloons, and flew aeroplanes in search of their quantum quarry.</p>
<p>They were rewarded for their efforts with, among other things, strange particles, a completely new type of matter that defied the predictions of the time and opened the door to a veritable zoo of subatomic building blocks.</p>
<p>The second half of the 20th century saw a trans-Atlantic race to build bigger and bigger particle accelerators to artificially produce cosmic rays in the controlled conditions of the laboratory and tame the particle zoo. This race was, arguably, won by <a href="http://press.web.cern.ch/press-releases/2015/05/us-cern-agreement-paves-way-new-era-scientific-discovery">the LHC</a>. As we approach the new, unknown energy frontier of Run 2, we are therefore once again in need of a new generation of particle hunters. We need experimental physicists who are able to painstakingly pore over every byte of data in search of “what’s next”.</p>
<h2>Monopole mission</h2>
<p>Personally, I have eschewed supersymmetric searches (been there, done that) and, along with the students of the <a href="http://www.thelangtonstarcentre.org/">Langton Star Centre</a>, <a href="http://home.web.cern.ch/students-educators/updates/2013/11/teens-join-moedal-collaboration">joined the MoEDAL Collaboration</a>. This experiment is looking for Paul Dirac’s hypothesised magnetic monopole. Based in the LHCb cavern at Point 8, <a href="http://moedal.web.cern.ch">MoEDAL</a> (Monopole and Exotics Detector at the LHC) will use a number of novel detector technologies to look for tracks generated by the heavy, highly-ionising magnetic monopoles that could, in theory, be produced in the proton-proton collisions.</p>
<p>Magnetic monopoles are the magnetic equivalent of single electric charges – like a magnet with only a north or south pole, and not both - and their discovery would shake physics to its electromagnetic core. It’s a high-risk, high-reward search – but by providing alternatives to the traditional detector methodologies of CMS and ATLAS, we’re ensuring that as many bases are covered as possible.</p>
<p>We don’t know what we will find in Run 2. It could be monopoles, dark matter, micro-black holes, extra dimensional excitations, gravitons or something else entirely. What’s certain is this: if we are to find anything, we are going to have to be incredibly clever about how we go about it. We may even <a href="http://home.web.cern.ch/about/updates/2014/11/cern-makes-public-first-data-lhc-experiments">need your help</a>. If we don’t find anything, it might be the beginning of the end of what terrestial, collider-based physics can tell us about the Universe. But even a null result from Run 2 <a href="https://www.youtube.com/watch?v=QP3wSSHYdG8">would still be a result</a>, and an important one at that.</p>
<p>So, it is the dawn of a new era for particle physics. It is time for the experimentalists to once again outshine their theoretical friends. It is open season for the particle hunters.</p>
<p><em>You can find out more about the MoEDAL experiment at this year’s <a href="http://sse.royalsociety.org/2015/monopole-quest/">Royal Society Summer Science Exhibition</a>, 30 June - 5 July, London.</em></p><img src="https://counter.theconversation.com/content/42849/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tom Whyntie has previously received funding from UK Science and Technology Facilities Council (STFC). He is also affiliated with the Langton Star Centre, the research facility attached to the Simon Langton School in Canterbury, Kent, and the STFC-funded GridPP Collaboration.</span></em></p>The restart of experiments at CERN’s Large Hardron Collider could mark the start of a new era of discovery or a big disappointment.Tom Whyntie, Visiting Academic and GridPP Dissemination Officer, Queen Mary University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/427752015-06-03T14:14:14Z2015-06-03T14:14:14ZLarge Hadron Collider is back to change our understanding of the universe … again<p>The Large Hadron Collider (LHC) has just begun smashing particles together at higher energies than ever before. This marks the start of the second run of the world’s largest physics experiment, the huge particle accelerator that sits beneath the Alps and in 2012 was used to prove the existence of the <a href="https://theconversation.com/definitely-maybe-evidence-grows-for-positive-id-of-higgs-boson-12790">Higgs boson</a>.</p>
<p>Now, after more than two years’ work <a href="https://theconversation.com/goodbye-for-a-while-to-the-large-hadron-collider-12238">upgrading the accelerator</a> systems and the particle detectors (and more years of preparation before that), the team at research group CERN are ready to start using the LHC to answer more questions about how the universe works.</p>
<p>The goal is to explain the missing pieces in our understanding of fundamental physics. One example is the nature of the so-called <a href="http://home.web.cern.ch/about/physics/dark-matter">dark matter</a> that scientists say we can’t see directly but that dominates the universe. Another is the imbalance between matter and antimatter in the present-day universe. Our current theories suggest there would have been almost exactly equal amounts of matter and antimatter in the early universe. But somehow the antimatter decayed, allowing the universe that we know made entirely of matter to emerge.</p>
