What is the Future of Particle Accelerators?

well good evening everyone it's great to see you here I am very very excited about tonight because I have surrounded me here an illustrious panel of some of the world's best and some of the world's most important I should say a particle accelerator physicists who are working on the next generation after the Large Hadron Collider so just to get a little bit of a status of where we're at can I see a show of hands for how many of you have heard of the Large Hadron Collider before good the media has done its job excellent ok so my name is Susie she Thank You Martin's the introduction I'm an accelerator physicist at the University of Oxford and I tend to design smaller machines for different applications which is what a lot of our projects called accelerators for humanity has been about but we couldn't be talking about particle accelerators unless we really brought out the big guns and talked about accelerators for particle physics so I think you're aware already that the Large Hadron Collider is the highest energy hadron that is proton Collider ever built 27 kilometers in circumference underneath the border between France and Switzerland near Geneva and it is doing a fantastic job at colliding protons together and uncovering the secrets of the universe but I'm often asked when I talk about particle accelerators well what's gonna come next what is the next big thing after the LHC and that is effectively what we're here to talk about so the four people I have surrounding me I'll just give you a quick introduction to each of them and then I'm going to ask them to introduce their kind of pet project or their ideas on what might be coming after the Large Hadron Collider so furthest on your left my right is professor phil burrows phil is a professor in physics at the University of Oxford and he's also the associate director of the John Adams Institute for accelerator science which is one of two accelerator institutes in the UK and it's also the one that I work so it feels actually in my department so feel that she did his degree and PhD in particle physics first at Oxford uni and then he actually moved to the USA for about a decade working at MIT and on slack the linear collider which was the first electron positron Collider in the world um he then returned to Oxford then became a professor at Queen Mary University and then came back to Oxford again you've spend a lot of time in Oxford Phil as a professor and in his current position as director of the John Adams so phil has been P I that is principal investigator of the UK's team on linear electron positron Collider development and working on the international linear collider and the compact linear collider which he'll explain a little bit more about what those three projects are he's been principal investigator of the clique UK collaboration since 2011 and since 2014 has been the spokesperson of the clique that is compact linear accelerator collaboration which involves about 300 people 60 institutes and 31 countries around the world right that's film um which could you welcome feel good give a round applause thank you okay so the next person along the line is dr. Frank simmerman now I'm particularly excited to have Frank here because Frank's actually come all the way over from CERN Frank is a senior scientist in at CERN in the accelerator beams department which is obviously the home of the Large Hadron Collider Frank has worked it seems on just about every project major project going did his PhD at the University of Hamburg on a machine called Hera which is a proton ring and has worked at major labs around the world including Daisy in Germany slack in the US and has worked its own from 1999 I believe so Frank has published text books in accelerator physics wrote the handbook he's the editor of the main journal in the accelerator field the physical review accelerator and beams I know you're gonna rush out and read it right now it's good it's a good read Frank that's good he's also coordinator of a work package of one of the major European coordination in accelerator research and development called EU car the work package is called extreme beams which is kind of cool I like it and since 2014 has also been deputy core data of the CERN hosted future circular Collider study which is mostly I think what you'll be addressing tonight hopefully so please welcome Franks okay so first on my left your right this is Professor Ken Leung who is a professor of particle physics at Imperial College in London and he's done a lot of work at CERN on muon proton scattering as a graduate student apparently and and then returned to the UK to join an experiment at Daisy in Hamburg in fact these two discovered they were almost colleagues at Daisy by one year I think we discovered and there's contributed to the design and construction of that experiments that's particle physics experiment um now came got fascinated by the discovery of neutrino oscillations at one point in career and your career seems to have turned direction and really focus on neutrinos and and muons since that time so Ken chairs the International design study for a machine called the neutrino Factory which hopefully we'll hear more about and his spokesman for an experiment called the muon ionization cooling experiment which has being carried out at the Rutherford Appleton lab in Oxfordshire and is also chair of the International Committee for future accelerators neutrino panel so Ken focuses mostly on neutrino and muon accelerators at the moment so please welcome Ken and finally but by no means least Stuart mangles dr. Stuart mangles on my far left here is a senior lecturer in physics at Imperial College London where he also did his PhD and here's a faculty member of the John Adams Institute as well I should say now Stuart's focus is a little different from the other from the other four of us here in fact in that he's actually by definition