tag:theconversation.com,2011:/uk/topics/lhc-13349/articlesLHC – The Conversation2021-10-19T11:04:14Ztag:theconversation.com,2011:article/1701332021-10-19T11:04:14Z2021-10-19T11:04:14ZNew physics: latest results from Cern further boost tantalising evidence<figure><img src="https://images.theconversation.com/files/426951/original/file-20211018-57123-1i3a8rx.jpg?ixlib=rb-1.1.0&rect=0%2C26%2C1592%2C1159&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's more going on in the universe than we know.</span> <span class="attribution"><a class="source" href="https://flickr.com/photos/zoltlevay/17290564055/in/photolist-skUEin-2jpVGiL-SmMs6J-25HSziS-26CVPhm-2jGcDsw-ZUtHrQ-2hYELzE-2jrDPQ5-2hYTHbt-2hMCnmp-Zxttv9-ac29Ct-kX7TJF-2mgGPXm-KK7dFy-VXFewH-2m493mC-23yam7D-2htZuyS-PAuyY2-2kZk4Sv-ANHfHd-2gqkJuK-vpPXp2-J9FLaV-JDEPLy-2jpUttD-2m8vFgG-qDywSW-4hq6fG-2hXF5T9-28prfUU-2hYCngf-Mg6wGM-Nky8yz-2hYEXQz-j5pqja-VPCZMh-UUESai-zdR8je-2hnbV4q-2jt14fV-UXEgSc-CmHioc-2hnbUQ9-E3gqc3-KYm3GB-BpjFZt-2hAkpkX">Zolt Levay/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The Large Hadron Collider (LHC) sparked worldwide excitement in March as particle physicists reported <a href="https://theconversation.com/evidence-of-brand-new-physics-at-cern-why-were-cautiously-optimistic-about-our-new-findings-157464">tantalising evidence</a> for new physics - potentially a new force of nature. Now, <a href="https://arxiv.org/abs/2110.09501">our new result</a>, yet to be peer reviewed, from Cern’s gargantuan particle collider seems to be adding further support to the idea.</p>
<p>Our current best theory of particles and forces is known as the <a href="https://home.cern/science/physics/standard-model">standard model</a>, which describes everything we know about the physical stuff that makes up the world around us with unerring accuracy. The standard model is without doubt the most successful scientific theory ever written down and yet at the same time we know it must be incomplete.</p>
<p>Famously, it describes only three of the <a href="https://www.space.com/four-fundamental-forces.html">four fundamental forces</a> – the electromagnetic force and strong and weak forces, leaving out gravity. It has no explanation for the <a href="https://theconversation.com/from-machos-to-wimps-meet-the-top-five-candidates-for-dark-matter-51516">dark matter</a> that astronomy tells us dominates the universe, and cannot explain <a href="https://theconversation.com/cern-study-sheds-light-on-one-of-physics-biggest-mysteries-why-theres-more-matter-than-antimatter-113947">how matter survived</a> during the big bang. Most physicists are therefore confident that there must be more cosmic ingredients yet to be discovered, and studying a variety of fundamental particles known as beauty quarks is a particularly promising way to get hints of what else might be out there.</p>
<p>Beauty quarks, sometimes called bottom quarks, are <a href="https://home.cern/science/physics/standard-model">fundamental particles</a>, which in turn make up bigger particles. There are six flavours of quarks that are dubbed up, down, strange, charm, beauty/bottom and truth/top. Up and down quarks, for example, make up the protons and neutrons in the atomic nucleus.</p>
<p>Beauty quarks are unstable, living on average just for about 1.5 trillionths of a second before decaying into other particles. The way beauty quarks decay can be strongly influenced by the existence of other fundamental particles or forces. When a beauty quark decays, it transforms into a set of lighter particles, such as electrons, through the influence of the weak force. One of the ways a new force of nature might make itself known to us is by subtly changing how often beauty quarks decay into different types of particles. </p>
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Read more:
<a href="https://theconversation.com/a-new-force-of-nature-the-inside-story-of-fresh-evidence-from-cern-thats-exciting-physicists-podcast-158198">A new force of nature? The inside story of fresh evidence from Cern that's exciting physicists – podcast</a>
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<p>The March paper was based on data from the LHCb experiment, one of four giant particle detectors that record the outcome of the ultra high-energy collisions produced by the LHC. (The “b” in LHCb stands for “beauty”.) It found that beauty quarks were decaying into electrons and their heavier cousins called muons at different rates. This was truly surprising because, according to the standard model, <a href="https://www.isis.stfc.ac.uk/Pages/What-is-a-muon.aspx">the muon</a> is basically a carbon copy of the electron – identical in every way except for being around 200 times heavier. This means that all the forces should pull on electrons and muons with equal strength – when a beauty quark decays into electrons or muons via the weak force, it ought to do so equally often. </p>
<p>Instead, my colleagues found that the muon decay was only happening about 85% as often as the electron decay. Assuming the result is correct, the only way to explain such an effect would be if some new force of nature that pulls on electrons and muons differently is interfering with how beauty quarks decay. </p>
<p>The result caused huge excitement among particle physicists. We’ve been searching for signs of something beyond the standard model for decades, and despite ten years of work at the LHC, nothing conclusive has been found so far. So discovering a new force of nature would be a huge deal and could finally open the door to answering some of the deepest mysteries facing modern science. </p>
<h2>New results</h2>
<p>While the result was tantalising, it wasn’t conclusive. All measurements come with a certain degree of uncertainty or “error”. In this case there was only around a one in 1,000 chance that the result was down to a random statistical wobble – or “three sigma” as we say in particle physics parlance. </p>
<p>One in 1,000 may not sound like a lot, but we make a very large number of measurements in particle physics and so you might expect a small handful to throw up outliers just by random chance. To be really sure that the effect is real, we’d need to get to five sigma – corresponding to less than a one in a million chance of the effect being down to a cruel statistical fluke.</p>
<p>To get there, we need to reduce the size of the error, and to do this we need more data. One way to achieve this is simply to run the experiment for longer and record more decays. The LHCb experiment is currently <a href="https://gtr.ukri.org/projects?ref=ST%2FV003127%2F1">being upgraded</a> to be able to record collisions at a much higher rate in future, which will allow us to make much more precise measurements. But we can also get useful information out of the data we’ve already recorded by looking for similar types of decays that are harder to spot.</p>
<figure class="align-center ">
<img alt="Image of the LHCb experiment." src="https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.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">
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<span class="caption">LHCb experiment.</span>
<span class="attribution"><span class="source">Cern</span></span>
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<p>This is what my colleagues and I have done. Strictly speaking, we never actually study beauty quark decays directly, since all quarks are always bound together with other quarks to make larger particles. The March study looked at beauty quarks that were paired up with “up” quarks. Our result studied two decays: one where the beauty quarks that were paired with “down” quarks and another where they were also paired with up quarks. That the pairing is different shouldn’t matter, though – the decay that’s going on deep down is the same and so we’d expect to see the same effect, if there really is a new force out there.</p>
<p>And that is exactly what we’ve seen. This time, muon decays were only happening around 70% as often as the electron decays but with a larger error, meaning that the result is about “two sigma” from the standard model (around a two in a hundred chance of being a statistical anomaly). This means that while the result isn’t precise enough on its own to claim firm evidence for a new force, it does line up very closely with the previous result and adds further support to the idea that we might be on the brink of a major breakthrough.</p>
<p>Of course, we should be cautious. There is some way to go still before we can claim with a degree of certainty that we really are seeing the influence of a fifth force of nature. My colleagues are currently working hard to squeeze as much information as possible out of the existing data, while busily preparing for the first run of the upgraded LHCb experiment. Meanwhile, other experiments at the LHC, as well at the <a href="https://www.belle2.org">Belle 2 experiment in Japan</a>, are closing in on the same measurements. It’s exciting to think that in the next few months or years a new window could be opened on the most fundamental ingredients of our universe.</p><img src="https://counter.theconversation.com/content/170133/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Harry Cliff is employed by the University of Cambridge, is a member of the LHCb collaboration and receives funding from STFC. </span></em></p>Particle physicists might be on the brink of a major breakthrough.Harry Cliff, Particle physicist, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1626872021-06-18T12:21:25Z2021-06-18T12:21:25ZCern: how we’re probing the universe’s origins using record precision measurements<figure><img src="https://images.theconversation.com/files/407198/original/file-20210618-18-1h7sua8.jpg?ixlib=rb-1.1.0&rect=0%2C35%2C5973%2C3898&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cern has measure a tiny mass difference by colliding huge amounts of particles.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/fragmentation-highenergy-collisions-between-atomic-subatomic-1443036710">Jurik Peter/Shutterstock</a></span></figcaption></figure><p>What happened at the beginning of the universe, in the very first moments? The truth is, we don’t really know because it takes huge amounts of energy and precision to recreate and understand the cosmos on such short timescales in the lab. But scientists at the Large Hadron Collider (LHC) at CERN, Switzerland aren’t giving up. </p>
<p>Now our <a href="https://home.cern/news/news/physics/lhcb-measures-tiny-mass-difference-between-particles">LHCb experiment</a> has measured one of the smallest difference in mass between two particles ever, which will allow us to discover much more about our enigmatic cosmic origins. </p>
<p>The Standard Model of particle physics describes <a href="https://theconversation.com/explainer-what-are-fundamental-particles-38339">the fundamental particles</a> which make up the universe, and the forces that act between them. The elementary particles include quarks, of which there are six – up, down, strange, charm, top and bottom. Similarly there are six “leptons” which include the electron, a heavier cousin called the muon, and the still heavier tau, each of which has an associated neutrino. There are also “antimatter partners” of all quarks and leptons which are identical particles apart from an opposite charge. </p>
<p>The Standard Model is experimentally verified to an incredible degree of accuracy but has some significant shortcomings. 13.8 billion years ago, the universe was created in the Big Bang. The theory suggests this event should have produced equal amounts of matter and “antimatter”. Yet today, the universe <a href="https://theconversation.com/explainer-what-is-antimatter-53414">is almost entirely made up of matter</a>. And that’s lucky, because antimatter and matter annihilate in a flash of energy when they meet.</p>
<p>One of the biggest open questions in physics today is why is there more matter than antimatter. Were there processes at play in the early universe that favoured matter over antimatter? To get closer to the answer, we have studied a process where matter transforms into antimatter and vice versa. </p>
<p>Quarks are bound together to form particles called baryons – including the protons and neutrons that make up the atomic nucleus – or mesons, which consist of quark-antiquark pairs. Mesons with zero electric charge continually undergo a phenomenon called mixing by which they spontaneously change into their antimatter particle, and vice versa. In this process, the quark turns into an anti-quark and the anti-quark turns into a quark.</p>
<p>It can do this because of quantum mechanics, which <a href="https://theconversation.com/physicists-prove-quantum-spookiness-and-start-chasing-schrodingers-cat-48190">governs the universe</a> on the tiniest of scales. According to this counter-intuitive theory, particles can be in many different states at the same time, essentially being a mix of many different particles – a feature called superposition. It is only when you measure its state that it “picks” one of them. A type of meson called D0, for example, which contains charm quarks, is in a superposition of two normal matter particles called D1 and D2. The rate at which the D0 meson turns into its anti-particle and back again, an oscillation, depends on the difference in masses of D1 and D2. </p>
<h2>Tiny masses</h2>
<p>It is difficult to measure mixing in D0 mesons, but <a href="https://www.desy.de/f/seminar/Staric.pdf">it was done</a> for the first time in 2007. However, until now, nobody has reliably measured the mass difference between D1 and D2 that determines how quickly the D0 oscillates into its antiparticle. </p>
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<img alt="Figure of the D1 and D2 meson." src="https://images.theconversation.com/files/407197/original/file-20210618-24-1844qru.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/407197/original/file-20210618-24-1844qru.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=333&fit=crop&dpr=1 600w, https://images.theconversation.com/files/407197/original/file-20210618-24-1844qru.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=333&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/407197/original/file-20210618-24-1844qru.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=333&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/407197/original/file-20210618-24-1844qru.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=419&fit=crop&dpr=1 754w, https://images.theconversation.com/files/407197/original/file-20210618-24-1844qru.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=419&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/407197/original/file-20210618-24-1844qru.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=419&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The D1 and D2 mesons, which are a manifestation of the quantum superposition of the D0 particle and its antiparticle.</span>
<span class="attribution"><span class="source">Cern</span></span>
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<p>Our latest discovery, <a href="https://home.cern/news/news/physics/lhcb-measures-tiny-mass-difference-between-particles">announced at the Charm conference</a>, changes this. We measured a parameter that corresponds to a mass difference of 6.4x10<sup>-6</sup> electron Volts (a measure of energy) or 10<sup>-38</sup> grams – one of the smallest mass differences between two particles ever measured.</p>
<p>We then calculated that the oscillation between the D0 and its antimatter partner takes around 630 picoseconds (1 ps = 1 millionth millionth of a second). This may seem fast, but the D0 meson doesn’t live long – it isn’t stable in the lab and falls apart (decays) into other particles after only 0.4 picoseconds. So it will typically disappear long before this oscillation occurs, posing a serious experimental challenge. </p>
<p>The key is precision. We know from theory that these oscillations follow the path of a a familiar type of wave (sinusoidal). Measuring the start of the wave very precisely, we can infer its full period as we know its shape. The measurement therefore had to reach record precision on several fronts. This is made possible by the unprecedented amount of charm particles produced at the LHC. </p>
<p>But why is this important? To understand why the universe produced less antimatter than matter we need to learn more about the asymmetry in the production of the two, a process known as CP-violation. It has already been shown that some unstable particles decay in a different way to their corresponding antimatter particle. This may have contributed <a href="https://theconversation.com/cern-study-sheds-light-on-one-of-physics-biggest-mysteries-why-theres-more-matter-than-antimatter-113947">to the abundance of matter in the universe</a> – with <a href="https://www.nobelprize.org/prizes/physics/2008/kobayashi/lecture/">previous discoveries</a> of it leading to Nobel Prizes.</p>
<p>We also want to find CP-violation in the process of mixing. If we start with millions of D0 particles and millions of D0 antiparticles, will we end up with more D0 normal matter particles after some time? Knowing the oscillation rate is a key step towards this goal. While we did not find an asymmetry this time, our result and further precision measurements can help us find it in the future. </p>