<p>Physicists have proposed a range of theories, <a href="http://home.web.cern.ch/about/physics/supersymmetry">such as “supersymmetry”</a>, to answer these questions and that also predict the existence of new particles and subtle changes to the behaviour of known particles. By colliding particles at energies measured at 13 teraelectronvolts, researchers may also find evidence of the hidden extra dimensions that feature in many theories. Or it could show that the Higgs boson, the particle associated with giving mass to the other particles that make up matter, is one of a whole family of related particles.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/83813/original/image-20150603-2963-6ok9uw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83813/original/image-20150603-2963-6ok9uw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83813/original/image-20150603-2963-6ok9uw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83813/original/image-20150603-2963-6ok9uw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83813/original/image-20150603-2963-6ok9uw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83813/original/image-20150603-2963-6ok9uw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83813/original/image-20150603-2963-6ok9uw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Energy levels up.</span>
<span class="attribution"><span class="source">M Brice/CERN</span></span>
</figcaption>
</figure>
<p>The significance of almost doubling the energy at which particles are fired around the LHC is that the resulting collisions should produce new particles that were inaccessible before. Rarer processes should also become more frequent and so easier to distinguish from the approximately 600m “ordinary” collisions that occur in each experiment each second. And the rate at which Higgs bosons are produced should increase, allowing researchers to determine their true nature.</p>
<p>There are several different experiments scheduled for the higher-energy LHC. My team at the University of Lancaster is part of the <a href="http://atlas.ch">ATLAS experiment</a> and we will be looking studying how the Higgs boson decays into a particle called the tau, a heavier version of the electron. We will be seeing if the decay exhibits what is called <a href="http://cerncourier.com/cws/article/cern/28092">CP violation</a>, a process that distinguishes between matter and antimatter and might help explain the matter-antimatter imbalance.</p>
<p>The improvements to the ATLAS detector for measuring the paths of the particles produced by collisions and the points where they decay mean we in Lancaster will be able to make really precise measurements of CP violation and particle lifetimes in more conventional particles. The extremely large samples of the relevant decays will also contribute to the high precision required to see the influence of any new physics effects such as supersymmetry.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/83812/original/image-20150603-2966-1rs9yi0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/83812/original/image-20150603-2966-1rs9yi0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=309&fit=crop&dpr=1 600w, https://images.theconversation.com/files/83812/original/image-20150603-2966-1rs9yi0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=309&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/83812/original/image-20150603-2966-1rs9yi0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=309&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/83812/original/image-20150603-2966-1rs9yi0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=388&fit=crop&dpr=1 754w, https://images.theconversation.com/files/83812/original/image-20150603-2966-1rs9yi0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=388&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/83812/original/image-20150603-2966-1rs9yi0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=388&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Smashing job.</span>
<span class="attribution"><span class="source">CMS/CERN</span></span>
</figcaption>
</figure>
<p>We will also be looking for other new particles, particularly those that decay into two “jets” of ordinary particles. This is really important for understanding how often you get double collisions between the particles inside the protons. The energy signature from these double collisions can mimic some of the effects predicted by new theories. So we need to understand the collisions before we can claim them as evidence for those theories. </p>
<p>The two year period during which the LHC was offline was an intensely busy time for the accelerator and detector teams. But the work will now intensify at major analysis centres such as Lancaster to extract the relevant results from the large volumes of data the LHC is producing. For the young physicists doing their PhD studies or in their first research positions and the older hands directing them, this is the most exciting time when the work all comes together.</p>
<p>What will be found is unknown – and an unexpected finding could transform our whole programme of work. Whatever nature reveals, it will be interesting and potentially could profoundly change our view of the fundamental workings of the universe.</p><img src="https://counter.theconversation.com/content/42775/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Jones receives funding from STFC.</span></em></p>CERN’s huge particle accelerator has been switched back on after a two-year upgrade to continue its search for answers.Roger Jones, Professor of Physics, Head of Department, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/386642015-03-11T17:56:27Z2015-03-11T17:56:27ZWhat will we find next inside the Large Hadron Collider?<figure><img src="https://images.theconversation.com/files/74513/original/image-20150311-24209-1s37umw.jpg?ixlib=rb-1.1.0&rect=75%2C0%2C810%2C612&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What lies within?</span> <span class="attribution"><span class="source">Maximilien Brice/CERN</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>The Large Hadron Collider, the world’s largest scientific experiment, is due to restart this month <a href="http://www.bbc.co.uk/news/science-environment-21421460">after two years of downtime</a> for maintenance and upgrading. There’s no doubt that having played its role in the discovery of the Higgs boson in 2012, what the media christened the “God particle”, expectations for what the <a href="http://home.web.cern.ch/topics/large-hadron-collider">27km particle accelerator</a> at CERN could achieve this time have certainly been set high.</p>