of plasma physicist I suppose so he researches plasma-based accelerators and he's been doing that for the past 15 years using a technique called laser Wakefield acceleration so Stuart has has a growing interest in that field in both developing laser Wakefield accelerators both for particle physics and for other applications and improving the quality of the beams from them he's also involved in a project at Daisy Daisy keeps cropping up doesn't it called flash forward which will use intense beams of electrons to drive a plasma wave so that's not going to make a huge amount of sense right now but it will when Stuart gives us a bit of an introduction later so please welcome Stuart ok so that that is my illustrious panel which is why I'm so excited to dig into some of the science behind what they do so what I asked each of my panel to do was actually basically provide a five-minute kind of introduction pitch to the types of projects that they work on it that they think might happen in the future so the first contribution to that is Phil burrows so hopefully we have some slides to ofg Phil ok thank you very much Susie is the microphone working can everybody hear me okay super well ladies and gentlemen thank you very much for giving up a rather lovely Friday evening in September to come and join us in this conversation about possible future large accelerator projects now you've already identified yourselves as a very erudite audience because everybody's heard of the Large Hadron Collider and everybody knows that large modern high-energy particle accelerators are circular such as the LHC that you see on the photograph here well they're circular that is except when they're not and so this is a photograph of the two-mile-long linear collider Stanford in California and in fact Frank and I had the privilege to work together on this project in the 1990s and you can see manifestly that it is linear it is two miles long so what do we do what do we want to do with linear electron-positron colliders where we want to take subatomic particles electrons we want to collide them with their antimatter partners positrons which have the opposite electric charge when electrons meet positrons matter and antimatter annihilate energy is released and what condenses out of that energy are exciting types of new elementary particles for example the Higgs boson which I'm sure most of you will have heard of that was discovered only a couple of years ago at CERN for example top quarks which have very heavy types of subatomic building blocks of matter and of course who knows maybe dark matter particles supersymmetric particles something that has yet to be discovered about which we would be very excited and very keen to know so linear electron-positron colliders are the way forward to serve as factories for mass producing Higgs bosons top quarks and hopefully dark matter and other types of new particles we're talking about hundreds of thousands of Higgs bosons hundreds of thousands of top quarks samples that will allow us to really measure the properties of these particles with exquisite precision and understand what they are now there are two major projects which are being proposed for implementation for high energy future eeep lassie - electron positron linear colliders this one is the international linear collider to cut a long story short you stick electrons in at one end you stick positrons in at the other end you accelerate them together and you do matter-antimatter annihilation x' in the middle the rest of the detail you don't need to worry about the footprint of this machine is about 30 kilometres our friends in Japan of the particle physics community in Japan very much wants to host this machine in the northern part of Japan just north of the city of Sendai you can see on the map there the footprint of the machine if you look closely you can see a cross section through the geology of the mountains in the Kitakami region so this project we hope very much will be real in Japan now another project which is perhaps a little bit further away is the compact linear collider and I Susie said I'm privileged to be the the spokesman or if you like principal investigator of this project again don't worry about the details it's a slightly bigger version of the international linear collider it's designed to get to somewhat higher energies of these collisions and never let it be said that accelerator physicists don't have a sense of humor because compact means fifty kilometers long but that's a jolly sight more compact than it would be if it weren't made with this wonderful technology Susie mentioned I think it's important to note that these are global scale projects so in the case of the compact linear collider three hundred people fifty Institute's 31 countries so my joke at this point is the Sun never sets on my Empire now if that project were realized it would be realized in the Geneva region at CERN so here you see a little map the little white circle in the middle is the Large Hadron Collider and then you can see magenta green and blue linear arrays of dots and those represent the different stages of this project leading eventually up to an energy of 3000 Giga electron volts or accelerating particles to energies of you know 1.5 trillion votes for the electrons and 1.5 trillion votes for the positron so these are very high energy machines so what I would hope to argue this evening is that the way ahead is linear linear colliders allow collisions of point-like particles under controlled conditions they allow factory level production of things such as Higgs bosons which we really need to understand having just discovered them a few years ago why linear well I'm the problem and Frank of course will talk about this in his presentation when you try to accelerate electrons or positrons in a circle they emit x-rays this is called synchrotron radiation and at some point as fast as you're trying to accelerate them