360° tour: ATLAS Experiment - Inside CERN's largest detector! [CC]

hi and welcome to a very special Atlas 2 special in two ways it's a 360° tour so you can feel free to look around a little bit while I'll guide you through the cabin and to the Atlas experiment and also because we're gonna see some special places that you wouldn't even be able to see when taking one of the regular tours here coming to CERN you can already see here in the background our beautiful mural painting of the Atlas detector just note that even its big already it's maybe only half the size of what the actual experiment will have to offer but you'll see that later downstairs so let's have a look so here we are in the Atlas building just in front of one of the elevators and the first layer of security check which I'll go through and I'll meet you on the other side so here we are just in front of the elevator that can take us down to the Atlas experiment and you can already see here a schematic drawing of of the detector and a few things that we are about to see on the ground so just to give you a bit of an idea and a bit of a perspective the whole thing the experiment is about 45 meters long it's about 25 meters high and 25 meters deep it's more or less symmetric forward and backward the protons or particles in general the head runs from the Large Hadron Collider they enter from the left and they enter from the right and they collide in the very center of the detector and then the detector is essentially some sort of camera you could say that tries to take a picture and tries to record and measure everything that he leaves the interaction point so particles that are produced they will stream outside of the detector and we try to measure everything that is produced in these collisions with our detector by the different colors you can also see that our detector the Atlas experiment is made of different layers different types of detectors that all have their own purpose they measure different quantities they target different types or categories of particles and we have at the very center we have tracking detectors so they are trying to reconstruct where the collisions happens they trying to reconstruct where particles at least charged particles went so they track the particle as it traverses through the detector then here in green and in orange we have so-called color images and electromagnetic and in hydronic color image that measure the energy of particles by essentially stopping them and one of them the inner one the electromagnetic targets electrons and photons whereas the other one targets Hedren so particles like the proton or the neutron that you might know then further out in blue we have the muon spectrometer which is in principle another tracking detector that we use to measure the momentum of nuance again mewls being essentially the only stand a model particle that is detectable in our detector that leaves the calorimeter and we measure momentum of those again out here to measure momentum in general both inside and out here you need magnetic fields we have a so-called solenoid magnetic field in the center and the very characteristic toroidal magnetic field in the music drama too so what you see in gray here is superconducting magnets that provide a magnetic field to bend the charged muons so that we can measure their momentum and identify them in the mute spectrometer and then here you see a beam pipe shielding which is essentially just concrete that protects the detectives from radiation that happens close to the beam and you'll see some of these components on our way down to the experiment so we'll get the lift and go down about 92 meters underground to have a look at the experiment so we'll take a lift down outside the the actual Kevin has an extra Kevin and houses computing and cooling equipment and then we'll take our way into the Kevin and we'll end up roughly around here what is in this picture between the two big wheels that you see here only that the left of the two big wheels will be moved towards the right one this will be removed and this and this part will be taken out so that scientists and engineers have a chance to get to the inside of the detector to do repairs and upgrades of the whole system let's take the elevator and have a look down so let's take the lift down to about 92 meters on the ground we're gonna be roughly at the base level of the Kevin so as I said the experiment is about 25 meters high so the beam pipe is roughly in the middle about 12 meters above us it's so-called level 4 which we're gonna pass by later on the LHC in general is not horizontal completely horizontal in Earth it's slightly high - is the juror and slightly lower towards the Lake Geneva you can also see that in the experimental setup that there is this slight tilt in see the 27-kilometer ring that provides the proteins for the collisions and that we want to observe in edna's as i showed you on the schematic at the surface so now we had about minus 92 meters let's have a look here's another level of security and I'm going to see you on the other side [Music] [Music] [Music] so now we are at the base of the experiment we look over here you can already see through the gleams of it the orange structure you see here right next to me isn't that not part of the experiment it's a support structure to hold one of the end caps of Detroit magnets that will see the better later on that has been taken out of its design position and move to the side so that access to the inside of the detector is as possible but you can already see here that building section experiment this complexity in science requires a lot of planning and thinking there's hundreds of cables of pipes tubes dates are going in dates are going out so many many things you have to take into consideration when you design such an experiment and we'll see a few of these things later while we explore the cavern together so let's have a look now we're at the far end towards the inside of the experiment the anti-clockwise so this way we're looking towards LHC jeans and towards Lake Geneva whereas the other side is in rough wine side that points towards alleys and the Jura mountains we see already sort of one of these big wheels that I've shown you on the drawing at the beginning on the other side of the lift that's it's here actually both of them put together and then this big structure here is holding the end cap of the Toyota magnet as you can see already there that's like let's go further up it's never a bit of a better so this is level four you can see the beam pipe there now sort of roughly sent it on this level and you can also see sort of the structure of these detectives that sit here at the very end detecting muons that go towards the center so it's a big wheel that is sort of symmetric there's a symmetry in it and point sort of towards the detector trying