<p>The <a href="http://home.web.cern.ch/topics/higgs-boson">Higgs boson</a> is a possible explanation for the origin of mass, something predicted in 1964 by Peter Higgs and several other physicists, and the discovery of which led to the award of <a href="https://theconversation.com/nobel-prize-in-physics-goes-to-discovery-of-the-higgs-boson-19014">a Nobel Prize for physics</a> for Higgs and François Englert in 2013.</p>
<p>So why did it take so long to discover it? As Einstein showed in his mass-energy equivalence (E=MC<sup>2),</sup> the mass of a particle is a measure of its energy content. If a particle is more massive, it has a greater energy content, and conversely to create a massive particle requires a great deal of energy. So simply put, it wasn’t until the Large Hadron Collider (LHC) was capable of colliding beams of protons with sufficient energy that the Higgs Boson could be created with its mass of 126 billion electron volts (<a href="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ev.html">gigaelectronvolts</a>, or GeV). In particle physics it is usual to give masses in terms of energy, and while 126GeV is equivalent to only 2.24x1025kg, this mass is about 127 times larger than a single proton.</p>
<p>So the intention is that following a two-year upgrade the LHC’s new, more powerful electromagnets will be sufficient to accelerate two beams of protons to 6.5 trillion electron volts (teraelectronvolts, or TeV), increasing the potential collision energy from 8TeV in 2012 to 13TeV. And with greater collision energy comes the possibility of creating and detecting new particles of even greater mass. The expectation is that the LHC’s experiments could uncover new particles known as <a href="http://home.web.cern.ch/about/physics/z-boson">Z particles</a>, new Higgs bosons, and even <a href="http://home.web.cern.ch/about/physics/dark-matter">particles of dark matter</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/74517/original/image-20150311-24168-1m2cvgi.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/74517/original/image-20150311-24168-1m2cvgi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/74517/original/image-20150311-24168-1m2cvgi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=465&fit=crop&dpr=1 600w, https://images.theconversation.com/files/74517/original/image-20150311-24168-1m2cvgi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=465&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/74517/original/image-20150311-24168-1m2cvgi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=465&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/74517/original/image-20150311-24168-1m2cvgi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=584&fit=crop&dpr=1 754w, https://images.theconversation.com/files/74517/original/image-20150311-24168-1m2cvgi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=584&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/74517/original/image-20150311-24168-1m2cvgi.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=584&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A map of subatomic particles, known and hypothesised.</span>
<span class="attribution"><a class="source" href="http://en.wikipedia.org/wiki/File:Standard_Model_of_Elementary_Particles.svg">MissMJ</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>From Higgs to Z</h2>
<p>Discovered at CERN in 1983, the Z particle is a force carrier – a particle that carries one of the <a href="http://csep10.phys.utk.edu/astr162/lect/cosmology/forces.html">four fundamental forces</a> of nature: the gravitational, electromagnetic, strong and weak forces. The Z particle <a href="http://www.livescience.com/49254-weak-force.html">carries the weak force</a>, which is implicated in subatomic reactions. A related, theorised particle that could be next to be discovered is the <a href="http://press.web.cern.ch/backgrounders/w-prime-and-z-prime">Z prime particle</a>, or Z’. This would help our understanding of gravitons, the carriers of the gravitational force that are theorised but have not yet been detected.</p>
<p>Taking the constituents of the universe as a whole, we have a good understanding of about 5% of it. The remaining 95% is made up of <a href="http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/">about 68% dark energy and 27% dark matter</a>. With a little over 84% of the universe’s mass being dark – not detectable by any known means – if the LHC can in some way shed some light on the nature of this matter it will move our understanding of the universe forward.</p>
<p>With an upgraded LHC able to provide higher collision energies and the possibility of creating new particles – whether those currently theorised or not – it will have a significant impact on our fundamental understanding of the laws of nature and the accepted model that is used to try and explain them.</p>
<p>Some may point to the cost of the LHC upgrade, <a href="http://www.bbc.co.uk/news/science-environment-21941666">estimated at around £70m</a>, as a cost beyond the public purse in these cash-strapped times of austerity. But the possibilities for what it can add to our understanding of the world cannot be ignored either, nor the benefits they might have in other areas, for example medical imaging. Considering how regularly sums far larger than £70m of taxpayers’ money are squandered, CERN’s role as a global educational tool for physicists, mathematicians and engineers must be considered excellent value for money.</p><img src="https://counter.theconversation.com/content/38664/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gren Ireson receives funding from the European Union and Particle Physics and Astronomy Research Council.