they're radiating energy away and so it's generally agreed that to get the very highest energies one should avoid this synchrotron radiation and therefore the future is linear machine with no synchrotron radiation there elegantly expandable because you can always make them that bit longer and therefore get to higher energies and and they are intrinsically upgradeable because once you have your nice 30 kilometer long tunnel when Stewart comes along in 50 years when his technology is working you can always stick it in to this beautiful tunnel and you can get to higher energies by upgrading the facility that you have as technology comes along and as you're able to get to higher and higher energies so elegantly expandable and intrinsically upgradable and the technologies that we're developing with many applications this is my last couple of slides Susie as you know so this is the European x-ray free electron laser at the Daisy laboratory again in Hamburg and the technology that we've developed superconducting niobium radiofrequency accelerating cavities the shiny thing bottom left there this technology developed for these big high-energy machines such as the international linear collider has now been deployed in a two kilometre machine in Hamburg it's a 10% scale model of the real ILC machine and this will serve tens of thousands of scientists by producing x-rays to look at the structure of matter materials through structural biology through biomedicine chemistry and so on so this is an example the spin-off of the technology for the great benefit of wider science and I love this slide this is another example of the application of linear accelerating technology the gentleman in the bottom left are carrying at roughly 1 meter long accelerating structure made of copper they develop structures like that for the purpose of getting to high energies the big two mile long machine at Stanford that you see upstairs and today there is one of those structures in more than 10,000 x-ray therapy machines that are deployed in hospitals all over the world are more than 10,000 of these machines worldwide and in the UK alone 10,000 people per day are treated with cancer therapy from machines like this which are employing technology developed with a view to very high energy linear colliders so I think at that point I'd better stop and I'll give my colleagues chance to get their 10 cents worth Wow or sales pitch okay so having heard the sales pitch for linear colliders as I said in my introduction at the moment there's a large study at CERN happening for a circular Collider instead so Frank over to you of course I disagree with the statement of fear that the future is linear maybe can I stand up here I have some problem with the eyesight it's difficult for me to see all those things okay here see his history of coal I receive electron-positron colliders in blue and center of mass and hadron colliders proton colliders in red and this is a logarithmic scale of the center of mass energy so it's over the last 50 or 60 years you can see dramatic progress in the collision energy so we got effectors housing also in the energy of electron positron collisions and affect a hundred in the energy of hadron collider lightly above hundred and so we're not so many as you can see there were not so many hadron colliders and they used to be more electron positron could so and these colliders extremely successful because they allowed us to construct the so-called standard model of particle physics in the standard model we have meta particles which consists of quarks and leptons and we have Faust's carriers which are these bosons here and there's a different particle the Higgs boson which is neither matter nor force it is completely different from the other so many of these are the heavier particles he ever discovered of kaleidos it's be a Collider at select discover the charm quark and to tower left on the Petra discovered the glue one that was in Europe a daisy that was the only such discovery which didn't give a Nobel Prize for some reason then the SPP bias at CERN discovered the Z and W boson the tavataan discovered a top quark and then the LHC as you may know a few years ago I discovered a new particle the Higgs boson so the colliders essential in unraveling this part of the heavier part of the standard model and they have proven a powerful instrument for discovery and purpose measurement okay but this we have the standard model but many questions are not explained by the Sun our model here's an incomplete list so standard model only describes a known met as a visible matter which is about five percent of the universe there's a large part which is called dark matter which is visible in the rotational speed of the galaxies if you believe in in a Newton and Einstein then you need additional matter to explain the observed rotation velocity seen in the universe and then in addition there is something called dark net dark energy I think that can maybe even later explains the dark energy that comprises even larger this comprise even larger part of the of the of the unknown so so maybe three quarters of the energy of the universe is the dark energy and we don't know what it is and then we have matter we have only matter if you have no antimatter planets antimatter way to give matter and not antimatter and why do the masses of these fundamental particles differ by certain orders of magnitude send the people anyway gravity is not really included understand a lot and is very difficult to combine it with quantum physics and with the other forces and then there's a search forward equation which is so far has so far not been accomplished also I think that some people try to develop it 100 years ago already okay so we are on a future circular kalila when a response to the upgrade of the so-called European strategy for particle physics in 2013 they requested a study of a post elegy Collider complex after the Large Hadron