[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:09.39,0:00:12.81,Default,,0000,0000,0000,,Michael Büker: Yes, alright, thank\Nyou very much, okay. I’m glad
Dialogue: 0,0:00:12.81,0:00:16.51,Default,,0000,0000,0000,,that you all found your way here\Nand it’s been mentioned already,
Dialogue: 0,0:00:16.51,0:00:19.92,Default,,0000,0000,0000,,this is Comic Sans, which as you\Nknow is the official type-font
Dialogue: 0,0:00:19.92,0:00:23.93,Default,,0000,0000,0000,,of awesome particle physics stuff.\N{\i1}laughter{\i0}
Dialogue: 0,0:00:23.93,0:00:27.99,Default,,0000,0000,0000,,But in the interest of our mental\Nsanity, I will keep it to other fonts.
Dialogue: 0,0:00:27.99,0:00:32.50,Default,,0000,0000,0000,,So from here on Comic Sans\Nis just a bad memory.
Dialogue: 0,0:00:32.50,0:00:36.10,Default,,0000,0000,0000,,Okay, two things: First the\Ntitle, Breaking Baryons,
Dialogue: 0,0:00:36.10,0:00:39.10,Default,,0000,0000,0000,,which of course is an allusion\Nto Breaking Bad, was inspired
Dialogue: 0,0:00:39.10,0:00:44.52,Default,,0000,0000,0000,,by the wonderful talk from last year which\Nwas called “How I Met Your Pointer”.
Dialogue: 0,0:00:44.52,0:00:48.15,Default,,0000,0000,0000,,And which was also very successful\Nand you can check out that talk,
Dialogue: 0,0:00:48.15,0:00:51.92,Default,,0000,0000,0000,,I got the link there. And this\Ntalk goes especially well
Dialogue: 0,0:00:51.92,0:00:56.09,Default,,0000,0000,0000,,with another talk that we’ll have\Ntomorrow by a real particle physicist,
Dialogue: 0,0:00:56.09,0:00:58.72,Default,,0000,0000,0000,,at least a bit more than myself.
Dialogue: 0,0:00:58.72,0:01:02.46,Default,,0000,0000,0000,,And it’s called “Desperately Seeking\NSUSY” which is about particle theories
Dialogue: 0,0:01:02.46,0:01:05.96,Default,,0000,0000,0000,,and the real cutting edge physical\Nquestions. This is going to be
Dialogue: 0,0:01:05.96,0:01:09.95,Default,,0000,0000,0000,,happening tomorrow. Allright, so\Nwe’re going to start out with my talk
Dialogue: 0,0:01:09.95,0:01:14.51,Default,,0000,0000,0000,,and I’m going to be talking about the\Nquestions of “what are we doing?”,
Dialogue: 0,0:01:14.51,0:01:18.33,Default,,0000,0000,0000,,“why?” and “what kind of stuff do we\Nuse?”. And I’m gonna spend some time
Dialogue: 0,0:01:18.33,0:01:22.19,Default,,0000,0000,0000,,on explaining this last part\Nespecially. What is it that we do
Dialogue: 0,0:01:22.19,0:01:27.78,Default,,0000,0000,0000,,and how does this work? So, what\Nwe do is we give a very high energy
Dialogue: 0,0:01:27.78,0:01:32.02,Default,,0000,0000,0000,,to small particles which\Nwe call accelerating.
Dialogue: 0,0:01:32.02,0:01:36.52,Default,,0000,0000,0000,,But from a certain level of energy\Nthis doesn’t really make sense,
Dialogue: 0,0:01:36.52,0:01:40.71,Default,,0000,0000,0000,,because we don’t actually make them go\Nfaster. Once they reach the speed of light
Dialogue: 0,0:01:40.71,0:01:43.93,Default,,0000,0000,0000,,they can’t go any faster. We just\Nturn up the energy and the speed
Dialogue: 0,0:01:43.93,0:01:48.14,Default,,0000,0000,0000,,doesn’t really change. This is technically\Nuseful but it also gives rise
Dialogue: 0,0:01:48.14,0:01:53.52,Default,,0000,0000,0000,,to doubts about the term accelerating,\Nbut anyway, we just call it ‘accelerate’.
Dialogue: 0,0:01:53.52,0:01:56.71,Default,,0000,0000,0000,,There’s 2 basic types of devices that\Nyou see there, you have storage rings,
Dialogue: 0,0:01:56.71,0:02:00.45,Default,,0000,0000,0000,,which are the circular facilities that\Nmost of you know. And then there is
Dialogue: 0,0:02:00.45,0:02:03.27,Default,,0000,0000,0000,,linear accelerators which are in\Ncomparison very boring, so I’m
Dialogue: 0,0:02:03.27,0:02:07.72,Default,,0000,0000,0000,,not going to be talking about them\Na lot. We make the particles collide
Dialogue: 0,0:02:07.72,0:02:11.37,Default,,0000,0000,0000,,which is the reason for giving them high\Nenergies, we want them to smash head-on.
Dialogue: 0,0:02:11.37,0:02:14.95,Default,,0000,0000,0000,,And then this last part which is about\Nthe most difficult thing is we just
Dialogue: 0,0:02:14.95,0:02:19.68,Default,,0000,0000,0000,,see what happens. Which is not\Nat all as easy as it might sound.
Dialogue: 0,0:02:19.68,0:02:23.52,Default,,0000,0000,0000,,So why are we doing this? You all\Nknow this formula but I’m going to try
Dialogue: 0,0:02:23.52,0:02:26.69,Default,,0000,0000,0000,,and put it in terms which are\Na little bit closer to our hearts,
Dialogue: 0,0:02:26.69,0:02:30.57,Default,,0000,0000,0000,,as we are here at Congress.\NI might postulate that
Dialogue: 0,0:02:30.57,0:02:35.76,Default,,0000,0000,0000,,parts, like electrical parts, building\Nparts, are actually the same as a device.
Dialogue: 0,0:02:35.76,0:02:39.20,Default,,0000,0000,0000,,Now this is not quite wrong but it\Ndoesn’t feel exactly right, either.
Dialogue: 0,0:02:39.20,0:02:44.04,Default,,0000,0000,0000,,I mean, if you have some parts and then\Nbuild a device from it, it’s not the same.
Dialogue: 0,0:02:44.04,0:02:49.22,Default,,0000,0000,0000,,It’s made from the same thing but you do\Nrequire a certain amount of conversion.
Dialogue: 0,0:02:49.22,0:02:53.04,Default,,0000,0000,0000,,You have a building process, you have\Nspecific rules how you can assemble
Dialogue: 0,0:02:53.04,0:02:56.94,Default,,0000,0000,0000,,the parts to make a device and\Nif you do it wrong it will not work.
Dialogue: 0,0:02:56.94,0:03:01.40,Default,,0000,0000,0000,,And this is actually pretty similar to the\Nnotion of energy being equivalent to mass,
Dialogue: 0,0:03:01.40,0:03:04.97,Default,,0000,0000,0000,,because energy can be converted into mass\Nbut it’s not at all easy and it follows
Dialogue: 0,0:03:04.97,0:03:08.91,Default,,0000,0000,0000,,a lot of very strict rules. But\Nwe can use this principle
Dialogue: 0,0:03:08.91,0:03:12.75,Default,,0000,0000,0000,,when we analyze how particle\Nreactions are used to take a look at
Dialogue: 0,0:03:12.75,0:03:17.90,Default,,0000,0000,0000,,what mass and what energy forms\Nthere are. Now suppose we are
Dialogue: 0,0:03:17.90,0:03:21.84,Default,,0000,0000,0000,,thinking about a device\Nwhich is very, very rare,
Dialogue: 0,0:03:21.84,0:03:26.64,Default,,0000,0000,0000,,such as a toaster that runs Net-BSD.\N{\i1}laughter{\i0}
Dialogue: 0,0:03:26.64,0:03:29.98,Default,,0000,0000,0000,,Now as you can see from the photo\Nand the fact that you see a photo,
Dialogue: 0,0:03:29.98,0:03:33.52,Default,,0000,0000,0000,,I’m not making this shit up. There\Nis a toaster that runs Net-BSD but
Dialogue: 0,0:03:33.52,0:03:37.10,Default,,0000,0000,0000,,that’s beside the point. Now if we\Nare particle physicists and we want
Dialogue: 0,0:03:37.10,0:03:41.32,Default,,0000,0000,0000,,to research this question, we know\Nthat parts are the same as a device,
Dialogue: 0,0:03:41.32,0:03:45.63,Default,,0000,0000,0000,,so if we just get enough parts and\Ndo the right kind of things to them,
Dialogue: 0,0:03:45.63,0:03:49.34,Default,,0000,0000,0000,,there might just turn out, out of\Nnowhere a toaster that runs Net BSD.
Dialogue: 0,0:03:49.34,0:03:54.58,Default,,0000,0000,0000,,So let’s give it a try. We produce\Ncollisions with technical parts
Dialogue: 0,0:03:54.58,0:03:58.79,Default,,0000,0000,0000,,and if we do enough of it, and if we\Ndo it right, then there is going to be
Dialogue: 0,0:03:58.79,0:04:02.52,Default,,0000,0000,0000,,this result. Now from these pictures\Nyou can see, that doesn’t seem
Dialogue: 0,0:04:02.52,0:04:07.25,Default,,0000,0000,0000,,to make a lot of sense. You will not\Nget a toaster from colliding vehicles.
Dialogue: 0,0:04:07.25,0:04:10.59,Default,,0000,0000,0000,,{\i1}laughter{\i0}\NBut as particle physics go,
Dialogue: 0,0:04:10.59,0:04:14.16,Default,,0000,0000,0000,,this is the best we can do. We\Njust smash stuff into each other
Dialogue: 0,0:04:14.16,0:04:17.75,Default,,0000,0000,0000,,and we hope that some other stuff\Ncomes out which is more interesting.
Dialogue: 0,0:04:17.75,0:04:22.60,Default,,0000,0000,0000,,And that’s what we do. So to\Nput it in the technical terms,
Dialogue: 0,0:04:22.60,0:04:26.57,Default,,0000,0000,0000,,we use storage rings which are this\None circular kind of accelerator
Dialogue: 0,0:04:26.57,0:04:30.52,Default,,0000,0000,0000,,to produce collisions. Lots\Nof them with high energy.
Dialogue: 0,0:04:30.52,0:04:34.88,Default,,0000,0000,0000,,And then we put some enormous\Nexperimental devices there
Dialogue: 0,0:04:34.88,0:04:38.48,Default,,0000,0000,0000,,and we use them to analyze what\Nhappens. Now first let’s talk about
Dialogue: 0,0:04:38.48,0:04:43.03,Default,,0000,0000,0000,,these storage rings. This schematic\Nview is what a storage ring is
Dialogue: 0,0:04:43.03,0:04:47.01,Default,,0000,0000,0000,,mostly made of, and you can see right\Naway, that it’s not actually a circle.
Dialogue: 0,0:04:47.01,0:04:50.28,Default,,0000,0000,0000,,And this is true for any storage ring.\NIf you look at them closely they are
Dialogue: 0,0:04:50.28,0:04:54.23,Default,,0000,0000,0000,,not a perfect circle, you always\Nhave acceleration parts which are
Dialogue: 0,0:04:54.23,0:04:58.22,Default,,0000,0000,0000,,not actually curved. So we\Nhave the 2 basic elements
Dialogue: 0,0:04:58.22,0:05:02.27,Default,,0000,0000,0000,,of a curved part which is just “the\Ncurve” and then you have a straight part
Dialogue: 0,0:05:02.27,0:05:06.54,Default,,0000,0000,0000,,which is there for acceleration. Now you\Nhave this separation, it would be nicer
Dialogue: 0,0:05:06.54,0:05:11.01,Default,,0000,0000,0000,,to have a ring but it’s much more easy\Nthis way. You have the acceleration
Dialogue: 0,0:05:11.01,0:05:13.79,Default,,0000,0000,0000,,where it is straight and because it is\Nstraight you don’t need to worry about
Dialogue: 0,0:05:13.79,0:05:18.06,Default,,0000,0000,0000,,making the particles go on a curved\Npath. So you can just leave out
Dialogue: 0,0:05:18.06,0:05:22.51,Default,,0000,0000,0000,,the magnetic fields. We\Nneed magnetic fields
Dialogue: 0,0:05:22.51,0:05:26.67,Default,,0000,0000,0000,,to keep them on a curve, but we need\Nelectrical fields to accelerate them.
Dialogue: 0,0:05:26.67,0:05:30.47,Default,,0000,0000,0000,,Now we could try and assemble these\Ninto one kind of device. A device
Dialogue: 0,0:05:30.47,0:05:34.41,Default,,0000,0000,0000,,that uses an electric field to accelerate\Nthe particles and at the same time
Dialogue: 0,0:05:34.41,0:05:38.04,Default,,0000,0000,0000,,uses a magnetic field to keep them on\Na curved path. Now this is the first thing
Dialogue: 0,0:05:38.04,0:05:41.28,Default,,0000,0000,0000,,that was tried. These kinds of\Naccelerators where called cyclotrons,
Dialogue: 0,0:05:41.28,0:05:43.71,Default,,0000,0000,0000,,but they were very inefficient, you\Ncouldn’t go to high energies, it was
Dialogue: 0,0:05:43.71,0:05:47.84,Default,,0000,0000,0000,,very difficult. So the evolution went to
Dialogue: 0,0:05:47.84,0:05:51.44,Default,,0000,0000,0000,,this way where you just\Nphysically separate the 2 tasks.
Dialogue: 0,0:05:51.44,0:05:54.99,Default,,0000,0000,0000,,You have a straight part for acceleration,\Nyou have a curved part for the curve
Dialogue: 0,0:05:54.99,0:05:57.89,Default,,0000,0000,0000,,and then that’s much more easy.\NOkay, so let’s take a look at the
Dialogue: 0,0:05:57.89,0:06:01.26,Default,,0000,0000,0000,,acceleration part of things. You\Nmay know computer games
Dialogue: 0,0:06:01.26,0:06:05.34,Default,,0000,0000,0000,,where you go racing about and then\Nyou have some kind of arrows
Dialogue: 0,0:06:05.34,0:06:08.56,Default,,0000,0000,0000,,on the ground and if you go over them in\Nthe right direction they make you faster.
Dialogue: 0,0:06:08.56,0:06:12.27,Default,,0000,0000,0000,,This is a kind of booster if you will.
Dialogue: 0,0:06:12.27,0:06:16.23,Default,,0000,0000,0000,,If you happen to go around the wrong\Nway and you go onto these arrows,
Dialogue: 0,0:06:16.23,0:06:19.60,Default,,0000,0000,0000,,they will slow you down, which makes sense\Nbecause you’re going the wrong way,
Dialogue: 0,0:06:19.60,0:06:23.67,Default,,0000,0000,0000,,you shouldn’t be trying that. And this is
Dialogue: 0,0:06:23.67,0:06:27.63,Default,,0000,0000,0000,,the same effect we can think of when we\Nthink about what an electrical field does
Dialogue: 0,0:06:27.63,0:06:31.59,Default,,0000,0000,0000,,to a charged particle. If a charged\Nparticle moves through an electrical field
Dialogue: 0,0:06:31.59,0:06:36.08,Default,,0000,0000,0000,,in the ‘right’ direction so to speak\Nit will speed the particle up,
Dialogue: 0,0:06:36.08,0:06:38.89,Default,,0000,0000,0000,,taking energy from the field and to the\Nparticle making it go faster. But if you
Dialogue: 0,0:06:38.89,0:06:42.43,Default,,0000,0000,0000,,go the wrong way, then this particle\Nwill slow down and it will
Dialogue: 0,0:06:42.43,0:06:48.17,Default,,0000,0000,0000,,give off energy. If we where to try and…
Dialogue: 0,0:06:48.17,0:06:51.61,Default,,0000,0000,0000,,let’s say we have a level editor,\Nright? And we can edit this level
Dialogue: 0,0:06:51.61,0:06:55.61,Default,,0000,0000,0000,,where this little vehicle is going and\Nwe want to make it go really fast.
Dialogue: 0,0:06:55.61,0:06:58.06,Default,,0000,0000,0000,,So what do we do? We just take this\Nacceleration path, we just take
Dialogue: 0,0:06:58.06,0:07:02.45,Default,,0000,0000,0000,,these arrows and we put them in a long\Nline. Let’s put 4, 5, 10 of them
Dialogue: 0,0:07:02.45,0:07:06.16,Default,,0000,0000,0000,,in a row, so if we go over them\Nwe’ll be really fast at the end.
Dialogue: 0,0:07:06.16,0:07:09.28,Default,,0000,0000,0000,,Now suppose the level editor\Ndoes not allow this. It’s just
Dialogue: 0,0:07:09.28,0:07:12.80,Default,,0000,0000,0000,,by the rules of the game it’s not possible\Nto put a bunch of arrows in a row.
Dialogue: 0,0:07:12.80,0:07:17.66,Default,,0000,0000,0000,,Which sucks, because then we can’t\Nreally make them go really fast.
Dialogue: 0,0:07:17.66,0:07:22.35,Default,,0000,0000,0000,,But then we just ask an engineer\Nwho’s got this shit together.
Dialogue: 0,0:07:22.35,0:07:25.92,Default,,0000,0000,0000,,And what is he going to suggest?\NYou know what he’s going to suggest.
Dialogue: 0,0:07:25.92,0:07:30.24,Default,,0000,0000,0000,,Can I hear it? Come on, “inverse the\Npolarity”, that’s what he always does!
Dialogue: 0,0:07:30.24,0:07:39.05,Default,,0000,0000,0000,,{\i1}laughter and applause{\i0}
Dialogue: 0,0:07:39.05,0:07:43.42,Default,,0000,0000,0000,,So we inverse the polarity. And we are\Ngoing to make our track look like this.