</span></em></p>Ticking off subatomic particles one by one, now let’s see what an LHC upgrade will do.Gren Ireson, Professor of physics, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/376382015-02-24T19:30:25Z2015-02-24T19:30:25ZThe LHC is back and it’s ready to probe the limits of matter<figure><img src="https://images.theconversation.com/files/72728/original/image-20150223-21887-hkve6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A 3D artist has dissected the LHC in this composite image, showing a cut-out section of a superconducting dipole magnet. The beam pipes are represented as clear tubes, with counter-rotating proton beams shown in red and blue</span> <span class="attribution"><a class="source" href="http://home.web.cern.ch/about/updates/2015/02/cerns-two-year-shutdown-drawing-close">Daniel Dominguez/CERN</a></span></figcaption></figure><p>Since <a href="https://theconversation.com/goodbye-for-a-while-to-the-large-hadron-collider-12238">shutting down</a> in early 2013, the most powerful particle accelerator on the planet, the <a href="http://home.web.cern.ch/topics/large-hadron-collider">Large Hadron Collider</a> (LHC), has been sitting dormant. Over the past two years this scientific colossus situated at CERN near Geneva, Switzerland, has undergone a series of repairs and upgrades. But now it is ready to reawaken from it’s slumber. </p>
<p>This new era will see a collider with almost double the previous energy, with collisions at <a href="http://home.web.cern.ch/about/engineering/restarting-lhc-why-13-tev">13 TeV</a>. Scaled up into our macroscopic world, the force of these collisions between protons is roughly equivalent to an apple hitting the moon hard enough to create a crater more than 9.5km (6 miles) across. </p>
<p>This new energy frontier will allow researchers to probe beyond the current boundaries of our understanding of the fundamental structure of matter in search of new discoveries.</p>
<h2>Detector upgrades</h2>
<p>In order to make the most of the new accelerator conditions, the discovery experiments, ATLAS and CMS, have undergone further upgrades during the shutdown period. </p>
<p>Most notably the <a href="http://home.web.cern.ch/about/experiments/atlas">ATLAS experiment</a> has added an entirely new detector, the <a href="http://atlas.ch/news/2014/a-new-sub-detector-for-ATLAS.html">Insertable b-Layer</a>, or IBL. This sits very close to the point where the protons slam into each other, creating a cascade of other subatomic particles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/72735/original/image-20150223-21879-vohz2t.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/72735/original/image-20150223-21879-vohz2t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/72735/original/image-20150223-21879-vohz2t.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/72735/original/image-20150223-21879-vohz2t.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/72735/original/image-20150223-21879-vohz2t.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/72735/original/image-20150223-21879-vohz2t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/72735/original/image-20150223-21879-vohz2t.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/72735/original/image-20150223-21879-vohz2t.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A visualisation of particles colliding in the ATLAS detector back in 2012. New experiments will be run at a higher energy and may yield even more startling results.</span>
<span class="attribution"><a class="source" href="http://cds.cern.ch/record/1459496">ATLAS team/CERN</a></span>
</figcaption>
</figure>
<p>Because the IBL sits closer to the action than the original detectors – which are also still in use – it provides an additional measurement point for particles originating from the collisions, allowing greater accuracy on the resulting measurements. </p>
<p>The IBL will be especially important for identifying heavy particles, such as <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/particles/quark.html">bottom quarks</a>, which are produced during decays of short-lived particles such as the Higgs boson and are crucial for measurements of the top quark (which decays to a bottom quark and <a href="http://home.web.cern.ch/about/physics/w-boson-sunshine-and-stardust">W boson</a>). </p>
<h2>Beyond the Higgs boson</h2>
<p>During the first run of the LHC in 2012, the ATLAS and <a href="http://home.web.cern.ch/about/experiments/cms">CMS</a> experiments ended the 50 year hunt for the <a href="https://theconversation.com/explainer-the-higgs-boson-particle-280">Higgs boson</a>, which was predicted by the <a href="http://physics.info/standard/">Standard Model</a> –- a theory governing all particles, forces and interactions. </p>
<p>Having measured the mass of the Higgs boson by looking at the way it decays into other particles, LHC scientists then went one step further. In 2013 they measured the properties of the boson, all of which proved consistent with the predictions of the Standard Model. </p>
<p>Now physicists want to know if the Higgs they found is hiding any surprises. And, perhaps more importantly, what may be lurking beyond it. The increase in LHC energy is coupled with an increase in <a href="http://www.lhc-closer.es/1/4/9/0">luminosity</a>, which allows physicists to probe rare events with greater frequency. </p>
<p>This high luminosity in concert with the increase in energy provides an unprecedented environment to interrogate fundamental physics beyond the limits of our current knowledge. The first thing to do with the new data is to study the Higgs boson in depth to see if anything disagrees with prediction. </p>
<p>This could be a window into new physics. Because the Higgs boson loves mass, scientists suspect that it might interact with a range of hidden, massive particles that we cannot see, such as potential candidates for <a href="https://theconversation.com/au/topics/dark-matter">dark matter</a>. </p>