to cover as much in terms of angle as possible and getting close as possible to the beam pipe let's go to level six which gives us the chance to actually go around the whole experiment together and get a view and now we are at level 6 which gives us the chance actually go around the whole experiment and let's have a look here first as I said this is part of the mute spectrometer at the very end of Atlas same way on the other side as we gonna see later and you can see very nicely this type of detector which is a so-called monitor drift tube it's essentially a tube with a wire inside and and a gas mixture that charged particles so muons that go through that has ionized and then you get a readout signal at one of the wires it's a fairly simple sort of setup but there's another nice thing you can see here is that you have sort of different layers that always overlap each other a little bit which is one of sort of principles and designing such an experiment that you don't want to give any particle that leaves the collision the chance to leave the detector unseen so you build detected that overlap slightly there's other reasons to do that to have these overlaps where one of these is to sort of be as efficient as possible in reconstructing particles and not leave them any chance to leave the detector if it's particles that we can't see obviously that's particles like neutrinos that only in check through we can take that we are not able to see at all in the detecting all miss you through indirect measurements we can get an idea of that but then let's take a chance and to go around to the experiment to give you a sigh an idea of the size we want @c the a side of abstinence you can see as I mentioned with the schematic drawing one of the big wheels that's usually sitting at the end of the structure here as we move to the left so you see two support structures here which is the two big wheels then you see in the background the silver part is the end cap of the turret magnet which has been moved out and to the side so that we can get for example this piece the big sort of reddish kind of element here with a lot of cables around which is the end cap of the calorimeters so the detectives we've measured the energy of for example electrons and protons and so forth and you can also see that these yellow bits they're not part of the detective it's flat forms and haven't moved in to allow people to work on the various components and to get access to the inner parts of the detector which you can not entirely see another thing that's very characteristic to see here and in general for athletes is the toroid magnets that I mentioned before it's this silver ridge structure with the red band around it that's eight of these this is the barrel to right the end cap also has an Eightfold symmetry that's one at each side but these barrel altering magnets are essentially what gives adlets this very characteristic shape and also this very characteristic toroidal magnetic field that bends the muons in spectrometer to allow for the second step of momentum measurement you see also here these big sort of silver boxes with the black sort of layer in between this is again pods of the muon spectrometer as you can see on the left we go back to the wheel quickly there's different types of detectors so there's not just these tubes that I mentioned before the monitor drift tubes there's other types of detectors both from the end Club and in the inner part the Barrow card and that is because we have detectives for the mewn spectrometer that can a be very precise in the measurement but are a little bit slower and giving sort of a feedback and we have two textures that are really fast and we need that for the so-called triggered system which is a two-level system that we have in Atlas our first level is implemented in Hardware on the detectors essentially and the second level is on computers close to here basically in a room next to the cavern a system that has to decide whether condition is of interest and whether we want to keep an event or whether we throw it away and we actually throw away a lot because a lot of the conditions that happen at the LHC are not necessarily of interest and we're not able to store all the collisions so we have to do a sort of a very fast and a very hard decision on which event we want it safe and keep for data analysis in the end then another thing that I mentioned the LHC is slightly tilted if you look very closely down there on this orange support structure so that at the very top of it you see sort of this pattern of orange feet and black holes and if you look very closely you see that the holes and the feeds also they increase in size from the left to the right and this is essentially to correct for this slight tilt that we have to deal with and another thing unites we see here again as I mentioned before oh that's a lot of things you have to think about in designing such an experiment like how do you get the voltage in I mean how do you get sort of are you able to steer your experiment your your detective so you have to send data and you have to get voltage and current in to have the detectors operate you have to get data all Sizzix data and just conditions data so telling you what what state the detectors in what temperatures at and so forth talking about temperature some other detectors certainly the magnets the magnets which are superconducting they have to be cooled the magnets essentially to minus 272 Kelvin about some of the detectives operated room temperatures others like the tracking detectors at the very center they operate at temperatures maybe around 10 degrees below zero in cells yet so a lot of cooling liquid for example has to go in there it's vacuum pipes so all these things have to be taken into account not just because you have to get the stuff in and out but also because every piece of material that you put in the detector that is not the detecting element itself essentially also boats have an influence on the measurements you take because the particles that are free to be in the collisions they can interact with with the material they can lose energy by doing that and then what you measure in the end might be sort of washed out due to that we have to take that into account also when you for example simulate event an essential part of doing a physics analysis is also simulate events so generate sort of non real events but as close as possible to real events in the computer both for processes we know well and for processes we think nature might look like we have to do that and also through these simulations you have to take into account this extra material and you have to simulate the interaction or the possible interaction of particles with that material all right this is the first look at this side of the detector so let's try and have a look at the other side of the