Dialogue: 0,0:07:43.42,0:07:46.60,Default,,0000,0000,0000,,So we have an arrow which gives us a boost\Nin the right direction and then there’s
Dialogue: 0,0:07:46.60,0:07:50.26,Default,,0000,0000,0000,,an arrow in the wrong direction.\NIf we go over the track in this way,
Dialogue: 0,0:07:50.26,0:07:54.18,Default,,0000,0000,0000,,we’ll speed up and slow down and speed\Nup and slow down. And in the end
Dialogue: 0,0:07:54.18,0:07:57.53,Default,,0000,0000,0000,,we won’t win anything. But here is where\NGeordi comes into play, because
Dialogue: 0,0:07:57.53,0:08:01.73,Default,,0000,0000,0000,,we’ll be switching polarities at just the\Nright moment and if we switch polarities
Dialogue: 0,0:08:01.73,0:08:05.32,Default,,0000,0000,0000,,at the precise moment that we are\Nin between two of these fields,
Dialogue: 0,0:08:05.32,0:08:09.07,Default,,0000,0000,0000,,then the next one will be an accelerating\Nfield. And it goes on and on like this,
Dialogue: 0,0:08:09.07,0:08:12.27,Default,,0000,0000,0000,,we always switch the direction\Nof the arrows at the right moment
Dialogue: 0,0:08:12.27,0:08:16.43,Default,,0000,0000,0000,,when we are in between the two. And\Nfrom the point of view of the vehicle
Dialogue: 0,0:08:16.43,0:08:19.85,Default,,0000,0000,0000,,it will look like there is an accelerating\Nfield followed by an accelerating field,
Dialogue: 0,0:08:19.85,0:08:23.72,Default,,0000,0000,0000,,followed by an accelerating field.\NWhich is the same as we tried to build
Dialogue: 0,0:08:23.72,0:08:27.07,Default,,0000,0000,0000,,but which the game, or in the case\Nof real accelerators the universe
Dialogue: 0,0:08:27.07,0:08:30.90,Default,,0000,0000,0000,,just wouldn’t allow. So we’re tricking\Nthe universe by using Geordi’s tip
Dialogue: 0,0:08:30.90,0:08:34.72,Default,,0000,0000,0000,,and inversing the polarity at just the\Nright moments. And this is what is done
Dialogue: 0,0:08:34.72,0:08:41.58,Default,,0000,0000,0000,,in particle accelerators and this is\Ncalled Radio Frequency Acceleration.
Dialogue: 0,0:08:41.58,0:08:44.45,Default,,0000,0000,0000,,Now this kind of device that you see\Nthere is the device that is used
Dialogue: 0,0:08:44.45,0:08:48.33,Default,,0000,0000,0000,,for this actual process in actual\Naccelerators. It’s about as big
Dialogue: 0,0:08:48.33,0:08:51.67,Default,,0000,0000,0000,,as a human child, but it\Nweighs a bit more, it weighs
Dialogue: 0,0:08:51.67,0:08:55.81,Default,,0000,0000,0000,,several hundred kilograms.\NAnd in contrast to a child
Dialogue: 0,0:08:55.81,0:08:59.78,Default,,0000,0000,0000,,it’s made of a metal called Niobium.\NNow Niobium is a rare metal,
Dialogue: 0,0:08:59.78,0:09:03.41,Default,,0000,0000,0000,,but it’s not super rare, and it fulfills
Dialogue: 0,0:09:03.41,0:09:06.78,Default,,0000,0000,0000,,3 basic requirements that\Nwe have for these devices.
Dialogue: 0,0:09:06.78,0:09:10.48,Default,,0000,0000,0000,,It’s ductile, which means you can\Neasily shape it, because you see
Dialogue: 0,0:09:10.48,0:09:14.17,Default,,0000,0000,0000,,that this shape is really weird, you got\Nthese kind of cone things going on,
Dialogue: 0,0:09:14.17,0:09:19.67,Default,,0000,0000,0000,,and they must be very precise. If these\Ncones on the inside of the cavity
Dialogue: 0,0:09:19.67,0:09:25.13,Default,,0000,0000,0000,,are off by just micrometers the whole\Nthing won’t work. So you need a metal
Dialogue: 0,0:09:25.13,0:09:28.39,Default,,0000,0000,0000,,which can be formed very well.
Dialogue: 0,0:09:28.39,0:09:31.97,Default,,0000,0000,0000,,Then you must be able to make it\Nsuperconductive, to cool it down
Dialogue: 0,0:09:31.97,0:09:35.77,Default,,0000,0000,0000,,to a temperature where it will\Nlose its electrical resistance.
Dialogue: 0,0:09:35.77,0:09:39.03,Default,,0000,0000,0000,,The electrical resistance will go down\Nto almost zero, some nano-Ohms
Dialogue: 0,0:09:39.03,0:09:43.17,Default,,0000,0000,0000,,is what’s left. So that’s the second\Nrequirement for this metal,
Dialogue: 0,0:09:43.17,0:09:46.22,Default,,0000,0000,0000,,and the third one is: it shouldn’t\Nbe ‘super’ expensive. I guess
Dialogue: 0,0:09:46.22,0:09:50.48,Default,,0000,0000,0000,,you could use platinum or something but\Nthen you couldn’t pay for the accelerator
Dialogue: 0,0:09:50.48,0:09:54.78,Default,,0000,0000,0000,,and as we are going to see, the\Naccelerator is expensive enough as it is.
Dialogue: 0,0:09:54.78,0:09:58.06,Default,,0000,0000,0000,,So Niobium is what is used\Nfor this kind of device and
Dialogue: 0,0:09:58.06,0:10:04.69,Default,,0000,0000,0000,,as I said, we cool it down to about\N4 Kelvins, which is -269°C
Dialogue: 0,0:10:04.69,0:10:09.59,Default,,0000,0000,0000,,or 4°C above absolute Zero.\NAnd at this temperature,
Dialogue: 0,0:10:09.59,0:10:12.67,Default,,0000,0000,0000,,the electrical resistance of the metal\Nis almost zero which we need
Dialogue: 0,0:10:12.67,0:10:16.57,Default,,0000,0000,0000,,for the high frequency\Nfields that we put in.
Dialogue: 0,0:10:16.57,0:10:19.95,Default,,0000,0000,0000,,What we used to cool these things is\Nliquid helium, so when they’re in use
Dialogue: 0,0:10:19.95,0:10:23.58,Default,,0000,0000,0000,,inside the accelerator they’re not\Nnaked, exposed like you see here,
Dialogue: 0,0:10:23.58,0:10:27.30,Default,,0000,0000,0000,,they are enclosed by huge tanks\Nwhich are super tight and must
Dialogue: 0,0:10:27.30,0:10:31.89,Default,,0000,0000,0000,,hold on to large pressures and\Nbe super temperature efficient,
Dialogue: 0,0:10:31.89,0:10:36.19,Default,,0000,0000,0000,,very well insulating\Nbecause these must keep
Dialogue: 0,0:10:36.19,0:10:39.84,Default,,0000,0000,0000,,the liquid helium inside. But on\Nthe outside there is the tunnel
Dialogue: 0,0:10:39.84,0:10:43.51,Default,,0000,0000,0000,,of the accelerator and that’s where people\Nwalk around. Not while the accelerator is
Dialogue: 0,0:10:43.51,0:10:46.75,Default,,0000,0000,0000,,running, but people walk around to do\Nmaintenance and stuff. So you must have
Dialogue: 0,0:10:46.75,0:10:51.06,Default,,0000,0000,0000,,a temperature differential between room\Ntemperature next to the accelerator
Dialogue: 0,0:10:51.06,0:10:55.78,Default,,0000,0000,0000,,and 4 Kelvin inside the tank\Nwhere this cavity is sitting.
Dialogue: 0,0:10:55.78,0:10:59.30,Default,,0000,0000,0000,,So you have a temperature difference\Nof 300 degrees, which this tank
Dialogue: 0,0:10:59.30,0:11:02.54,Default,,0000,0000,0000,,around the cavity must keep. So that’s\Na very hard job, actually cooling
Dialogue: 0,0:11:02.54,0:11:07.36,Default,,0000,0000,0000,,is one of the more difficult things
Dialogue: 0,0:11:07.36,0:11:11.64,Default,,0000,0000,0000,,from an engineering point of view.\NThe thing which feeds the fields
Dialogue: 0,0:11:11.64,0:11:16.09,Default,,0000,0000,0000,,– the actual changing electrical\Nfields are polarity switched –
Dialogue: 0,0:11:16.09,0:11:19.66,Default,,0000,0000,0000,,into these cavities are called klystrons.\NThere’s a picture of a klystron,
Dialogue: 0,0:11:19.66,0:11:23.89,Default,,0000,0000,0000,,it’s the longish device sitting on the\Nbottom. And they’re usually about
Dialogue: 0,0:11:23.89,0:11:28.75,Default,,0000,0000,0000,,as big as a refrigerator or two.\NAnd these klystrons produce
Dialogue: 0,0:11:28.75,0:11:31.99,Default,,0000,0000,0000,,radio waves not very much unlike that
Dialogue: 0,0:11:31.99,0:11:35.44,Default,,0000,0000,0000,,which you hear in your car when you just\Nturn on the radio. It’s not modulated
Dialogue: 0,0:11:35.44,0:11:38.73,Default,,0000,0000,0000,,in the same way, so there’s no\Nsound information encoded,
Dialogue: 0,0:11:38.73,0:11:42.29,Default,,0000,0000,0000,,but it’s extremely strong.\NYou can see on the bottom
Dialogue: 0,0:11:42.29,0:11:46.29,Default,,0000,0000,0000,,that one of these klystrons as it is in\Nuse at the LHC has a transmitting power
Dialogue: 0,0:11:46.29,0:11:51.68,Default,,0000,0000,0000,,of 300 Kilowatts. Now if you think of the\Ntransmitting power of the Fernsehturm
Dialogue: 0,0:11:51.68,0:11:54.86,Default,,0000,0000,0000,,like the Hertz-Turm which is right next\N- no, that way -
Dialogue: 0,0:11:54.86,0:11:59.07,Default,,0000,0000,0000,,which is right next to the conference\Ncenter, or even the Fernsehturm in Berlin.
Dialogue: 0,0:11:59.07,0:12:02.90,Default,,0000,0000,0000,,It has about half the transmitting\Npower of one of these klystrons.
Dialogue: 0,0:12:02.90,0:12:06.39,Default,,0000,0000,0000,,Now for the LHC accelerator\N16 of them are used.
Dialogue: 0,0:12:06.39,0:12:09.49,Default,,0000,0000,0000,,So that’s a lot of transmitting power.\NAnd because the power is so high
Dialogue: 0,0:12:09.49,0:12:13.11,Default,,0000,0000,0000,,we don’t actually use cables.\NUsually you transfer your…
Dialogue: 0,0:12:13.11,0:12:15.63,Default,,0000,0000,0000,,when you have some oscillator and\Nyou’re checking out some signals,
Dialogue: 0,0:12:15.63,0:12:18.56,Default,,0000,0000,0000,,you just put cables between\Nyour source and your device.
Dialogue: 0,0:12:18.56,0:12:22.62,Default,,0000,0000,0000,,This is not what’s used here, because\Ncables get way too complicated
Dialogue: 0,0:12:22.62,0:12:26.24,Default,,0000,0000,0000,,when you have these high energies.
Dialogue: 0,0:12:26.24,0:12:28.75,Default,,0000,0000,0000,,So what is used, is waveguides and that\Nis what you can see on the top there
Dialogue: 0,0:12:28.75,0:12:32.59,Default,,0000,0000,0000,,in this picture. It looks like an\Nair duct, it looks like there’s some
Dialogue: 0,0:12:32.59,0:12:36.09,Default,,0000,0000,0000,,sort of air conditioning system and the\Nair moves through. That’s not what it is.
Dialogue: 0,0:12:36.09,0:12:39.80,Default,,0000,0000,0000,,It is a waveguide which is designed\Nto have the radio waves inside
Dialogue: 0,0:12:39.80,0:12:44.51,Default,,0000,0000,0000,,radiate in a certain direction.\NThink of a series of mirrors,
Dialogue: 0,0:12:44.51,0:12:50.62,Default,,0000,0000,0000,,long rectangular mirrors and you put\Nthem all with the mirroring area inside.
Dialogue: 0,0:12:50.62,0:12:54.12,Default,,0000,0000,0000,,So you have a tube which is mirroring\Ninside. And then at one side
Dialogue: 0,0:12:54.12,0:12:57.09,Default,,0000,0000,0000,,you shine in a bright light. Now the\Nlight can’t escape anywhere and it
Dialogue: 0,0:12:57.09,0:13:00.09,Default,,0000,0000,0000,,always hits the mirrors so it\Ngoes on in a straight path.
Dialogue: 0,0:13:00.09,0:13:04.01,Default,,0000,0000,0000,,You’ve built yourself a waveguide\Nfor light. Now this here,
Dialogue: 0,0:13:04.01,0:13:07.22,Default,,0000,0000,0000,,this clunky looking metal\Npart is a waveguide
Dialogue: 0,0:13:07.22,0:13:12.11,Default,,0000,0000,0000,,but for high frequency, high energy radio\Nwaves which are fed into the cavities.
Dialogue: 0,0:13:12.11,0:13:16.04,Default,,0000,0000,0000,,And that’s how acceleration happens.\NNow let’s talk about the curves.
Dialogue: 0,0:13:16.04,0:13:21.49,Default,,0000,0000,0000,,This is where it gets less\Nfidgety and more… boom!
Dialogue: 0,0:13:21.49,0:13:24.64,Default,,0000,0000,0000,,So these devices you see here, there’s\N2 devices sitting next to each other,
Dialogue: 0,0:13:24.64,0:13:27.69,Default,,0000,0000,0000,,identical devices. These\Nare the cryo-dipoles.
Dialogue: 0,0:13:27.69,0:13:30.29,Default,,0000,0000,0000,,Again, they have the word “cryo” in\Nthem because they are also cooled
Dialogue: 0,0:13:30.29,0:13:36.45,Default,,0000,0000,0000,,by liquid helium down to\Na temperature of about -270°C.
Dialogue: 0,0:13:36.45,0:13:40.13,Default,,0000,0000,0000,,They’re 40 meters long, they weigh\N35 tons and each of these babies
Dialogue: 0,0:13:40.13,0:13:44.75,Default,,0000,0000,0000,,costs about half a million Swiss Francs.
Dialogue: 0,0:13:44.75,0:13:49.67,Default,,0000,0000,0000,,And as you can see one line above that,\Nthere’s 1200 of these curve dipoles
Dialogue: 0,0:13:49.67,0:13:54.72,Default,,0000,0000,0000,,in the LHC. So there you have\Na cost of 1.5 to 2 billion dollars
Dialogue: 0,0:13:54.72,0:13:57.85,Default,,0000,0000,0000,,in the curve magnets alone.\NWe’re not talking acceleration,
Dialogue: 0,0:13:57.85,0:14:01.59,Default,,0000,0000,0000,,we’re not talking about power use, we are\Nnot talking about the helium that you need
Dialogue: 0,0:14:01.59,0:14:05.55,Default,,0000,0000,0000,,for cooling or the power that you need for\Ncooling. It’s just building these things,
Dialogue: 0,0:14:05.55,0:14:08.77,Default,,0000,0000,0000,,just building the curve, 27 kilometers.
Dialogue: 0,0:14:08.77,0:14:12.25,Default,,0000,0000,0000,,And that’s what you have there as a\Ncost. Now what they do is, they make
Dialogue: 0,0:14:12.25,0:14:15.42,Default,,0000,0000,0000,,a huge magnetic field, because in\Na magnetic field a charged particle
Dialogue: 0,0:14:15.42,0:14:19.30,Default,,0000,0000,0000,,will go on a curve. That’s\Nwhat we want, right? But
Dialogue: 0,0:14:19.30,0:14:23.97,Default,,0000,0000,0000,,to make these particles with a very high\Nenergy and keep them on a tight curve…
Dialogue: 0,0:14:23.97,0:14:27.01,Default,,0000,0000,0000,,now in particle physics’ terms\Nlet’s say that 27 kilometers
Dialogue: 0,0:14:27.01,0:14:30.92,Default,,0000,0000,0000,,to go around one way is a tight curve.
Dialogue: 0,0:14:30.92,0:14:35.46,Default,,0000,0000,0000,,We need a current of 12,000 amps.\NWhich is a large current
Dialogue: 0,0:14:35.46,0:14:38.58,Default,,0000,0000,0000,,that goes through these dipoles.\NWhich is the reason why we have them
Dialogue: 0,0:14:38.58,0:14:44.85,Default,,0000,0000,0000,,superconductingly cooled, because\Notherwise you put 12,000 amps
Dialogue: 0,0:14:44.85,0:14:48.46,Default,,0000,0000,0000,,through a piece of metal and it just melts\Naway. You don’t get a magnetic field,
Dialogue: 0,0:14:48.46,0:14:52.82,Default,,0000,0000,0000,,maybe for a microsecond or 2.\NBut you want to sustain a stable field
Dialogue: 0,0:14:52.82,0:14:57.03,Default,,0000,0000,0000,,of 8.5 Tesla to make these\Nprotons go around on a curve.
Dialogue: 0,0:14:57.03,0:15:00.89,Default,,0000,0000,0000,,So, yeah, that’s a big thing.\NThere’s also niobium in there,
Dialogue: 0,0:15:00.89,0:15:05.57,Default,,0000,0000,0000,,not the big clunky parts like the cavity\Nwe saw, but thin niobium wires,
Dialogue: 0,0:15:05.57,0:15:09.50,Default,,0000,0000,0000,,actually half niobium, half titanium\Nmost of the time. But since
Dialogue: 0,0:15:09.50,0:15:14.43,Default,,0000,0000,0000,,there are so many magnets and it’s\Nso long a curve, there is 600 tons
Dialogue: 0,0:15:14.43,0:15:18.76,Default,,0000,0000,0000,,of atomic niobium in this\Nentire accelerator thing.