<p>Next year, the LHC will switch on after a long shut down and the new upgraded LHCb detector will take much more data, boosting the sensitivity of these measurements further. Meanwhile, theoretical physicists are working on new calculations to interpret this result. The LHCb physics programme will also be complemented by the <a href="https://www.belle2.org">Belle-II experiment</a> in Japan. These are exciting prospects for investigating matter-antimatter asymmetry and the oscillations of mesons.</p>
<p>While we cannot yet completely solve the mysteries of the universe, our latest discovery has put the next piece in the puzzle. The new upgraded LHCb detector will open the door to an era of precision measurements that have the potential to uncover yet unknown phenomena – and perhaps physics beyond the Standard Model.</p><img src="https://counter.theconversation.com/content/162687/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martha Hilton receives funding from STFC (Science Technology Facilities Council). </span></em></p><p class="fine-print"><em><span>Nathan Jurik received funding from the STFC (Science Technology Facilities Council).</span></em></p><p class="fine-print"><em><span>Sascha Stahl does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Record precision measurements at Cern may help explain why the universe has more matter than antimatter.Martha Hilton, PhD candidate in Particle Physics, University of ManchesterNathan Jurik, Research Fellow of Particle Physics, Syracuse UniversitySascha Stahl, Research staff at CERN, CERNLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1585642021-04-08T16:35:08Z2021-04-08T16:35:08ZHow we found hints of new particles or forces of nature – and why it could change physics<figure><img src="https://images.theconversation.com/files/394026/original/file-20210408-17-1ngm55l.jpg?ixlib=rb-1.1.0&rect=154%2C132%2C7172%2C4726&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The muon experiment.</span> <span class="attribution"><a class="source" href="https://vms.fnal.gov/asset/detail?recid=1950114">Reidar Hahn/Fermilab</a></span></figcaption></figure><p>Seven years ago, a huge magnet was transported over 3,200 miles (5,150km) across land and sea, in the hope of studying a subatomic particle called a muon.</p>
<p>Muons are closely related to electrons, which orbit every atom and form the building blocks of matter. The electron and muon both have properties precisely predicted by our current best scientific theory describing the subatomic, quantum world, the <a href="https://theconversation.com/explainer-standard-model-of-particle-physics-2539">standard model of particle physics</a>. </p>
<p>A whole generation of scientists have dedicated themselves to measuring these properties in exquisite detail. In 2001, an experiment hinted that one property of the muon was not exactly as the standard model predicted, but new studies were needed to confirm. Physicists moved part of the experiment to a new accelerator, at Fermilab, and started taking more data.</p>
<p>A <a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.141801">new measurement</a> has now confirmed the initial result. This means new particles or forces may exist that aren’t accounted for in the standard model. If this is the case, the laws of physics will have to be revised and no one knows where that may lead.</p>
<iframe src="https://embed.acast.com/60087127b9687759d637bade/606490a356dcab18893447f3?cover=true&ga=false" frameborder="0" allow="autoplay" width="100%" height="110"></iframe>
<p>This latest result comes from an international collaboration, of which we are both a part. Our team has been using particle accelerators to measure a property called the magnetic moment of the muon.</p>
<p>Each muon behaves like a tiny bar magnet when exposed to a magnetic field, an effect called the magnetic moment. Muons also have an intrinsic property called “spin”, and the relation between the spin and the magnetic moment of the muon is known as the g-factor. The “g” of the electron and muon is predicted to be two, so g minus two (g-2) should be measured to be zero. This is what’s we’re testing at Fermilab.</p>
<p>For these tests, scientists have used accelerators, the same kind of technology Cern uses at the LHC. The Fermilab accelerator produces muons in very large quantities and measures, very precisely, how they interact with a magnetic field. </p>
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Read more:
<a href="https://theconversation.com/evidence-of-brand-new-physics-at-cern-why-were-cautiously-optimistic-about-our-new-findings-157464">Evidence of brand new physics at Cern? Why we're cautiously optimistic about our new findings</a>
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<p>The muon’s behaviour is influenced by “virtual particles” that pop in and out of existence from the vacuum. These exist fleetingly, but for long enough to affect how the muon interacts with the magnetic field and change the measured magnetic moment, albeit by a tiny amount. </p>
<p>The standard model predicts very precisely, to better than one part in a million, what this effect is. As long as we know what particles are bubbling in and out of the vacuum, experiment and theory should match. But, if experiment and theory don’t match, our understanding of the soup of virtual particles may be incomplete.</p>
<h2>New particles</h2>
<p>The possibility of new particles existing is not idle speculation. Such particles might help in explaining several of the big problems in physics. Why, for example, does the universe have <a href="https://theconversation.com/why-do-astronomers-believe-in-dark-matter-122864">so much dark matter</a> – causing the galaxies to rotate faster than we’d expect – and why has nearly all the anti-matter created in the Big Bang disappeared? </p>
<p>The problem to date has been that nobody has seen any of these proposed new particles. It was hoped the LHC at Cern would produce them in collisions between high energy protons, but they’ve not yet been observed. </p>
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<img alt="A truck carrying a much wider cargo down a road." src="https://images.theconversation.com/files/393806/original/file-20210407-19-1b2ee57.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/393806/original/file-20210407-19-1b2ee57.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393806/original/file-20210407-19-1b2ee57.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393806/original/file-20210407-19-1b2ee57.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393806/original/file-20210407-19-1b2ee57.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393806/original/file-20210407-19-1b2ee57.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393806/original/file-20210407-19-1b2ee57.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">
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<span class="caption">Moving the muon ring.</span>
<span class="attribution"><a class="source" href="https://vms.fnal.gov/asset/detail?recid=1819456">Reidar Hahn/Fermilab</a></span>
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<p>The new measurement used the same technique as an experiment at “Brookhaven National Laboratory in New York, at the beginning of the century, which itself followed a series of measurements at Cern.</p>
<p>The Brookhaven experiment measured a discrepancy with the standard model that had a one in 5,000 chance of being a statistical fluke. This is approximately the same probability as throwing a coin 12 times in a row, all heads up. </p>
<p>This was tantalising, but way below the threshold for discovery, which is generally required to be better than one in 1.7 million – or 21 coin throws in a row. To determine whether new physics was in play, scientists would have to increase the sensitivity of the experiment by a factor of four.</p>
<p>To make the improved measurement, the magnet at the heart of the experiment had to be moved in 2013 3,200 miles from Long Island along sea and road, to Fermilab, outside Chicago, whose accelerators could produce a copious source of muons. </p>
<p>Once in place, a new experiment was built around the magnet with state of the art detectors and equipment. The muon g-2 experiment began taking data in 2017, with a collaboration of veterans from the Brookhaven experiment and a new generation of physicists.</p>
<p>The new results, from the first year of data at Fermilab, are in line with the measurement from the Brookhaven experiment. Combining results reinforces the case for a disagreement between experimental measurement and the standard model. The chances now lie at about one in 40,000 of the discrepancy being a fluke – still shy of the gold standard discovery threshold.</p>
<figure class="align-center ">
<img alt="A graph showing the prediction for the muon magnetic moment and the experimental results." src="https://images.theconversation.com/files/393970/original/file-20210408-23-17mxxvq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/393970/original/file-20210408-23-17mxxvq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/393970/original/file-20210408-23-17mxxvq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/393970/original/file-20210408-23-17mxxvq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/393970/original/file-20210408-23-17mxxvq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/393970/original/file-20210408-23-17mxxvq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/393970/original/file-20210408-23-17mxxvq.jpeg?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">
<figcaption>
<span class="caption">The prediction and the results.</span>
<span class="attribution"><a class="source" href="https://news.fnal.gov/wp-content/uploads/2021/04/Muon-g-2-results-plot.jpg">Ryan Postel, Fermilab/Muon g-2 collaboration</a></span>
</figcaption>
</figure>
<h2>The LHC</h2>
<p>Intriguingly, a <a href="https://theconversation.com/evidence-of-brand-new-physics-at-cern-why-were-cautiously-optimistic-about-our-new-findings-157464">recent observation by the LHCb experiment</a> at Cern also found possible deviations from the standard model. What’s exciting is that this also refers to the properties of muons. This time it’s a difference in how muons and electrons are produced from heavier particles. The two rates are expected to be the same in the standard model, but the experimental measurement found them to be different. </p>
<p>Taken together, the LHCb and Fermilab results strengthen the case that we’ve observed the first evidence of the standard model prediction failing, and that there are new particles or forces in nature out there to be discovered. </p>
<p>For the ultimate confirmation, this needs more data both from the Fermilab muon experiment and from Cern’s LHCb experiment. Results will be forthcoming in the next few years. Fermilab already has four times more data than was used in this recent result, currently being analysed, Cern has started taking more data and a new generation of muon experiments is being built. This is a thrilling era for physics.</p><img src="https://counter.theconversation.com/content/158564/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Themis Bowcock receives funding from UKRI. </span></em></p><p class="fine-print"><em><span>Mark Lancaster receives funding from UKRI (STFC), Horizon 2020.</span></em></p>New particles or forces may exist that aren’t accounted for in the standard model.Themis Bowcock, Professor of Particle Physics, University of LiverpoolMark Lancaster, Professor of Physics, University of ManchesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1574642021-03-23T08:15:51Z2021-03-23T08:15:51ZEvidence of brand new physics at Cern? Why we’re cautiously optimistic about our new findings<figure><img src="https://images.theconversation.com/files/390883/original/file-20210322-23-1liv6sm.jpg?ixlib=rb-1.1.0&rect=218%2C114%2C7450%2C4150&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Particle collisions are starting to reveal unexpected results. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/particles-collision-hadron-collider-astrophysics-concept-1406326886">vchal/Shutterstock</a></span></figcaption></figure><p>When Cern’s gargantuan accelerator, the Large Hadron Collider (LHC), fired up ten years ago, hopes abounded that new particles would soon be discovered that could help us unravel physics’ deepest mysteries. Dark matter, microscopic black holes and hidden dimensions <a href="https://theconversation.com/from-black-holes-to-dark-matter-an-astrophysicist-explains-26019">were just some</a> of the possibilities. But aside from the <a href="https://theconversation.com/explainer-the-higgs-boson-particle-280">spectacular discovery</a> of the Higgs boson, the project has <a href="https://theconversation.com/could-the-higgs-nobel-be-the-end-of-particle-physics-18978">failed to</a> yield any clues as to what might lie beyond the <a href="https://theconversation.com/explainer-standard-model-of-particle-physics-2539">standard model of particle physics</a>, our current best theory of the micro-cosmos.</p>
<p>So our <a href="http://arxiv.org/abs/2103.11769">new paper</a> from LHCb, <a href="https://theconversation.com/explainer-how-does-an-experiment-at-the-large-hadron-collider-work-42846">one of the four giant LHC experiments</a>, will probably set physicists’ hearts beating just a little faster. After analysing trillions of collisions produced over the last decade, we may be seeing evidence of something altogether new – potentially the carrier of a brand new force of nature.</p>
<p>But the excitement is tempered by extreme caution. The standard model has withstood every experimental test thrown at it since it was assembled in the 1970s, so to claim that we’re finally seeing something it can’t explain requires extraordinary evidence. </p>
<h2>Strange anomaly</h2>
<p>The standard model describes nature on the smallest of scales, comprising <a href="https://theconversation.com/explainer-what-are-fundamental-particles-38339">fundamental particles</a> known as leptons (such as electrons) and quarks (which can come together to form heavier particles such as protons and neutrons) and the forces they interact with. </p>
<p>There are many different kinds of quarks, some of which are unstable and can decay into other particles. The new result relates to an experimental anomaly that was <a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.151601">first hinted at in 2014</a>, when LHCb physicists spotted “beauty” quarks decaying in unexpected ways. </p>
<p>Specifically, beauty quarks appeared to be decaying into leptons called “muons” less often than they decayed into electrons. This is strange because the muon is in essence a carbon-copy of the electron, identical in every way except that it’s around 200 times heavier. </p>
<p>You would expect beauty quarks to decay into muons just as often as they do to electrons. The only way these decays could happen at different rates is if some never-before-seen particles were getting involved in the decay and tipping the scales against muons.</p>
<p>While the 2014 result was intriguing, it wasn’t precise enough to draw a firm conclusion. Since then, a number of other anomalies have appeared in related processes. They have all individually been too subtle for researchers to be confident that they were genuine signs of new physics, but tantalisingly, they all seemed to be pointing in a similar direction. </p>
<figure class="align-center ">
<img alt="Image of the LHCb experiment." src="https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/390889/original/file-20210322-19-nytkho.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">
<figcaption>
<span class="caption">LHCb experiment.</span>
<span class="attribution"><span class="source">Cern</span></span>
</figcaption>
</figure>
<p>The big question was whether these anomalies would get stronger as more data was analysed or melt away into nothing. In 2019, LHCb performed the <a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.191801">same measurement</a> of beauty quark decay again but with extra data taken in 2015 and 2016. But things weren’t much clearer than they’d been five years earlier.</p>
<h2>New results</h2>
<p>Today’s result doubles the existing dataset by adding the sample recorded in 2017 and 2018. To avoid accidentally introducing biases, the data was analysed “blind” – the scientists couldn’t see the result until all the procedures used in the measurement had been tested and reviewed.</p>
<p><a href="https://www.imperial.ac.uk/people/mitesh.patel">Mitesh Patel</a>, a particle physicist at Imperial College London and one of the leaders of the experiment, described the excitement he felt when the moment came to look at the result. “I was actually shaking,” he said. “I realised this was probably the most exciting thing I’ve done in my 20 years in particle physics.” </p>
<p>When the result came up on the screen, the anomaly was still there – around 85 muon decays for every 100 electron decays, but with a smaller uncertainty than before.</p>
<p>What will excite many physicists is that the uncertainty of the result is now over “three sigma” – scientists’ way of saying that there is only around a one in a thousand chance that the result is a random fluke of the data. Conventionally, particle physicists call anything over three sigma “evidence”. However, we are still a long way from a confirmed “discovery” or “observation” – that would require five sigma.</p>