Collider based at CERN and this would be a larger circular thing here you see the LHC look small as unfiltered but here we don't talk about a long line but we have another circle which is now hundred kilometer and circumference which put go around the city of Geneva and the nearby mountain which is called slf and it would pass under the Lake Geneva so we are quite fortunate on this side of the Geneva site is like as a rather shallow only 15 meter deep but on the other side it becomes very very deep opposite side at Montreux so there's no problem just say LHC is 100 meter under the surface and this FCC before we 200 meters under the surface so there is no issue going under the lake but we are limited we cannot build something much bigger as 100 kilometer because under the one side as the Earth's here and on the other side as a dual amount and below we don't want thousand meter deep access shafts at all so we have a somewhat limited to this hundred kilometer now we would like to go up in energy an order of magnitude beyond the LHC there are reasons to believe that going up in effect or ten or so in energy will help us understand the Higgs the Higgs mechanism more properties of the X part of the potential of the Higgs and also perhaps help us understand dog meta and with luck dark energy so to go to 100 TV in this ring we need 16 Tesla magnets type of magnets and the LHC has a Tesla and that was already extremely difficult and if you want to go from 816 says that we need the new technology so we need a new suit we need a new type of superconductor to make these magnets there is a simple equation so actually energy of a Hadron Collider is very easy it's just proportional to the magnetic field and the circumference so we had increasing both the increasing circumference by effect offer almost and the increasing the Miami feed by factor 2 which is already quite challenging and together we get almost effect or eight in energy so so if he builds this new tunnel we can also think about putting other colliders and the standard for example we can put an electron positron circular Collider and that would have a very excellent performance at the energies where we can produce a Higgs particle so this would also be a very beautiful Hicks Factory and also a nice factory of top quarks so we can actually produce all the known particles and in very large quantities and my job is extreme precision to see any deviation from the standard model which would give us a hint at which next energy scale in new physics should appear of course we can also collide electrons with protons as we did in here and in handbook where I started so people who want to make a superhero is 10 times and high energy and 10 200 times the luminosity so this could also be possible and in addition we have a less ambitious study we developed the six intercept Magnus we could install these magnets also in the LHC existing a reciept tunnel and that would allow us to double the energy of the Large Hadron Collider this is a time scale of the large circular Santa was left was a electron positron Collider the study's design started in the mid-1970s and you see it took I don't know more than 10 years so conce to design and construct it and then it operated five years for physics and as the LHC and this will be followed by high luminosity upgrades which is a extension of the LHC to give ten times the performance which is called the higher luminosity LHC and so the LHC at hydro Sarah she will together run for about twenty five twenty seven years from 2010 to about twenty thirty seven so we have about twenty years time now to develop a mesh concept for a future Collider so we have started this future circular attack future circular Collider design which actually four different colliders in one study and aim for prototyping phase if it is supported by the next update of the you beam Saji in 2019 we could go into a prototyping phase a construction and ideally we would like to start the physics at this new machine when the LHC physics terminate so in the second half of the twentieth so we must advance fast not because we have less time available that had been available for the LHC and this machine is much bigger and it's even more advanced technology so we don't have so much time and our intermediate goal is to have a solid conceptual design by the end of 2018 so we are about half way in this process and we would we are looking at all the items including this construction schedule that cost the key technologies and parameter space for operation and one goal is that we absolutely must ensure that the promise performance can be achieved this has been the case for lap and Alesi boasts both machines reached a design and performance in a very short time and so in principle we know that for this type of machine we should be able to each the promise performance but the design study will ensure that there is enough margin to accomplish this okay here's just a picture on the magnet technologies for a long time the US United States was leading the high field magnet development in Berkeley already in the early 2000 says they reach the 16 Tesla huge was this magnet here and last year at Sun we built similar magnets which also reached a 16 Tesla field so in principle we have a demonstration that was using the nagham Seaton superconductor we can achieve 16 Tesla field which is twice the field of the LHC Magnus Pisa which are based on niobium titanium superconductor so but we need some margin so we are not quite as I guess these these tests - I have no aperture for the beam so we need to have we need have a beam pipe inside the magnet to Excel to bend our particles and to bring some Souza's magnets so we still need some development to have accelerate a quality magnets at the six inches of field and also we like to make these magnets as cheap as possible so there's a ante effort to reduce the cost of the superconductor and of the - okay - my last slide