<p>If the Higgs boson is partying with as yet undiscovered particles, physicists hope that their newly improved particle collider and upgraded detector instruments will allow them to crash the party -– and find out something about the attendees!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/72739/original/image-20150223-19701-10s5fbw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/72739/original/image-20150223-19701-10s5fbw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/72739/original/image-20150223-19701-10s5fbw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=781&fit=crop&dpr=1 600w, https://images.theconversation.com/files/72739/original/image-20150223-19701-10s5fbw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=781&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/72739/original/image-20150223-19701-10s5fbw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=781&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/72739/original/image-20150223-19701-10s5fbw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=981&fit=crop&dpr=1 754w, https://images.theconversation.com/files/72739/original/image-20150223-19701-10s5fbw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=981&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/72739/original/image-20150223-19701-10s5fbw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=981&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Candidate Higgs boson events from collisions between protons in the LHC. The top event in the CMS experiment shows a decay into two photons (dashed yellow lines and green towers). The lower event in the ATLAS experiment shows a decay into four muons (red tracks).</span>
<span class="attribution"><a class="source" href="http://cds.cern.ch/record/1630222">ATLAS and CMS, Collaborations</a></span>
</figcaption>
</figure>
<h2>Supersymmetry, dark matter and other exotica</h2>
<p>Even if the Higgs boson were to continue to agree with the Standard Model predictions, the value of its mass is still suggestive of other interesting goings-on in the universe. </p>
<p>When LHC physicists measured the Higgs mass, they found it was lower than what they anticipated. This might make sense if it was being caused – or protected – by one or more particles that exist at a higher mass and were governed by some new “symmetry”. </p>
<p><a href="https://theconversation.com/could-the-higgs-nobel-be-the-end-of-particle-physics-18978">Supersymmetry</a> is one such extension of the Standard Model that would yield additional partners of the known objects that may appear in high-energy LHC collisions. </p>
<p>These particles could act as “bodyguards” of the Higgs, influencing its measured mass. These supersymmetric particles could potentially be produced in the next run of the LHC, perhaps even as early as this year. </p>
<p>One natural consequence of certain supersymmetric models is the production of invisible stable massive particles that are weakly interacting. Such a particle would be an excellent candidate for dark matter, the mysterious invisible matter that we have thus far only detected via its gravitational effect. </p>
<p>Providing clues as to the nature of dark matter is one of the main motivators of the increased energy and intensity of the LHC collisions. Any evidence of dark matter and/or results consistent with supersymmetry would be hugely significant and would open up a new chapter in our understanding of the universe at a fundamental level. </p>
<p>But the experiments must be prepared for <em>any</em> possible signature to be manifested in their collisions, and subsequently mine the data for evidence of exotic resonant structures, extra dimensions or long-lived particles among many other possibilities.</p>
<p>So 2015 promises to be a once in a lifetime opportunity for a generation of physicists who will turn on and commission a machine at unprecedented energies. With new discoveries potentially just around the corner this may well be a defining time in the field of high energy particle physics.</p><img src="https://counter.theconversation.com/content/37638/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Paul Jackson works in the Department of Physics at the University of Adelaide. He receives funding from the Australian Research Council under the Future Fellowship scheme. He is affiliated with the ARC Centre of Excellence for Particle Physics and the Terascale and is the recipient of a 2015 Australia-Harvard Fellowship.</span></em></p>The Large Hadron Collider is ramping up to probe even deeper into the fundamental constituents of matter.Paul Jackson, Particle physicist, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/340812014-12-15T03:45:09Z2014-12-15T03:45:09ZAn electron’s near-light-speed tour of the Australian Synchrotron<figure><img src="https://images.theconversation.com/files/66365/original/image-20141204-7280-3v2o0f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">By the time you've read this caption, electrons in the synchrotron storage ring will have travelled a distance equivalent to 41 times around the Earth.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/manfredmajer/13168276114">manfred majer/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>There’s a place in Melbourne where particles routinely whiz around at 99.99998% the <a href="http://www.grc.nasa.gov/WWW/k-12/Numbers/Math/Mathematical_Thinking/how_fast_is_the_speed.htm">speed of light</a> – the <a href="http://www.synchrotron.org.au">Australian Synchrotron</a>. By accelerating charged particles to release extremely intense light known as <a href="http://dictionary.reference.com/browse/synchrotron%20radiation?s=t">synchrotron radiation</a>, the synchrotron gives scientists a mighty toolkit of advanced analytical and imaging techniques. </p>
<p>Depending on the speed of the particles, the radiation released can be infrared, visible or ultraviolet light, or X-rays of varying energy.</p>
<p>So how do these charged particles get to such high speeds? Let’s take a look at the synchrotron and its array of super-powerful magnets that accelerate electrons to close to the speed of light.</p>
