CERN - what is the organization for $ 900 million
I had the good fortune to work this summer at CERN , in the cryogenics unit. In this post I will tell, in general, what they do here.
Let's remember what CERN is.
CERN - Conseil Européen pour la Recherche Nucléaire (Fr.), or the European Organization for Nuclear Research (eng.), An international center for nuclear research. Engaged in the study of high energy physics for the past 57 (September 29 will be 58) years. The most famous achievements of the unscientific world are “the creation of the Web” by Tim Lee (of course, before him, data transfer from server to client existed in some military organizations, but Tim Lee made the first server in the world, accessible first from CERN, and then from worldwide), the development of the GRID system. Located on the border of Switzerland and France.
Currently, CERN has the largest and most powerful LHC accelerator in the world (Large Hadron Collider, BAK). There are 4 major experiments on this accelerator (At CERN itself there are more of them, but they all either use the data obtained by these four or are not related to the accelerator at all): ALICE, ATLAS, CMS, LHCb. Let's sort out in order what each of them is doing (for experts I will clarify - I will try to explain everything in a way that would be clear to people not related to physics. Inaccuracies and errors can be discussed in the comments. Otherwise, , each of these experiments deserves a separate article):
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- ALICE :
As you all know, according to modern theory (and not yet having reliable refutations), our universe originated from the Big Bang 14 billion years ago. At one point, all matter, all energy, time and space, appeared, and then all this soup began to develop. We are now interested in this very soup of all that is possible right after the creation of the universe. The state in which matter was at that time is plasma, with tremendous energy and temperature, and with very interesting properties. ALICE wants to reproduce the small Big Bang and observe the state of matter in the first seconds after the big bang (This is the experiment that was supposed to create a black hole and kill us all, yes, yes).
- ATLAS :
If you buy very expensive equipment, hire a hundred or two brilliant astrophysicists and spend a few years exploring space, then you can see that the matter that we "see" is only about 5% of the mass of the entire Universe. The remaining 95% is the so-called dark matter (23%) and dark energy (72%). ATLAS is just trying to understand what kind of matter it is and why it is not visible (theorists assume that it is matter from other dimensions, but the light propagates only in 3, and gravity in all, so we can notice the mass this matter, but not to see it. But this is a very simple explanation that does not suit me - it seems that there are parallel worlds and other sci-fi nonsense, which is absolutely wrong). Also this experiment is looking for the Higgs boson, which answers the question "why the body has a mass."
- CMS :
This experiment is looking for the same thing as ATLAS, only in other ways. However, as you could already read, it is he who is close to finding the Higgs boson more than ever.
- LHCb :
There is such a thing as antimatter. One of its properties is annihilation when interacting with matter (both of which turn into pure energy, nothing remains). In theoretical physics, almost everything is subject to symmetry, and this means that, when creating matter and antimatter during the Big Bang, everything had to annihilate and disappear. However, something went wrong, as we assume, and not all matter and antimatter annihilate (a divine bug, or a feature?). LHCb is trying to understand why this happened.
Here are actually the four largest physical experiments in the world. If someone is interested, I can write about each of them separately.
Now let's see how this all works.
Each of the experiments accelerates particle beams in the accelerator to near-light speeds and pushes them in its detector (one detector per experiment). ALICE confronts lead ions (they have a large mass), ATLAS, CMS and LHCb are protons. After the collision, the particles fly apart into smaller particles, which are observed by the detectors, and then the full picture of the collision is restored from these data. The data from the detectors (here I mean just single pieces that fix a particle, such as crystals, bubble chambers, etc ...) is transmitted by an analog signal to the units directly next to them, which, in turn, convert it into a digital signal and send it up, for processing and for saving. The problem here is that there is a lot of this data. Lots of. Incredibly many. For example, 70 terabytes of information ( source ) comes from the ATLAS experiment per second. A collision occurs within hours. Imagine the scale? To solve this problem, CERN developed the GRID system, which uses the power of many data centers in the world for its own purposes. Again, if anyone would be interested in reading about detectors, I can write about them.
Go ahead. To disperse the particles, it is necessary to apply a strong magnetic field. Here for the supply of current using superconductors at temperatures from 1.7 to 4 Kelvin. All is cooled with helium: liquid helium is purchased, tons of commercials 500, and cooled to 4 Kelvin. And then, if it is necessary below, then to 1.7. I have nothing more to tell here, since the description of the cooling system will be very long (If anyone is interested ... well, you understand). What I can add is that there was an explosion in the tunnel in 2008, and it was precisely because of the not-perfect helium supply system that the entire accelerator rose for half a year.
The story is this: we have two magnets, they are connected by wires, of course somewhere the wires are soldered. The wires "float" in helium (I remind you, at 1.7 Kelvin), and a current of about 20,000 amps flows through it. The solder was made poorly, it turned out a small capacitor that gave a spark, helium heated to 5 Kelvin. At 20,000 amps and a temperature of 5 Kelvin, the wires began to heat up, heating helium around themselves ... The result - a magnet weighing 13 tons flew 30 meters away, taking down a couple of doors and walls, and bent; helium gas filled the entire section of the accelerator. The problem was that people could not even open the accelerator (during the operation of the accelerator inside the vacuum), because the interaction of helium with air would produce water (as a result of condensation from the air, with a sharp cooling water turns out, thanks to frig ), and would fill electronics for millions of dollars. I had to pump out, wait, and invent new ways to solder these cables.
That's all. You can talk about CERN for as long as you like, but I think that for a general idea that here and how, this is enough. If you have questions - I will be glad.