this shows you the hadron colliders unraveling this secrets of the universe so there used to be the Tevatron in the Chicago it's a semi so-called fami lab it was operated from 1983 to 2011 at 2 T V center of mass energy then now we have the LHC factor 7 higher energy with some boosters important discoveries and then we are planning to make the next step and also I would love the future to be linear if he wanted to use this linear collider technology to build 100 T V Collider he would need three thousand kilometer and with this technology we are we are staying below 100 kilometer so that is still a very doable we think that circular colliders are still the way forward if you want to see 100 T V and this in the century ok thank you Frank all right so so we can start to see a little bit of a conversation maybe developing between linear colliders and circular colliders so a few a few key points there that we'll come back to in a bit was first of all the time scale of some of these projects which I'll come back to second of all that the the electron-positron machines you know in fills the linear collider version you know sort of three kilometers long maybe no sorry 30 kilometers long 50 kilometers long but to actually do the same thing for hadrons would be you say three thousand kilometers long that's your estimate approximately okay so I'm so it was seeing this it's some different physics involved there and how difficult it is to accelerate those particles and the energies you need to reach the physics that you're looking for which we'll come back to in a bit so the two other other speakers here have slightly different few points I think and one of the topics that Phil covered with synchrotron radiation and that's a really important topic in building accelerators because if you bend a particle around a corner it loses energy so at some point you're just fighting to put that energy back in and can I think some of the machines you'll talk about have a different approach to tackling that so that's right yeah so I think actually the what's exciting is actually the breadth of science that can be addressed by these different techniques so what I'm supposed to talk about is a different kind of particle that you could use to do the science and so the jargon titles and neutrino factory and muon Collider the key thing is the accelerate muons and I hope they'll become obvious why so here is the particle content of the standard model you've seen that already you've got quarks that make up what we call the hadrons if you have up and down you can make protons you have electrons for that now means you can make atoms and that's basically all you need for real life there are two more families and there they're there or you just want as you go to the left on that plot and you've got a whole line of particles which are called the neutrinos so they when I did the particle physics course at Imperial in 98 they were massless and then there was discovery of neutrino oscillations which means they are not massless they have some mass that means they do not go at the speed of light they have no conserved quantum numbers that's important that means that a neutrino can change from being the partner of the electron to be in the partner of the muon as it travels through space and time so it's really like a traveling Schrodinger's cat one minute it's alive at the next minute it's dead and the good thing is that the weak interaction has got the opening the box thing because of the weak interaction picks out the flavor and you can tell so that's how we know that they've got mass okay so I'm going to talk a little bit about the neutrinos what we do technically is we take the neutrinos we invent three mass eigenstates for them so there are three types of neutrino that are distinguished by their mass we mix them up and that's how we get the flavors and we want to measure the way in which that happens so there's can you see that on the bigger screen I can't see this so here's the cosmic abundance of different particle types and you'll notice that neutrinos are second only to the number of protons noise on that it's on the right-hand side of the screen I hope in that figure the other thing you want to know is that the mass of neutrinos is way different from everybody else several orders of magnitude different so we found the Higgs fantastic all the charged particles we think get their mass from the Higgs neutrinos are several orders of magnitude lower same mechanism different mechanism we need to find out okay here's the history of the universe starting from the Big Bang in one slide yeah so the important thing is that neutrinos really have some impact here so the impact of neutrino so if we start at the recent past we know that the universe is expanding and we know there is dark matter in the universe as was already explained we know there's dark energy so neutrinos are rather special they don't have conserved quantum numbers they've got mass we don't know how they got the mass and those theories in principle offer explanations for those we need to understand the neutrino neutrinos are almost massless they're not masters so they go almost at the speed of light they only interact weakly so they can communicate over vast distances of space and time so they can contribute to making the universe look uniform on large scales the large-scale structure and also galaxy formation might be to do with neutrino mass inflation so inflation is really important and the Bank of England tries to try to deal with it but particle theorists look at phase transitions of particles in the early universe and there are theories which have really really heavy neutrinos which are partners to the ones that we observe and the phase transition where they go out of interaction is perhaps driving the inflation so we all need to understand neutrinos and finally if you meet antimatter you will annihilate there is no antimatter we can calculate