<p>Synchrotron radiation also <a href="http://www.ugr.es/%7Ebattaner/escritos/granada_paper.pdf">exists in nature</a>, notably in the outskirts of the <a href="http://www.nasa.gov/multimedia/imagegallery/image_feature_567.html">Crab Nebula</a>, 6,523 <a href="https://theconversation.com/explainer-light-years-and-units-for-the-stars-16995">light-years</a> from Earth, where crowds of electrons travelling at close to the speed of light trace a curved path under the influence of powerful magnetic fields. </p>
<h2>Radiation generation</h2>
<p>From <a href="http://xdb.lbl.gov/Section2/Sec_2-2.html">humble beginnings</a> in the 1940s as an unwanted by-product of particle accelerators, synchrotron radiation has become the power behind numerous practical outcomes of major benefit to Australia.</p>
<p>A good way to explain how radiation is produced when a particle is accelerated is to look at what happens to the electric field around a charged particle when the particle moves.</p>
<p>All charged particles are surrounded by electric fields. Accelerating the charged particle creates fluctuations in the electric field that propagate outwards. As the electric field changes, it in turn generates an associated magnetic field.</p>
<p>These fluctuations manifest as <a href="http://missionscience.nasa.gov/ems/02_anatomy.html">electromagnetic waves</a> which are waves propagated by simultaneous periodic variations of electric and magnetic field intensity. And so an accelerating charge emits electromagnetic radiation, which may include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays or gamma rays. (You can see how the process works using this <a href="http://phet.colorado.edu/sims/radiating-charge/radiating-charge_en.html">interactive simulation</a>.)</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/74n8L5X2YSI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Discover the diverse types of research at the Australian Synchrotron.</span></figcaption>
</figure>
<p>Synchrotron electrons aren’t the only example of accelerating charges emitting electromagnetic radiation. But synchrotron radiation has interesting properties because the electrons are moving at velocities very close to the speed of light.</p>
<p>If you were an electron, you would “see” that you were emitting radiation in all directions. But from the point of view of the mere humans at the synchrotron, relativity means that the radiation is emitted in a very tight forward-facing cone.</p>
<p>Relativity also increases the frequency of the radiation, so most of the light is in the X-ray part of the electromagnetic spectrum, with some ultraviolet, visible and infrared light as well.</p>
<p>The opening angle of the cone of radiation depends on the energy of the electron beam. Higher-energy beams generate cones with smaller opening angles; in other words, tighter cones. These smaller emission angles concentrate the light and make synchrotron radiation extremely bright when seen head-on, which is what most samples get.</p>
<h2>An electron’s journey</h2>
<p>The heart of the Australian Synchrotron is its light source. As used in this context, the term “synchrotron” is in fact short for “synchrotron light source”. To an accelerator physicist, a synchrotron is actually a particular type of particle accelerator. But I digress.</p>
<p>At the Australian Synchrotron, the light source is a maze of high-tech equipment that generates bunches of electrons, accelerates them to almost the speed of light and forces them round a curved path to produce light from X-ray to infrared wavelengths for use in scientific and industrial research programs.</p>
<p>The electrons begin their journey in the electron gun, which works a bit like the cathode ray tubes in old television sets. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66260/original/image-20141203-3654-1iociv3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Outside …</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66262/original/image-20141203-3648-h4d715.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">… and inside the electron gun.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>They’re liberated from a metal cathode heated to 1,000C and shot into the linear accelerator in bunches of around 100 million electrons spaced just two nanoseconds apart, travelling at more than 640 million km/h, almost 60% of the speed of light. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0gf85P0PiBg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The linear accelerator further accelerates the electrons to more than 100 billion km/h or roughly 99.9987% of the speed of light. The radiowave energy used to speed up the electrons comes from a klystron, a type of power amplifier commonly used in radar and radio/ TV broadcasting.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66258/original/image-20141203-3645-hsotm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66258/original/image-20141203-3645-hsotm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66258/original/image-20141203-3645-hsotm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66258/original/image-20141203-3645-hsotm4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66258/original/image-20141203-3645-hsotm4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66258/original/image-20141203-3645-hsotm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66258/original/image-20141203-3645-hsotm4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66258/original/image-20141203-3645-hsotm4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Moving from the electron gun into the start of the linear accelerator.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Next is the booster ring, where large electromagnets steer the electron bunches around a near-circular path and control their shape and size. A radiofrequency cavity increases their energy every time they go past.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/uYcEZ3H5FbE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>After 600 milliseconds and 1.38-million laps, the bunches are travelling at 99.99998% of the speed of light and have 30 times the energy they had when they left the linear accelerator.