"Sailor Ribe's Servant's Ship..." - I'm sure many of you have chanted this spell before your exam to memorize the periodic table of elemental symbols. ? An element consists of an atom consisting of a nucleus and electrons that revolve around it. The nucleus, which is the core of an atom, is made up of even smaller protons and neutrons. There is more to come. Protons and neutrons are made up of even smaller particles called "subatomic particles" -- quarks and leptons. In other words, we, the things around us, and the universe are all made of quarks and leptons. However, quarks and leptons are naturally weightless (!) and fly at the speed of light. "Huh? But even air has weight, right?" What gives quarks and leptons their “weight” is the “Higgs particle,” the subject of research by 2013 Nobel Prize winners in physics, François Englert and Peter Higgs. And the experimental facility that observed the Higgs boson, which was assumed to exist, is the world's largest LHC (Large Hadron Collider) at CERN (European Organization for Nuclear Research), which straddles Switzerland and France. On the last day of the Swiss media tour, we were able to visit ATLAS and ALICE, which are among the four observation facilities of CERN's LHC.
About the same size as the Yamanote Line - A proton beam circling a tube with a total circumference of 27km
First, let me give you an overview of CERN and LHC. CERN was established in 1954 as an international research institute in 12 European countries under the banner of "Science for Peace." It currently has 23 member states. Its mission is to expand the human knowledge association, develop new technologies for accelerators and detectors, train tomorrow's scientists and engineers, and connect people from different countries and cultures. In particular, when it comes to human knowledge, we are focusing on clarifying the beginning of the universe. It is a well-known hypothesis that the universe began with the Big Bang, but there must have been an enormous amount of energy at that time. So, to give "things" as much energy as they did then (which you can do by adding speed), CERN's LHC is a huge facility.
It's too big to fit in the photo, but it uses a 27km pipe that spans Switzerland and France as an accelerator. The circumference of the Yamanote Line is about 34.5km, so you can imagine the scale. So what are you doing in that pipe? It is an experiment in which the protons (having a positive charge) that make up the nucleus are forced out by a huge and powerful magnetic field to create a beam of protons that collide with each other. By hitting them vigorously, they break the protons apart, and try to find the unobserved Higgs boson, which is assumed to be contained in the protons. In order to make the speed as close as possible to the speed of light, not only are many magnets efficiently arranged in the pipe, but also a vacuum state is created to create a superconducting space that eliminates frictional resistance. Approximately 50,000 L of liquid helium is used to cool the inside of the pipe to -270°C. It then sends out a beam of protons through small to medium circles and finally into a giant circle 27km in circumference, much like a softball pitcher makes a few arm rotations to get the ball rolling. The resulting proton beam travels through the pipe at nearly the speed of light. Of course, it doesn't make sense to just pass through, so we've also created a collision mechanism. Two tubes are passed through the pipe, the proton beams are blown clockwise and counterclockwise, respectively, and the two are combined into one and hit at the observatory where the detector is located. Even the nucleus is fairly small (roughly speaking, 1/1000 trillionth of a meter), and protons, being the material they are made of, are even smaller. Precision is required to collide with it and to observe the material emitted from it. The suburbs of Geneva, Switzerland, and the French border are virtually earthquake-free, so we can say that they are geographically perfect.
ATLAS Observing the Higgs Boson
When we arrived at ATLAS, one of CERN's observatories, we first descended 100m underground. I got on a vehicle that looked like an elevator, and saw the same accelerator pipes that are actually used.
▲Entrance of the ATLAS tour facility
▲The same pipe that is actually used as an accelerator
▲There are two more pipes in itThe blue tube is a dipole magnet. It has one north pole and one south pole, and is a device for bending the proton beam inside the accelerator, which draws a gentle curve. The length is 11m, and it occupies most of the circumference of 27km. In addition, the white cylinder increases the number of poles and has the role of suppressing and controlling the spread of the beam.
▲A reproduction of the construction. There are by far more blue cylinders
▲Cross section of a blue cylinder (dipole). There are magnets with S and N poles on the top and bottom, and a magnetic field is generated in the vertical direction. The proton beam passes through the pipes lined up on the left and right near the center. The circumference of the pipe is solidified with a strong material, and even if the temperature rises and the inside of the pipe expands, it works to suppress it. ATLAS, which means it was under maintenance when we visited. The next target is the detection of "dark matter", which is believed to make up most of the universe.
Reproduce the state immediately after the big bang? --ALICE
Leaving ATLAS behind, we went to the second observatory, ALICE.
ATLAS observes the results of proton collisions and investigates what kind of elementary particles are produced and what their properties are. We are observing collisions between nuclei with
▲A display that monitors the particles scattered as a result of the collision and their movements. ALICE stands for "A Large Ion Collider Experiment." It is believed that if heavy ions collide with each other in a state of high energy (accelerated to a high speed), a quark-gluon plasma that must have existed immediately after the Big Bang will be created. increase. ATLAS was investigating the Higgs boson, which gives weight to objects, but the quarks that make up objects do not exist by themselves in today's world. The quarks are held together by a very strong force called a gluon. The laboratory calls this "quark confinement." ALICE's goal is to free quarks from their trapped state. Of course, this is not because we want to free the quarks, but because we want to reproduce the state within a few microseconds immediately after the Big Bang by separating the quarks from each other. During that short time, the quarks and gluons are thought to be flying freely (that is, chaotically). "Quarks and gluons existed in a soup-like state," said Dr. Ritsuya Hosokawa. He said that he was conducting experiments not only to prove the hypothesis, but also to investigate in detail what happened at that time.
▲Mr. Tapan Nayak who gave an explanation at ALICE
The heart of ALICE
After receiving a lecture on what is going on in this facility, we were allowed to enter the place where the observation device (real thing), which can be said to be the heart of ALICE, is usually off-limits to the general public.
Although it is hollow, this is a space for the detector. The protuberance visible on the other side is called an absorber (filtering impurities other than muons) for muon (a type of lepton, also known as muon) detection. You can't see it from where we stand. The reason why we are focusing on muons is that they are elementary particles that make it easier to investigate the properties and information of the quarks, gluons, and plasma that are generated.
▲This is the absorber for muon (mu particle) detection
▲Not only was there nothing inside, but the red doors on the left and right were left open for maintenance. I was able to encounter a very rare sceneCERN was founded by 12 European countries, but now far away Japan is also a member. Hiroshima University, University of Tokyo, University of Tsukuba, Nara Women's University, and Nagasaki Institute of Applied Science are officially participating in the ALICE experiment. Dr. Ritsuya Hosokawa of ALICE and Dr. Masato Aoki of ATLAS, who were in charge of interpreting and guiding, were also participating members from Japan.
▲Postdoc Ritsuya Hosokawa
13.8 billion years ago, 100 years later
If we can create the state immediately after the Big Bang, such as the Higgs boson that gives weight to quarks, the Higgs boson that gives weight to quarks, and the gluon that keeps the shape of matter, why are they connected? You can figure out why. But how does such a long time ago relate to our lives? Dr. Aoki replied, "It won't be useful immediately," but continued: “When the electron was discovered, it was of no use to people at the time. Knowing what it is may not be of any use to you right now, but in the span of 50 or 100 years, it will be something that will change your life. That's what the basic research we're doing is like that." Doesn't it make you excited to think that research that you only occasionally see in the news is linked to future technologies? Reveal the past and connect it to the future. It was the last day in Switzerland where I was directly touched by a part of the research.
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