from the bodies in this room a very strong limit on the amount of antimatter in the universe and nobody can explain that on there are theories so they're the same as the ones that are generating this inflation that take all the antimatter away we really need to understand neutrinos okay so here's the evolution of the universe on a different scale and what you're seeing is where the different different accelerators contribute the LHC if you can pick it out I can't now can point at the screen but it's useless so you can see where the LHC contributes accelerators today go up to the yellow light the white line which is on the left hand side the vertical white line so you want to go beyond and there have been two or three ways of getting there that have already been described that's really exciting there's another way which I want to explain yeah right so there is an electron that's what you need to make matter there's another particle which has exactly the same properties it's called the muon the only way it differs from the electron is that is 200 times as heavy and it decays into an electron and actually into neutrinos the fact that this 200 times as heavy makes it technically good to do the kind of things that you can do with electrons and positrons so you can accelerate them there you can do that efficiently and actually you can show that it's more cost-effective if you can produce enough of them they decay in particular they decay democratically into muon and electron neutrinos and that's critical for what you need to do the science you need new ease because you look need to look at transitions that are not that are not disappearing so you need to see and you try not turn into something else new in where you get for the neutrino right yeah thank you thank you Susie okay so for both the energy frontier so how'd you get the very very high energy and how do you study the properties of neutrinos muons are ideal because they're heavy and they decay to the right particles there is a problem and that is that they decay so the advantage is also the disadvantage they decay in 2.2 microseconds if they are not moving and you produce them from the decay of pan so once you've got your muons they typically occupy a large volume so I want you to think of a watermelon in three-dimensional space but they're highly divergent the cost of your acceleration is roughly going as the size squared and then you've got the stored energy so there's a real premium in making it smaller to study neutrinos you've got to earn the watermelon into a cucumber because the length is okay but the width you've got to shrink down and so that means that what we have to do is demonstrate a technique to reduce the face space that's ionization cooling what we can't point what we do is we shoot the muon beam through an is over it loses energy that means the transverse the momentum transverse to the beam and the longitudinal mentum go down equally you accelerate in one direction that means the ratio has gone down and you've squeezed the beam down experiment we're doing it rather for lab now is going to demonstrate that so you look at the top which is the concept you can see how we want to realize it and that's what it looks like in the hall so I'm only saying that we're going to demonstrate the key technology and then we can make the accelerators that can do what I just tried to explain and to finish on the size of this thing on the left hand side with the red squiggle you can see the border of the Fermi National Accelerator Laboratory in the US and you can see the muon Collider fitting on that side for comparison you can see the LHC that's the blue circle the IRC which is the Green Line or click and on the right hand side is what used to be called the V LHC so it's roughly speaking the FCC that Frank was just describing so it's not that so these are different techniques they do slightly different science and I think there's a great strength in the breadth of science that you can do with these different things thank you very much ok thank you so one of one of the the key things I should point out at this stage is that one of the useful things about muons is because they're slightly heavier they emit less synchrotron radiation so there's this issue of the being losing energy as it goes around a ring is not such an issue in so I think that the point to make is if you're radiating energy but you want to keep colliding at the same energy you got to put the energy back and that has to come out of the power station so if you radiate less energy you have to put less power in and that's why there is an energy about 1 and 1/2 TV where the muon colliders are more cost effective to operate maybe not to build ok right so now into something completely different yeah I don't think I need to introduce any further than that just completely different go ahead Stuart so so far you've heard about all these different parts of accelerators and future projects and I think they have one thing in common they're all massive machines and so if you like what I'd look at what the question I'm looking at is why are they so big and more importantly can we make them a lot smaller so phil was right I'm not sure I agree with the 50 years but but we are talking about a technology that could be used a bit further in the future I'm very happy with that yeah and so I again compulsory picture overhead predict future of a big accelerator here is and I went for SI units rather than miles it's about 3 kilometers long this is slack in America and and the front the thing is that all of these parts of accelerators are basically using the same technology to accelerate particles ok whether or not they are writing electrons protons or muons they're using an electric field to accelerate a particle inside a vacuum tube so it's a low pressure vessel with nothing inside it and then you put a radio frequency wave traveling through it which accelerates the particles