<p>Theorists have shown it is possible to explain this anomaly (and others) by recognising the existence of brand new particles that are influencing the ways in which the quarks decays. One possibility is a fundamental particle called a “Z prime” – in essence a carrier of a brand new force of nature. This force would be extremely weak, which is why we haven’t seen any signs of it until now, and would interact with electrons and muons differently. </p>
<p>Another option is the hypothetical “<a href="https://home.cern/news/news/physics/hunt-leptoquarks">leptoquark</a>” – a particle that has the unique ability to decay to quarks and leptons simultaneously and could be part of a larger puzzle that explains why we see the particles that we do in nature. </p>
<h2>Interpreting the findings</h2>
<p>So have we finally seen evidence of new physics? Well, maybe, maybe not. We do a lot of measurements at the LHC, so you might expect at least some of them to fall this far from the standard model. And we can never totally discount the possibility that there’s some bias in our experiment that we haven’t properly accounted for, even though this result has been checked extraordinarily thoroughly. Ultimately, the picture will only become clearer with more data. LHCb is undergoing a major upgrade to dramatically increase the rate it can record collisions. </p>
<p>Even if the anomaly persists, it will probably only be fully accepted once an independent experiment confirms the results. One exciting possibility is that we might be able to detect the new particles responsible for the effect being created directly in the collisions at the LHC. Meanwhile, the <a href="https://www.belle2.org">Belle II experiment</a> in Japan should be able to make similar measurements.</p>
<p>What then, could this mean for the future of fundamental physics? If what we are seeing is really the harbinger of some new fundamental particles then it will finally be the breakthrough that physicists have been yearning for for decades. </p>
<p>We will have finally seen a part of the larger picture that lies beyond the standard model, which ultimately could allow us to unravel any number of established mysteries. These include the nature of the invisible dark matter that fills the universe, or the nature of the Higgs boson. It could even help theorists unify the fundamental particles and forces. Or, perhaps best of all, it could be pointing at something we have never even considered. </p>
<p>So, should we be excited? Yes. Results like this don’t come around very often, the hunt is definitely on. But we should be cautious and humble too; extraordinary claims require extraordinary evidence. Only time and hard work will tell if we have finally seen the first glimmer of what lies beyond our current understanding of particle physics.</p><img src="https://counter.theconversation.com/content/157464/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Harry Cliff works for the University of Cambridge. He receives funding from STFC. He is a member of the LHCb collaboration and a 'user' at CERN. </span></em></p><p class="fine-print"><em><span>Konstantinos Alexandros Petridis receives funding from STFC. He works for the University of Bristol and is a member of the LHCb collaboration at CERN.</span></em></p><p class="fine-print"><em><span>Paula Alvarez Cartelle works for the University of Cambridge. She receives funding from STFC. She is a member of the LHCb collaboration at CERN. </span></em></p>If the finding really is the result of new fundamental particles then it will finally be the breakthrough that physicists have been yearning for for decades.Harry Cliff, Particle physicist, University of CambridgeKonstantinos Alexandros Petridis, Senior lecturer in Particle Physics, University of BristolPaula Alvarez Cartelle, Lecturer of Particle Physics, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1472262020-12-21T12:05:25Z2020-12-21T12:05:25ZCERN: discovery sheds light on the great mystery of why the universe has less ‘antimatter’ than matter<figure><img src="https://images.theconversation.com/files/374225/original/file-20201210-21-lsz3bz.jpg?ixlib=rb-1.1.0&rect=14%2C5%2C1982%2C739&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's a lot of matter in the universe, here the cat paw nebula of dust and gas.</span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure><p>It’s one of the greatest puzzles in physics. All the particles that make up the matter around us, such electrons and protons, have <a href="https://theconversation.com/explainer-what-is-antimatter-53414">antimatter versions</a> which are nearly identical, but with mirrored properties such as the opposite electric charge. When an antimatter and a matter particle meet, they annihilate in a flash of energy. </p>
<p>If antimatter and matter are truly identical but mirrored copies of each other, they should have been produced in equal amounts in the Big Bang. The problem is that would have made it all annihilate. But today, there’s nearly no antimatter left in the universe – it appears only in some radioactive decays and in a small fraction of cosmic rays. So what happened to it? Using the <a href="https://home.cern/news/news/physics/lhcb-sees-new-form-matter-antimatter-asymmetry-strange-beauty-particles">LHCb experiment</a> at CERN to study the difference between matter and antimatter, we have <a href="https://arxiv.org/abs/2012.05319">discovered a new way</a> that this difference can appear.</p>
<p>The existence of antimatter was predicted by physicist <a href="https://www.nobelprize.org/prizes/physics/1933/dirac/biographical/">Paul Dirac</a>’s equation describing the motion of electrons in 1928. At first, it was not clear if this was just a mathematical quirk or a description of a real particle. But in 1932 Carl Anderson <a href="https://timeline.web.cern.ch/carl-anderson-discovers-positron">discovered</a> an antimatter partner to the electron – the positron – while studying cosmic rays that rain down on Earth from space. Over the next few decades physicists found that all matter particles have antimatter partners.</p>
<p>Scientists believe that in the very hot and dense state shortly after the Big Bang, there must have been processes that gave preference to matter over antimatter. This created a small surplus of matter, and as the universe cooled, all the antimatter was destroyed, or annihilated, by an equal amount of matter, leaving a tiny surplus of matter. And it is this surplus that makes up everything we see in the universe today.</p>
<p>Exactly what processes caused the surplus is unclear, and physicists have been on the lookout for decades. </p>
<h2>Known asymmetry</h2>
<p>The behaviour of quarks, which are the fundamental building blocks of matter along with leptons, can shed light on the difference between matter and antimatter. Quarks <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/quark.html">come in many different kinds</a>, or “flavours”, known as up, down, charm, strange, bottom and top plus six corresponding anti-quarks. </p>
<p>The up and down quarks are what make up the protons and neutrons in the nuclei of ordinary matter, and the other quarks can be produced by high-energy processes – for instance by colliding particles in accelerators such as the Large Hadron Collider at CERN. </p>
<p>Particles consisting of a quark and an anti-quark are called mesons, and there are four neutral mesons (B<sup>0</sup><sub>S</sub>, B<sup>0</sup>, D<sup>0</sup> and K<sup>0</sup>) that exhibit a fascinating behaviour. They can spontaneously turn into their antiparticle partner and then back again, a phenomenon that was observed for the first time in the 1960. Since they are unstable, they will “decay” – fall apart – into other more stable particles at some point during their oscillation. This decay <a href="https://theconversation.com/cern-study-sheds-light-on-one-of-physics-biggest-mysteries-why-theres-more-matter-than-antimatter-113947">happens slightly differently for mesons compared with anti-mesons</a>, which combined with the oscillation means that the rate of the decay varies over time.</p>
<p>The rules for the oscillations and decays are given by a theoretical framework called the <a href="https://www.nobelprize.org/prizes/physics/2008/summary/">Cabibbo-Kobayashi-Maskawa (CKM) mechanism</a>. It predicts that there is a difference in the behaviour of matter and antimatter, but one that is too small to generate the surplus of matter in the early universe required to explain the abundance we see today. </p>
<p>This indicates that there is something we don’t understand and that studying this topic may challenge some of our most fundamental theories in physics.</p>
<h2>New physics?</h2>
<p>Our recent result from the LHCb experiment is a study of neutral B<sup>0</sup><sub>S</sub> mesons, looking at their decays into pairs of charged K mesons. The B<sup>0</sup><sub>S</sub> mesons were created by colliding protons with other protons in the Large Hadron Collider where they oscillated into their anti-meson and back three trillion times per second. The collisions also created anti-B<sup>0</sup><sub>S</sub> mesons that oscillate in the same way, giving us samples of mesons and anti-mesons that could be compared. </p>
<p>We counted the number of decays from the two samples and compared the two numbers, to see how this difference varied as the oscillation progressed. There was a slight difference – with more decays happening for one of the B<sup>0</sup><sub>S</sub> mesons. And for the first time for
B<sup>0</sup><sub>S</sub> mesons, we observed that the difference in decay, or asymmetry, varied according to the oscillation between the B<sup>0</sup><sub>S</sub> meson and the anti-meson.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.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">LHCb.</span>
<span class="attribution"><span class="source">Maximilien Brice et al./CERN</span></span>
</figcaption>
</figure>
<p>In addition to being a milestone in the study of matter-antimatter differences, we were also able to measure the size of the asymmetries. This can be translated into measurements of several parameters of the underlying theory. Comparing the results with other measurements provides a consistency check, to see if the currently accepted theory is a correct description of nature. Since the small preference of matter over antimatter that we observe on the microscopic scale cannot explain the overwhelming abundance of matter that we observe in the universe, it is likely that our current understanding is an approximation of a more fundamental theory. </p>
<p>Investigating this mechanism that we know can generate matter-antimatter asymmetries, probing it from different angles, may tell us where the problem lies. Studying the world on the smallest scale is our best chance to be able to understand what we see on the largest scale.</p><img src="https://counter.theconversation.com/content/147226/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lars Eklund works for Uppsala University and is affiliated with the University of Glasgow, which would both benefit from any publicity generated by this article. He has received funding from STFC in the UK . </span></em></p>New physics may be needed to explain why there’s more matter than antimatter in the universe.Lars Eklund, Professor of Particle Physics, University of GlasgowLicensed 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/1277822019-11-28T09:12:34Z2019-11-28T09:12:34ZOur place in the universe will change dramatically in the next 50 years – here’s how<figure><img src="https://images.theconversation.com/files/304062/original/file-20191127-112512-5wha1m.jpg?ixlib=rb-1.1.0&rect=17%2C51%2C5734%2C3776&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Is there anybody out there?</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/eorb_1PkoB8">Greg Rakozy/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>In 1900, so the story goes, prominent physicist Lord Kelvin addressed the British Association for the Advancement of Science with these words: “There is nothing new to be discovered in physics now.”</p>
<p>How wrong he was. The following century completely turned physics on its head. A huge number of <a href="https://www.nobelprize.org/prizes/themes/the-nobel-prize-in-physics-1901-2000">theoretical and experimental discoveries</a> have transformed our understanding of the universe, and our place within it.</p>
<p>Don’t expect the next century to be any different. The universe has many mysteries that still remain to be uncovered – and new technologies will help us to solve them over the next 50 years.</p>
<p>The first concerns the fundamentals of our existence. Physics predicts that the Big Bang produced equal amounts of the matter you are made of and something called <a href="https://theconversation.com/explainer-what-is-antimatter-53414">antimatter</a>. Most particles of matter have an antimatter twin, identical but with the opposite electric charge. When the two meet, they annihilate each other, with all their energy converted into light.</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 the universe today is made almost entirely out of matter. So <a href="https://theconversation.com/explainer-what-is-antimatter-53414">where has all the antimatter gone</a>?</p>
<p>The Large Hadron Collider (LHC) has offered some insight into this question. It collides protons at unimaginable speeds, creating heavy particles of matter and antimatter that decay into lighter particles, several of which had never been seen before.</p>
<p>The LHC has shown that matter and antimatter decay at slightly different rates. This goes part – but nowhere near all – of the way to explaining why we see an asymmetry in nature.</p>
<p>The problem is that compared to the precision physicists are used to, the LHC is like playing table tennis with a tennis racquet. As protons are made up of smaller particles, when they collide their innards get sprayed all over the place, making it much harder to spot new particles among the debris. This makes it difficult to accurately measure their properties for further clues to why so much antimatter has disappeared.</p>
<p><a href="https://www.linearcollider.org">Three new colliders</a> will <a href="https://www.linearcollider.org">change the game</a> in the coming decades. Chief among them is the <a href="https://theconversation.com/cern-large-hadron-collider-replacement-plans-unveiled-heres-what-it-could-discover-109983">Future Circular Collider (FCC)</a> – a 100km tunnel encircling Geneva, which will use the 27km LHC as a slipway. Instead of protons, the colliders will smash together electrons and their antiparticles, positrons, at much higher speeds than the LHC could achieve.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/304073/original/file-20191127-112526-sjtqy7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304073/original/file-20191127-112526-sjtqy7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304073/original/file-20191127-112526-sjtqy7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304073/original/file-20191127-112526-sjtqy7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304073/original/file-20191127-112526-sjtqy7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304073/original/file-20191127-112526-sjtqy7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304073/original/file-20191127-112526-sjtqy7.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">The LHC’s 27km collider is nothing compared to what’s coming.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cern-france-25-june-2019-part-1460343230">Belish/Shutterstock</a></span>
</figcaption>
</figure>
<p>Unlike protons, electrons and positrons are indivisible – so we’ll know exactly what we’re colliding. We’ll also be able to vary the energy at which the two collide, to produce specific antimatter particles, and measure their properties – particularly the way they decay – much more accurately.</p>
<p>These investigations could reveal entirely new physics. One possibility is that the disappearance of antimatter could be related to the existence of dark matter – the thus far undetectable particles that make up a whopping 85% of mass in the universe. The absence of antimatter and prevalence of dark matter probably owe themselves to the <a href="https://www.scientificamerican.com/article/higgs-boson-could-explain-antimatter/">conditions present during the Big Bang</a>, so these experiments probe right into the origins of our existence.</p>
<p>Its impossible to predict how as-yet hidden discoveries from collider experiments will change our lives. But the last time we looked at the world through a more powerful magnifying glass, we discovered subatomic particles and the world of quantum mechanics – which we’re currently harnessing to revolutionise <a href="https://theconversation.com/why-are-scientists-so-excited-about-a-recently-claimed-quantum-computing-milestone-124082">computing</a>, <a href="https://theconversation.com/explainer-what-is-proton-therapy-16100">medicine</a> and <a href="https://theconversation.com/for-decades-a-distant-dream-the-countdown-to-nuclear-fusion-may-have-finally-begun-17801">energy production</a>.</p>
<h2>Alone no more?</h2>