Dialogue: 0,0:15:18.76,0:15:22.61,Default,,0000,0000,0000,,And this was a fourth of the\Nworld production of niobium
Dialogue: 0,0:15:22.61,0:15:26.95,Default,,0000,0000,0000,,which comes mostly from Brazil by the way.\NThis was a fourth of the world production
Dialogue: 0,0:15:26.95,0:15:30.97,Default,,0000,0000,0000,,of niobium for 5 years.\NSo that’s where it all went.
Dialogue: 0,0:15:30.97,0:15:35.77,Default,,0000,0000,0000,,It just went into the accelerator.\NAnd now if we have this running,
Dialogue: 0,0:15:35.77,0:15:39.26,Default,,0000,0000,0000,,we have it up, we have it cooled, we have\Na large current going, we got our nice
Dialogue: 0,0:15:39.26,0:15:43.11,Default,,0000,0000,0000,,big magnetic fields. And\Nthere is energy stored.
Dialogue: 0,0:15:43.11,0:15:46.91,Default,,0000,0000,0000,,I mean we put in a lot of power and the\Nmagnetic fields are up and they’re stable
Dialogue: 0,0:15:46.91,0:15:50.92,Default,,0000,0000,0000,,and that means that there’s magnetic\Nenergy stored in this. And the amount
Dialogue: 0,0:15:50.92,0:15:53.99,Default,,0000,0000,0000,,of energy that is stored in the curve\Nmagnets alone of the LHC when it’s running
Dialogue: 0,0:15:53.99,0:15:58.01,Default,,0000,0000,0000,,is 11 gigajoules. Sounds like a lot,
Dialogue: 0,0:15:58.01,0:16:03.77,Default,,0000,0000,0000,,let’s compare it to something: If we\Nhave an absurdly long freight train
Dialogue: 0,0:16:03.77,0:16:07.70,Default,,0000,0000,0000,,with let’s say 15,000 tons. I hear that\Nnormal freight trains in Germany
Dialogue: 0,0:16:07.70,0:16:11.81,Default,,0000,0000,0000,,or England have about 5000 tons.\NSo let’s take a big freight train
Dialogue: 0,0:16:11.81,0:16:18.37,Default,,0000,0000,0000,,and multiply it by 3. If this\Nfreight train goes at 150 km/h,
Dialogue: 0,0:16:18.37,0:16:21.90,Default,,0000,0000,0000,,then the kinetic energy, the\Nmovement energy of this train
Dialogue: 0,0:16:21.90,0:16:26.84,Default,,0000,0000,0000,,is equivalent to the magnetic\Nenergy that is stored in the LHC.
Dialogue: 0,0:16:26.84,0:16:29.97,Default,,0000,0000,0000,,And that is why we don’t want\Nany problem with the cooling.
Dialogue: 0,0:16:29.97,0:16:33.74,Default,,0000,0000,0000,,{\i1}laughter{\i0}
Dialogue: 0,0:16:33.74,0:16:39.74,Default,,0000,0000,0000,,Because if we get a problem with\Nthe cooling, bad things happen.
Dialogue: 0,0:16:39.74,0:16:44.47,Default,,0000,0000,0000,,This is a photograph of what at CERN\Nat the LHC they just call “the incident”.
Dialogue: 0,0:16:44.47,0:16:47.09,Default,,0000,0000,0000,,{\i1}laughter{\i0}
Dialogue: 0,0:16:47.09,0:16:50.06,Default,,0000,0000,0000,,Which was a tiny mishap that\Nhappened just a few weeks
Dialogue: 0,0:16:50.06,0:16:54.06,Default,,0000,0000,0000,,after the LHC was taken into\Noperation for the first time in 2008.
Dialogue: 0,0:16:54.06,0:16:57.23,Default,,0000,0000,0000,,And it shut the machine\Ndown for about 8 months.
Dialogue: 0,0:16:57.23,0:17:00.39,Default,,0000,0000,0000,,So that was a bad thing. It’s\Na funny story when they where
Dialogue: 0,0:17:00.39,0:17:03.29,Default,,0000,0000,0000,,constructing these magnets; now\Nwhat you see here is the connection
Dialogue: 0,0:17:03.29,0:17:07.85,Default,,0000,0000,0000,,between 2 of these magnets. I told you\Nthat each of them weighs 35 tons.
Dialogue: 0,0:17:07.85,0:17:12.74,Default,,0000,0000,0000,,So here you have a connection between\N2 parts that are 35 tons in weight each.
Dialogue: 0,0:17:12.74,0:17:18.10,Default,,0000,0000,0000,,And they’re shifted by almost half\Na meter. So it takes a bit of boom.
Dialogue: 0,0:17:18.10,0:17:21.63,Default,,0000,0000,0000,,So what happened was: the cooling broke\Ndown and the helium escaped and
Dialogue: 0,0:17:21.63,0:17:25.57,Default,,0000,0000,0000,,the sheer force of the helium expanding,\Nbecause if you have liquid helium
Dialogue: 0,0:17:25.57,0:17:29.81,Default,,0000,0000,0000,,and it instantly evaporates into gaseous\Nhelium then the volume multiplies
Dialogue: 0,0:17:29.81,0:17:33.65,Default,,0000,0000,0000,,by a very large amount.\NAnd what they had was…
Dialogue: 0,0:17:33.65,0:17:36.72,Default,,0000,0000,0000,,what I hear is that the tunnel of the\NLHC, which has a diameter of about
Dialogue: 0,0:17:36.72,0:17:41.01,Default,,0000,0000,0000,,let’s say 6 or 7 meters was\Nfilled with nothing but helium
Dialogue: 0,0:17:41.01,0:17:44.51,Default,,0000,0000,0000,,which pushed away the air\Nfor about 100 meters
Dialogue: 0,0:17:44.51,0:17:48.14,Default,,0000,0000,0000,,around this incident. So the helium\Nevaporated, it pushed everything away,
Dialogue: 0,0:17:48.14,0:17:52.96,Default,,0000,0000,0000,,it made everything really cold, some\Ncables broke and some metal broke.
Dialogue: 0,0:17:52.96,0:17:57.01,Default,,0000,0000,0000,,And the funny thing now is, the\Nengineers that built the LHC,
Dialogue: 0,0:17:57.01,0:18:00.21,Default,,0000,0000,0000,,before they did that, visited\NHamburg. Because here there is
Dialogue: 0,0:18:00.21,0:18:03.51,Default,,0000,0000,0000,,a particle accelerator which is\Nnot quite as large. The LHC
Dialogue: 0,0:18:03.51,0:18:07.77,Default,,0000,0000,0000,,has 27 kilometers; here in Hamburg we\Nhave a particle accelerator called HERA
Dialogue: 0,0:18:07.77,0:18:12.49,Default,,0000,0000,0000,,which had 6.5 kilometers. So it’s\Nthe same ballpark, it’s not as big.
Dialogue: 0,0:18:12.49,0:18:15.75,Default,,0000,0000,0000,,And in HERA they had a safety system\Nagainst these kinds of cryo failures,
Dialogue: 0,0:18:15.75,0:18:19.63,Default,,0000,0000,0000,,they’re called quenches.\NThey had a protection system,
Dialogue: 0,0:18:19.63,0:18:23.48,Default,,0000,0000,0000,,which protects this exact part.\NNow we’re talking about “Yeah,
Dialogue: 0,0:18:23.48,0:18:26.71,Default,,0000,0000,0000,,how should we build this? Should\Nwe have a quench-protection
Dialogue: 0,0:18:26.71,0:18:31.03,Default,,0000,0000,0000,,at the connection between the dipoles?”\NAnd the HERA people in Hamburg said:
Dialogue: 0,0:18:31.03,0:18:34.69,Default,,0000,0000,0000,,“Well we have it, it’s a good thing,\Nyou shouldn’t leave it out,
Dialogue: 0,0:18:34.69,0:18:38.63,Default,,0000,0000,0000,,if you build the LHC.” Well,\Nthey left it out. {\i1}laughter{\i0}
Dialogue: 0,0:18:38.63,0:18:43.47,Default,,0000,0000,0000,,They ran out of time, they ran out of\Nmoney, the LHC project was under pressure.
Dialogue: 0,0:18:43.47,0:18:45.95,Default,,0000,0000,0000,,Because they had promised to build\Na big machine by that time and
Dialogue: 0,0:18:45.95,0:18:49.45,Default,,0000,0000,0000,,they weren’t really finished, so they\Ncut some edges. Well this was
Dialogue: 0,0:18:49.45,0:18:53.93,Default,,0000,0000,0000,,the edge they cut and it cost them\N8 months of operation. Which says
Dialogue: 0,0:18:53.93,0:18:59.36,Default,,0000,0000,0000,,that they really should have listened to\Nthe people of Hamburg. Okay, so,
Dialogue: 0,0:18:59.36,0:19:03.94,Default,,0000,0000,0000,,in summary of the operations of\Na storage ring we can just say this:
Dialogue: 0,0:19:03.94,0:19:07.04,Default,,0000,0000,0000,,They get perfectly timed kicks\Nwith our polarity switching
Dialogue: 0,0:19:07.04,0:19:11.70,Default,,0000,0000,0000,,at just the right moment by radio waves\Ngenerated in these large klystrons
Dialogue: 0,0:19:11.70,0:19:16.11,Default,,0000,0000,0000,,from the funny looking metal\Ntubes that we called cavities.
Dialogue: 0,0:19:16.11,0:19:18.46,Default,,0000,0000,0000,,And some big-ass superconducting\Nmagnets keep them on a curve
Dialogue: 0,0:19:18.46,0:19:22.78,Default,,0000,0000,0000,,when they are not being accelerated.\NNow the trick is, one of these kicks
Dialogue: 0,0:19:22.78,0:19:26.43,Default,,0000,0000,0000,,like moving through the cavity once, may\Nnot give you all the energy you want,
Dialogue: 0,0:19:26.43,0:19:30.16,Default,,0000,0000,0000,,in fact it doesn’t. But if you\Nmake them go round in the ring,
Dialogue: 0,0:19:30.16,0:19:34.15,Default,,0000,0000,0000,,they come by every couple of\Nnanoseconds. So you just have them
Dialogue: 0,0:19:34.15,0:19:37.66,Default,,0000,0000,0000,,run through your acceleration all the\Ntime. Which is the big difference
Dialogue: 0,0:19:37.66,0:19:40.62,Default,,0000,0000,0000,,between the storage ring and a linear\Naccelerator. A linear accelerator
Dialogue: 0,0:19:40.62,0:19:44.40,Default,,0000,0000,0000,,is basically a one shot operation but\Nhere, you just give them an energy kick
Dialogue: 0,0:19:44.40,0:19:48.88,Default,,0000,0000,0000,,every time they come around, which\Nis often, we’re going to see that.
Dialogue: 0,0:19:48.88,0:19:52.88,Default,,0000,0000,0000,,So that’s the summary of what\Nthe storage rings do. Now,
Dialogue: 0,0:19:52.88,0:19:56.57,Default,,0000,0000,0000,,the machine layout, if you\Nlook at a research center
Dialogue: 0,0:19:56.57,0:20:01.16,Default,,0000,0000,0000,,which has a bunch of accelerators,\Nit almost always goes like this:
Dialogue: 0,0:20:01.16,0:20:05.03,Default,,0000,0000,0000,,You have some old, small storage\Nrings and then they built
Dialogue: 0,0:20:05.03,0:20:08.62,Default,,0000,0000,0000,,newer ones which were\Nbigger. So this is just
Dialogue: 0,0:20:08.62,0:20:12.42,Default,,0000,0000,0000,,a historical development, first\Nyou build small machines, then
Dialogue: 0,0:20:12.42,0:20:14.92,Default,,0000,0000,0000,,techniques get better, engineering gets\Nbetter, you build bigger machines. But
Dialogue: 0,0:20:14.92,0:20:18.64,Default,,0000,0000,0000,,you can actually use that, it’s very\Nuseful because the older machines,
Dialogue: 0,0:20:18.64,0:20:22.64,Default,,0000,0000,0000,,you can use as pre-accelerators.\NFor a variety of reasons it’s useful
Dialogue: 0,0:20:22.64,0:20:26.37,Default,,0000,0000,0000,,to not put in your particles with\Nan energy of zero and then
Dialogue: 0,0:20:26.37,0:20:30.18,Default,,0000,0000,0000,,have them accelerated up to the energy you\Nwant. You want to pre-accelerate them,
Dialogue: 0,0:20:30.18,0:20:33.46,Default,,0000,0000,0000,,make them a little faster at a time.\NThat’s what you do, you just
Dialogue: 0,0:20:33.46,0:20:37.84,Default,,0000,0000,0000,,take the old accelerators. And if\Nwe look at the accelerator layout
Dialogue: 0,0:20:37.84,0:20:42.20,Default,,0000,0000,0000,,of some real world research centers,\Nyou can actually see this. On the left
Dialogue: 0,0:20:42.20,0:20:47.02,Default,,0000,0000,0000,,you have CERN in Geneva and on the\Nright you have DESY here in Hamburg.
Dialogue: 0,0:20:47.02,0:20:51.14,Default,,0000,0000,0000,,And you can see that there are smaller\Naccelerators, which are the older ones,
Dialogue: 0,0:20:51.14,0:20:54.14,Default,,0000,0000,0000,,and you have bigger accelerators\Nwhich are connected to them.
Dialogue: 0,0:20:54.14,0:20:59.41,Default,,0000,0000,0000,,And that’s this layout of the machines.\NOkay, now let’s talk about collisions.
Dialogue: 0,0:20:59.41,0:21:03.41,Default,,0000,0000,0000,,This is a nice picture of a collision.\NIt’s not actually a proton collision
Dialogue: 0,0:21:03.41,0:21:08.27,Default,,0000,0000,0000,,but a heavy-ion collision, which\Nthey do part of the time in the LHC.
Dialogue: 0,0:21:08.27,0:21:11.52,Default,,0000,0000,0000,,They are extremely hard to produce, we’re\Ngoing to see that, but still we make
Dialogue: 0,0:21:11.52,0:21:15.69,Default,,0000,0000,0000,,an awful lot of them.\NSo let’s see, first of all
Dialogue: 0,0:21:15.69,0:21:19.33,Default,,0000,0000,0000,,let’s talk about what the beam looks like,\Nbecause we’re going to be colliding beams.
Dialogue: 0,0:21:19.33,0:21:23.22,Default,,0000,0000,0000,,So what are these beams? Is it\Na continuous stream of particles?
Dialogue: 0,0:21:23.22,0:21:27.78,Default,,0000,0000,0000,,Well it’s not. Because the acceleration\Nthat we use, these radio frequency,
Dialogue: 0,0:21:27.78,0:21:31.96,Default,,0000,0000,0000,,polarity shifting mechanisms, they\Nmake the particles into bunches.
Dialogue: 0,0:21:31.96,0:21:35.73,Default,,0000,0000,0000,,So you don’t have a continuous stream,\Nyou have separate bunches.
Dialogue: 0,0:21:35.73,0:21:38.61,Default,,0000,0000,0000,,But how large are these bunches?\NIs there one particle per bunch?
Dialogue: 0,0:21:38.61,0:21:41.15,Default,,0000,0000,0000,,You’ve got a particle, you wait\Na while, there’s another particle?
Dialogue: 0,0:21:41.15,0:21:44.65,Default,,0000,0000,0000,,Well, it’s not like that.\NBecause if it were like that,
Dialogue: 0,0:21:44.65,0:21:49.30,Default,,0000,0000,0000,,if we had single particles coming after\None another, it would be impossible
Dialogue: 0,0:21:49.30,0:21:52.75,Default,,0000,0000,0000,,to hit them. You have to aim\Nthe beams very precisely.
Dialogue: 0,0:21:52.75,0:21:56.62,Default,,0000,0000,0000,,I mean, think about it. One comes\Naround 27 kilometers around the ring.
Dialogue: 0,0:21:56.62,0:21:59.95,Default,,0000,0000,0000,,The other comes around 27\Nkilometers going the other way.
Dialogue: 0,0:21:59.95,0:22:03.48,Default,,0000,0000,0000,,And now you want them to hit. You have\Nto align your magnets very precisely.
Dialogue: 0,0:22:03.48,0:22:07.06,Default,,0000,0000,0000,,You can think of it like this:\NYou have a guy in Munich
Dialogue: 0,0:22:07.06,0:22:10.79,Default,,0000,0000,0000,,and you have a guy in Hamburg and\Nthey each have a rifle. And the bullets
Dialogue: 0,0:22:10.79,0:22:14.55,Default,,0000,0000,0000,,of the rifle are let’s say one centimeter\Nin size. So the guy in Hamburg
Dialogue: 0,0:22:14.55,0:22:17.39,Default,,0000,0000,0000,,shoots in the air and the guy in Munich\Nshoots in the air, and they are supposed
Dialogue: 0,0:22:17.39,0:22:22.49,Default,,0000,0000,0000,,to make the bullets hit in the\Nmiddle, over, let’s say Frankfurt.
Dialogue: 0,0:22:22.49,0:22:25.72,Default,,0000,0000,0000,,Which they’re not going to manage.\NAnd which is actually way too simple.
Dialogue: 0,0:22:25.72,0:22:32.20,Default,,0000,0000,0000,,Because if the bullet is really\None centimeter in size,
Dialogue: 0,0:22:32.20,0:22:37.36,Default,,0000,0000,0000,,then the equivalent distance that the two\Nshooters should be away from each other,
Dialogue: 0,0:22:37.36,0:22:40.65,Default,,0000,0000,0000,,if we want to make it the same\Ndifficulty as these protons,
Dialogue: 0,0:22:40.65,0:22:45.05,Default,,0000,0000,0000,,would not be between Hamburg and Munich.\NIt would be from here to fucking Mars.