detector and also here in between so now we're roughly at the middle of the detector in terms of length along the beam five of the LHC you see there's a lot of infrastructure lots turns hundred thousands of cables that go in and out of the detector to be able to operate such a complex machine in the end so now it's the other side of of the detective Slough lines in the NFC and you can see it looks slightly different on this side that it's because here the end cap of the calorimeter is still instead of Mars in place you can see sort of the silvery wheel in the end with the boxes at the side that's the end cap that on the other side we've moved out of of the detector still you have reads excess sort of platform to be able to do maintenance and make it possible for the team to upgrade and repair the detector we needed what you see here in the middle if the so-called small wheel which is the first sort of layer first component slightly smaller yet still about nine meters in diameter of the moon spectrometer so it's to some extent similar to the big wheels but it's it's much closer this is actually one of the components that within the next month four years we want to replace five so-called new small wheels that will allow us to do more precise measurement to improve the quality of the trigger that I mentioned before to do this fast selection of events to basically select less wrong signals so for fake signals that in the end turn out to be not what we want yeah and then you obviously instead of its flu bit in the middle there the center of the big wheel which is the beam pipe shielding so in the center of that you have the beam pipe that at this stage is already just one pipe essentially where it's sort of remote parts of the LHC you actually have two green pipes where the two beams and opposite directory are separated yeah close to the experiment in general for the four experiments the two beams are guided into one five and then brought into collision at the very center of the detector you look powerful to the top you also get an idea of one of the except shafts this is actually the smaller of the two that we have substantially above each side of the experiment there is one of these shaft to be able to know where things like the support structure and orange that you see down there where again you also see sort of these fellows the change in height and things like the myself to be able to work on these experiments and to perform repairs and upgrades we see when we go to the other side we're going to see at the shaft on the on the other side as well okay another thing that's very essential if you have lots of people working down here its ventilation so you'll see that also in the other shaft that we're going to see in a moment a lot of air has to be cycled through so that people can work here and in cases of emergency that fresh air can be brought in and and polluted air can be brought out so now we're still on the clock line side in terms of the LHC but we are on the other side of the experiment where we came into the cabin and also on this side you can see this end kept all right that has been taken out of the sort of central structure and moved to the side to make room to access the inner path to get things like the new small wheel or potentially also the end cap of the calorimeter out of the detector and now we're going to go sort of down this hall a little bit to give you an idea as I mentioned before there's a lot of cooling infrastructure that also has to be in place to allow for the operation of its family so here you get a good idea of they said all the support structure and the ways you have to sort of take into account that some of the parts are removable so you also have to adjust for that so it's not just types it's also sort of flexible elements in it there is as I said you have to get a lot of cleaning liquid in and out you have to get electricity connected and all these things things that you have to take into account like this let's have a look to the other side again to basically close our our circle so here we are again on the other side we see the turret anklet magnet on this side and two small wheels now that we completed sort of our little tour round experiment you maybe also got an idea of the science as I said it's about 46 metres in length here about 25 metres in diameter so in that direction and next we're gonna see another special place you wouldn't be able to see on a regular tour that will give us a bit of an idea of the height so we go up to almost the the last door here if you look within that direction I'm pointing here you see sort of what I meant before lots of ventilation we'll see it better from the top again as well that has two broad has to be brought into the cabin and since we also to climate eyes the Kevin that it's almost at a constant temperature all year long so that some parts of the detective can operate it they're sort of ideal operational temperature let's have a look stream offload so now we're almost at the top 11:11 I'm a little bit out of breath but it gives you may be a good idea of the signs if you look down there it's a little platform that's where we have been and looked at the inside of the detector then we took the tool to the other side of the Kevin over there and back to here and then came up to level 11 so it not just gives you a good idea or of the signs and a bit of time to look around also gives me some time to also say a few other words obviously such a big experiment also needs a lot of people to be able to run it even to build it at the beginning so adlets is it's a collaboration with about three five thousand members all over the world from many many different countries and many different institutions that are a part of this collaboration that together make it possible to build structure thing and to operate it so when the LHC is running which will hopefully happen again in 2021 we couldn't be here that's one thing and we would basically be trying to operate both the LHC and the Atlas experiment 24/7 but you essentially want to take any collision you can get your hands on if it's good collisions so the LHC is trying to run as much as possible and we're trying to be as efficient as possible in recording the data having the system up and ready at all times if possible and in the recent past we had more than 95% of the system up and running for most of the component it goes even closer to 100 percent with which is with about by more than 100 million channels in its system so 100 million independent readout elements that can give you data and that you have to put together to reconstruct the collisions that happen every 25 nanoseconds so in principle every second we have 40 million collisions that happen and that is a rate that it's even particles leaving the condition point at the speed of light which most standard model particles