<p>Just as much remains to be discovered on the cosmic scale – not least the age-old question of whether we’re alone in the universe. Despite the recent discovery of liquid water on <a href="https://theconversation.com/nasa-streaks-of-salt-on-mars-mean-flowing-water-and-raise-new-hopes-of-finding-life-48182">Mars</a>, there is not yet any evidence of microbial life. Even if found, the planet’s harsh environment means it would be incredibly primitive.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/nasa-streaks-of-salt-on-mars-mean-flowing-water-and-raise-new-hopes-of-finding-life-48182">NASA: streaks of salt on Mars mean flowing water, and raise new hopes of finding life</a>
</strong>
</em>
</p>
<hr>
<p>The search for life on planets in other star systems has so far not borne fruit. But the upcoming <a href="https://www.jwst.nasa.gov">James Webb Space Telescope</a>, launching in 2021, will revolutionise the way that we detect habitable exoplanets.</p>
<p>Unlike previous telescopes, which measure the dip in a star’s light as an orbiting planet passes in front of it, James Webb will use an instrument called a <a href="https://www.space.com/what-is-a-coronagraph.html">coronagraph</a> to block the light from a star entering the telescope. This works in much the same way as using your hand to block sunlight from entering your eyes. The technique will allow the telescope to directly observe small planets that would ordinarily be overwhelmed by the bright glare of the star they orbit.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/304067/original/file-20191127-112545-8ozaan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304067/original/file-20191127-112545-8ozaan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304067/original/file-20191127-112545-8ozaan.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304067/original/file-20191127-112545-8ozaan.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304067/original/file-20191127-112545-8ozaan.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304067/original/file-20191127-112545-8ozaan.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304067/original/file-20191127-112545-8ozaan.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">
<figcaption>
<span class="caption">An illuminated full scale model of the James Webb Telescope.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/james-webb-telescope-illuminated-night-full-1202860798">Bobby Bradley/Shutterstock</a></span>
</figcaption>
</figure>
<p>Not only will the James Webb telescope be able to detect new planets, but it will also be able to determine if they’re able to support life. When the light from a star reaches a planet’s atmosphere, certain wavelengths are absorbed, leaving gaps in the reflected spectrum. Much like a <a href="https://hubblesite.org/contents/articles/spectroscopy-reading-the-rainbow">barcode</a>, these gaps provide a signature for the atoms and molecules of which the planet’s atmosphere is made.</p>
<p>The telescope will be able to read these “barcodes” to detect whether a planet’s atmosphere has the necessary conditions for life. In 50 years’ time, we could have targets for future interstellar space missions to determine what, or who, may live there.</p>
<p>Closer to home, Jupiter’s moon, Europa, has been identified as somewhere in our own solar system that could harbour life. Despite its cold temperature (−220°C), gravitational forces from the ultra-massive planet it orbits may slosh water beneath the surface around sufficiently to prevent it from freezing, making it a possible home for microbial or even aquatic life.</p>
<p>A new mission called <a href="https://europa.nasa.gov">Europa Clipper</a>, set for launch in 2025, will confirm whether a sub-surface ocean exists and identify a suitable landing site for a subsequent mission. It will also observe jets of liquid water fired out from the planet’s icy surface to see if any organic molecules are present.</p>
<p>Whether its the tiniest building blocks of our existence or the vastness of space, the universe still holds a number of mysteries about its workings and our place within it. It will not give up its secrets easily – but the chances are that the universe will look fundamentally different in 50 years’ time.</p><img src="https://counter.theconversation.com/content/127782/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robin Smith receives research funding from the US Department of Energy. He is a member of the Labour Party.</span></em></p>From the subatomic to the cosmic, don’t think for a second that we’re at the end of scientific history.Robin Smith, Lecturer in Physics, Sheffield Hallam UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1139472019-03-21T09:48:11Z2019-03-21T09:48:11ZCERN: Study sheds light on one of physics’ biggest mysteries – why there’s more matter than antimatter<figure><img src="https://images.theconversation.com/files/265076/original/file-20190321-93057-15af7f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Milky Way as seen from Yellowstone National Park.</span> <span class="attribution"><span class="source">Neal Herbert/Flickr</span></span></figcaption></figure><p>Why do we exist? This is arguably the most profound question there is and one that may seem completely outside the scope of particle physics. But <a href="https://home.cern/news/press-release/physics/lhcb-sees-new-flavour-matter-antimatter-asymmetry">our new experiment</a> at CERN’s Large Hadron Collider has taken us a step closer to figuring it out.</p>
<p>To understand why, let’s go back in time some 13.8 billion years to the Big Bang. This event produced equal amounts of the matter you are made of and something called <a href="https://theconversation.com/explainer-what-is-antimatter-53414">antimatter</a>. It is believed that every particle has an antimatter companion that is virtually identical to itself, but with the opposite charge. When a particle and its antiparticle meet, they annihilate each other – disappearing in a burst of light.</p>
<p>Why the universe we see today is made entirely out of matter is one of the greatest mysteries of modern physics. Had there ever been an equal amount of antimatter, everything in the universe would have been annihilated. Our research <a href="https://cds.cern.ch/record/2668357/">has unveiled</a> a new source of this asymmetry between matter and antimatter.</p>
<p>Antimatter was first postulated by <a href="https://en.wikipedia.org/wiki/Arthur_Schuster">Arthur Schuster</a> in 1896, given a theoretical footing by <a href="https://www.nobelprize.org/prizes/physics/1933/dirac/biographical/">Paul Dirac</a> in 1928, and discovered in the form of anti-electrons, dubbed positrons, by <a href="https://timeline.web.cern.ch/carl-anderson-discovers-positron">Carl Anderson</a> in 1932. The positrons occur in natural radioactive processes, such as in the decay of Potassium-40. This means your average banana (which contains Potassium) emits a positron every 75 minutes. These then annihilate with matter electrons to produce light. Medical applications like PET scanners produce antimatter in the same process.</p>
<p>The fundamental building blocks of matter that make up atoms are elementary particles called quarks and leptons. There are <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/quark.html">six kinds of quarks</a>: up, down, strange, charm, bottom and top. Similarly, there are <a href="https://www.universetoday.com/46935/leptons/">six leptons</a>: the electron, muon, tau and the three neutrinos. There are also antimatter copies of these twelve particles that differ only in their charge.</p>
<p>Antimatter particles should in principle be perfect mirror images of their normal companions. But experiments show this isn’t always the case. Take for instance particles known as <a href="https://www.britannica.com/science/meson">mesons</a>, which are made of one quark and one anti-quark. Neutral mesons have a fascinating feature: they can spontaneously turn into their anti-meson and vice versa. In this process, the quark turns into an anti-quark or the anti-quark turns into a quark. But experiments have shown that this can happen more in one direction than the opposite one – creating more matter than antimatter over time. </p>
<h2>Third time’s a charm</h2>
<p>Among particles containing quarks, only those including strange and bottom quarks have been found to exhibit such asymmetries – and these were hugely important discoveries. The very <a href="https://www.nobelprize.org/prizes/physics/1980/summary/">first observation</a> of asymmetry involving strange particles in 1964 allowed theorists to predict the existence of six quarks – at a time when only three were known to exist. The discovery of asymmetry in bottom particles in 2001 was the <a href="https://www.nobelprize.org/prizes/physics/2008/summary/">final confirmation of the mechanism</a> that led to the six-quark picture. Both discoveries led to Nobel Prizes. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264993/original/file-20190320-93063-r7pdv4.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">LHCb.</span>
<span class="attribution"><span class="source">Maximilien Brice et al./CERN</span></span>
</figcaption>
</figure>
<p>Both the strange and bottom quark carry a negative electric charge. The only positively charged quark that in theory should be able to form particles that can exhibit matter-antimatter asymmetry is charm. Theory suggests that if it does, then the effect should be tiny and difficult to detect. </p>
<p>But the LHCb experiment has now managed to observe such an asymmetry in particles called <a href="https://en.wikipedia.org/wiki/D_meson">D-meson</a> – which are comprised of charm quarks – for the first time. This is made possible by the unprecedented amount of charm particles produced directly in the LHC collisions, which I pioneered a decade ago. The result indicates that the chance of this being a statistical fluctuation is about 50 in a billion. </p>
<p>If this asymmetry is not coming from the same mechanism causing the strange and bottom quark asymmetries, this leaves room for new sources of matter-antimatter asymmetry that can add to the total such asymmetry in the early universe. And that’s important as the few known cases of asymmetry can’t explain why the universe contains so much matter. The charm discovery alone will not be sufficient to fill this gap, but it is an essential puzzle piece in the understanding of the interactions of fundamental particles.</p>
<h2>Next steps</h2>
<p>The discovery will be followed by an increased number of theoretical works, which help to interpret the result. But more importantly, it will outline further tests to deepen the understanding following our finding – with a number of such tests already ongoing.</p>
<p>Over the coming decade, the upgraded LHCb experiment will boost the sensitivity for these kinds of measurements. This will be complemented by the <a href="https://belle2.desy.de/">Japan-based Belle II experiment</a>, which is just starting to operate. These are exciting prospects for research into matter-antimatter asymmetry.</p>
<p>Antimatter is also at the heart of a number of other experiments. Whole anti-atoms are being produced at <a href="https://home.cern/science/accelerators/antiproton-decelerator">CERN’s Antiproton Decelerator</a>, which feeds a number of experiments conducting high precision measurements. The <a href="https://ams.nasa.gov/">AMS-2 experiment</a> aboard the International Space Station is on the lookout for antimatter of cosmic origin. And a number of current and future experiments will tackle the question of whether there is antimatter-matter asymmetry among neutrinos. </p>
<p>While we still cannot completely solve the mystery of the universe’s matter-antimatter asymmetry, our latest discovery has opened the door to an era of precision measurements that have the potential to uncover yet unknown phenomena. There’s every reason to be optimistic that physics will one day be able to explain why we are here at all.</p><img src="https://counter.theconversation.com/content/113947/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marco Gersabeck receives funding from the UK Research and Innovation Science and Technology Facilities Council. He works for the University of Manchester. </span></em></p>A new experiment at CERN has discovered a source of asymmetry between matter and antimatter that could help explain why we are here at all.Marco Gersabeck, Lecturer in Physics, University of ManchesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1099832019-01-18T11:14:10Z2019-01-18T11:14:10ZCERN: Large Hadron Collider replacement plans unveiled – here’s what it could discover<figure><img src="https://images.theconversation.com/files/254350/original/file-20190117-32834-1ucehjm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Move over, Large Hadron Collider. </span> <span class="attribution"><span class="source">CERN</span></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 (LHC) at CERN</a> is the most powerful particle accelerator in the world. During its ten years of operations it has led to remarkable discoveries, including <a href="https://theconversation.com/could-the-higgs-nobel-be-the-end-of-particle-physics-18978">the long sought-after Higgs boson</a>. On January 15, an international team of physicists <a href="https://home.cern/news/press-release/accelerators/international-collaboration-publishes-concept-design-post-lhc">unveiled the concept design for a new particle accelerator</a> that would dwarf the LHC. </p>
<p>The “<a href="https://home.cern/science/accelerators/future-circular-collider">Future Circular Collider</a>” is conceived as a successor to the LHC, and – if given the green light – it would allow physicists to seek answers to some of greatest mysteries in physics. This includes finding out what the vast majority of the universe is actually made of or discovering <a href="https://theconversation.com/mystery-particle-spotted-discovery-would-require-physics-so-weird-that-nobody-has-even-thought-of-it-106260">entirely new physics</a>. </p>
<p>The proposal envisages a new 100km circumference tunnel that would be bored through the Earth, encircling the city of Geneva and the surrounding countryside. The 27km LHC would feed particles into the the new collider – like a motorway slipway. This would ultimately allow it to collide particles with energies around seven times higher than the LHC can manage. This would let this collider create particles that are beyond the reach of the LHC – pushing particle physics deep into an unexplored microscopic realm.</p>
<h2>Portal to a dark world</h2>
<p>The Future Circular Collider is really several projects in one. The first phase imagines a machine that collides electrons with their so-called “antimatter versions”, positrons. All particles are thought to have an <a href="https://theconversation.com/explainer-what-is-antimatter-53414">antimatter companion</a>, virtually identical to itself but with opposite charge. When a matter and an antimatter particle meet, they completely annihilate each other, with all their energy converted into new particles. </p>
<p>The collision energy of such a collider could be very precisely controlled. Also, collisions would be very “clean” compared to the LHC, which collides protons (particles that make up the atomic nucleus along with neutrons). Protons are not fundamental particles like electrons, but haphazard bags of smaller particles including quarks and gluons. When protons collide, their innards get sprayed all over the place, making it much harder to spot new particles among the debris. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/254352/original/file-20190117-32804-6zzpni.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/254352/original/file-20190117-32804-6zzpni.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=336&fit=crop&dpr=1 600w, https://images.theconversation.com/files/254352/original/file-20190117-32804-6zzpni.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=336&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/254352/original/file-20190117-32804-6zzpni.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=336&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/254352/original/file-20190117-32804-6zzpni.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/254352/original/file-20190117-32804-6zzpni.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/254352/original/file-20190117-32804-6zzpni.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Detector layout.</span>
<span class="attribution"><span class="source">CERN</span></span>
</figcaption>
</figure>
<p>The primary goal of the electron-positron collider would be to study the Higgs boson, the particle <a href="https://theconversation.com/nobel-prize-in-physics-goes-to-discovery-of-the-higgs-boson-19014">implicated in the origin of the masses</a> of the other fundamental particles. The new collider would create millions of Higgs bosons and measure their properties in unprecedented detail. </p>