Dialogue: 0,0:22:45.05,0:22:49.47,Default,,0000,0000,0000,,{\i1}laughter and applause{\i0}\NI calculated that shit.
Dialogue: 0,0:22:49.47,0:22:54.20,Default,,0000,0000,0000,,{\i1}applause{\i0}
Dialogue: 0,0:22:54.20,0:22:57.65,Default,,0000,0000,0000,,We don’t even have rifles on Mars\Nanyway. {\i1}laughter{\i0}
Dialogue: 0,0:22:57.65,0:23:01.69,Default,,0000,0000,0000,,So what we got is, we got large\Nbunches, very large bunches.
Dialogue: 0,0:23:01.69,0:23:04.89,Default,,0000,0000,0000,,And in fact there’s 10^11\Nprotons per bunch, which is
Dialogue: 0,0:23:04.89,0:23:11.03,Default,,0000,0000,0000,,100 Billion. This is where I called Sagan\N“ you going Millions of Millions“
Dialogue: 0,0:23:11.03,0:23:15.12,Default,,0000,0000,0000,,Okay, so you got 100 Billion\Nprotons in one bunch.
Dialogue: 0,0:23:15.12,0:23:19.27,Default,,0000,0000,0000,,And the bunches go by one after the other.\NNow, if you stand next to the LHC
Dialogue: 0,0:23:19.27,0:23:23.16,Default,,0000,0000,0000,,and you were capable of observing these\Nbunches, you would see one fly by
Dialogue: 0,0:23:23.16,0:23:28.17,Default,,0000,0000,0000,,every 25 nanoseconds. So you go “there’s\Na bunch, now it’s 25 nanoseconds,
Dialogue: 0,0:23:28.17,0:23:32.77,Default,,0000,0000,0000,,there is the next one”. And there’s about\N7.5 meters between the bunches.
Dialogue: 0,0:23:32.77,0:23:36.76,Default,,0000,0000,0000,,Now, 7.5 meters corresponds to\N25 nanoseconds, you see that
Dialogue: 0,0:23:36.76,0:23:42.94,Default,,0000,0000,0000,,the speed is very big and indeed\Nit’s almost the speed of light.
Dialogue: 0,0:23:42.94,0:23:45.59,Default,,0000,0000,0000,,Which is just, we accelerate them\Nand at some point they just go
Dialogue: 0,0:23:45.59,0:23:48.64,Default,,0000,0000,0000,,with the speed of light and we just push\Nup the energy, we don’t make them
Dialogue: 0,0:23:48.64,0:23:53.75,Default,,0000,0000,0000,,go any faster actually. And if you\Nwere to identify the bunches,
Dialogue: 0,0:23:53.75,0:23:58.94,Default,,0000,0000,0000,,which actually you can, you would\Nsee that there are 2800 bunches
Dialogue: 0,0:23:58.94,0:24:02.89,Default,,0000,0000,0000,,going by; and then when\Nyou have number 2809,
Dialogue: 0,0:24:02.89,0:24:06.62,Default,,0000,0000,0000,,that’s actually the first one that you\Ncounted which has come round again.
Dialogue: 0,0:24:06.62,0:24:10.16,Default,,0000,0000,0000,,Per direction! So in total\Nwe have over 5000 bunches
Dialogue: 0,0:24:10.16,0:24:15.47,Default,,0000,0000,0000,,of 100 Billion protons each. So\Nthat’s the beam we are dealing with.
Dialogue: 0,0:24:15.47,0:24:19.61,Default,,0000,0000,0000,,Oh, and a funny thing: you get charged\Nparticles moving, it’s actually a current,
Dialogue: 0,0:24:19.61,0:24:22.68,Default,,0000,0000,0000,,right? In a wire you have\Na current running through it,
Dialogue: 0,0:24:22.68,0:24:27.15,Default,,0000,0000,0000,,there’s electrons moving or holes moving\Nand you get a current. If you were
Dialogue: 0,0:24:27.15,0:24:31.80,Default,,0000,0000,0000,,to measure the current of the\NLHC, it would be 0.6 milliamps,
Dialogue: 0,0:24:31.80,0:24:34.33,Default,,0000,0000,0000,,which is a small current, but\Nwe’re doing collisions anyway
Dialogue: 0,0:24:34.33,0:24:38.27,Default,,0000,0000,0000,,and not power transmission,\Nso that’s fine. {\i1}laughter{\i0}
Dialogue: 0,0:24:38.27,0:24:42.78,Default,,0000,0000,0000,,This is a diagram of what the actual\Ninteraction point geometry looks like.
Dialogue: 0,0:24:42.78,0:24:46.34,Default,,0000,0000,0000,,You get the beams from different\Ndirections, think of it like the top one
Dialogue: 0,0:24:46.34,0:24:50.01,Default,,0000,0000,0000,,coming from the right, the bottom\None coming from the left;
Dialogue: 0,0:24:50.01,0:24:53.48,Default,,0000,0000,0000,,and they are kicked into intersecting\Npaths by magnets. You have
Dialogue: 0,0:24:53.48,0:24:57.59,Default,,0000,0000,0000,,very complicated, very precise\Nmagnetic fields aligning them,
Dialogue: 0,0:24:57.59,0:25:01.85,Default,,0000,0000,0000,,so that they intersect. And it’s\Nactually a bit of a trying-out game.
Dialogue: 0,0:25:01.85,0:25:05.97,Default,,0000,0000,0000,,I’ve heard this from\Naccelerator operators.
Dialogue: 0,0:25:05.97,0:25:09.41,Default,,0000,0000,0000,,You shift the position of the beams\Nrelative to each other by small amounts
Dialogue: 0,0:25:09.41,0:25:12.88,Default,,0000,0000,0000,,and you just see where the collisions\Nhappen. You go like: “Ah yeah, okay,
Dialogue: 0,0:25:12.88,0:25:17.22,Default,,0000,0000,0000,,there’s lots of collisions, ah, now\Nthey’re gone, I’m going back.”
Dialogue: 0,0:25:17.22,0:25:20.44,Default,,0000,0000,0000,,And you do it like that. You can save the\Nsettings and load them and calculate them
Dialogue: 0,0:25:20.44,0:25:24.30,Default,,0000,0000,0000,,but it’s actually easier\Nto just try it out.
Dialogue: 0,0:25:24.30,0:25:28.35,Default,,0000,0000,0000,,If we think of how much stuff we’ve\Ngot going on: you got a packet,
Dialogue: 0,0:25:28.35,0:25:31.24,Default,,0000,0000,0000,,a bunch of 100 Billion\Nprotons coming one way,
Dialogue: 0,0:25:31.24,0:25:35.10,Default,,0000,0000,0000,,you got another packet of 100 Billion\Nprotons coming the other way.
Dialogue: 0,0:25:35.10,0:25:39.64,Default,,0000,0000,0000,,Now the interaction point area is as small\Nas the cross section of a human hair.
Dialogue: 0,0:25:39.64,0:25:43.27,Default,,0000,0000,0000,,You can see that, it’s one hundredth\Nof a square millimeter.
Dialogue: 0,0:25:43.27,0:25:46.11,Default,,0000,0000,0000,,Now how many collisions do\Nyou think we have? We’ve got…
Dialogue: 0,0:25:46.11,0:25:48.12,Default,,0000,0000,0000,,Audience: Three!\N{\i1}Michael laughs{\i0}
Dialogue: 0,0:25:48.12,0:25:51.85,Default,,0000,0000,0000,,Michael: …it’s actually not that bad.\NWe got about 20 in the LHC.
Dialogue: 0,0:25:51.85,0:25:56.45,Default,,0000,0000,0000,,And the funny thing is, people\Nconsider this a bit too much.
Dialogue: 0,0:25:56.45,0:25:59.60,Default,,0000,0000,0000,,The effect is called pile-up. And the\Nbad thing about pile-up is you’ve got
Dialogue: 0,0:25:59.60,0:26:03.59,Default,,0000,0000,0000,,beams intersecting, you’ve got bunches\N‘crossing’ – that’s what we call it.
Dialogue: 0,0:26:03.59,0:26:06.72,Default,,0000,0000,0000,,And there’s not just one collision which\Nyou can analyze, there is a bunch of them,
Dialogue: 0,0:26:06.72,0:26:10.11,Default,,0000,0000,0000,,around 20. And that makes that\Nmore difficult for the experiments,
Dialogue: 0,0:26:10.11,0:26:15.72,Default,,0000,0000,0000,,we’re going to see why. Well, and if we\Nhave 20 collisions every bunch crossing
Dialogue: 0,0:26:15.72,0:26:19.58,Default,,0000,0000,0000,,and the bunches come by every\N25 nanoseconds, that gives us a total
Dialogue: 0,0:26:19.58,0:26:24.69,Default,,0000,0000,0000,,of 600 Million collisions per\Nsecond. Per interaction point.
Dialogue: 0,0:26:24.69,0:26:27.77,Default,,0000,0000,0000,,Which we don’t have just one of. We\Nhave 4 experiments, each experiment
Dialogue: 0,0:26:27.77,0:26:31.37,Default,,0000,0000,0000,,has its own interaction point. So\Nin total, we have about 2 Billion
Dialogue: 0,0:26:31.37,0:26:36.66,Default,,0000,0000,0000,,proton-proton collisions happening\Nevery second when the LHC is running.
Dialogue: 0,0:26:36.66,0:26:39.58,Default,,0000,0000,0000,,Now let’s look at experiments.\N{\i1}laughs{\i0}
Dialogue: 0,0:26:39.58,0:26:44.07,Default,,0000,0000,0000,,Yeah, this is a photograph of one part of\Nthe ATLAS experiment being transported.
Dialogue: 0,0:26:44.07,0:26:47.69,Default,,0000,0000,0000,,And as for the scale of this thing, well,\Nin the physics community, we call this
Dialogue: 0,0:26:47.69,0:26:53.70,Default,,0000,0000,0000,,a huge device.\N{\i1}laughter{\i0}
Dialogue: 0,0:26:53.70,0:26:57.15,Default,,0000,0000,0000,,I have a diagram of the experiment\Nwhere this is built in and
Dialogue: 0,0:26:57.15,0:27:00.51,Default,,0000,0000,0000,,you’re going to recognize the part\Nwhich is the one I’ve circled there.
Dialogue: 0,0:27:00.51,0:27:04.29,Default,,0000,0000,0000,,So the real thing is even bigger.\NAnd down at the very bottom,
Dialogue: 0,0:27:04.29,0:27:08.19,Default,,0000,0000,0000,,just to the center of the\Nexperiment, there’s people.
Dialogue: 0,0:27:08.19,0:27:12.86,Default,,0000,0000,0000,,Which if I check it like this,\Nthey’re about 15 pixels high.
Dialogue: 0,0:27:12.86,0:27:16.49,Default,,0000,0000,0000,,So that’s the scale of the experiment.
Dialogue: 0,0:27:16.49,0:27:20.25,Default,,0000,0000,0000,,The experiment has the interaction point\Nat the center, so you got a beam line
Dialogue: 0,0:27:20.25,0:27:23.57,Default,,0000,0000,0000,,coming in from the left, you got the other\Nbeam line coming in from the right.
Dialogue: 0,0:27:23.57,0:27:27.28,Default,,0000,0000,0000,,And in the very core of the experiment\Nis where the interactions,
Dialogue: 0,0:27:27.28,0:27:31.14,Default,,0000,0000,0000,,where the collisions happen. And then\Nyou got the experiment in layers,
Dialogue: 0,0:27:31.14,0:27:35.24,Default,,0000,0000,0000,,like an onion, going around\Nthem in a symmetrical way.
Dialogue: 0,0:27:35.24,0:27:38.37,Default,,0000,0000,0000,,Inside you have a huge magnetic\Nfield which is almost as big
Dialogue: 0,0:27:38.37,0:27:42.47,Default,,0000,0000,0000,,as the curve magnets we were talking about\Nwhen I was describing the storage ring.
Dialogue: 0,0:27:42.47,0:27:46.13,Default,,0000,0000,0000,,This is about 4 Teslas,\Nso it’s also a very big field.
Dialogue: 0,0:27:46.13,0:27:50.16,Default,,0000,0000,0000,,But now we got a 4 Tesla field\Nnot just over the beam pipe
Dialogue: 0,0:27:50.16,0:27:54.34,Default,,0000,0000,0000,,which is about 5 centimeters in diameter,\Nbut through the entire experiment;
Dialogue: 0,0:27:54.34,0:27:58.08,Default,,0000,0000,0000,,and this thing is like 20-25 meters.\NSo you’ve got a 4 Tesla field
Dialogue: 0,0:27:58.08,0:28:01.91,Default,,0000,0000,0000,,which should span more than 20 meters.
Dialogue: 0,0:28:01.91,0:28:07.41,Default,,0000,0000,0000,,And, just for shits and giggles,\Nit’s got 3000 kilometers of cables.
Dialogue: 0,0:28:07.41,0:28:11.06,Default,,0000,0000,0000,,Which is a lot; and if you just\Npull some random plug
Dialogue: 0,0:28:11.06,0:28:16.27,Default,,0000,0000,0000,,and don’t tell anyone which one it\Nwas you’re making a lot of enemies.
Dialogue: 0,0:28:16.27,0:28:19.98,Default,,0000,0000,0000,,So the innermost thing is what we\Ncall the inner tracking. It is located
Dialogue: 0,0:28:19.98,0:28:23.21,Default,,0000,0000,0000,,just centimeters off the beam line,\Nit’s supposed to be very very close to
Dialogue: 0,0:28:23.21,0:28:26.29,Default,,0000,0000,0000,,where the actual interactions happen.
Dialogue: 0,0:28:26.29,0:28:29.18,Default,,0000,0000,0000,,And this thing is made to leave the\Nparticles undisturbed, they should just
Dialogue: 0,0:28:29.18,0:28:32.59,Default,,0000,0000,0000,,fly trough this inner tracking detector.\NAnd the detector will tell us
Dialogue: 0,0:28:32.59,0:28:35.91,Default,,0000,0000,0000,,where they were, but not actually\Nstop them or deflect them.
Dialogue: 0,0:28:35.91,0:28:40.05,Default,,0000,0000,0000,,This gives us precise location data,\Nas to how many particles there were,
Dialogue: 0,0:28:40.05,0:28:44.03,Default,,0000,0000,0000,,what way they were flying,\Nand, from the curve,
Dialogue: 0,0:28:44.03,0:28:47.57,Default,,0000,0000,0000,,what momentum they have. Outside\Nof that we’ve got calorimeters.
Dialogue: 0,0:28:47.57,0:28:51.30,Default,,0000,0000,0000,,Now these are supposed to be stopping\Nthe particles. A particle goes through
Dialogue: 0,0:28:51.30,0:28:55.36,Default,,0000,0000,0000,,the inner tracking without being disturbed\Nbut in the calorimeter it should stop.
Dialogue: 0,0:28:55.36,0:28:58.97,Default,,0000,0000,0000,,And it should deposit all its energy there\Nand which is why we have to put around it
Dialogue: 0,0:28:58.97,0:29:03.10,Default,,0000,0000,0000,,the inner tracking. You see, if we put the\Ncalorimeter inside, it stops the particle,
Dialogue: 0,0:29:03.10,0:29:07.77,Default,,0000,0000,0000,,outside of that nothing happens. So we\Nhave the calorimeters outside of that.
Dialogue: 0,0:29:07.77,0:29:12.07,Default,,0000,0000,0000,,And then we got these funny wing things\Ngoing on. That’s the muon detectors.
Dialogue: 0,0:29:12.07,0:29:15.49,Default,,0000,0000,0000,,They are there for one\Nspecial sort of particle.
Dialogue: 0,0:29:15.49,0:29:19.61,Default,,0000,0000,0000,,Out of the… 50, let’s say 60\N– depends on the way you count –
Dialogue: 0,0:29:19.61,0:29:22.86,Default,,0000,0000,0000,,elementary particles that we\Nhave. These large parts are
Dialogue: 0,0:29:22.86,0:29:26.25,Default,,0000,0000,0000,,just for the muons. Because the\Nmuons have the property,
Dialogue: 0,0:29:26.25,0:29:29.99,Default,,0000,0000,0000,,the tendency to go through all sorts of\Nmatter undisturbed. So you just need to
Dialogue: 0,0:29:29.99,0:29:33.27,Default,,0000,0000,0000,,throw a huge amount of matter\Nin the way of these muons, like:
Dialogue: 0,0:29:33.27,0:29:36.75,Default,,0000,0000,0000,,“let’s have a brick wall and then\Nanother one”. And then you
Dialogue: 0,0:29:36.75,0:29:42.03,Default,,0000,0000,0000,,may be able to stop the muons,\Nor just measure them.
Dialogue: 0,0:29:42.03,0:29:45.06,Default,,0000,0000,0000,,This is to give you an idea of the\Ncomplexity of the instrument
Dialogue: 0,0:29:45.06,0:29:49.17,Default,,0000,0000,0000,,on the inside. This is the inner tracking\Ndetector, it’s called a pixel detector;
Dialogue: 0,0:29:49.17,0:29:52.73,Default,,0000,0000,0000,,and you see guys walking around in\Nprotective suits. That is not for fun
Dialogue: 0,0:29:52.73,0:29:56.92,Default,,0000,0000,0000,,or just for the photo, this is a very,\Nvery precise instrument. But it’s sitting
Dialogue: 0,0:29:56.92,0:30:00.10,Default,,0000,0000,0000,,inside this huge experiment which – again,
Dialogue: 0,0:30:00.10,0:30:03.91,Default,,0000,0000,0000,,I calculated that shit – is about\Nas large as a space shuttle
Dialogue: 0,0:30:03.91,0:30:07.42,Default,,0000,0000,0000,,and weighs as much as the\NEiffel Tower. And inside
Dialogue: 0,0:30:07.42,0:30:12.03,Default,,0000,0000,0000,,they’ve got electronics, almost a ton\Nof electronics which is so precise
Dialogue: 0,0:30:12.03,0:30:16.03,Default,,0000,0000,0000,,that it makes your smartphone\Nlook like a rock. So there you go,
Dialogue: 0,0:30:16.03,0:30:19.97,Default,,0000,0000,0000,,it’s a very, very complicated sort of\Nexperiment. Let’s talk about triggering,
Dialogue: 0,0:30:19.97,0:30:24.36,Default,,0000,0000,0000,,because as I said there’s 600 Million\Nevents happening inside this.