would do you will have three about three years sort of collision events in the detector at the same time because the particles created in the in one collision leaving sort of detected towards the outside they won't reach the outside the muons spectrometer for example in case of a muon they won't reach it before the next collision or the second to next collision already happened so it's also in terms of readout and understanding and disentangling sort of all the things that happen at the same time it's quite the challenge both on the hardware and on the software side and the reconstruction algorithms that try to make sort of sense out of the individual measurements you have in the detectives another thing that makes this complicated is that with the bunches of photons so it's not continuous beams in the NHC it's bunches roughly the size of a few centimetres that with millions hundreds thousands of millions of photons in each bunch that pass through each other and typically there's maybe one interesting collision so one that has for example a high momentum transfer so that a new particle that they're not energy than the condition that we can create a new particle one might be interesting but there's lots of others happening at the same time that are not necessarily interesting for the physics that we're interested in because it's it's no momentum no energy transfer particles just barely hitting each other not much happening but nevertheless you see some sort of result of these collisions also in the detector so typically in sort of the latest data taking run that we had we had about thirty four on average religions happening in one bunch crossing at the same time so the detectives especially the inner detectives as I said at the very beginning they are supposed to reconstruct the tracks of charged particles and they're also supposed to reconstruct the vertex so the point of origin where these strikes came from where these particles were created so they try to reconstruct those to disentangle sort of these individual up to 60 or 70 we had some time in in the LHC collisions that happen at the same time another very challenging thing especially if you want to do sort of very very precise measurements that in one or another way are influenced by these additional collisions happen at the same time and since I talked about simulation earlier also these kinds of events which we call pileup so these multiple collisions happen at the same time they have to be simulated as well and to sort of get an idea to get a better understanding and maybe develop sort of methods to get more independent of these additional collisions so it's for example in the sort of next step of the LHC after the next run so a few more years into the future we have the high luminosity LHC in store and there you'll have hundreds of religions happening at the same time so that's another reason why we have to do upgrades of the detector this is one of the reasons why the new small wheel the so-called new small wheel comes in one hopefully by the end of the year and another one in the next sort of shutdown right and then I said before you can also have a look up if you look up so the the shaft here this is the bigger of the two it's about 18 meters in diameter you see again lots of ventilation it has to happen to be able to work down here we often see that's read sort of installation going around this is fire protection this is sort of special devices that produce dedicated a special kind of foam that sort of suffocates fire but you can still so people can still breathe in it so you can find your way out of the cabin without suffocation but yeah as I said you can look up you see basically the inner the under side of the roof of the building that is on top of the efforts heaven so almost where we've been at the start and everything that you see in here essentially was lowered through one of the two shafts there's a few components like the the end tip that in principle I mean the the calorimeter in Kippur the the toroid magnet and tip that could be built on the surface and then lower it down in one piece but most of these components were lowered down and then down here with these cranes you see here so the yellow is sort of a heavy weight lifting train put into place so it's a bit like building a ship in a bottle to build an experiments such as everything but you don't have much space to to move around and as you see there it's also not fair not much faith between the top of the experiment and the crane itself so it's also from that point of view an interesting challenge to build such an experiment all right so I hope you you know I have a good impression of what Atlas looks like and also maybe a little bit of what it takes to build an experiment such as Rattlers and let slowly make our way back down to the ground of the Kevin and then back up to the surface so to go down let's take the elevator all right so on the way down we'll take the elevator small little elevator that's it it's in total 12 levels and which make it quite an exercise if you have to walk it several times but now we're going back to the ground level the basis of the experiment and then make our way out of the experiment out of the Kevin back to the surface again [Music] all right so we go in your pickup so it's do it - 92 meets us on the ground we don't back it up to the surface and out of the of the experiment involved if you have any questions feel free to contact us and switch we medium feel free to write as an email that you find all the details all social media channels on our web page at the stop sign and we're looking forward to hearing from you you can come to journey and visits are all year long it's free of charge that's about some interesting things to see if we are still in the shutdown or again the shutdown things you can also try to register for a visit to the underground to not just have a virtual 362 but an ancient work but as I said today we actually were able to visit a few places that you would make on a regular tour so let me take you outside in it so here we are again at the surface in front of the in front of a beautiful mural I hope you enjoyed it so I hope you learned something I hope you gather an impression of Atlas I hope you had a look around took advantage of the 360 you can just watch the video again and look where you want stuck where you want to have a look around and as mentioned before feel free to get in touch with us if you have any questions on social media when Twitter Instagram Facebook or write an email if you have any questions on what we're doing and why we're doing it and of course have a look at the webpage before it follows all the channels you

Channel: ATLAS Experiment

Views: 34,434

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Id: On1WbLKP8DA

Length: 44min 46sec (2686 seconds)

Published: Thu Apr 23 2020