<p>Such precision measurements offer numerous possibilities for new discoveries. One of the most tantalising is that the Higgs could act as portal connecting the world of ordinary atomic matter that we inhabit, with a hidden world of particles that are otherwise undetectable. Some 85% of all the matter in the universe in the universe is “dark”, made up of particles <a href="https://theconversation.com/from-machos-to-wimps-meet-the-top-five-candidates-for-dark-matter-51516">we have never been able to see</a>. We only know it exists because of the gravitational pull it has on surrounding matter. Excitingly, an electron-positron collider could reveal the Higgs boson decaying into these hidden particles.</p>
<p>In the second phase, the collider would be replaced by a far more powerful proton-proton collider – reaching collision energies of 100 trillion electron volts. This would be a discovery machine, capable of creating a huge range of new particles that physicists suspect may lie beyond the reach of the LHC. </p>
<p>In particular, it would almost completely explore the energy range where most forms of dark matter are likely to be found. It would also be able to probe the conditions that existed a trillionth of a second after the Big Bang. This moment in the universe’s history is crucial as it is when the Higgs field – an all-pervading energy field that the Higgs boson is a little ripple in – collapsed into its current state, which is what generated the masses of the fundamental particles. </p>
<p>Understanding how the Higgs field acquired its current energy is one of the greatest outstanding problems in physics, as it appears to be unbelievably finely tuned to allow atoms – and therefore stars, planets and people – to exist. </p>
<p>As a physicist working on the <a href="http://lhcb-public.web.cern.ch/lhcb-public/">LHC beauty experiment</a>, I personally hope this new collider could eventually also help us solve the <a href="https://theconversation.com/how-the-supernemo-experiment-could-help-solve-the-mystery-of-the-origin-of-matter-in-the-universe-88039">riddle of why the universe is made almost entirely from matter </a> and not antimatter.</p>
<h2>Hefty price tag</h2>
<p>The first phase of the new collider would come online in the 2040s, after the final run of the upgraded LHC. The more powerful proton-proton collider would be installed in the 2050s. Both projects come with a hefty price tag: €9 billion for the electron-positron machine and a further €15 billion for the proton-proton collider. This has raised understandable criticism that the money could be better spent elsewhere, for example in tackling climate change. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/254342/original/file-20190117-32825-1xojhpw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/254342/original/file-20190117-32825-1xojhpw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/254342/original/file-20190117-32825-1xojhpw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/254342/original/file-20190117-32825-1xojhpw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/254342/original/file-20190117-32825-1xojhpw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/254342/original/file-20190117-32825-1xojhpw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/254342/original/file-20190117-32825-1xojhpw.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">Map.</span>
</figcaption>
</figure>
<p><a href="https://europeanspallationsource.se/john-womersley">John Womersley</a>, a senior physicist involved in the Future Circle Collider, told me that beyond the value of fundamental knowledge in its own right, there will be other significant short-term benefits. He said: “The FCC will push the development of innovative technologies to solve new challenges. The World Wide Web, Wi-Fi and superconducting magnets in MRI machines were all developed to meet the needs of fundamental physics.” The project also has huge power to inspire the next generation of physicists.</p>
<p>Ultimately, such an ambitious scheme will only be possible through a large international collaboration, with funding from dozens of countries. The project already includes 1,300 contributors from 150 universities, research institutes and industrial partners around the world. Meanwhile, a <a href="https://gizmodo.com/plans-revealed-for-enormous-particle-collider-in-china-1830444169">similar collider project</a> is also being considered by China, perhaps the only country capable of mobilising the resources necessary to build such a vast machine on its own.</p>
<p>The advocates of the Future Circular Collider hope that the project will be adopted in the new European strategy for particle physics, to be published in 2020. If accepted, it will begin a long process of research and development, but also of persuading national governments and the general public that the exciting fundamental research that could be performed at the collider is worth investing in. </p>
<p>The political challenges are undoubtedly enormous, but physicists are determined not to give up the quest for a deeper understanding of our universe.</p><img src="https://counter.theconversation.com/content/109983/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Harry Cliff is employed as a particle physicist at the University of Cambridge, is a member of the LHCb Experiment at CERN and is working on public engagement for the Future Circular Collider collaboration.</span></em></p>A new collider at CERN could push particle physics deep into an unexplored microscopic realm.Harry Cliff, Particle physicist, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1062602018-11-05T13:07:27Z2018-11-05T13:07:27ZMystery particle spotted? Discovery would require physics so weird that nobody has even thought of it<figure><img src="https://images.theconversation.com/files/243858/original/file-20181105-83635-194cuwl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">CMS detector.</span> <span class="attribution"><span class="source">Laura Gilchrist/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>There was a huge amount of excitement when the Higgs boson was first spotted back in 2012 – a discovery that bagged the <a href="https://theconversation.com/could-the-higgs-nobel-be-the-end-of-particle-physics-18978">Nobel Prize for Physics in 2013</a>. The particle completed the so-called <a href="https://home.cern/about/physics/standard-model">standard model</a>, our current best theory of understanding nature at the level of particles.</p>
<p>Now scientists at the Large Hadron Collider (LHC) at Cern think they may have <a href="https://www.theguardian.com/science/2018/oct/31/has-new-ghost-subatomic-particle-manifested-at-large-hadron-collider">seen another particle</a>, detected as a peak at a certain energy in the data, although the finding is yet to be confirmed. Again there’s a lot of excitement among particle physicists, but this time it is mixed with a sense of anxiety. Unlike the Higgs particle, which confirmed our understanding of physical reality, this new particle seems to threaten it. </p>
<p>The new result – consisting of a mysterious bump in the data at 28 GeV (a unit of energy) – <a href="https://arxiv.org/abs/1808.01890">has been published</a> as a preprint on ArXiv. It is not yet in a peer-reviewed journal – but that’s not a big issue. The LHC collaborations have very tight internal review procedures, and we can be confident that the authors have done the sums correctly when they report a “4.2 standard deviation significance”. That means that the probability of getting a peak this big by chance – created by random noise in the data rather than a real particle – is only 0.0013%. That’s tiny – 13 in a million. So it seems like it must a real event rather than random noise – but nobody’s opening the champagne yet.</p>
<h2>What the data says</h2>
<p>Many LHC experiments, which smash beams of protons (particles in the atomic nucleus) together, find evidence for new and exotic particles by looking for an unusual build up of known particles, such as photons (particles of light) or electrons. That’s because heavy and “invisible” particles such as the Higgs are often unstable and tend to fall apart (decay) into lighter particles that are easier to detect. We can therefore look for these particles in experimental data to work out whether they are the result of a heavier particle decay. The LHC <a href="https://home.cern/about/updates/2018/09/lhcb-experiment-discovers-two-perhaps-three-new-particles">has found many new particles</a> by such techniques, and they have all fitted into the standard model.</p>
<p>The new finding comes from an experiment involving the <a href="https://home.cern/about/experiments/cms">CMS detector</a>, which recorded a number of pairs of muons – <a href="https://theconversation.com/particle-physicists-discover-mysterious-structure-in-great-pyramid-heres-how-they-did-it-86783">well known and easily identified particles</a> that are similar to electrons, but heavier. It analysed their energies and directions and asked: if this pair came from the decay of a single parent particle, what would the mass of that parent be?</p>
<p>In most cases, pairs of muons come from different sources – originating from two different events rather than the decay of one particle. If you try to calculate a parent mass in such cases it would therefore spread out over a wide range of energies rather than creating a narrow peak specifically at 28GeV (or some other energy) in the data. But in this case it certainly looks like there’s a peak. Perhaps. You can look at the figure and you can judge for yourself.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/243860/original/file-20181105-83648-1qhdfby.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/243860/original/file-20181105-83648-1qhdfby.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=576&fit=crop&dpr=1 600w, https://images.theconversation.com/files/243860/original/file-20181105-83648-1qhdfby.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=576&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/243860/original/file-20181105-83648-1qhdfby.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=576&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/243860/original/file-20181105-83648-1qhdfby.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=724&fit=crop&dpr=1 754w, https://images.theconversation.com/files/243860/original/file-20181105-83648-1qhdfby.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=724&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/243860/original/file-20181105-83648-1qhdfby.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=724&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">New data.</span>
<span class="attribution"><span class="source">CMS Collaboration</span></span>
</figcaption>
</figure>
<p>Is this a real peak or is it just a statistical fluctuation due to the random scatter of the points about the background (the dashed curve)? If it’s real that means that a few of these muon pairs did indeed come from just a large parent particle that decayed by emitting muons – and no such 28 GeV particle has ever been seen before.</p>
<p>So it is all looking rather intriguing, but, history has taught us caution. Effects this significant have appeared in the past, only to vanish when more data is taken. The Digamma(750) anomaly is a <a href="https://en.wikipedia.org/wiki/750_GeV_diphoton_excess">recent example</a> from a long succession of false alarms – spurious “discoveries” due to equipment glitches, over-enthusiastic analysis or just bad luck. </p>
<p>This is partly due to something called the <a href="https://en.wikipedia.org/wiki/Look-elsewhere_effect">“look elsewhere effect</a>”: although the probability of random noise producing a peak if you look specifically at a value of 28 GeV may be 13 in a million, such noise could give a peak somewhere else in the plot, maybe at 29GeV or 16GeV. The probabilities of these being due to chance are also tiny when considered respectively, but the sum of these tiny probabilities is not so tiny (though still pretty small). That means it is not impossible for a peak to be created by random noise.</p>
<p>And there are some puzzling aspects. For example, the bump appeared in one LHC run but not in another, when the energy was doubled. One would expect any new phenomena to get bigger when the energy is higher. It may be that there are reasons for this, but at the moment it’s an uncomfortable fact.</p>
<h2>New physical reality?</h2>
<p>The theory is even more incongruous. Just as experimental particle physicists spend their time looking for new particles, theorists spend their time thinking of new particles that it would make sense to look for: particles that would fill in the missing pieces of the standard model, or explain <a href="https://theconversation.com/from-machos-to-wimps-meet-the-top-five-candidates-for-dark-matter-51516">dark matter</a> (a type of invisible matter), or both. But no one has suggested anything like this.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/243651/original/file-20181102-83654-1f24iz4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/243651/original/file-20181102-83654-1f24iz4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=553&fit=crop&dpr=1 600w, https://images.theconversation.com/files/243651/original/file-20181102-83654-1f24iz4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=553&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/243651/original/file-20181102-83654-1f24iz4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=553&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/243651/original/file-20181102-83654-1f24iz4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=695&fit=crop&dpr=1 754w, https://images.theconversation.com/files/243651/original/file-20181102-83654-1f24iz4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=695&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/243651/original/file-20181102-83654-1f24iz4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=695&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">CMS model of a Higgs boson decaying into two jets of hadrons and two electrons.</span>
<span class="attribution"><span class="source">Lucas Taylor/CERN</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>For example, theorists suggest we could find a lighter version of the Higgs particle. But anything of that ilk would not decay to muons. A light <a href="https://home.cern/about/physics/z-boson">Z boson</a> or a <a href="https://epp.slac.stanford.edu/research/heavy-photon-search">heavy photon</a> have also been talked about, but they would interact with electrons. That means we should have probably discovered them already as electrons are easy to detect. The potential new particle does not match the properties of any of those proposed.</p>
<p>If this particle really exists, then it is not just outside the standard model but outside it in a way that nobody anticipated. Just as Newtonian gravity gave way to Einstein’s general relativity, the standard model will be superseded. But the replacement will not be any of the favoured candidates that has already been proposed to extend standard model: including <a href="https://home.cern/about/physics/supersymmetry">supersymmetry</a>, extra dimensions and <a href="https://theconversation.com/stephen-hawking-had-pinned-his-hopes-on-m-theory-to-fully-explain-the-universe-heres-what-it-is-93440">grand unification theories</a>. These all propose new particles, but none with properties like the one we might have just seen. It will have to be something so weird that nobody has suggested it yet. </p>
<p>Luckily the other big LHC experiment, ATLAS, has similar data from their experiments The team is still analysing it, and will report in due course. Cynical experience says that they will report a null signal, and this result will join the gallery of statistical fluctuations. But maybe – just maybe – they will see something. And then life for experimentalists and theorists will suddenly get very busy and very interesting.</p><img src="https://counter.theconversation.com/content/106260/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Barlow is a member of the Liberal Democrats</span></em></p>Scientists at Cern’s Large Hadron Collider have seen something that may force us to abandon everything we thought we knew about the world on the level of particles.Roger Barlow, Research Professor and Director of the International Institute for Accelerator Applications, University of HuddersfieldLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/670732016-10-17T14:13:32Z2016-10-17T14:13:32ZHow an army of engineers battles contamination and sleep deprivation to take hadron collider to new heights<figure><img src="https://images.theconversation.com/files/141785/original/image-20161014-30240-1jggoup.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">LHC CERN</span> </figcaption></figure><p>The <a href="http://home.cern/topics/large-hadron-collider">Large Hadron Collider at CERN</a> is the world’s largest particle accelerator, and experiments like this have reached a scale where physicists are no longer able to build them alone. Instead, qualified engineers now lead the construction of these behemoths. And we are part of a team of engineers and physicists working on upgrading the LHC and eventually <a href="http://physicsworld.com/cws/article/news/2014/feb/06/cern-kicks-off-plans-for-lhc-successor">constructing a successor</a>. </p>