Dialogue: 0,0:30:24.36,0:30:27.60,Default,,0000,0000,0000,,That’s 40 Million bunch crossings.\NNow: how are we going to analyze this?
Dialogue: 0,0:30:27.60,0:30:31.72,Default,,0000,0000,0000,,Is there a guy writing everything\Ndown? Obviously not.
Dialogue: 0,0:30:31.72,0:30:35.54,Default,,0000,0000,0000,,So this experiment with all the tracking\Nand the calorimeters and the muons
Dialogue: 0,0:30:35.54,0:30:39.80,Default,,0000,0000,0000,,and everything has about\N100 Million electronic channels.
Dialogue: 0,0:30:39.80,0:30:43.41,Default,,0000,0000,0000,,And one channel could be the measurement\Nof a voltage, or a temperature
Dialogue: 0,0:30:43.41,0:30:47.33,Default,,0000,0000,0000,,or a magnetic field or whatever. So\Nwe’ve got 100 Million different values,
Dialogue: 0,0:30:47.33,0:30:52.54,Default,,0000,0000,0000,,so to speak. And that makes\Nabout 1.5 Megabytes per crossing,
Dialogue: 0,0:30:52.54,0:30:57.22,Default,,0000,0000,0000,,per every event readout. Which\Ngives us – multiplied by 40 Million –
Dialogue: 0,0:30:57.22,0:31:01.26,Default,,0000,0000,0000,,gives us about 60 terabytes\Nof raw data per second.
Dialogue: 0,0:31:01.26,0:31:05.61,Default,,0000,0000,0000,,That’s bad. I looked it up, I guess
Dialogue: 0,0:31:05.61,0:31:10.34,Default,,0000,0000,0000,,the best RAM you can do is about\N1 terabyte per second or something.
Dialogue: 0,0:31:10.34,0:31:14.95,Default,,0000,0000,0000,,So we’re obviously not going to tackle\Nthis by just putting in fast hardware,
Dialogue: 0,0:31:14.95,0:31:18.69,Default,,0000,0000,0000,,because it’s not going\Nto be fast enough. Plus,
Dialogue: 0,0:31:18.69,0:31:24.45,Default,,0000,0000,0000,,the reconstruction of an event is done\Nby about 5 Million lines of C++ code.
Dialogue: 0,0:31:24.45,0:31:29.57,Default,,0000,0000,0000,,Programmed by some 2000-3000\Ndevelopers around the world.
Dialogue: 0,0:31:29.57,0:31:33.33,Default,,0000,0000,0000,,It simulates for one crossing\N30 Million objects, which is
Dialogue: 0,0:31:33.33,0:31:36.84,Default,,0000,0000,0000,,the protons and other stuff flying around.
Dialogue: 0,0:31:36.84,0:31:44.41,Default,,0000,0000,0000,,And it is allocated to take 15 seconds\Nof one core’s computing time.
Dialogue: 0,0:31:44.41,0:31:47.77,Default,,0000,0000,0000,,To calculate it all, you would\Nneed about 600 million cores.
Dialogue: 0,0:31:47.77,0:31:50.33,Default,,0000,0000,0000,,That’s not happening. I mean,\Neven if we took over the NSA
Dialogue: 0,0:31:50.33,0:31:54.13,Default,,0000,0000,0000,,{\i1}laughter{\i0}\Nand used all of their data-centers
Dialogue: 0,0:31:54.13,0:31:57.44,Default,,0000,0000,0000,,for LHC calculations, it still wouldn’t be\Nenough. So we have to do something
Dialogue: 0,0:31:57.44,0:32:02.57,Default,,0000,0000,0000,,about this huge mass of data. And\Nwhat we do is, we put in triggers.
Dialogue: 0,0:32:02.57,0:32:07.17,Default,,0000,0000,0000,,The trigger is supposed to reduce the\Nnumber of events that we look at.
Dialogue: 0,0:32:07.17,0:32:10.83,Default,,0000,0000,0000,,The first level trigger looks at\Nevery collision that happens.
Dialogue: 0,0:32:10.83,0:32:13.84,Default,,0000,0000,0000,,And it’s got 25 nanoseconds\Nof time to decide:
Dialogue: 0,0:32:13.84,0:32:17.41,Default,,0000,0000,0000,,Is this an interesting collision?\NIs it not an interesting collision?
Dialogue: 0,0:32:17.41,0:32:21.83,Default,,0000,0000,0000,,We tell it to eliminate\N99.7% of all collisions.
Dialogue: 0,0:32:21.83,0:32:26.48,Default,,0000,0000,0000,,So only every 400th collision\Nis allowed for this trigger to go:
Dialogue: 0,0:32:26.48,0:32:30.28,Default,,0000,0000,0000,,“Oh, yeah, okay that looks interesting,\Nlet’s give it to Level 2 trigger”.
Dialogue: 0,0:32:30.28,0:32:34.15,Default,,0000,0000,0000,,So then we end up with about 100,000\Nevents per second. Which get us
Dialogue: 0,0:32:34.15,0:32:38.66,Default,,0000,0000,0000,,down to 150 Gigabytes per second. Now\Nwe could handle this from the data flow,
Dialogue: 0,0:32:38.66,0:32:43.45,Default,,0000,0000,0000,,but still we can’t simulate it. So\Nwe’ve got another level trigger.
Dialogue: 0,0:32:43.45,0:32:46.72,Default,,0000,0000,0000,,This is where the two\Nexperiments at the LHC differ:
Dialogue: 0,0:32:46.72,0:32:50.03,Default,,0000,0000,0000,,the CMS experiment has just a\NLevel 2 trigger; does it all there.
Dialogue: 0,0:32:50.03,0:32:53.30,Default,,0000,0000,0000,,The ATLAS experiment goes the more\Ntraditional way, it has a Level 2 trigger
Dialogue: 0,0:32:53.30,0:32:57.50,Default,,0000,0000,0000,,and a Level 3 trigger. In the end these\Ncombined have about 10 microseconds
Dialogue: 0,0:32:57.50,0:33:01.45,Default,,0000,0000,0000,,of time, which is a bit more and it gives\Nthem a chance to look at the events
Dialogue: 0,0:33:01.45,0:33:05.92,Default,,0000,0000,0000,,more closely. Not just, let’s say:\N“Was it a collision of 2 protons
Dialogue: 0,0:33:05.92,0:33:09.30,Default,,0000,0000,0000,,or of 3 protons?”; “Were there\N5 muons coming out of it
Dialogue: 0,0:33:09.30,0:33:12.81,Default,,0000,0000,0000,,or 3 electrons and 2 muons?” This is\Nthe sort of thing they’re looking at.
Dialogue: 0,0:33:12.81,0:33:16.37,Default,,0000,0000,0000,,And certain combinations the triggers\Nwill find interesting or not.
Dialogue: 0,0:33:16.37,0:33:20.12,Default,,0000,0000,0000,,Let’s say 5 muons, I don’t give a shit\Nabout that. “3 muons and 2 electrons?
Dialogue: 0,0:33:20.12,0:33:23.48,Default,,0000,0000,0000,,Allright, I want to analyze it”. So\Nthat’s what the trigger does.
Dialogue: 0,0:33:23.48,0:33:27.64,Default,,0000,0000,0000,,Now this Level 2 and 3 trigger,\Nagain, have to kick out about
Dialogue: 0,0:33:27.64,0:33:31.07,Default,,0000,0000,0000,,99.9% of the events. They’re\Nsupposed to leave us with
Dialogue: 0,0:33:31.07,0:33:36.36,Default,,0000,0000,0000,,about 150 events per second. Which\Ngives a data volume of a measly
Dialogue: 0,0:33:36.36,0:33:40.03,Default,,0000,0000,0000,,300 Megabytes per second and that’s\Nsomething we can handle. We push it
Dialogue: 0,0:33:40.03,0:33:45.78,Default,,0000,0000,0000,,to computers all around the world.\NAnd then we get the simulations going.
Dialogue: 0,0:33:45.78,0:33:50.90,Default,,0000,0000,0000,,This is a display, this is\Nwhat you see in the media.
Dialogue: 0,0:33:50.90,0:33:55.36,Default,,0000,0000,0000,,If you take one of these events – just\None of the interesting events which
Dialogue: 0,0:33:55.36,0:34:00.74,Default,,0000,0000,0000,,actually reach the computers – because\Nthose 40 million bunch crossings… well,
Dialogue: 0,0:34:00.74,0:34:04.15,Default,,0000,0000,0000,,most of them don’t reach the computers,\Nthey get kicked out by the triggers.
Dialogue: 0,0:34:04.15,0:34:08.24,Default,,0000,0000,0000,,But out of the remaining 100 or 200\Nevents per second, let’s say this is one.
Dialogue: 0,0:34:08.24,0:34:12.85,Default,,0000,0000,0000,,It’s an actual event and it’s been\Ncalculated into a nice picture here.
Dialogue: 0,0:34:12.85,0:34:17.51,Default,,0000,0000,0000,,Now, normally they don’t do that, it’s\Nanalyzed automatically by code
Dialogue: 0,0:34:17.51,0:34:21.09,Default,,0000,0000,0000,,and it’s analyzed by the physics data.\NAnd they only make these pretty pictures
Dialogue: 0,0:34:21.09,0:34:25.34,Default,,0000,0000,0000,,if they want to show something to\Nthe press. To the left you have
Dialogue: 0,0:34:25.34,0:34:29.33,Default,,0000,0000,0000,,what’s called a Feynman Diagraph.\NThat’s just a fancy physical way
Dialogue: 0,0:34:29.33,0:34:34.04,Default,,0000,0000,0000,,of saying what’s happening there. And\Nit involves the letter H on the left side,
Dialogue: 0,0:34:34.04,0:34:37.18,Default,,0000,0000,0000,,which means there’s a Higgs involved.\NWhich is why this event was particularly
Dialogue: 0,0:34:37.18,0:34:42.28,Default,,0000,0000,0000,,interesting to the people\Nanalyzing the data at the LHC.
Dialogue: 0,0:34:42.28,0:34:47.23,Default,,0000,0000,0000,,And you see a bunch of tracks, you see\Nthe yellow tracks all curled up inside,
Dialogue: 0,0:34:47.23,0:34:51.29,Default,,0000,0000,0000,,that’s a bunch of protons hitting\Neach other. The interesting thing is
Dialogue: 0,0:34:51.29,0:34:55.71,Default,,0000,0000,0000,,what happens for example above\Nthere with the blue brick kind of things.
Dialogue: 0,0:34:55.71,0:35:00.05,Default,,0000,0000,0000,,There’s a red line going through\Nthese bricks. This indicates a muon.
Dialogue: 0,0:35:00.05,0:35:05.48,Default,,0000,0000,0000,,A muon which was created in\Nthis event there in the center.
Dialogue: 0,0:35:05.48,0:35:08.98,Default,,0000,0000,0000,,And it went out and the\Nbricks symbolize the way
Dialogue: 0,0:35:08.98,0:35:13.14,Default,,0000,0000,0000,,the reaction was seen by the experiment.
Dialogue: 0,0:35:13.14,0:35:16.88,Default,,0000,0000,0000,,There was actually just a bunch of bricks\Nlighting up. You got, I don’t know,
Dialogue: 0,0:35:16.88,0:35:21.32,Default,,0000,0000,0000,,500 bricks around it and brick 237\Nsays: “Whoop, there was a signal”.
Dialogue: 0,0:35:21.32,0:35:24.30,Default,,0000,0000,0000,,And they go: “Allright, may have been\Na muon moving through the detector”.
Dialogue: 0,0:35:24.30,0:35:28.70,Default,,0000,0000,0000,,When you put it all together you\Nget an event display like this. Okay,
Dialogue: 0,0:35:28.70,0:35:32.59,Default,,0000,0000,0000,,so we got to have computers analyzing\Nthis. And with all the 4 experiments
Dialogue: 0,0:35:32.59,0:35:36.57,Default,,0000,0000,0000,,running at the LHC, which is not just\NCMS and ATLAS I mentioned but also
Dialogue: 0,0:35:36.57,0:35:41.63,Default,,0000,0000,0000,,LHCb and ALICE, they produce about\N25 Petabytes of data per year.
Dialogue: 0,0:35:41.63,0:35:46.23,Default,,0000,0000,0000,,And this cannot be stored at CERN alone.\NIt is transferred to data centers
Dialogue: 0,0:35:46.23,0:35:50.78,Default,,0000,0000,0000,,around the world by what is called\Nthe LHC Optical Private Network.
Dialogue: 0,0:35:50.78,0:35:55.53,Default,,0000,0000,0000,,They’ve got a network of fibers going from\NCERN to other data-centers in the world.
Dialogue: 0,0:35:55.53,0:36:00.43,Default,,0000,0000,0000,,And it consists of 11 dedicated\N10-Gigabit-per-second lines
Dialogue: 0,0:36:00.43,0:36:04.41,Default,,0000,0000,0000,,going from CERN outwards. If we\Ncombine this, it gives us a little over
Dialogue: 0,0:36:04.41,0:36:08.33,Default,,0000,0000,0000,,100 Gigabits of data\Nthroughput, which is about
Dialogue: 0,0:36:08.33,0:36:11.88,Default,,0000,0000,0000,,the bandwidth that this congress has.
Dialogue: 0,0:36:11.88,0:36:14.56,Default,,0000,0000,0000,,Which is nice, but here it’s dedicated\Nto science data and not just porn
Dialogue: 0,0:36:14.56,0:36:20.25,Default,,0000,0000,0000,,and cat pictures.\N{\i1}laughter and applause{\i0}
Dialogue: 0,0:36:20.25,0:36:23.93,Default,,0000,0000,0000,,{\i1}applause{\i0}
Dialogue: 0,0:36:23.93,0:36:27.58,Default,,0000,0000,0000,,From there it’s distributed outwards\Nfrom these 11 locations to about
Dialogue: 0,0:36:27.58,0:36:31.49,Default,,0000,0000,0000,,170 data centers in all the\Nworld. And the nice thing is,
Dialogue: 0,0:36:31.49,0:36:35.09,Default,,0000,0000,0000,,this data, these 25 Petabytes\Nper year, is available
Dialogue: 0,0:36:35.09,0:36:38.31,Default,,0000,0000,0000,,to all the scientists working\Nwith it. There’s about… well,
Dialogue: 0,0:36:38.31,0:36:41.44,Default,,0000,0000,0000,,everybody can look at it, but there’s\Nabout 3000 people in the world
Dialogue: 0,0:36:41.44,0:36:45.27,Default,,0000,0000,0000,,knowing what it means. So all these\Npeople have free access to the data,
Dialogue: 0,0:36:45.27,0:36:48.90,Default,,0000,0000,0000,,you and I would have free access to the\Ndata, just thinking it’s cool to have
Dialogue: 0,0:36:48.90,0:36:53.26,Default,,0000,0000,0000,,a bit of LHC data on your harddrive maybe.\N{\i1}laughter{\i0}
Dialogue: 0,0:36:53.26,0:36:57.85,Default,,0000,0000,0000,,All in all, we have 250,000\Ncores dedicated to this task,
Dialogue: 0,0:36:57.85,0:37:01.99,Default,,0000,0000,0000,,which is formidable. And about\N100 Petabytes of storage
Dialogue: 0,0:37:01.99,0:37:05.73,Default,,0000,0000,0000,,which is actually funny, because\N25 Petabytes of data are accumulated
Dialogue: 0,0:37:05.73,0:37:10.09,Default,,0000,0000,0000,,per year and the LHC has been\Nrunning for about 4 years.
Dialogue: 0,0:37:10.09,0:37:13.60,Default,,0000,0000,0000,,So you can see that they buy the\Nstorage as the machine runs. Because
Dialogue: 0,0:37:13.60,0:37:17.54,Default,,0000,0000,0000,,100 Petabytes, okay, that’s what we have\Nso far. If we want to keep it running,
Dialogue: 0,0:37:17.54,0:37:21.73,Default,,0000,0000,0000,,we need to buy more disks. Right! Now,
Dialogue: 0,0:37:21.73,0:37:25.38,Default,,0000,0000,0000,,what does the philosoraptor\Nsay about the triggers?
Dialogue: 0,0:37:25.38,0:37:29.11,Default,,0000,0000,0000,,If the triggers are supposed to eliminate\Nthose events which are irrelevant,
Dialogue: 0,0:37:29.11,0:37:33.42,Default,,0000,0000,0000,,which is not interesting, well,\Nwho tells them what’s irrelevant?
Dialogue: 0,0:37:33.42,0:37:37.23,Default,,0000,0000,0000,,Or to put it in the terms\Nof Conspiracy-Keanu:
Dialogue: 0,0:37:37.23,0:37:43.12,Default,,0000,0000,0000,,“What if the triggers throw away the\Nwrong 99.something % of events?”
Dialogue: 0,0:37:43.12,0:37:48.23,Default,,0000,0000,0000,,I mean, if I say: “If there’s an event\Nwith 5 muons going to the left,
Dialogue: 0,0:37:48.23,0:37:52.50,Default,,0000,0000,0000,,kick it out!”. What if that’s actually\Nsomething that’s very, very interesting?