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66256/original/image-20141203-3613-nvnsrg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The linear accelerator (L) joins the booster ring.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>They’re ready to move into their final home, the storage ring, a long stainless steel vacuum chamber that operates at a pressure similar to the moon’s atmosphere.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66259/original/image-20141203-3651-7g5lns.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Inside the storage ring tunnel.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>The electrons circulate in the storage ring for approximately 30-40 hours, travelling the equivalent of more than seven laps around the Earth every second.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/n6ho-tv6XtE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>As they pass through magnets that control their movements, they emit synchrotron radiation, like their counterparts in interstellar space. More radiofrequency cavities add energy to the electrons to compensate for energy lost. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66264/original/image-20141203-3633-1ta2zsy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A radiofrequency cavity boosts energy of electron bunches.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Three main kinds of magnet are colour-coded yellow, green or red according to function:</p>
<ul>
<li>yellow dipole (two poles) bending magnets steer the electron bunches and can act as a source of synchrotron radiation</li>
<li>red quadrupole magnets focus the electron bunches</li>
<li>green sextupole magnets help correct for focusing errors and steer the beam on the correct path.</li>
</ul>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66266/original/image-20141203-3654-jsmsox.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The actual storage ring is the metal tube running through the middle of the red and green magnets.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Some experiments require more powerful or more highly coherent synchrotron radiation light than the yellow dipoles can produce. For these, specialised magnets called insertion devices are inserted into the line of storage ring magnets.</p>
<p>Insertion devices consist of a large array of small but very strong magnets that either undulate or wiggle the electron bunches as they pass through. Undulators produce highly intense, highly coherent light compared to dipole radiation, while wigglers produce highly intense, higher energy light.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=587&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=587&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=587&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=738&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=738&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66263/original/image-20141203-3625-1jqrg1q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=738&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Insertion devices.</span>
<span class="attribution"><span class="source">Australian Synchrotron</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>The most powerful insertion device at the Australian Synchrotron is the A$1.3 million superconducting multi-pole wiggler magnet (affectionately called the silver wiggler) that provides X-rays for the imaging and medical beamline.</p>
<h2>In the control room</h2>
<p>The Australian Synchrotron light source is operated and maintained by specialist control room staff and accelerator physicists. They make sure a consistent and reliable supply of high-quality X-ray and infrared photons is available for the thousands of researchers who use the synchrotron’s unique capabilities each year.</p>
<p>The accelerator science team also conducts a research and development program to further improve synchrotron photon characteristics for particular experiments, and contributes to international efforts to pave the way for future machines. </p>
<p>Key results to date include:</p>
<ul>
<li><p>better thermal stability for optical beamline components (from using frequent <a href="http://www.synchrotron.org.au/about-us/australian-synchrotron-development-plan/asdp-accelerator-and-facility-upgrades/top-up-mode-project">top-ups</a> to keep an almost-constant number of electrons in the storage ring rather than twice-daily injections)</p></li>
<li><p>a smaller beam with more photons (due to an electron beam with reduced <a href="http://www.synchrotron.org.au/about-us/our-facilities/accelerator-physics/as-physicists-achieve-new-low">vertical emittance</a>, a measure of the spread of individual particles in a beam) to enable faster data collection from the tiniest of samples, smaller than five micrometres across (one twentieth the width of a typical human hair).</p></li>
</ul>
<p>Three years ago the Australian Synchrotron broke the world record for low vertical emittance in an electron beam, with an electron beam that was only a few micrometres high in places, or as fine as spider silk.</p>
<p>That’s pretty much the end for the electrons, in the capable hands of the accelerator specialists. But what happens to the light the electrons produce is another story.</p><img src="https://counter.theconversation.com/content/34081/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nancy Mills works for The Australian Synchrotron.</span></em></p>There’s a place in Melbourne where particles routinely whiz around at 99.99998% the speed of light – the Australian Synchrotron. By accelerating charged particles to release extremely intense light known…Nancy Mills, Science writer, Australian SynchrotronLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/338762014-11-05T18:11:51Z2014-11-05T18:11:51ZCheaper, more compact particle accelerators are a step closer<figure><img src="https://images.theconversation.com/files/63783/original/2hhdwtf7-1415210898.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Before the big bang.</span> <span class="attribution"><span class="source">SLAC National Accelerator Laboratory</span></span></figcaption></figure><p>Scientists working on an experiment at the <a href="https://www6.slac.stanford.edu/">SLAC National Accelerator Laboratory</a> in the US have taken a step forward in developing a technology which could significantly reduce the size of particle accelerators. The technology is able to accelerate particles more rapidly than conventional accelerators at a much smaller size.</p>