<p>On the surface CERN is a 1960s glass and concrete building. It’s often described as what people 50 years ago thought the future might look like. The cafeteria looks like any other, except you probably don’t get as many Nobel Prize winners in most canteens. But the real work goes on underneath the surface. The tunnel that houses the LHC is 27km in circumference, which is the same as the Circle Line in London’s underground system. But while the deepest London tube line is only 60 meters down, the LHC is 175 metres below ground. In the tunnel is also 50,000 tonnes of equipment weighing the same as six Eiffel Towers.</p>
<p>The LHC <a href="https://theconversation.com/explainer-how-does-an-experiment-at-the-large-hadron-collider-work-42846">works by colliding two beams</a> of particles at very high energy, travelling in a circle close to the speed of light before they are crashed into each other. The particles used are protons – positively charged particles that make up the atomic nucleus, along with neutrons – that are attracted to negatively charged plates. Metallic chambers called “<a href="https://home.cern/about/engineering/radiofrequency-cavities">radiofrequency cavities</a>” contain strong electromagnetic fields that are used to accelerate the protons. </p>
<p>The LHC has the world’s highest accelerator magnet and the world’s largest superconducting system at 10,000 superconducting magnets. These have wires with zero electrical resistance at low temperatures, meaning they can create intense magnetic fields. LCH also has the highest current controlled to very high precision and the highest proton-beam energy (13 TeV). So to build an accelerator like the LHC we need electrical engineers, electronic engineers, mechanical engineers and civil engineers with a huge range of specialisations including radio frequency acceleration systems, cryogenics, control, tunnel drilling and mechanical stability.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/141990/original/image-20161017-4764-1qo0i67.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/141990/original/image-20161017-4764-1qo0i67.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/141990/original/image-20161017-4764-1qo0i67.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/141990/original/image-20161017-4764-1qo0i67.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/141990/original/image-20161017-4764-1qo0i67.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/141990/original/image-20161017-4764-1qo0i67.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/141990/original/image-20161017-4764-1qo0i67.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Atlas detector.</span>
<span class="attribution"><span class="source">Image Editor/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The energy stored in each beam is the same as an airbus jet travelling at take-off speed and can melt 12 tonnes of copper. So the materials used must be able to take this hit, and this requires a lot of engineers testing them and controlling systems that avoid the beam depositing all its energy in one spot. Energy management is also a big task – the LHC requires 120MW, which is 10% of the entire energy budget of Geneva – and 50% of the largest power station in the northwest of England.</p>
<h2>Risky business</h2>
<p>When running, the machine is too radioactive to go into. This radiation <a href="http://www.lhc-closer.es/taking_a_closer_look_at_lhc/0.ionizing_radiation">is produced</a> when protons interact with the nuclei of surrounding material or gas. But every few years it undergoes a long shutdown to allow engineers to install new components. On the surface the collider entrance looks much like a building site, and hard hats must be worn. There are many risks – including high radiation levels from stray protons hitting the walls and generating showers of particles, high voltages, cold cryogenic gasses in confined spaces (which have exploded in the past), as well as the usual heavy items falling and of being in a tunnel deep beneath the surface. </p>
<p>There is a long wait as the lift takes you down into the depths. The detectors are pretty big to begin with but when you get close and see on a small scale the amount of electronics packed into every space of a three-storey tall detector you realise the scale of the engineering involved. The same goes for the tunnels themselves. </p>
<p>A lot of the engineering work conducted at CERN isn’t in the tunnels, however, but in the many testing laboratories or assembly areas. Lancaster University is involved in testing the LHC’s acceleration cavities. Huge radio-frequency amplifiers (like big mobile phones) blast the cavities with enormous powers to test if they can withstand the massive electric fields generated in the particle accelerators. Because of radiation, everything is controlled from a little room filled with racks of computers and electronics. The cavities are sensitive to dirt and dust, which can cause them to fail. They are therefore cleaned with water so pure it can eat through metal pipes. To remove the surface layer we also use acid mixtures containing the extremely potent <a href="https://chronicleflask.com/2013/04/16/the-acid-that-really-does-eat-through-everything/">hydrofluoric acid</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/141991/original/image-20161017-4740-1o76ewy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/141991/original/image-20161017-4740-1o76ewy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/141991/original/image-20161017-4740-1o76ewy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/141991/original/image-20161017-4740-1o76ewy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/141991/original/image-20161017-4740-1o76ewy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/141991/original/image-20161017-4740-1o76ewy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/141991/original/image-20161017-4740-1o76ewy.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">
<figcaption>
<span class="caption">LHC tunnel.</span>
<span class="attribution"><span class="source">Julian Herzog/wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Often these tests run continuously so one of us – Graeme – often spends 24 hours in a concrete room with no windows staring at a screen. But once you know what’s on the screen, and what every blip means, it’s definitely more exciting. </p>
<p>CERN makes a lot of the specialist components themselves so there are also large workshops with massive cutting and welding machines, staffed by some of the world’s top technicians. </p>
<h2>Bigger and better</h2>
<p>We are now working with the physicists to design the LHC’s successor, which will be 100km in circumference. Before that the LHC will be upgraded to operate with ten times the number of collisions to allow the physicists to discover new particles faster.</p>
<p>The UK is involved in this through the High Luminosity-LHC-UK project, led by the Universities of Manchester and Lancaster, in which engineers work with physicists to create the new technology. This will involve building new superconducting radio-frequency systems that create 3m-volt electric fields to align the bunches of protons to within nanometer precision. A superconducting material, which has zero electrical resistance at low temperatures, allows these devices to store energy with very low energy loss. </p>
<p>Engineers are also looking at special “collimators” which remove stray particles in the beam and hence must be able to take huge energy being deposited on them. This involves creating superconducting cables that can transport the huge currents required to power the magnets from the surface to the tunnel without loss. Physicists and CERN engineers will also develop new ways of measuring the proton beams.</p>
<p>CERN is leading to ground-breaking scientific research that is advancing our knowledge of the world around us. And it is through the collaborative work of the world’s finest engineers, alongside the best scientific minds, that are making these discoveries possible.</p><img src="https://counter.theconversation.com/content/67073/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Graeme Burt receives funding from STFC and CERN. </span></em></p><p class="fine-print"><em><span>Robert Appleby receives funding from STFC.</span></em></p>We hear a lot about the marvellous science going on at CERN. But what goes on behind the scenes?Graeme Burt, Senior lecturer in engineering, Lancaster UniversityRobert Appleby, Reader of High Energy Particle Physics, University of ManchesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/564562016-04-20T11:12:02Z2016-04-20T11:12:02ZWhat the European Union can learn from CERN about international co-operation<figure><img src="https://images.theconversation.com/files/115512/original/image-20160317-30247-10egagz.png?ixlib=rb-1.1.0&rect=177%2C0%2C1058%2C726&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://cds.cern.ch/tools/mediaarchive.py/copyright_notice?recid=833187&master_path=https://mediastream.cern.ch/MediaArchive/Photo/Masters/2005/0504012/0504012.JPG&ln=en&reference=CERN-SI-0504012&tirage=">CERN</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Can Europe work? This is the real question being asked of British people on June 23. Behind the details of subsidies, regulations and eurozones lies a more fundamental puzzle: can different nationalities retain their own identities and work together, without merging into some bland United States of Europe?</p>
<p>I would like to suggest that there may be an example to follow in the history of <a href="http://home.cern/about">CERN</a>, the international research organisation based in Switzerland, and home to the world-famous particle accelerators used recently by teams of thousands of scientists from many nations to confirm the existence of the <a href="https://theconversation.com/uk/topics/higgs-boson">Higgs boson</a>.</p>
<p>There are many similarities between CERN and the EU. The former was founded in 1954 and the latter in 1957, when the <a href="http://www.britannica.com/event/Treaty-of-Rome">Treaty of Rome</a> was signed (although it was then called the European Economic Community). Both CERN and the EU have grown over the years. The EU started with six countries and now brings together 28. CERN has grown from an initial 12 members, including the UK, to 21. </p>
<p>Both also emerged as a response to a post-war world in which the two superpowers dominated, not only militarily but also economically and scientifically. The US and the USSR were supreme on either side of the iron curtain, and with their great resources they pushed ahead with prestige research: space travel, electronics, and nuclear physics.</p>
<p>The European nations were impoverished by the financial and human cost of the war. Many of its greatest (often Jewish) scientists had fled to the US and were slow to come back. None had the people or the capacity to compete on their own. </p>
<h2>Teamwork</h2>
<p>CERN has proved remarkably, and enduringly, successful. The recent discovery of the Higgs particle at the Large Hadron Collider is just the latest in a string of ambitious but successful accelerator projects and scientific discoveries that have rewritten the particle physics textbooks. It was at CERN that the world wide web was invented, changing the lives of billions of people.</p>
<p>Nations such as France, Germany, and the UK, which were once proud of their national accelerator laboratories eventually had to abandon their independent programmes and convenient particle accelerators at Saclay, Hamburg and Harwell had to be sidelined in favour of the central machine.</p>
<p>Herwig Schopper, a past CERN director general, wrote a <a href="http://link.springer.com/book/10.1007/978-3-540-89301-1">fascinating account</a>
of the high-level negotiations needed to persuade the national governments to support the construction of the LEP accelerator (the LHC’s precursor). All kinds of tactics were needed to placate national stubbornness – such as over money in the UK and national pride in Italy. He also details the schmoozing and diplomacy skills that need to be deployed by the head of CERN to keep every national government happy.</p>
<p>It has not always been a smooth ride. There have been strong disagreements about the size of the total budget and how it should be shared between member states.</p>
<p>As national science budgets have come under pressure, the millions spent on CERN have inevitably been eyed jealously by other scientific disciplines. Why spend quite so much on particle physics when high quality grant applications in other fields – the “unfunded alphas” – were being turned down due to a lack of funds? </p>
<p>So the existence of CERN and the way it is organised have come under strong scrutiny. In the 1980s, the <a href="http://cds.cern.ch/record/63800?ln=no">Abragam committee</a> was set up, at the insistence of the UK, to look for 25% savings at CERN. But in the end it recommended the budget should be kept as it was. And as recently as 2009, Austria threatened to leave. It was only dissuaded after an international outcry. </p>
<p>So the organisation has survived – not unscathed, and not unchanged – but it has survived.</p>
<h2>Life and work at CERN</h2>
<p>Although there is a small core of permanent CERN employees, most of the men and women working at the laboratory, on the experiments and accelerators, are visitors from national universities and institutes, or postdoctoral researchers on short-term contracts. Many will take up university posts in due course.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/115508/original/image-20160317-30237-pj30q9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/115508/original/image-20160317-30237-pj30q9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/115508/original/image-20160317-30237-pj30q9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/115508/original/image-20160317-30237-pj30q9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/115508/original/image-20160317-30237-pj30q9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/115508/original/image-20160317-30237-pj30q9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/115508/original/image-20160317-30237-pj30q9.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">Too busy doing bad-ass experiments to argue about fishing quotas.</span>
<span class="attribution"><a class="source" href="https://cds.cern.ch/record/1969029/files/IMG_2250.jpg?subformat=icon-1440">CERN</a></span>
</figcaption>
</figure>
<p>So the members of the workforce retain their national links and national characteristics. Identity is important. The French, Germans and Italians I have worked with appear to have conformed to their national sterotypes, and I suspect they find my behaviour typically “British”. (I remember when, walking back from lunch to our experiment, we were hit by a sudden violent hailstorm. Everyone ran for cover – but the UK contingent just kept walking). The most popular topic of conversation in the canteen is probably – apart from work, of course – the idiosyncratic features of different languages. Being thrown together to work in international teams does not blur the differences, it sharpens them.</p>
<p>So European co-operation, at least in this example, works. European particle physics has overtaken not only the former eastern bloc, but even the United States, which now has nothing to match it.</p>
<p>It seems that Europe really exists, it is not just a collection of countries that happen to be adjacent on the map. It means something to be a European, at least in the context of scientific co-operation, without in any way lessening one’s identity as British (or English, Welsh, or Scottish for that matter). Hopefully we can now make that work in other fields as well.</p><img src="https://counter.theconversation.com/content/56456/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Barlow receives research funding from CERN and from STFC to work with CERN. He is a member of the Institute of Physics and the Royal Statistical Society. This article does not reflect the views of the research councils.</span></em></p>There have been squabbles of course, but the science project in Geneva is an example of putting differences aside to pursue common goals.Roger Barlow, Research Professor and Director of the International Institute for Accelerator Applications, University of HuddersfieldLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/553562016-04-19T14:02:03Z2016-04-19T14:02:03ZBig data has not revolutionised medicine – we need big theory alongside it<figure><img src="https://images.theconversation.com/files/119143/original/image-20160418-1266-fsdhyp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Genomes don't translate easily into an understanding of disease.</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=Y32E6C_-CI2e4_ZBJ_97dg&searchterm=dna%20sequence&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=129618455">www.shutterstock.com</a></span></figcaption></figure><p>Science rests on data, of that there can be no doubt. But peer through the hot haze of hype surrounding the use of big data in biology and you will see plenty of cold facts that suggest we need fresh thinking if we are to turn the swelling ocean of “omes” – <a href="https://ghr.nlm.nih.gov/primer/hgp/genome">genomes</a>, <a href="http://www.thehpp.org/">proteomes</a> and <a href="http://www.nature.com/scitable/definition/transcriptome-296">transcriptomes</a> – into new drugs and treatments.</p>