Dialogue: 0,0:37:52.50,0:37:56.01,Default,,0000,0000,0000,,How should we tell? We need to\Nthink about this very precisely.
Dialogue: 0,0:37:56.01,0:37:59.32,Default,,0000,0000,0000,,And I’m going to tell you about\Nan example in history where
Dialogue: 0,0:37:59.32,0:38:02.80,Default,,0000,0000,0000,,this went terribly wrong, at least for\Na few years. We’re talking about
Dialogue: 0,0:38:02.80,0:38:06.82,Default,,0000,0000,0000,,the discovery of the positron.\NA positron is a piece of anti-matter;
Dialogue: 0,0:38:06.82,0:38:10.77,Default,,0000,0000,0000,,it is the anti-electron. It was\Ntheorized in 1928, when
Dialogue: 0,0:38:10.77,0:38:15.44,Default,,0000,0000,0000,,theoretical physicist Dirac put up a bunch\Nof equations. And he said: “Right,
Dialogue: 0,0:38:15.44,0:38:20.03,Default,,0000,0000,0000,,there should be something which is like\Nan electron, but has a positive charge.
Dialogue: 0,0:38:20.03,0:38:22.47,Default,,0000,0000,0000,,Some kind of anti-matter.” Well,\Nthat’s not what he said, but that’s
Dialogue: 0,0:38:22.47,0:38:26.74,Default,,0000,0000,0000,,what he thought. But it was\Nonly identified in 1931.
Dialogue: 0,0:38:26.74,0:38:30.31,Default,,0000,0000,0000,,They had particle experiments back then,\Nthey were seeing tracks of particles
Dialogue: 0,0:38:30.31,0:38:34.09,Default,,0000,0000,0000,,all the time. But they couldn’t\Nidentify the positron for 3 years,
Dialogue: 0,0:38:34.09,0:38:37.21,Default,,0000,0000,0000,,even though it was there on paper.\NSo what happened? Well,
Dialogue: 0,0:38:37.21,0:38:41.23,Default,,0000,0000,0000,,you see the picture on the left. This\Nis the actual, let’s say baby picture
Dialogue: 0,0:38:41.23,0:38:44.46,Default,,0000,0000,0000,,of the positron. I’m going to\Nbuild up a scheme on the right
Dialogue: 0,0:38:44.46,0:38:48.44,Default,,0000,0000,0000,,to show you a bit more, to\Ngive you a better overview of
Dialogue: 0,0:38:48.44,0:38:52.15,Default,,0000,0000,0000,,what we are actually talking about.\NIn the middle you’ve got a metal plate.
Dialogue: 0,0:38:52.15,0:38:55.20,Default,,0000,0000,0000,,And then there’s a track which is bending\Nto the left, which is indicated here
Dialogue: 0,0:38:55.20,0:39:01.89,Default,,0000,0000,0000,,by the blue line. Now if we analyze\Nthis from a physical point of view,
Dialogue: 0,0:39:01.89,0:39:05.27,Default,,0000,0000,0000,,it tells us that the particle\Ncomes from below,
Dialogue: 0,0:39:05.27,0:39:08.31,Default,,0000,0000,0000,,hits something in the metal plate\Nand then continues on to the top.
Dialogue: 0,0:39:08.31,0:39:12.90,Default,,0000,0000,0000,,So the direction of movement\Nis from the bottom to the top.
Dialogue: 0,0:39:12.90,0:39:17.31,Default,,0000,0000,0000,,The amount by which its curvature\Nreduces when it hits the metal plate
Dialogue: 0,0:39:17.31,0:39:21.78,Default,,0000,0000,0000,,tells us it has about the mass of\Nan electron. Okay, so far so good.
Dialogue: 0,0:39:21.78,0:39:26.02,Default,,0000,0000,0000,,But then it has a positive charge.\NBecause we know the…
Dialogue: 0,0:39:26.02,0:39:29.58,Default,,0000,0000,0000,,we know the orientation of the magnetic\Nfield. And that tells us: “Well,
Dialogue: 0,0:39:29.58,0:39:33.28,Default,,0000,0000,0000,,if it bends to the left, it\Nmust be a positive particle.”
Dialogue: 0,0:39:33.28,0:39:37.02,Default,,0000,0000,0000,,So we have a particle with the mass of\Nan electron, but with a positive charge.
Dialogue: 0,0:39:37.02,0:39:43.19,Default,,0000,0000,0000,,And people were like “Wat?”.\N{\i1}laughter{\i0}
Dialogue: 0,0:39:43.19,0:39:46.16,Default,,0000,0000,0000,,So then someone ingenious came\Nup and thought of a solution:
Dialogue: 0,0:39:46.16,0:39:48.48,Default,,0000,0000,0000,,‘They developed the picture\Nthe wrong way around!?’
Dialogue: 0,0:39:48.48,0:39:52.30,Default,,0000,0000,0000,,{\i1}laughter and applause{\i0}
Dialogue: 0,0:39:52.30,0:39:59.47,Default,,0000,0000,0000,,{\i1}applause{\i0}
Dialogue: 0,0:39:59.47,0:40:02.78,Default,,0000,0000,0000,,It’s what they thought. Well it’s wrong,\Nof course, there’s such a thing as
Dialogue: 0,0:40:02.78,0:40:08.50,Default,,0000,0000,0000,,a positron. And it’s like an electron,\Nbut it’s positively charged. But…
Dialogue: 0,0:40:08.50,0:40:13.52,Default,,0000,0000,0000,,to put it in a kind of summary maybe:\Nyou can only discover that
Dialogue: 0,0:40:13.52,0:40:17.18,Default,,0000,0000,0000,,which you can accept as a result.\NThis sounds like I’m Mahatma Gandhi
Dialogue: 0,0:40:17.18,0:40:23.20,Default,,0000,0000,0000,,or something but it’s just what we call\Nscience. {\i1}laughter{\i0}
Dialogue: 0,0:40:23.20,0:40:27.74,Default,,0000,0000,0000,,Okay, so to recap: What have we\Nseen, what have we talked about?
Dialogue: 0,0:40:27.74,0:40:32.21,Default,,0000,0000,0000,,We saw from the basic principle,\Nthat if we have energy in a place,
Dialogue: 0,0:40:32.21,0:40:36.19,Default,,0000,0000,0000,,then that can give rise to other forms of\Nmatter, which I called ‘parts = a device’.
Dialogue: 0,0:40:36.19,0:40:39.36,Default,,0000,0000,0000,,You got your little parts, you do\Nsome stuff, out comes a device.
Dialogue: 0,0:40:39.36,0:40:43.10,Default,,0000,0000,0000,,We have storage rings which give\Na lot of energy to the particles
Dialogue: 0,0:40:43.10,0:40:46.70,Default,,0000,0000,0000,,and in which they move around in huge\Nbunches. Billions of billions of protons
Dialogue: 0,0:40:46.70,0:40:51.02,Default,,0000,0000,0000,,in a bunch and then colliding. Which\Ngives in the huge experiments
Dialogue: 0,0:40:51.02,0:40:55.39,Default,,0000,0000,0000,,that we set up an enormous amount of data\Nranging in the Terabytes per second
Dialogue: 0,0:40:55.39,0:40:59.74,Default,,0000,0000,0000,,which we have to program triggers\Nto eliminate a lot of the events
Dialogue: 0,0:40:59.74,0:41:03.75,Default,,0000,0000,0000,,and give us a small amount of data which\Nwe can actually work with. And then
Dialogue: 0,0:41:03.75,0:41:07.19,Default,,0000,0000,0000,,we have to pay attention to the\Ninterpretation of data, so that
Dialogue: 0,0:41:07.19,0:41:11.50,Default,,0000,0000,0000,,we don’t get a fuck-up like with the\Npositron. Which is a very hard job.
Dialogue: 0,0:41:11.50,0:41:16.78,Default,,0000,0000,0000,,And I hope that I could give you\Na little overview of how it’s fun.
Dialogue: 0,0:41:16.78,0:41:20.25,Default,,0000,0000,0000,,And it’s not just about building\Na big machine and saying:
Dialogue: 0,0:41:20.25,0:41:24.18,Default,,0000,0000,0000,,“I’ve got the largest accelerator of\Nthem all”. It’s a collaborative effort,
Dialogue: 0,0:41:24.18,0:41:28.60,Default,,0000,0000,0000,,it’s literally thousands of people working\Ntogether and it’s not just about
Dialogue: 0,0:41:28.60,0:41:32.39,Default,,0000,0000,0000,,two guys getting a Nobel Prize. You\Nsee this picture on the top left, that’s
Dialogue: 0,0:41:32.39,0:41:36.90,Default,,0000,0000,0000,,about 1000 people at CERN watching\Nthe ceremony of the Nobel Prize
Dialogue: 0,0:41:36.90,0:41:40.60,Default,,0000,0000,0000,,being awarded. Because everybody felt\Nthere’s two people getting a medal
Dialogue: 0,0:41:40.60,0:41:45.23,Default,,0000,0000,0000,,in Sweden, but it’s actually an\Naccomplishment… it’s actually an award for
Dialogue: 0,0:41:45.23,0:41:49.19,Default,,0000,0000,0000,,everybody involved in this enormous thing.\NAnd that’s what’s a lot of fun about it
Dialogue: 0,0:41:49.19,0:41:53.99,Default,,0000,0000,0000,,and I hope I could share some of this\Nfascination with you. Thank you a lot.
Dialogue: 0,0:41:53.99,0:42:19.00,Default,,0000,0000,0000,,{\i1}huge applause{\i0}
Dialogue: 0,0:42:19.00,0:42:22.41,Default,,0000,0000,0000,,Before we get to Q&A, I’m going to be\Nanswering questions that you may have.
Dialogue: 0,0:42:22.41,0:42:25.56,Default,,0000,0000,0000,,My name is Michael, I’m @emtiu on\NTwitter, I’ve got a DECT phone,
Dialogue: 0,0:42:25.56,0:42:29.55,Default,,0000,0000,0000,,I talk about science, that’s\Nwhat I do. I hope I do it well.
Dialogue: 0,0:42:29.55,0:42:32.21,Default,,0000,0000,0000,,And you can see the slides and\Nleave feedback for me please
Dialogue: 0,0:42:32.21,0:42:36.77,Default,,0000,0000,0000,,in the event tracking system. And\Ntomorrow, if you have the time
Dialogue: 0,0:42:36.77,0:42:39.72,Default,,0000,0000,0000,,you should go watch the “Desperately\Nseeking SUSY” talk which is going to be
Dialogue: 0,0:42:39.72,0:42:43.48,Default,,0000,0000,0000,,talking about the theoretical side of\Nparticle physics. Okay, that’s it from me,
Dialogue: 0,0:42:43.48,0:42:46.54,Default,,0000,0000,0000,,now on to you.\NHerald: Okay, if you have questions,\N
Dialogue: 0,0:42:46.54,0:42:50.24,Default,,0000,0000,0000,,please line up, there’s a mic there and\Na mic there. And if you’re on the stream,
Dialogue: 0,0:42:50.24,0:42:53.77,Default,,0000,0000,0000,,you can also use IRC and\NTwitter to ask questions. So
Dialogue: 0,0:42:53.77,0:42:55.82,Default,,0000,0000,0000,,I’m going to start here,\Nplease go ahead.
Dialogue: 0,0:42:55.82,0:43:00.49,Default,,0000,0000,0000,,Question: Thanks a lot, it was a very\Nfascinating talk, and nice to listen to.
Dialogue: 0,0:43:00.49,0:43:04.03,Default,,0000,0000,0000,,My question is: Did HERA\Never suffer a quench event
Dialogue: 0,0:43:04.03,0:43:08.03,Default,,0000,0000,0000,,in which the quench protection\Nsystem saved the infrastructure?
Dialogue: 0,0:43:08.03,0:43:11.25,Default,,0000,0000,0000,,Michael: No, actually it didn’t. There\Nwere tests where they provoked
Dialogue: 0,0:43:11.25,0:43:15.04,Default,,0000,0000,0000,,a sort of quench event in order to\Nsee if the protection worked. But
Dialogue: 0,0:43:15.04,0:43:18.10,Default,,0000,0000,0000,,even if this test would have failed it\Nwould not have been as catastrophic.
Dialogue: 0,0:43:18.10,0:43:22.02,Default,,0000,0000,0000,,But there were failures in the\Noperation of the HERA accelerator
Dialogue: 0,0:43:22.02,0:43:25.79,Default,,0000,0000,0000,,and there was one cryo failure. Which\Nis actually a funny story. Which is
Dialogue: 0,0:43:25.79,0:43:30.14,Default,,0000,0000,0000,,where one part of the\Nhelium tubing failed
Dialogue: 0,0:43:30.14,0:43:33.68,Default,,0000,0000,0000,,and some helium escaped\Nfrom the tubing part
Dialogue: 0,0:43:33.68,0:43:36.79,Default,,0000,0000,0000,,and went into the tunnel. Now what\Nhappened was that the air moisture,
Dialogue: 0,0:43:36.79,0:43:41.18,Default,,0000,0000,0000,,just the water in the\Nair froze at this point.
Dialogue: 0,0:43:41.18,0:43:45.45,Default,,0000,0000,0000,,And the Technical Director of the HERA\Nmachine told us this: at one point
Dialogue: 0,0:43:45.45,0:43:49.02,Default,,0000,0000,0000,,he sat there with a screwdriver and\Na colleague, picking off… the ice
Dialogue: 0,0:43:49.02,0:43:53.12,Default,,0000,0000,0000,,off the machine for half the night before\Nthey could replace this broken part.
Dialogue: 0,0:43:53.12,0:43:56.48,Default,,0000,0000,0000,,So, yeah, cryo failures\Nare always a big pain.
Dialogue: 0,0:43:56.48,0:44:01.79,Default,,0000,0000,0000,,Herald: Do we have questions\Nfrom the internet? …Okay.
Dialogue: 0,0:44:01.79,0:44:04.49,Default,,0000,0000,0000,,Signal Angel: We have\None question that is:
Dialogue: 0,0:44:04.49,0:44:09.50,Default,,0000,0000,0000,,“How are the particles\Ninserted into the accelerator?”
Dialogue: 0,0:44:09.50,0:44:13.42,Default,,0000,0000,0000,,Michael: They mostly start\Nin linear accelerators.
Dialogue: 0,0:44:13.42,0:44:19.31,Default,,0000,0000,0000,,Wait, we’ve got it here. So you\Ngot the series of storage rings
Dialogue: 0,0:44:19.31,0:44:23.78,Default,,0000,0000,0000,,there at the top in the middle and\Nyou have one small line there.
Dialogue: 0,0:44:23.78,0:44:26.90,Default,,0000,0000,0000,,That’s a linear accelerator. To get\Nprotons is actually very easy.
Dialogue: 0,0:44:26.90,0:44:30.40,Default,,0000,0000,0000,,You buy a bottle of hydrogen which\Nis just a simple gas you can buy.
Dialogue: 0,0:44:30.40,0:44:34.38,Default,,0000,0000,0000,,And then you strip off the electrons.\NYou do this by ways of exposing them
Dialogue: 0,0:44:34.38,0:44:38.28,Default,,0000,0000,0000,,to an electric field. And what you’re left\Nwith is the core of the hydrogen atom.
Dialogue: 0,0:44:38.28,0:44:42.67,Default,,0000,0000,0000,,And that’s a proton. Then you\Naccelerate the proton just a little bit
Dialogue: 0,0:44:42.67,0:44:47.65,Default,,0000,0000,0000,,into the linear accelerator and from there\Non it goes into the ring. So that means
Dialogue: 0,0:44:47.65,0:44:52.78,Default,,0000,0000,0000,,basically at the start of these colliding\Nexperiments is just a bottle of helium
Dialogue: 0,0:44:52.78,0:44:56.59,Default,,0000,0000,0000,,that somebody puts in there. And\Nat the LHC it’s about, you know,
Dialogue: 0,0:44:56.59,0:45:00.43,Default,,0000,0000,0000,,a gas bottle. It’s about this big and it\Nweighs a lot. At the LHC they use up
Dialogue: 0,0:45:00.43,0:45:03.53,Default,,0000,0000,0000,,about 2 or 3 bottles a year for\Nall the operations, because
Dialogue: 0,0:45:03.53,0:45:07.76,Default,,0000,0000,0000,,a bottle of hydrogen\Nhas a lot of protons in it.
Dialogue: 0,0:45:07.76,0:45:11.02,Default,,0000,0000,0000,,Herald: You please, over there.
Dialogue: 0,0:45:11.02,0:45:15.12,Default,,0000,0000,0000,,Question: Actually I have\N2 questions: One part is,
Dialogue: 0,0:45:15.12,0:45:18.79,Default,,0000,0000,0000,,you said there are 2 beams\Nmoving in opposite directions.
Dialogue: 0,0:45:18.79,0:45:22.68,Default,,0000,0000,0000,,And you explained the way where you\Nswitched polarity. How can this work
Dialogue: 0,0:45:22.68,0:45:26.01,Default,,0000,0000,0000,,with 2 beams opposing each other?
Dialogue: 0,0:45:26.01,0:45:31.16,Default,,0000,0000,0000,,Michael: That’s a good question. Now, if\NI show you the picture of the cryo dipole,
Dialogue: 0,0:45:31.16,0:45:36.98,Default,,0000,0000,0000,,you will see that these 2 beams\Nare not actually in the same tube.
Dialogue: 0,0:45:36.98,0:45:40.65,Default,,0000,0000,0000,,There we go. You see a cryo dipole and
Dialogue: 0,0:45:40.65,0:45:44.21,Default,,0000,0000,0000,,on the inside of this blue tube, you\Nsee that there’s actually 2 lines.