up as late as it goes along you can work out the energy that you're elected your electric your charge particle can get up to by just taking the strength of electric field which is measured in volts per meter or mega volts per meter if you like million volts per meter by the distance okay so and all because they were using basically the same technology and they're all working at around about 10 to 100 of the right at the top and 100 mega volts per meter so just some very simple math that tells you if you want to get a particle to just 1 GeV you still need 10 to 100 meters of accelerator if you want to get to 100 GeV then you need depending on the technology between 10 and 100 kilometers I didn't put a hundred TV on there and so the only would effectively the only way we can make things shorter is well there are two ways one is we can use the same accelerating structure over and over again which is a circular accelerator but then we hit the problem of magnet strength and rate a synchrotron radiation or we can turn up the electric field strength they're the only basically the only two things we can do in fact that technol the technology to get up to 100 mega volts per meter that's that's already really hard yeah that's a really cutting-edge technology in in vacuum at accelerators and why so why can't they do any higher well the problem is if you I don't know if you've ever tried this but if you have two electrodes and you put a large voltage between them in air you get a spark forming between them now if you turn down the pressure so if you put that except that those that capacitor in in vacuum you can put a larger voltage before the vacuum before you get breakdown but you it doesn't matter how low inverting pressure you go you will always get to the point where there there's just one electron and one or two electrons between those two plates and that will cause an avalanche that will will mean that you get sparks forming inside your accelerator and that's the sort of fundamental limit of why if you're using this this conventional technology sorry you can't go any higher than about 100 microvolts per meter and that's because you turn up the field and it's just gonna start forming sparks which degrade the whole structure they may even destroy it and so if you like what I'm trying to look at and I have been over the last decade or so is could we do something else could we actually solve this breakdown problem and start with something that either well one thing would be nice if you could find something that just didn't break down not sure what that exists but instead actually the acceleration in something that's already broken down so if you take a volume of gas and you fully ionized it it can't iron eyes anymore and actually that's called a plasma and plasma scan support huge electric fields so I think we have already demonstrated sort of fairly useful fields depending on your definition at ten thousand mega volts per meter so just to give you an idea of it I would say compared to conventional accelerators it's very early days as we've been doing things for a while and in my lifetime that heat in in terms of how long I've been doing it I'm significantly before there are did my microphone disco golf yeah it's come back on okay but there are definitely things going on so this picture here is an overview of the Rutherford Appleton law lab the one of the national labs in the UK here and there are three GeV so small particle accelerators in this picture the first one is at the top here that's the diamond light source it's an act it's a machine not for doing particle physics before making x-rays for all sorts of scientists and at the heart of it is a three GV electron beam in the bottom here is Isis which is a neutron source and those neutrons are made by accelerating protons and using a process called Splashin to make neutrons and it at the heart of that is a sort of 1 GeV proton accelerator 0.8 I think and then so they're all you know pretty big machines somewhere in that building in there there is a a pretty big laser called Astra Gemini which we're now fairly routinely producing very messy compared to the beams come out of these machines but 2gv beams inside that lab they're the actual accelerator is this long the actual plasma apart is that long and so the the technology we're working on is I really like what Phil says if you could imagine replacing conventional accelerators with a plasma system you could suddenly make a massive upgrade so that's the sort of thing the time to go we're thing I think seems realistic but just to give you an idea of how much progress we're making here I've got a plot from one of my PhD students thesis Jason Cole so he took conventional electron accelerators and they're sort of energy as a function of time so you can see they started back in the 1940s and they made rapid progress for the first 30 years doubling energy about every two years I think it was then it kind of tailed off and then you get plasma accelerators which basically started in the mid 90s and we've been making similar progress over the last ten years ten 20 years as well so so our record is now the group at Berkeley have now produced 4gv electron beams in just a plasma that's 9 centimeters long - that big and that made that corresponds to an accelerating field that is 10,000 mega volts per meter so I haven't done the numbers but if you wanted to do this hundred TV machine if you could use that it would get a lot short you

Channel: The Royal Institution

Views: 47,744

Rating: 4.8847117 out of 5

Keywords: Ri, Royal Institution, particle accelerators, types of, physics, particle physics, CERN, science, debate, lecture, suzie sheehy, LHC

Id: YR66Z54mRaQ

Length: 42min 51sec (2571 seconds)

Published: Thu Oct 06 2016

Reddit Comments

[u/the_wurd_burd]

That's seriously one most well done panels I've ever seen. Obviously no discussion but very informative. Very cool. Thanks OP.