<p>The relatively <a href="http://www.scientificamerican.com/article/revolution-postponed/">meagre returns</a> from the human genome project reflect how DNA sequences do not translate readily into understanding of disease, let alone treatments. The rebranding of “<a href="https://theconversation.com/how-science-is-using-the-genetics-of-disease-to-make-drugs-better-30747">personalised medicine</a>” – the idea that decoding the genome will lead to treatments tailored to the individual – as “precision medicine” reflects the <a href="https://www.elsevier.com/connect/what-is-precision-medicine-and-can-it-work">dawning realisation</a> that using the -omes of groups of people to develop targeted treatments is quite different from using a person’s own genome.</p>
<p>Because we are all ultimately different, the only way to use our genetic information to predict how an individual will react to a drug is if we have a profound understanding of how the body works, so we can model the way that each person will absorb and interact with the drug molecule. This is tough to do right now, so the next best thing is precision medicine, where we look at how genetically similar people react and then assume that a given person will respond in a similar way.</p>
<p>Even the long-held dream that drugs can be routinely designed by knowing the atomic structure of proteins, in order to identify the location in a protein where a drug acts, has <a href="http://pubs.acs.org/doi/abs/10.1021/ci700332k">not been realised</a>.</p>
<p>Most importantly, the fact that “most published research findings are false”, as famously reported by <a href="http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.0020124">John Ioannidis</a>, an epidemiologist from Stanford University, underlines that data is not the same as facts; one critical dataset – the conclusions of peer reviewed studies – is not to be relied on without evidence of good experimental design and rigorous statistical analysis. Yet many now claim that we live in the “data age”. If you count research findings themselves as an important class of data, it is very worrying to find that they are more likely to be false (incorrect) than true.</p>
<p>“There’s no doubt of the impact of big data, which could contribute more than £200 billion to the UK economy alone over five years,” <a href="http://www.parliament.uk/business/committees/committees-a-z/commons-select/science-and-technology-committee/news-parliament-2015/big-data-dilemma-report-published-15-16/">says Roger Highfield</a>, director of external affairs at the Science Museum, London. But “the worship of big data has encouraged some to make the extraordinary claim that this marks the end of theory and the scientific method”.</p>
<h2>Useful but not profound</h2>
<p>The worship of big data downplays many issues, some profound. To make sense of all this data, researchers are using a type of artificial intelligence known as neural networks. But no matter their “depth” and sophistication, they merely fit curves to existing data. They can fail in circumstances beyond the range of the data used to train them. All they can, in effect, say is that “based on the people we have seen and treated before, we expect the patient in front of us now to do this”. </p>
<p>Still, they can be useful. Two decades ago, one of us (Peter) used big data and <a href="http://bit.ly/1SnfV6s">neural networks</a> to predict the thickening times of complex slurries (semi-liquid mixtures) from infrared spectrums of cement powders. But, even though this became a commercial offering, it has not brought us one iota closer to understanding what mechanisms are at play, which is what is needed to design new kinds of cement.</p>
<p>The most profound challenge arises because, in biology, big data is actually tiny relative to the complexity of a cell, organ or body. One needs to know which data is important for a particular objective. Physicists understand this only too well. The discovery of the Higgs boson at CERN’s Large Hadron Collider required petabytes of data; nevertheless, they used theory to guide their search. Nor do we predict tomorrow’s weather by averaging historic records of that day’s weather – mathematical models do a much better job with the help of daily data from satellites. </p>
<p>Some even dream of minting new physical laws by mining data. But the results to date <a href="https://www3.nd.edu/%7Emsen/Teaching/MathMeth/Reading/Lipson2009.pdf">are limited</a> and unconvincing. <a href="http://www.wiley.com/WileyCDA/WileyTitle/productCd-1118027795,miniSiteCd-IEEE2.html">As Edward put it</a>: “Does anyone really believe that data mining could produce the general theory of relativity?”</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/119145/original/image-20160418-1291-jo8d79.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119145/original/image-20160418-1291-jo8d79.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119145/original/image-20160418-1291-jo8d79.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119145/original/image-20160418-1291-jo8d79.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119145/original/image-20160418-1291-jo8d79.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119145/original/image-20160418-1291-jo8d79.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119145/original/image-20160418-1291-jo8d79.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&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 is tiny relative to the complexity of these brain cells.</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=rEfzJN1nBF4l4_iMvpcjHg&searchterm=neuron%20cell&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=267094166">www.shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Understand laws of biology</h2>
<p>Many advocates of big data in biology cling to the forlorn hope that we won’t need theory to form our understanding of the basis of health and disease. But trying to forecast a patient’s reaction to a drug based on the mean response of a thousand others is like trying to forecast the weather on a given date by averaging historic records of that day’s weather.</p>
<p>Equally, trying to find new drugs through machine learning based on accessing all known drugs and existing molecular targets is liable to fail because it is based on existing chemical structures and tiny changes in a potential drug can lead to dramatic differences in potency.</p>
<p>We need deeper conceptualisation, but the prevailing view is that the complexities of life do not easily yield to theoretical models. Leading biological and medical journals publish vanishingly little theory-led, let alone purely theoretical, work. Most data provides snapshots of health, whereas the human body is in constant flux. And very few students are trained to model it.</p>
<p>To effectively use the explosion in big data, we need to improve the modelling of biological processes. As one example of the potential, Peter is already <a href="http://pubs.acs.org/doi/pdf/10.1021/acs.jctc.5b00179">reporting results</a> that show how it will soon be possible to take a person’s genetic makeup and – with the help of sophisticated modelling, heavyweight computing and clever statistics – select the right customised drug in a matter of hours. In the longer term, we are also working on virtual humans, so treatments can be initially tested on a person’s digital doppelganger. </p>
<p>But, to realise this dream, we need to divert funding used to gather and process data towards efforts to discern the laws of biology. Yes, big data is important. But we need big theory too.</p><img src="https://counter.theconversation.com/content/55356/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Coveney receives funding from UK Research Councils (EPSRC, MRC), the European Commission, and UCL. </span></em></p><p class="fine-print"><em><span>Edward R Dougherty receives funding from the National Science Foundation, the National Institutes of Health, and the Los Alamos National Laboratory.</span></em></p>Big data is all well and good, but if we want medical breakthroughs, we’ll need big theory too.Peter Coveney, Professor of Physical Chemistry & Director of Centre for Computational Science, UCLEdward R Dougherty, Distinguished professor, Texas A&M UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/534142016-01-25T16:05:00Z2016-01-25T16:05:00ZExplainer: what is antimatter?<figure><img src="https://images.theconversation.com/files/109128/original/image-20160125-19660-nhp87q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's evidence that antimatter is produced in thunderstorms.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/computerhotline/20391956185/in/photolist-x4Y78t-p3YpHj-yKqDv-x5vJt8-tVoe6u-hBQj3T-o6SerG-yfsaB7-srUHRn-3FYBz-d8ySSU-feHppD-fB8TmL-7bc9YM-uCcZSS-35qj8A-cP1jnh-u4mgU-8sVyZB-9x843c-weQMvR-8s63Mj-8s1gUn-3DKMD-uU1BXG-vD97Bj-d8yTDL-f2Qm9-agNSLn-w8CJWj-6SHKPh-8cQwop-bWZ5MH-7beGV3-gmM1uT-8cEhoV-pejAy7-8m7YyG-m5dPPp-4Wz3yf-9x84hi-fJhdfL-x1P9Zk-afs3XS-gmMatW-ou7f1V-8cHAsE-6NsZQP-9x83WF-ozbPNN">Thomas Bresson/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Antimatter was one of the most exciting physics discoveries of the 20th century. Picked up by fiction writers <a href="http://angelsanddemons.web.cern.ch/antimatter">such as Dan Brown</a>, many people think of it as an “out there” theoretical idea – unaware that it is actually being produced every day. What’s more, <a href="https://theconversation.com/antimatter-measured-for-the-first-time-5782">research on antimatter</a> is actually helping us to <a href="https://theconversation.com/how-we-recreated-the-early-universe-in-the-laboratory-41399">understand</a> how the universe works.</p>
<p>Antimatter is a material composed of so-called antiparticles. It is believed that <a href="https://theconversation.com/explainer-what-are-fundamental-particles-38339">every particle we know of</a> has an antimatter companion that is virtually identical to itself, but with the opposite charge. For example, an electron has a negative charge. But its antiparticle, called a positron, has the same mass but a positive charge. When a particle and its antiparticle meet, they annihilate each other – disappearing in a burst of light. </p>
<p>Such particles were first predicted by British physicist Paul Dirac when he was trying to combine the <a href="https://theconversation.com/will-we-have-to-rewrite-einsteins-theory-of-general-relativity-50057">two great ideas of early modern physics</a>: relativity and quantum mechanics. Previously, scientists were stumped by the fact that it seemed to predict that particles could have energies lower than when they were at “rest” (ie pretty much doing nothing). This seemed impossible at the time, as it meant that energies could be negative.</p>
<p>Dirac, however, accepted that the equations were telling him that particles are really filling a whole “sea” of these lower energies – a sea that had so far been invisible to physicists as they were only looking “above the surface”. He envisioned that all of the “normal” energy levels that exist are accounted for by “normal” particles. However, when a particle jumps up from a lower energy state, it appears as a normal particle but leaves a “hole”, which appears to us as a strange, mirror-image particle – antimatter.</p>
<p>Despite initial scepticism, examples of these particle-antiparticle pairs were soon found. For example, they are produced when <a href="http://home.cern/about/physics/cosmic-rays-particles-outer-space">cosmic rays hit the Earth’s atmosphere</a>. There is even evidence that the energy in thunderstorms produces <a href="http://example.com/">anti-electrons</a>, called positrons. These are also produced in some radioactive decays, a process used in many hospitals in Positron Emission Tomography (PET) scanners, which allow precise imaging within human bodies. Nowadays, experiments at the Large Hadron Collider (LHC) can produce matter and antimatter, too.</p>
<h2>Matter-antimatter mystery</h2>
<p>Physics predicts that matter and antimatter must be created in almost equal quantities, and that this would have been the case during the Big Bang. What’s more, it is predicted that the laws of physics should be the same if a particle is interchanged with its antiparticle – a relationship <a href="http://www.symmetrymagazine.org/article/october-2005/explain-it-in-60-seconds">known as CP symmetry</a>. However, the universe we see doesn’t seem to obey these rules. It is almost entirely made of matter, so where did all the antimatter go? It is one of the biggest mysteries in physics to date.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/108716/original/image-20160120-26120-yta5eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/108716/original/image-20160120-26120-yta5eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=202&fit=crop&dpr=1 600w, https://images.theconversation.com/files/108716/original/image-20160120-26120-yta5eg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=202&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/108716/original/image-20160120-26120-yta5eg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=202&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/108716/original/image-20160120-26120-yta5eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=253&fit=crop&dpr=1 754w, https://images.theconversation.com/files/108716/original/image-20160120-26120-yta5eg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=253&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/108716/original/image-20160120-26120-yta5eg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=253&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Experimental area at CERN including the alpha experiment.</span>
<span class="attribution"><span class="source">Mikkel D. Lund/wikimeda</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Experiments have shown that some <a href="http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.13.138">radioactive decay processes</a> do not produce an equal amount of antiparticles and particles. But it is not enough to explain the disparity between amounts of matter and antimatter in the universe. Consequently, physicists such as myself at the LHC, on <a href="http://atlas.ch/">ATLAS</a>, <a href="http://cms.web.cern.ch/">CMS</a> and <a href="http://lhcb-public.web.cern.ch/lhcb-public/">LHCb</a>, and others doing experiments with neutrinos such as <a href="http://t2k-experiment.org/">T2K</a> in Japan, are looking for other processes that could explain the puzzle. </p>
<p>Other groups of physicists such as the <a href="http://alpha.web.cern.ch/">Alpha Collaboration</a> at CERN are working at much lower energies to see if the properties of antimatter really are the mirror of their matter partners. Their <a href="http://nature.com/articles/doi:10.1038/nature16491">latest results</a> show that an anti-hydrogen atom (made up of an anti-proton and an anti-electron, or positron) is electrically neutral to an accuracy of less than one billionth of the charge of an electron. Combined with other measurements, this implies that the positron is equal and opposite to the charge of the electron to better than one part in a billion – confirming what is expected of antimatter. </p>
<p>However, a great many mysteries remain. Experiments are also investigating whether <a href="http://www.universetoday.com/101893/will-antimatter-obey-gravitys-pull/">gravity affects antimatter</a> in the same way that it affects matter. If these exact symmetries are shown to be broken, it will require a fundamental revision of our ideas about physics, affecting not only particle physics but also our understanding of gravity and relativity. </p>
<p>In this way, antimatter experiments are allowing us to put our understanding of the fundamental workings of the universe to new and exciting tests. Who knows what we will find?</p><img src="https://counter.theconversation.com/content/53414/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Jones receives STFC.</span></em></p>Antimatter is at the heart of one of the biggest conundrums in physics. Here’s why.Roger Jones, Professor of Physics, Head of Department, Lancaster UniversityLicensed 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/387542015-03-13T10:50:10Z2015-03-13T10:50:10ZUpgraded LHC pushes physics into the unknown<figure><img src="https://images.theconversation.com/files/74715/original/image-20150312-7144-543jmc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Look into my high-energy particle physics and what do you see?</span> <span class="attribution"><span class="source">CERN</span></span></figcaption></figure><p>There’s a certain degree of anticipation and anxiety among scientists at CERN and beyond as the Large Hadron Collider prepares to roar back into life after a two-year break.</p>
<p>Upgraded with more powerful magnets to smash particles together with almost twice its previous energy, this will bring with it the opportunity to discover new, even more massive particles – just as with the Higgs boson – that will signpost the way beyond our current understanding of particle physics, the <a href="http://home.web.cern.ch/about/physics/standard-model">Standard Model</a>. Why do we think this? Because Einstein’s equation of energy-mass equivalence – more familiar to people as E=mc<sup>2</sup> – tells us that in order to make more massive particles we need more energy – even more than the LHC has been capable of delivering so far. </p>