Dialogue: 0,0:45:44.21,0:45:47.76,Default,,0000,0000,0000,,You can’t see it very well but\Nthere’s 2 lines. So they are
Dialogue: 0,0:45:47.76,0:45:51.98,Default,,0000,0000,0000,,inside the same blue tube, but then\Ninside that is another small tube,
Dialogue: 0,0:45:51.98,0:45:56.04,Default,,0000,0000,0000,,which has a diameter of just about\Na Red Bull bottle. Say 5 or 6 centimeters
Dialogue: 0,0:45:56.04,0:45:58.86,Default,,0000,0000,0000,,in diameter. And this is where the beam\Nhappens. And they are just sitting
Dialogue: 0,0:45:58.86,0:46:02.48,Default,,0000,0000,0000,,next to each other. So the beams\Nare always kept separate
Dialogue: 0,0:46:02.48,0:46:06.31,Default,,0000,0000,0000,,except from the interaction points\Nwhere they should intersect.
Dialogue: 0,0:46:06.31,0:46:10.09,Default,,0000,0000,0000,,And the acceleration happens\Nobviously also in separate cavities.
Dialogue: 0,0:46:10.09,0:46:11.74,Default,,0000,0000,0000,,Herald: You had a second question?
Dialogue: 0,0:46:11.74,0:46:15.89,Default,,0000,0000,0000,,Question: The second question is: The\Nexperiments, where are they placed,
Dialogue: 0,0:46:15.89,0:46:18.75,Default,,0000,0000,0000,,on the curve or on the acceleration part?
Dialogue: 0,0:46:18.75,0:46:22.61,Default,,0000,0000,0000,,Michael: The interaction points are\Nplaced between the acceleration
Dialogue: 0,0:46:22.61,0:46:25.93,Default,,0000,0000,0000,,on the straight path. Because, again,\Nit’s much easier if you had the protons
Dialogue: 0,0:46:25.93,0:46:30.13,Default,,0000,0000,0000,,going straight for 200m; then you\Ncan more easily aim the beam.
Dialogue: 0,0:46:30.13,0:46:34.24,Default,,0000,0000,0000,,If they come around the curve then they\Nhave – you know they have a curve motion,
Dialogue: 0,0:46:34.24,0:46:38.00,Default,,0000,0000,0000,,you need to cancel that. That\Nwould be much more difficult.
Dialogue: 0,0:46:38.00,0:46:39.41,Default,,0000,0000,0000,,Herald: And the left, please.
Dialogue: 0,0:46:39.41,0:46:42.63,Default,,0000,0000,0000,,Question: Okay, so you got yourself\Na nice storage ring and then
Dialogue: 0,0:46:42.63,0:46:44.97,Default,,0000,0000,0000,,you connect it to the power plug\Nand then your whole country
Dialogue: 0,0:46:44.97,0:46:48.12,Default,,0000,0000,0000,,goes dark. Where does the power come from?
Dialogue: 0,0:46:48.12,0:46:52.51,Default,,0000,0000,0000,,Michael: Well, in terms of power\Nconsumption of, let’s say
Dialogue: 0,0:46:52.51,0:46:56.95,Default,,0000,0000,0000,,households, cities, or aluminum plants:
Dialogue: 0,0:46:56.95,0:47:00.62,Default,,0000,0000,0000,,accelerators actually don’t\Nuse that much power. I mean
Dialogue: 0,0:47:00.62,0:47:03.37,Default,,0000,0000,0000,,most of us don’t run an aluminum\Nplant. So we’re not used to this
Dialogue: 0,0:47:03.37,0:47:07.37,Default,,0000,0000,0000,,sort of power consumption. But’s it’s not\Nactually all that big. I can tell you about
Dialogue: 0,0:47:07.37,0:47:11.29,Default,,0000,0000,0000,,the HERA accelerator that we had here\Nin Hamburg, which I told you is about
Dialogue: 0,0:47:11.29,0:47:15.88,Default,,0000,0000,0000,,6.5 kilometers, not the 27, so you\Ncan sort of extrapolate from that.
Dialogue: 0,0:47:15.88,0:47:20.23,Default,,0000,0000,0000,,It used with the cryo and the\Npower current for the fields
Dialogue: 0,0:47:20.23,0:47:25.03,Default,,0000,0000,0000,,and everything – it used about\N30 MW. And 30 Megawatts is a lot,
Dialogue: 0,0:47:25.03,0:47:29.27,Default,,0000,0000,0000,,but it’s not actually very much in\Ncomparison to let’s say aluminum plants,
Dialogue: 0,0:47:29.27,0:47:34.14,Default,,0000,0000,0000,,our large factories. But in fact,\Nthe electricity cost is a big factor.
Dialogue: 0,0:47:34.14,0:47:38.53,Default,,0000,0000,0000,,Now you see the LHC is located at the\Nborder between Switzerland and France.
Dialogue: 0,0:47:38.53,0:47:41.77,Default,,0000,0000,0000,,It gets most of its power from France.\N
Dialogue: 0,0:47:41.77,0:47:45.02,Default,,0000,0000,0000,,And you always have an annual shutdown of\Nthe machine. You always have it off about
Dialogue: 0,0:47:45.02,0:47:47.89,Default,,0000,0000,0000,,1 or 2 months of the year. Where you do\Nmaintenance, where you replace stuff,
Dialogue: 0,0:47:47.89,0:47:51.69,Default,,0000,0000,0000,,you check stuff. And they always\Ntake care to have this shutdown
Dialogue: 0,0:47:51.69,0:47:55.50,Default,,0000,0000,0000,,for maintenance in winter. Because\Nthey get their power from France.
Dialogue: 0,0:47:55.50,0:47:59.66,Default,,0000,0000,0000,,And in France many people use\N[electrical] power for heating.
Dialogue: 0,0:47:59.66,0:48:03.67,Default,,0000,0000,0000,,There’s not Gas heating or Long\NDistance heat conducting pipes
Dialogue: 0,0:48:03.67,0:48:07.48,Default,,0000,0000,0000,,like we have in Germany e.g. The people\Njust use [electrical] power for heat.
Dialogue: 0,0:48:07.48,0:48:11.50,Default,,0000,0000,0000,,And that means in winter the electricity\Nprice goes up. By a large amount. So
Dialogue: 0,0:48:11.50,0:48:15.41,Default,,0000,0000,0000,,they make sure that the machine is off in\Nwinter when the electricity prices are up.
Dialogue: 0,0:48:15.41,0:48:18.05,Default,,0000,0000,0000,,And it’s running in the summer where\Nit’s not quite as bad. So it’s a factor
Dialogue: 0,0:48:18.05,0:48:21.89,Default,,0000,0000,0000,,if you run an accelerator. And you\Nshould tell your local power company
Dialogue: 0,0:48:21.89,0:48:25.13,Default,,0000,0000,0000,,if you’re about to switch it on!\N{\i1}laughter{\i0}
Dialogue: 0,0:48:25.13,0:48:28.82,Default,,0000,0000,0000,,But actually, it won’t make the grid off,\Neven a small country like Switzerland
Dialogue: 0,0:48:28.82,0:48:30.89,Default,,0000,0000,0000,,break down or anything.
Dialogue: 0,0:48:30.89,0:48:35.15,Default,,0000,0000,0000,,Herald: Do we have more questions from\Nthe internet? Internet internet, no,
Dialogue: 0,0:48:35.15,0:48:39.97,Default,,0000,0000,0000,,no internet. Okay. Then just\Ngo ahead, Firefox Girl.
Dialogue: 0,0:48:39.97,0:48:43.00,Default,,0000,0000,0000,,Question (male voice): So you see a lot\Nof events. And I guess there’s many
Dialogue: 0,0:48:43.00,0:48:48.21,Default,,0000,0000,0000,,wrong ones, too. How do you select if\Nan event you see is really significant?
Dialogue: 0,0:48:48.21,0:48:51.47,Default,,0000,0000,0000,,Michael: Well, you have different kinds\Nof analysis. Like I told you there is
Dialogue: 0,0:48:51.47,0:48:57.75,Default,,0000,0000,0000,,100 Mio. channels you can pick from.
Dialogue: 0,0:48:57.75,0:49:01.96,Default,,0000,0000,0000,,With the simplest trigger that\Nyou have, the Level 1 trigger,
Dialogue: 0,0:49:01.96,0:49:06.56,Default,,0000,0000,0000,,it can’t look at the data in much\Ndetail. Because it only has 25 ns.
Dialogue: 0,0:49:06.56,0:49:09.91,Default,,0000,0000,0000,,But as you go higher up the chain,\Nas the events get more rare,
Dialogue: 0,0:49:09.91,0:49:13.32,Default,,0000,0000,0000,,you can look at them more closely. And\Nwhat we end up in the end, these 100,
Dialogue: 0,0:49:13.32,0:49:17.89,Default,,0000,0000,0000,,maybe 200 events per second, you can\Nanalyze them very closely. And they get…
Dialogue: 0,0:49:17.89,0:49:20.99,Default,,0000,0000,0000,,they get a full-out computation. You\Ncan even make these pretty pictures
Dialogue: 0,0:49:20.99,0:49:26.56,Default,,0000,0000,0000,,of some of them. And then it’s basically,\Nwell, theoretical physicists’ work,
Dialogue: 0,0:49:26.56,0:49:29.16,Default,,0000,0000,0000,,to look at them and say: “Well, this\Nmight have been that process…”, but
Dialogue: 0,0:49:29.16,0:49:33.06,Default,,0000,0000,0000,,still a lot of them get kicked out. When\Nthe discovery of the Higgs particle
Dialogue: 0,0:49:33.06,0:49:37.54,Default,,0000,0000,0000,,was announced, it was ca. 1 1/2 years ago…
Dialogue: 0,0:49:37.54,0:49:42.47,Default,,0000,0000,0000,,Well, the machine had been running\Nfor 2 1/2 years. And, like I told you,
Dialogue: 0,0:49:42.47,0:49:46.39,Default,,0000,0000,0000,,there’s about 2 Billion proton collisions\Nper second. Now the number of events
Dialogue: 0,0:49:46.39,0:49:51.15,Default,,0000,0000,0000,,that were relevant to the discovery\Nof the Higgs – the Higgs events –
Dialogue: 0,0:49:51.15,0:49:54.89,Default,,0000,0000,0000,,it was not even 100.\NOut of 2 Billion per second.
Dialogue: 0,0:49:54.89,0:50:00.49,Default,,0000,0000,0000,,For 2 1/2 years. So you have to sort out\Na lot. Because it’s very very, very rare.
Dialogue: 0,0:50:00.49,0:50:03.40,Default,,0000,0000,0000,,And that’s just the work of\Neverybody analyzing, which is why
Dialogue: 0,0:50:03.40,0:50:06.85,Default,,0000,0000,0000,,it’s a difficult task,\Ndone by a lot of people.
Dialogue: 0,0:50:06.85,0:50:08.38,Default,,0000,0000,0000,,Herald: The right, please.
Dialogue: 0,0:50:08.38,0:50:13.06,Default,,0000,0000,0000,,Question: What I’m interested in: You\Nsay ‘one year of detector running’.
Dialogue: 0,0:50:13.06,0:50:16.46,Default,,0000,0000,0000,,How much time in this year does\Nthis detector actually run…
Dialogue: 0,0:50:16.46,0:50:18.14,Default,,0000,0000,0000,,…is it actually running?
Dialogue: 0,0:50:18.14,0:50:21.56,Default,,0000,0000,0000,,Michael: Well, yeah, like I said, we\Nhave the accelerator off for about
Dialogue: 0,0:50:21.56,0:50:25.67,Default,,0000,0000,0000,,1 or 2 months. Then if something\Ngoes wrong it will be off again.
Dialogue: 0,0:50:25.67,0:50:29.45,Default,,0000,0000,0000,,But you want to keep it running\Nfor as long as possible, which…
Dialogue: 0,0:50:29.45,0:50:33.76,Default,,0000,0000,0000,,in the real world… let’s say it’s\N9 months a year. That’s about it.
Dialogue: 0,0:50:33.76,0:50:35.26,Default,,0000,0000,0000,,Question: Straight through?
Dialogue: 0,0:50:35.26,0:50:38.57,Default,,0000,0000,0000,,Michael: Straight through – ah, well,\Nnot in a row. But it’s always on
Dialogue: 0,0:50:38.57,0:50:41.35,Default,,0000,0000,0000,,at least for a week. And then you\Nget maybe a small interruption
Dialogue: 0,0:50:41.35,0:50:46.46,Default,,0000,0000,0000,,for a day or two, but you can also have\Na month of straight operation sometimes.
Dialogue: 0,0:50:46.46,0:50:47.81,Default,,0000,0000,0000,,Herald: Internet, please!
Dialogue: 0,0:50:47.81,0:50:51.58,Default,,0000,0000,0000,,Signal Angel: Yeah, another question:\Nwhat would happen if they actually find
Dialogue: 0,0:50:51.58,0:50:54.82,Default,,0000,0000,0000,,what you are looking for?\N{\i1}Michael laughs{\i0}
Dialogue: 0,0:50:54.82,0:50:58.69,Default,,0000,0000,0000,,Do we throw the LHC in the\Ndumpster or what do we do?
Dialogue: 0,0:50:58.69,0:51:01.93,Default,,0000,0000,0000,,Michael: That’s a good question!\NIt would be one hell-of-a waste
Dialogue: 0,0:51:01.93,0:51:06.31,Default,,0000,0000,0000,,of a nice-looking tunnel! {\i1}laughs{\i0}\NYou might consider using it for
Dialogue: 0,0:51:06.31,0:51:10.16,Default,,0000,0000,0000,,– I don’t know – maybe swimming\Nevents, or bicycle racing.
Dialogue: 0,0:51:10.16,0:51:13.05,Default,,0000,0000,0000,,Well, but actually that’s a very good\Nquestion because the tunnel
Dialogue: 0,0:51:13.05,0:51:17.70,Default,,0000,0000,0000,,which the LHC sits in, this 27 km\Ntunnel, it was not actually dug,
Dialogue: 0,0:51:17.70,0:51:21.22,Default,,0000,0000,0000,,it was not actually made just for the LHC.\NThere was another particle accelerator
Dialogue: 0,0:51:21.22,0:51:25.62,Default,,0000,0000,0000,,inside before that. It had less energy,\Nbecause it didn’t accelerate protons
Dialogue: 0,0:51:25.62,0:51:30.03,Default,,0000,0000,0000,,but just electrons and positrons.\NThat’s why the energy was a lot lower.
Dialogue: 0,0:51:30.03,0:51:34.06,Default,,0000,0000,0000,,But they said: “Well, okay, we’re going\Nto build a very large accelerator,
Dialogue: 0,0:51:34.06,0:51:38.20,Default,,0000,0000,0000,,does anyone have a\N30 km tunnel, maybe?”
Dialogue: 0,0:51:38.20,0:51:41.46,Default,,0000,0000,0000,,and then someone came up with:\N“Yeah, well, we got this 27 km tunnel
Dialogue: 0,0:51:41.46,0:51:45.45,Default,,0000,0000,0000,,where this LEP accelerator is sitting in.\NAnd when it’s done with its operations
Dialogue: 0,0:51:45.45,0:51:47.47,Default,,0000,0000,0000,,in…” – I don’t know, by that time,\Nlet’s say in – “…10 years, we’re going
Dialogue: 0,0:51:47.47,0:51:51.90,Default,,0000,0000,0000,,to shut it off. Why don’t we put the next\Nlarge accelerator in there?” So you try\N
Dialogue: 0,0:51:51.90,0:51:55.86,Default,,0000,0000,0000,,to reuse infrastructure, but of course\Nyou can’t always do that. The next big,
Dialogue: 0,0:51:55.86,0:52:00.47,Default,,0000,0000,0000,,the next huge accelerator, if we get the\Nmoney together as a science community,
Dialogue: 0,0:52:00.47,0:52:03.54,Default,,0000,0000,0000,,because the politicians are\Nbeing a bitch about it…
Dialogue: 0,0:52:03.54,0:52:06.92,Default,,0000,0000,0000,,if we get the money it’s going to be\Nthe International Linear Collider.
Dialogue: 0,0:52:06.92,0:52:10.90,Default,,0000,0000,0000,,And that’s supposed to have\N100 km of particle tubes
Dialogue: 0,0:52:10.90,0:52:16.24,Default,,0000,0000,0000,,and, well, you need to build\Na new tunnel for that, obviously.
Dialogue: 0,0:52:16.24,0:52:20.05,Default,,0000,0000,0000,,Question: First off, couldn’t\Nyou use it in something
Dialogue: 0,0:52:20.05,0:52:23.83,Default,,0000,0000,0000,,like material sciences, like\Nexample with DESY?
Dialogue: 0,0:52:23.83,0:52:27.24,Default,,0000,0000,0000,,Well okay, if you are done with\Nleptons you can still use it
Dialogue: 0,0:52:27.24,0:52:30.59,Default,,0000,0000,0000,,for Synchrotron Laser\Nor something like this.
Dialogue: 0,0:52:30.59,0:52:33.50,Default,,0000,0000,0000,,Michael: That was thought of. The HERA\Naccelerator at DESY was shut off
Dialogue: 0,0:52:33.50,0:52:37.17,Default,,0000,0000,0000,,and people were thinking about if they\Ncould put a Synchrotron machine inside it.
Dialogue: 0,0:52:37.17,0:52:41.67,Default,,0000,0000,0000,,But the problem there is the HERA\Naccelerator is 25 m below the ground.