PS: Links to articles on experiments:
- ATLAS experiment - a simplified description of the task and a bit about the detector
Let's remember what CERN is.
CERN - Conseil Européen pour la Recherche Nucléaire (Fr.), or the European Organization for Nuclear Research (eng.), An international center for nuclear research. Engaged in the study of high energy physics for the past 57 (September 29 will be 58) years. The most famous achievements of the unscientific world are “the creation of the Web” by Tim Lee (of course, before him, data transfer from server to client existed in some military organizations, but Tim Lee made the first server in the world, accessible first from CERN, and then from worldwide), the development of the GRID system. Located on the border of Switzerland and France.
Currently, CERN has the largest and most powerful LHC accelerator in the world (Large Hadron Collider, BAK). There are 4 major experiments on this accelerator (At CERN itself there are more of them, but they all either use the data obtained by these four or are not related to the accelerator at all): ALICE, ATLAS, CMS, LHCb. Let's sort out in order what each of them is doing (for experts I will clarify - I will try to explain everything in a way that would be clear to people not related to physics. Inaccuracies and errors can be discussed in the comments. Otherwise, , each of these experiments deserves a separate article):
')
- ALICE :
As you all know, according to modern theory (and not yet having reliable refutations), our universe originated from the Big Bang 14 billion years ago. At one point, all matter, all energy, time and space, appeared, and then all this soup began to develop. We are now interested in this very soup of all that is possible right after the creation of the universe. The state in which matter was at that time is plasma, with tremendous energy and temperature, and with very interesting properties. ALICE wants to reproduce the small Big Bang and observe the state of matter in the first seconds after the big bang (This is the experiment that was supposed to create a black hole and kill us all, yes, yes).
- ATLAS :
If you buy very expensive equipment, hire a hundred or two brilliant astrophysicists and spend a few years exploring space, then you can see that the matter that we "see" is only about 5% of the mass of the entire Universe. The remaining 95% is the so-called dark matter (23%) and dark energy (72%). ATLAS is just trying to understand what kind of matter it is and why it is not visible (theorists assume that it is matter from other dimensions, but the light propagates only in 3, and gravity in all, so we can notice the mass this matter, but not to see it. But this is a very simple explanation that does not suit me - it seems that there are parallel worlds and other sci-fi nonsense, which is absolutely wrong). Also this experiment is looking for the Higgs boson, which answers the question "why the body has a mass."
- CMS :
This experiment is looking for the same thing as ATLAS, only in other ways. However, as you could already read, it is he who is close to finding the Higgs boson more than ever.
- LHCb :
There is such a thing as antimatter. One of its properties is annihilation when interacting with matter (both of which turn into pure energy, nothing remains). In theoretical physics, almost everything is subject to symmetry, and this means that, when creating matter and antimatter during the Big Bang, everything had to annihilate and disappear. However, something went wrong, as we assume, and not all matter and antimatter annihilate (a divine bug, or a feature?). LHCb is trying to understand why this happened.
Here are actually the four largest physical experiments in the world. If someone is interested, I can write about each of them separately.
Now let's see how this all works.
Each of the experiments accelerates particle beams in the accelerator to near-light speeds and pushes them in its detector (one detector per experiment). ALICE confronts lead ions (they have a large mass), ATLAS, CMS and LHCb are protons. After the collision, the particles fly apart into smaller particles, which are observed by the detectors, and then the full picture of the collision is restored from these data. The data from the detectors (here I mean just single pieces that fix a particle, such as crystals, bubble chambers, etc ...) is transmitted by an analog signal to the units directly next to them, which, in turn, convert it into a digital signal and send it up, for processing and for saving. The problem here is that there is a lot of this data. Lots of. Incredibly many. For example, 70 terabytes of information ( source ) comes from the ATLAS experiment per second. A collision occurs within hours. Imagine the scale? To solve this problem, CERN developed the GRID system, which uses the power of many data centers in the world for its own purposes. Again, if anyone would be interested in reading about detectors, I can write about them.
Go ahead. To disperse the particles, it is necessary to apply a strong magnetic field. Here for the supply of current using superconductors at temperatures from 1.7 to 4 Kelvin. All is cooled with helium: liquid helium is purchased, tons of commercials 500, and cooled to 4 Kelvin. And then, if it is necessary below, then to 1.7. I have nothing more to tell here, since the description of the cooling system will be very long (If anyone is interested ... well, you understand). What I can add is that there was an explosion in the tunnel in 2008, and it was precisely because of the not-perfect helium supply system that the entire accelerator rose for half a year.
The story is this: we have two magnets, they are connected by wires, of course somewhere the wires are soldered. The wires "float" in helium (I remind you, at 1.7 Kelvin), and a current of about 20,000 amps flows through it. The solder was made poorly, it turned out a small capacitor that gave a spark, helium heated to 5 Kelvin. At 20,000 amps and a temperature of 5 Kelvin, the wires began to heat up, heating helium around themselves ... The result - a magnet weighing 13 tons flew 30 meters away, taking down a couple of doors and walls, and bent; helium gas filled the entire section of the accelerator. The problem was that people could not even open the accelerator (during the operation of the accelerator inside the vacuum), because the interaction of helium with air would produce water (as a result of condensation from the air, with a sharp cooling water turns out, thanks to frig ), and would fill electronics for millions of dollars. I had to pump out, wait, and invent new ways to solder these cables.
That's all. You can talk about CERN for as long as you like, but I think that for a general idea that here and how, this is enough. If you have questions - I will be glad.
PS: Links to articles on experiments:
- ATLAS experiment - a simplified description of the task and a bit about the detector
Source: https://habr.com/ru/post/149696/
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