<p>One of the most impressive aspects of particle accelerators used for research such as the Large Hadron Collider (LHC) at CERN is its physical size. Yet, even with a circumference of 27km, the LHC would be smaller than most of the next generation of proposed colliders. For example the <a href="https://www.linearcollider.org/">International Linear Collider</a> (ILC), a possible future collider of electrons and positrons (anti-electrons) could be 31km long, and there is even a proposal for a circular accelerator with an 80km circumference that could be built at CERN as part of the <a href="http://tlep.web.cern.ch/">Future Circular Colliders</a> (FCC) project.</p>
<p>The size of all of these machines is determined by our ability to build structures that can transfer energy to particles allowing us to accelerate them to greater speeds. The higher the speed, the greater the energy when these particle beams collide, giving scientists a better chance of answering fundamental questions about the universe. This is because higher energy collisions can create conditions that are similar to those existing when the universe was born. </p>
<p>Most current accelerators use a structure called an “rf cavity”, a carefully designed “box” through which the particle beam passes. The cavity transfers electromagnetic energy into the kinetic energy of particles, accelerating them. However, there is a limit to the amount of energy that an rf cavity can transfer to particles. This is because, despite operating in a vacuum, there is a risk that increasing electromagnetic fields can lead to lightning-like discharges of energy. </p>
<p>However, even routine experiments in places like the LHC require more energy than a single rf cavity can provide. That is why the current solution is to use very many cavities arranged in a straight line, if it is a linear machine such as the SLAC, or using the same cavity very many times if it is in a circular machine, such as the LHC. </p>
<p>Either solution <a href="https://theconversation.com/could-the-higgs-nobel-be-the-end-of-particle-physics-18978">presents challenges</a> and requires a large machine to fit in the many parts needed. This raises the costs. Any technology which can increase the acceleration with smaller parts and without the need for more machinery will make future accelerators more compact. </p>
<p>This matters because particle accelerators are not just for particle physicists. They are increasingly used in medicine, industry and security. For example, accelerators provide X-rays and particle beams for cancer therapy, for the fabrication of minuscule devices and for scanning the contents of everything from suitcases to freight containers. </p>
<p>The new technology which could promise more compact particle accelerators has just been published in a study in <a href="http://dx.doi.org/10.1038/nature13882">Nature</a>. The study suggests that, if bunches of electrons are passed through a short column of lithium vapour “plasma” in rapid succession, the electric field of the plasma is able to translate enough energy to accelerate particles hundreds of times quicker than the LHC. It is able to achieve all this while only being 30cm in length.</p>
<p>Plasma is a state of matter where atoms are broken down into positively charged ions and negatively charged electrons. Most of the matter in the sun exists as plasma, but we can create that state on Earth using high energy lasers. </p>
<p>The electric field between particles in a plasma can be extremely high. In this experiment, as the bunch of electrons passes through the plasma it causes the electrons of the plasma to move, leaving behind it a region of oscillating electrons. It is this oscillation which generate the “wakefield” which can then be used to accelerate a second set of trailing electrons following very close behind the first bunch. </p>
<p>Although previous experiments have shown even greater gains in energy, what makes this experiment interesting is the number of electrons accelerated and how evenly each of them acquires energy. Being able to accelerate large numbers of particles to the same energy simultaneously is a prerequisite for any future practical use of this technology called “plasma wakefield acceleration”. </p>
<p>Other groups around the world including the <a href="http://awake.web.cern.ch/awake/">AWAKE collaboration</a> at CERN and the <a href="http://phys.strath.ac.uk/alpha-x/pub/People/Strathclyde.html">ALPHA-X collaboration</a> based at the University of Strathclyde are pursuing different approaches to plasma wakefield acceleration using proton beams or lasers to generate the wakefield. Meanwhile there are already tentative designs being proposed for future accelerators that could make use of this technology, if accelerating large numbers of particles simultaneously can be made reliable.</p><img src="https://counter.theconversation.com/content/33876/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Bailey receives funding from the STFC (Science and Technology Facilities Council).</span></em></p>Scientists working on an experiment at the SLAC National Accelerator Laboratory in the US have taken a step forward in developing a technology which could significantly reduce the size of particle accelerators…Ian Bailey, Lecturer, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.