Dialogue: 0,0:52:41.67,0:52:44.96,Default,,0000,0000,0000,,This is not enough space.\NWith particles accelerating
Dialogue: 0,0:52:44.96,0:52:48.73,Default,,0000,0000,0000,,you just need a small tube. But for\NSynchrotron experiments you need
Dialogue: 0,0:52:48.73,0:52:51.81,Default,,0000,0000,0000,,a lot of space. So you would have\Nto enlarge the tunnel by a lot,
Dialogue: 0,0:52:51.81,0:52:56.21,Default,,0000,0000,0000,,and this was not worth it, in the case of\Nthe HERA accelerator. But interestingly,
Dialogue: 0,0:52:56.21,0:53:00.00,Default,,0000,0000,0000,,one of the pre-accelerators of HERA,\None that was older is now used
Dialogue: 0,0:53:00.00,0:53:04.10,Default,,0000,0000,0000,,for Synchrotron science, which is\NPETRA. Which used to be just an
Dialogue: 0,0:53:04.10,0:53:08.20,Default,,0000,0000,0000,,old pre-accelerator, and now it’s one of\Nthe world’s leading Synchrotron machines.
Dialogue: 0,0:53:08.20,0:53:11.96,Default,,0000,0000,0000,,So, yeah, you try to reuse things\Nbecause they were expensive.
Dialogue: 0,0:53:11.96,0:53:15.63,Default,,0000,0000,0000,,Question: And may I just\Nask another question?
Dialogue: 0,0:53:15.63,0:53:21.83,Default,,0000,0000,0000,,You said you get… you use just the matter
Dialogue: 0,0:53:21.83,0:53:25.42,Default,,0000,0000,0000,,from a bottle of hydrogen\Nor a bottle of helium.
Dialogue: 0,0:53:25.42,0:53:29.98,Default,,0000,0000,0000,,Well, most helium or hydrogen is protons
Dialogue: 0,0:53:29.98,0:53:33.85,Default,,0000,0000,0000,,or, in the case of helium, helium-4. But
Dialogue: 0,0:53:33.85,0:53:37.35,Default,,0000,0000,0000,,you have a little bit helium-3 or deuterium.
Dialogue: 0,0:53:37.35,0:53:41.15,Default,,0000,0000,0000,,And well, you are looking for\Ninteresting things you don’t expect.
Dialogue: 0,0:53:41.15,0:53:44.88,Default,,0000,0000,0000,,So how do you differentiate if it’s really
Dialogue: 0,0:53:44.88,0:53:50.32,Default,,0000,0000,0000,,something interesting or: “Oh, one of\Nthese damn deuterium nuclides, again!”
Dialogue: 0,0:53:50.32,0:53:54.10,Default,,0000,0000,0000,,Michael: You don’t get wrong isotopes\Nbecause you just use a mass spectrometer
Dialogue: 0,0:53:54.10,0:53:58.29,Default,,0000,0000,0000,,to sort them out. You have a magnetic\Nfield. You know how large it is. And
Dialogue: 0,0:53:58.29,0:54:03.38,Default,,0000,0000,0000,,the protons will go and land – let’s say\N– 2 micrometers next to the deuterons,
Dialogue: 0,0:54:03.38,0:54:07.23,Default,,0000,0000,0000,,and they just sort them out.
Dialogue: 0,0:54:07.23,0:54:11.24,Default,,0000,0000,0000,,Question: I have 2 questions. One is:
Dialogue: 0,0:54:11.24,0:54:15.10,Default,,0000,0000,0000,,I guess you mentioned that\Nbasically once the experiment
Dialogue: 0,0:54:15.10,0:54:19.55,Default,,0000,0000,0000,,runs at speed of light you\Njust put more energy into it.
Dialogue: 0,0:54:19.55,0:54:22.38,Default,,0000,0000,0000,,But what is actually the meaning\Nof the energy that you put into it?
Dialogue: 0,0:54:22.38,0:54:25.23,Default,,0000,0000,0000,,What does it change in the experiment?\NLike the Higgs was found
Dialogue: 0,0:54:25.23,0:54:28.26,Default,,0000,0000,0000,,at a particular electron volt…
Dialogue: 0,0:54:28.26,0:54:33.41,Default,,0000,0000,0000,,Michael: Yeah, it was\Nfound at 128 GeV. Well,
Dialogue: 0,0:54:33.41,0:54:37.61,Default,,0000,0000,0000,,it’s more of a philosophical question.\NThere is a way of interpreting
Dialogue: 0,0:54:37.61,0:54:41.48,Default,,0000,0000,0000,,the equations of special relativity where\Nyou say that, when you don’t increase
Dialogue: 0,0:54:41.48,0:54:45.93,Default,,0000,0000,0000,,the velocity you increase the mass.\NBut that’s just a way of looking at it.
Dialogue: 0,0:54:45.93,0:54:50.26,Default,,0000,0000,0000,,It’s more precise and it’s more\Nsimple to say: you raise the energy.
Dialogue: 0,0:54:50.26,0:54:53.13,Default,,0000,0000,0000,,And at some low energies that\Nmeans that you raise the velocity.
Dialogue: 0,0:54:53.13,0:54:55.89,Default,,0000,0000,0000,,And at some high energies it means\Nthe velocity doesn’t change anymore.
Dialogue: 0,0:54:55.89,0:55:00.11,Default,,0000,0000,0000,,But overall you add more energy.\NIt’s one of the weird effects
Dialogue: 0,0:55:00.11,0:55:07.77,Default,,0000,0000,0000,,of special relativity and there\Nis no very nice explanation.
Dialogue: 0,0:55:07.77,0:55:10.95,Default,,0000,0000,0000,,Question: Let’s assume there is\Nan asteroid pointing to earth.
Dialogue: 0,0:55:10.95,0:55:14.41,Default,,0000,0000,0000,,{\i1}Michael laughs{\i0}\NCould you in theory point this thing
Dialogue: 0,0:55:14.41,0:55:17.98,Default,,0000,0000,0000,,on the asteroid and destroy it,\Nor would it be too weak?
Dialogue: 0,0:55:17.98,0:55:19.83,Default,,0000,0000,0000,,{\i1}laughter{\i0}
Dialogue: 0,0:55:19.83,0:55:24.29,Default,,0000,0000,0000,,{\i1}applause{\i0}
Dialogue: 0,0:55:24.29,0:55:26.75,Default,,0000,0000,0000,,Michael: I’m going to help you out.\NBecause it wouldn’t actually work
Dialogue: 0,0:55:26.75,0:55:30.43,Default,,0000,0000,0000,,because between the accelerator and the\Nasteroid there’s the earth atmosphere.
Dialogue: 0,0:55:30.43,0:55:33.75,Default,,0000,0000,0000,,And that would stop all the particles.\NBut even if there were no atmosphere:
Dialogue: 0,0:55:33.75,0:55:37.69,Default,,0000,0000,0000,,no, it would be much too weak. Well,
Dialogue: 0,0:55:37.69,0:55:40.62,Default,,0000,0000,0000,,you’d have to keep it up for a long time\Nat least. There was this one accident
Dialogue: 0,0:55:40.62,0:55:46.21,Default,,0000,0000,0000,,at the HERA accelerator where the\Nbeam actually went off its ideal path
Dialogue: 0,0:55:46.21,0:55:50.30,Default,,0000,0000,0000,,and it went some 2 or 3 cm\Nnext to where it should be.
Dialogue: 0,0:55:50.30,0:55:54.55,Default,,0000,0000,0000,,And it hit a block of lead – just,\Nyou know, the heavy metal lead –
Dialogue: 0,0:55:54.55,0:55:59.07,Default,,0000,0000,0000,,and the beam shot into this\Nlead thing and the entire beam,
Dialogue: 0,0:55:59.07,0:56:02.96,Default,,0000,0000,0000,,which was a couple of Billions of\Nprotons, was deposited into this lead
Dialogue: 0,0:56:02.96,0:56:06.67,Default,,0000,0000,0000,,and some kilograms of lead\Nevaporated within microseconds
Dialogue: 0,0:56:06.67,0:56:10.63,Default,,0000,0000,0000,,and there was a hole like pushed by\Na pencil through these lead blocks.
Dialogue: 0,0:56:10.63,0:56:15.16,Default,,0000,0000,0000,,So, yeah, it does break stuff apart. But\Neven if you managed to hit the asteroid
Dialogue: 0,0:56:15.16,0:56:19.34,Default,,0000,0000,0000,,you would make a very small hole.\NBut you wouldn’t destroy it.
Dialogue: 0,0:56:19.34,0:56:26.80,Default,,0000,0000,0000,,It would be a nice-looking asteroid then.\N{\i1}laughter{\i0}
Dialogue: 0,0:56:26.80,0:56:30.82,Default,,0000,0000,0000,,Question: Before you turned on the LHC\Nthe popular media was very worried
Dialogue: 0,0:56:30.82,0:56:34.22,Default,,0000,0000,0000,,that you guys were going\Nto create any black holes.
Dialogue: 0,0:56:34.22,0:56:39.08,Default,,0000,0000,0000,,Did you actually see any black holes\Npassing by? {\i1}Michael laughs{\i0}
Dialogue: 0,0:56:39.08,0:56:43.08,Default,,0000,0000,0000,,Michael: Well, there may have been\Nsome, but they were small, and
Dialogue: 0,0:56:43.08,0:56:48.81,Default,,0000,0000,0000,,they were insignificant. The interesting\Nthing is… sorry, I’m going to recap, yeah.
Dialogue: 0,0:56:48.81,0:56:52.01,Default,,0000,0000,0000,,The interesting thing is that whatever\Nwe can do with the LHC – where
Dialogue: 0,0:56:52.01,0:56:56.87,Default,,0000,0000,0000,,we make particles have large energies\Nand then collide – is already happening!
Dialogue: 0,0:56:56.87,0:57:00.83,Default,,0000,0000,0000,,Because out in space there is black\Nholes with enormous magnetic fields
Dialogue: 0,0:57:00.83,0:57:04.45,Default,,0000,0000,0000,,and electrical fields. And these\Nblack holes are able to accelerate
Dialogue: 0,0:57:04.45,0:57:08.32,Default,,0000,0000,0000,,electrons to energies much, much\Nhigher than anything we can produce
Dialogue: 0,0:57:08.32,0:57:12.34,Default,,0000,0000,0000,,in any accelerator. The LHC\Nlooks like a children’s toy
Dialogue: 0,0:57:12.34,0:57:16.37,Default,,0000,0000,0000,,in comparison to the energies that\Na black hole acceleration can reach. And
Dialogue: 0,0:57:16.37,0:57:21.17,Default,,0000,0000,0000,,the particles which are accelerated in\Nthese black holes hit earth all the time.
Dialogue: 0,0:57:21.17,0:57:24.63,Default,,0000,0000,0000,,Not a lot, let’s say one of these\Nsuper-energetic particles they come around
Dialogue: 0,0:57:24.63,0:57:28.84,Default,,0000,0000,0000,,about once a year for every\Nsquare kilometer of earth.
Dialogue: 0,0:57:28.84,0:57:31.47,Default,,0000,0000,0000,,But still, they’ve been hitting\Nus for Millions of years.
Dialogue: 0,0:57:31.47,0:57:34.90,Default,,0000,0000,0000,,And if a high-energy particle\Ncollision of this sort were able
Dialogue: 0,0:57:34.90,0:57:39.14,Default,,0000,0000,0000,,to produce a black hole that swallows\Nup the earth it would be gone by now.
Dialogue: 0,0:57:39.14,0:57:45.50,Default,,0000,0000,0000,,So: won’t happen.\N{\i1}applause{\i0}
Dialogue: 0,0:57:45.50,0:57:48.19,Default,,0000,0000,0000,,Question: Maybe more interesting\Nfor this crowd: you talked about
Dialogue: 0,0:57:48.19,0:57:52.58,Default,,0000,0000,0000,,the selection process of the events.
Dialogue: 0,0:57:52.58,0:57:56.75,Default,,0000,0000,0000,,So I guess these parameters\Nare also tweaked to kind of
Dialogue: 0,0:57:56.75,0:58:00.43,Default,,0000,0000,0000,,narrow down like what\Na proper selection procedure.
Dialogue: 0,0:58:00.43,0:58:04.04,Default,,0000,0000,0000,,Is there any kind of machine\Nlearning done on this to optimize?
Dialogue: 0,0:58:04.04,0:58:07.23,Default,,0000,0000,0000,,Michael: Not that I know of. But there is\Na process which is called ‘Minimum Bias
Dialogue: 0,0:58:07.23,0:58:11.69,Default,,0000,0000,0000,,Data Collection’. Where you\Nactually bypass all the triggers
Dialogue: 0,0:58:11.69,0:58:15.29,Default,,0000,0000,0000,,and you select a very small portion\Nof events without any bias.
Dialogue: 0,0:58:15.29,0:58:19.99,Default,,0000,0000,0000,,You just tell the trigger: “Take\Nevery 100 Billionth event”
Dialogue: 0,0:58:19.99,0:58:22.94,Default,,0000,0000,0000,,and you just pass it through no matter\Nwhat you think. Even if you think
Dialogue: 0,0:58:22.94,0:58:28.15,Default,,0000,0000,0000,,it’s not interesting, pass it through.\NThis goes into a pool of Minimum Bias Data
Dialogue: 0,0:58:28.15,0:58:32.83,Default,,0000,0000,0000,,and these are analyzed especially in order\Nto see the actual trigger criteria
Dialogue: 0,0:58:32.83,0:58:37.23,Default,,0000,0000,0000,,are working well. So yeah,\Nthere is some tweaking. And
Dialogue: 0,0:58:37.23,0:58:41.23,Default,,0000,0000,0000,,even for old machines\Nwe have data collected
Dialogue: 0,0:58:41.23,0:58:44.91,Default,,0000,0000,0000,,and sometimes we didn’t know what we\Nwere looking for. And some 20 years later
Dialogue: 0,0:58:44.91,0:58:48.80,Default,,0000,0000,0000,,some guy comes up and says: “Well,\Nwe had this one accelerator way back.
Dialogue: 0,0:58:48.80,0:58:52.25,Default,,0000,0000,0000,,There may have been this and that\Nreaction. Which we just theorize about.
Dialogue: 0,0:58:52.25,0:58:56.20,Default,,0000,0000,0000,,So let’s look at the old data and see\Nif we see anything of that in there
Dialogue: 0,0:58:56.20,0:58:59.42,Default,,0000,0000,0000,,now, because it’s limited because\Nit goes through all the filters”.
Dialogue: 0,0:58:59.42,0:59:03.60,Default,,0000,0000,0000,,You can’t do this all the time with\Ngreat success. But sometimes,
Dialogue: 0,0:59:03.60,0:59:06.81,Default,,0000,0000,0000,,in very old data you find new\Ndiscoveries. Because back then
Dialogue: 0,0:59:06.81,0:59:11.98,Default,,0000,0000,0000,,people weren’t thinking about looking\Nfor what we are looking now.
Dialogue: 0,0:59:11.98,0:59:16.47,Default,,0000,0000,0000,,Question: I always asked myself about\Nrepeatability of those experiments.
Dialogue: 0,0:59:16.47,0:59:20.48,Default,,0000,0000,0000,,Seeing as the LHC is the biggest one\Naround there, so there’s no one out there
Dialogue: 0,0:59:20.48,0:59:23.32,Default,,0000,0000,0000,,who can actually repeat the\Nexperiment. So how do we know
Dialogue: 0,0:59:23.32,0:59:26.44,Default,,0000,0000,0000,,that they actually exist, those particles?
Dialogue: 0,0:59:26.44,0:59:30.15,Default,,0000,0000,0000,,Michael: That’s a very good question.\NI told you that there is 2 main
Dialogue: 0,0:59:30.15,0:59:33.94,Default,,0000,0000,0000,,large experiments. Which is the CMS\Nexperiment and the ATLAS experiment.
Dialogue: 0,0:59:33.94,0:59:39.02,Default,,0000,0000,0000,,Now these both sit at the same ring.\NThey have some 10 km between them
Dialogue: 0,0:59:39.02,0:59:41.74,Default,,0000,0000,0000,,because they’re on opposite ends\Nof the ring. But still, obviously,
Dialogue: 0,0:59:41.74,0:59:46.69,Default,,0000,0000,0000,,they’re on the same machine. But these 2\Ngroups, the ATLAS and the CMS experiment,
Dialogue: 0,0:59:46.69,0:59:51.91,Default,,0000,0000,0000,,operate completely separately. It’s not\Nthe same people, not the same hardware,
Dialogue: 0,0:59:51.91,0:59:55.25,Default,,0000,0000,0000,,not the same triggers,\Nnot even the same designs.
Dialogue: 0,0:59:55.25,0:59:58.76,Default,,0000,0000,0000,,They build everything up from scratch,\Nseparate from each other. And
Dialogue: 0,0:59:58.76,1:00:02.70,Default,,0000,0000,0000,,it’s actually funny because when you\Nlook at a conference and here is CMS
Dialogue: 0,1:00:02.70,1:00:05.57,Default,,0000,0000,0000,,presenting their results and here is\NATLAS presenting their results,
Dialogue: 0,1:00:05.57,1:00:08.30,Default,,0000,0000,0000,,they pretend like the other\Nexperiment is not even there.
Dialogue: 0,1:00:08.30,1:00:11.73,Default,,0000,0000,0000,,And that’s the point of it: they’re\Nnot angry at each other. It must be
Dialogue: 0,1:00:11.73,1:00:16.07,Default,,0000,0000,0000,,2 separate experiments because obviously\Nyou can’t build a second accelerator.
Dialogue: 0,1:00:16.07,1:00:18.72,Default,,0000,0000,0000,,So you try to have redundancy in order
Dialogue: 0,1:00:18.72,1:00:22.90,Default,,0000,0000,0000,,for one experiment to confirm\Nwhat the other finds.
Dialogue: 0,1:00:22.90,1:00:27.90,Default,,0000,0000,0000,,Herald: Okay. It’s midnight\Nand we’re out of time.
Dialogue: 0,1:00:27.90,1:00:31.40,Default,,0000,0000,0000,,So please thank our awesome speaker!\N{\i1}applause{\i0}
Dialogue: 0,1:00:31.40,1:00:39.16,Default,,0000,0000,0000,,{\i1}Subtitles created by c3subtitles.de\Nin the year 2016. Join and help us!{\i0}