<h2>Listen harder, hear more</h2>
<p>But energy is only part of the story; what’s also needed is greater precision, more sensitive detectors that allow for more nuanced data, which reveals rare events or subtle effects not previously observed. To this end, the <a href="http://home.web.cern.ch/about/how-detector-works">detectors</a> have been upgraded too.</p>
<p><a href="http://home.web.cern.ch/about/experiments/atlas">ATLAS</a>, one of the four main experiments built around the 27km of the LHC complex, has gained the capacity to measure the paths of the charged particles produced in the collisions. This has improved the accuracy with which we can measure the lifetimes of these ephemeral particles that in some cases exist only for a tiny fraction of time.</p>
<h2>Filter more noise</h2>
<p>The experiments have also increased the rate and selectivity with which they record collisions in the LHC. As a great deal of subatomic particle physics is already known, the more unusual, exciting events are hidden within a huge torrent of data representing more mundane particle interactions. The sheer <a href="http://www.lhc-closer.es/1/3/12/0">volume of raw data</a> – about a petabyte, or around 210,000 DVDs per second – from the experiments requires algorithms to rapidly filter and select the new and unusual events for further study while discarding the rest. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/74714/original/image-20150312-13499-vauldm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/74714/original/image-20150312-13499-vauldm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=425&fit=crop&dpr=1 600w, https://images.theconversation.com/files/74714/original/image-20150312-13499-vauldm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=425&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/74714/original/image-20150312-13499-vauldm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=425&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/74714/original/image-20150312-13499-vauldm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/74714/original/image-20150312-13499-vauldm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/74714/original/image-20150312-13499-vauldm.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">Particle collissions in the LHC have taken us to the edge of physics.</span>
<span class="attribution"><span class="source">CERN</span></span>
</figcaption>
</figure>
<p>Better selectivity is not the end of the problem, however. To cope with the volume of data produced by the experiments due to the more energetic collisions and more sensitive detectors means new software and storage procedures must be written. These will also transmit the data across the <a href="https://theconversation.com/number-crunching-higgs-boson-meet-the-worlds-largest-distributed-computer-grid-38696">worldwide distributed computing system</a>, which allows not just an accurate reconstruction of each collision from the traces recorded in the detectors, but also more rapid access for scientists to the records.</p>
<h2>Unanswered questions</h2>
<p>It’s a lot of hard work under tight budget constraints, but the effort is worth it. There are many open questions that the Standard Model simply cannot answer. </p>
<p>Is the recently discovered Higgs boson the particle the Standard Model predicts, or is it the first of a family of undiscovered, even more rare Higgs particles that are predicted by more complete but speculative theories such as <a href="http://home.web.cern.ch/about/physics/supersymmetry">Supersymmetry</a>? What is the nature of the <a href="http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/">dark matter</a> that astronomy tells us is far more abundant than the ordinary matter we’ve come to understand so well? How did a Big Bang that produced a balance of matter and antimatter result in the world of matter that we know today? </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/74724/original/image-20150312-7144-1mynaby.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/74724/original/image-20150312-7144-1mynaby.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/74724/original/image-20150312-7144-1mynaby.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/74724/original/image-20150312-7144-1mynaby.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/74724/original/image-20150312-7144-1mynaby.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/74724/original/image-20150312-7144-1mynaby.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/74724/original/image-20150312-7144-1mynaby.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/74724/original/image-20150312-7144-1mynaby.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&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 Standard Model of quarks and other particles, including the Higgs boson.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Standard_Model_of_Elementary_Particles.svg">MissMJ</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>My own principle interest in these questions is being addressed through studying the decays of particles containing quarks, the fundamental particles found inside the protons and neutrons that constitute an atomic nucleus. Of the six types of quarks it is the <a href="http://particleadventure.org/quarks.html">bottom quark</a> (also known as the beauty quark) that is particularly interesting as the way it decays displays a small bias for matter over antimatter, but not enough so far to explain the world we know.</p>
<p>However, through an odd but well understood quirk of quantum mechanics, new and massive particles even bigger than we can produce in the LHC can affect these particles’ decays and leave a trail to the new physics we need to develop to better explain the universe. Some of these studies are already underway at dedicated experiments like <a href="https://lhcb-public.web.cern.ch/lhcb-public/en/Physics/Beauty-en.html">LHCb</a>, which has already proved several <a href="http://www.extremetech.com/extreme/194644-scientists-at-the-large-hadron-collider-discover-two-new-supermassive-particles">hypothesied supermassive particles</a> within the Standard Model, but for others general purpose experiments like ATLAS can be better.</p>
<p>Unlike the first season of experiments with the LHC, once the <a href="http://news.ucsc.edu/2015/03/lhc-restart.html">first proton beam fires up</a> on March 23 we will not have such a clear roadmap of what to expect, or what to aim for. The first run was led by the knowledge that we would either find the Higgs and add to the Standard Model, or not find it and break the Standard Model in an act of creative destruction pushing us on to find better theories. </p>
<p>This time, there is a clear programme of work around the Standard Model, including the Higgs, but we have many guides that point towards new physics. Most analyses will advance science through excluding possibilities, but the new discoveries will be all the more enlightening. In a sense, we have entered a mode of more pure scientific discovery – and I for one cannot wait.</p><img src="https://counter.theconversation.com/content/38754/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Jones receives funding from STFC. He is affiliated with the Atlas Collaboration.</span></em></p>For less than the cost of a single Typhoon jetfighter, the upgraded LHC will push our understanding of physics to the brink.Roger Jones, Professor of Physics, Head of Department, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/386962015-03-12T14:45:10Z2015-03-12T14:45:10ZNumber-crunching Higgs boson: meet the world’s largest distributed computer grid<figure><img src="https://images.theconversation.com/files/74660/original/image-20150312-13508-1tqmvho.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The CERN datacentre is the ground zero, but only part, of a worldwide computing grid</span> <span class="attribution"><span class="source">Maximillien Brice/CERN</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>The world’s largest science experiment, the Large Hadron Collider, has potentially delivered one of physics’ “Holy Grails” in the form of the <a href="http://home.web.cern.ch/topics/higgs-boson">Higgs boson</a>. Much of the science came down to one number – 126, the Higgs boson’s mass as measured in gigaelectronvolts. But this three-digit number rested upon something very much larger and more complicated: the more than 60,000 trillion bytes (<a href="http://www.lhc-closer.es/1/3/12/0">60 petabytes</a>) of data produced by colliding subatomic particles in four years of experiments, and the enormous computer power needed to make sense of it all.</p>
<p>There is no single supercomputer at CERN responsible for this task. Aside from anything else, the political faffing that would have ensued from having to decide where to build such a machine would have slowed scientific progress. The actual solution is technically, and politically, much more clever: a <a href="http://home.web.cern.ch/about/computing/worldwide-lhc-computing-grid">distributed computing grid</a> spread across <a href="http://home.web.cern.ch/about/computing/grid-system-tiers">academic facilities around the world</a>.</p>
<h2>Many hands make lighter work</h2>
<p>This solution is the <a href="http://wlcg.web.cern.ch/">Worldwide LHC Computing Grid</a> (WLCG), the world’s largest distributed computing grid spread over 174 facilities in 40 countries. By distributing the computational workload around the planet, the vast torrents of precious particle data streaming from the collider can be delivered, processed, and pored over by thousands of physicists regardless of location or time of day or night. </p>
<p>CERN’s datacentre is considered Tier 0 and is linked by <a href="https://twiki.cern.ch/twiki/bin/view/LHCOPN/WebHome">dedicated fast fibre-optic links</a> to 15 Tier 1 facilities in Europe and the US, and <a href="http://gstat-wlcg.cern.ch/apps/topology/">a further 160 Tier 2 facilities</a> around the world. At Tier 0 the rate of data throughput hits around 10GB/s – about the equivalent of filling two DVDs every second. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/74649/original/image-20150312-13499-18z2fcj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/74649/original/image-20150312-13499-18z2fcj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/74649/original/image-20150312-13499-18z2fcj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=643&fit=crop&dpr=1 600w, https://images.theconversation.com/files/74649/original/image-20150312-13499-18z2fcj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=643&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/74649/original/image-20150312-13499-18z2fcj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=643&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/74649/original/image-20150312-13499-18z2fcj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=808&fit=crop&dpr=1 754w, https://images.theconversation.com/files/74649/original/image-20150312-13499-18z2fcj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=808&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/74649/original/image-20150312-13499-18z2fcj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=808&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">UK universities linked up to the GridPP.</span>
<span class="attribution"><span class="source">GridPP</span></span>
</figcaption>
</figure>
<p>During the first “season” of experiments on the LHC, now known as Run 1, the WLCG used up to 485,000 computer processing cores to crunch its way through around 2M sets of calculations a day. Around 10% of this number-crunching was performed by the <a href="http://www.gridpp.ac.uk/about/">GridPP Collaboration</a>, the UK’s contribution to the WLCG funded by the Science and Technology Facilities Council (STFC). Today Tier 0 is processing around <a href="http://home.web.cern.ch/about/computing">one million billion bytes</a> (a petabyte, or 1PB) every day – equivalent to about 210,000 DVDs.</p>
<p>But the grid has grown into something more - an expert community that has tirelessly turned technology into ground-breaking physics results. Now, with <a href="http://press.web.cern.ch/backgrounders/lhc-season-2-facts-figures">Run 2 and a second season of LHC experiments</a> due to start this month, the same experts will need to manage even greater amounts of data produced by particle collisions of even greater energy.</p>
<h2>Harder, better, faster, stronger</h2>
<p>Not only will Run 2 nearly double the experiments’ collision energy in order to probe theories such as supersymmetry, extra dimensions and magnetic monopoles – this round of humans vs protons will result in almost three times as many collisions per second in the collider. This increase will allow the properties of the Higgs boson to be studied in greater detail, perhaps even giving some understanding of why the particle that gives mass to others also has mass of its own.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/74659/original/image-20150312-13520-1sl8mnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/74659/original/image-20150312-13520-1sl8mnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/74659/original/image-20150312-13520-1sl8mnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/74659/original/image-20150312-13520-1sl8mnc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/74659/original/image-20150312-13520-1sl8mnc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/74659/original/image-20150312-13520-1sl8mnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/74659/original/image-20150312-13520-1sl8mnc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/74659/original/image-20150312-13520-1sl8mnc.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">Plotting the path of every particle and fragment generates data by the warehouse-full.</span>
<span class="attribution"><span class="source">ALICE/CERN</span></span>
</figcaption>
</figure>
<p>However, the debris left by exploded hadrons was hard enough to pick through last time – left as it was, the grid would have required six times the computational capacity in order to cope with the size of the figurative haystack in which physicists are looking for needles. But the grid has been upgraded <a href="http://press.web.cern.ch/backgrounders/lhc-season-2-stronger-machine">alongside the experimental apparatus</a> to cope with demand.</p>
<h2>Evolution, not revolution</h2>
<p>New techniques introduced to cope with the experiments’ demands include <a href="https://software.intel.com/en-us/articles/frequently-asked-questions-intel-multi-core-processor-architecture#_Essential_concepts">multi-core processing</a>. In order to compensate for the diminishing advances in processor speed, multi-core CPUs – processors designed as two, four or even eight CPUs in a single package – are being rolled out as worker nodes throughout the grid. </p>
<p>This has meant physicists have to rewrite their code to be multi-threaded in order to take advantage of the multiple cores by sending them tasks in parallel, but the result is much improved processing speeds. The grid then has to cleverly manage how these tasks are shared within a single site – not a trivial task when each site typically has thousands of nodes.</p>
<p>The huge amount of data transferred between sites also puts a burden on networks. This has been reduced by using <a href="https://root.cern.ch/drupal/content/about">xrootd</a>, a high-level protocol that provides a means for scientists to access the huge datasets stored across the grid in the most network-efficient way possible. By implementing a <a href="http://www.sciencedirect.com/science/article/pii/S2214579614000033">dynamic data placement</a> policy, the grid can learn how many copies to make of popular datasets and where best to put them for optimum performance. </p>
<p>It’s hard to say if Run 2 will give us answers to life, the universe, and everything. There are certainly a lot of scientists whose careers depend on some kind of new physics emerging from the four experimental <a href="http://home.web.cern.ch/about/how-detector-works">detectors</a> spaced around the LHC’s 27km circuit. Some will find what they’re looking for; others will not. But they will all rely for their work on the expertise of the computing technology team who support the world’s largest planet-wide computing network for many years to come.</p><img src="https://counter.theconversation.com/content/38696/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tom Whyntie is a member of the GridPP Collaboration and receives funding from the UK Science and Technology Facilities Council (STFC). He is affiliated with the Langton Star Centre, a research facility for schools, through the CERN@school programme and the LHC's MoEDAL experiment.</span></em></p><p class="fine-print"><em><span>Jeremy Coles is a member of the GridPP Collaboration and receives funding from the UK Science and Technology Facilities Council (STFC).</span></em></p>The ‘supercomputer’ that processes LHC’s data is a networked grid that spans the entire planet.Tom Whyntie, Visiting Academic and GridPP Dissemination Officer, Queen Mary University of LondonLicensed 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/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.