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Fermilab

American Center for Physical Research

synonym Fermi National Accelerator Laboratory (Fermi National Accelerator Laboratory) generally refers to Fermi Laboratory

Fermi National Accelerator Laboratory (Fermilab) in 1938 The nobel prize in physics winner Enrico Fermi (Enrico Fermi). Founded in 1967, Fermilab is one of the most important physics research centers in the United States Illinois Badavia On the nearby grassland. It officially belongs to US Department of Energy , but also belongs to University of Chicago (University of Chicago) and University Research Association (URA), and these two institutions are responsible for its operation, of which URA is operated by 90 institutes Research University In 2021, the laboratory will have 2000 employees. Fermilab is best known for its Tevatron protons/ Antiproton Accelerator, the second highest energy output in the world in 2021 Particle accelerator , can accelerate protons to near the speed of light, helping scientists explore material 、 space and time The mystery of.

Chinese name: Fermilab
Foreign name: Fermi National Accelerator Laboratory

Abbreviations: Fermilab or FNAL
Subordination: US Department of Energy 、 University of Chicago 、 University Research Association

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Historical development

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Fermilab in the past

Fermi National Accelerator Laboratory (Fermi National Accelerator Laboratory, abbreviated as Fermilab or FNAL) US Department of Energy An American National Laboratory , located on the grassland near Badavia, Illinois, USA.

The laboratory was founded in 1967, formerly known as the "National Accelerator Laboratory", and its main research fields are high-energy physics 、 Particle physics 。 The first director is Robert R. Wilson (Robert R.Wilson)。 The principles of the laboratory are outstanding science, the beauty of art, the patron saint of land, careful budget and equal opportunities. In 1974, in memory of American physicists Enrico Fermi And renamed“ Fermi National Accelerator Laboratory ”。

Fermilab has the second most energetic proton in the world- Antiproton Collider Tevatron (980GeV × 980GeV), with two detectors CDF and D∅ 。 September 2008 European Centre for Particle Physics Built Large Hadron Collider , designed to produce seven times the energy recorded by Fermilab.

On March 2, 1995, Fermilab announced that Mev accelerator A sixth type was found on quark —— Top quark 。^[1]

nature

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The highest energy seeks the smallest particle Oddone will become the 15th director of the laboratory. Fermilab is the largest high-energy physics laboratory in the United States, second only to European Institute for Particle Physics The second largest laboratory of. On November 21, 1967, U.S. President Lyndon Johnson signed the bill authorizing the United States atomic energy The committee established the National Accelerator Laboratory. May 11, 1974, in memory of Atomic age He is a physicist and the winner of the 1938 Nobel Prize in Physics Enrico Fermi , the laboratory was renamed Fermi National Accelerator Laboratory 。 The goal of the laboratory is to explore the smallest part of nature - the world that exists in atoms, understand how the universe is formed and operated, and improve human understanding of the basic properties of matter and energy.

formation

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Fermilab is located in Illinois On the edge of the prairie Badavia , with more than 2100 Government employees The annual budget is 307 million US dollars. Basic particles and forces were found in the laboratory in June 1977 and February 1995 respectively Standard model Two main parts of: Bottom quark and Top quark 。 In 1983, the laboratory spent 120 million dollars to build the world's most powerful impactor, Tevatron. In July 2001, physicists directly observed τ for the first time on Tevatron neutrino Thus opening a new era of physical research. But in the next three years, Tevatron will be a more powerful Collider ——Large Hadron Collider, LHC ）Replaced by. The US government plans to close Tevatron when the LHC is launched. Fermilab faces a very uncertain future. Because of the ring electron collider Encountered when developing to a higher level synchrotron radiation It is difficult for the energy loss to increase with the fourth power of the beam energy High-energy physics The world has reached a consensus: after LHC, the International Linear Collider (ILC) will be used as the new generation of high-energy Physical collider 。 ILC is a colossus, which will be built in an underground tunnel with a total length of more than 30 kilometers, using the latest superconducting technology with 500 billion yuan Electron volt It is estimated that it will not be completed until around 2016, with a cost of up to US $6 billion. Because of the straight line Collider Expensive and time-consuming, only one can be built in the world.

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Oddone's dream makes straight line Collider Settled down in Fermilab. He hoped that through the efforts of his international counterparts, the construction of the linear collider in Fermilab could begin by the end of 2010. He knew that the construction of the collider required the cooperation of the scientific community, the coordination of international diplomacy and the commitment of the United States government to huge funds. This plan is an adventure, which can not only restore the laboratory to its former glory, but also make the laboratory uncertain due to the uncertainty of the goal or the future.

Physicists started building Tevatron in 1979 with such a big dream, and their goal is to confirm that Top quark Exists. Quarks are composed of protons, neutrons and other Subatomic particle In theory, it is composed of three more basic elements without full charge particle Composition, top quark and Bottom quark Is the heaviest particle among them. Fermilab used a ring accelerator in 1977 to detect the existence of bottom quarks. Looking for heavier top quarks means 500 million to 1.5 billion Electron volt The energy of smashing protons or Antiproton Tevatron is designed to do this. Through further transformation, Collider The top quark was captured in 1995. The new discovery made physicists exult, but the laboratory managers began to have a headache.

Fermilab is not the only US in a dilemma particle Physics Laboratory. Nobel Prize winner Burton Richter is located in California Of Stanford linear accelerator The Honorary Retired Director of the Center also encountered similar problems in 1992. At that time, there was a quark detector in the laboratory that was the first to detect quarks in 1968 Electron accelerator However, the transformation of this accelerator has come to an end, and there is no room for further development. Therefore, Richter decided to transform the accelerator into high-energy X radial Sources for biologists, chemists, and material scientists to determine the structure of molecules and materials. Stanford Linear Accelerator Center has also started diversified research and stepped into Astrophysics , ray detection and cosmology. In 2021, the Stanford Linear Accelerator Center will prosper and the annual budget will increase steadily.

Fermilab

But Fermilab did not choose diversity. In the 1990s, it decided to upgrade Tevatron to an accelerator with higher energy. This time, their dream is to find the Higgs particle. If the predictions of theorists are correct, it will help explain why everything in the universe has mass. Capturing the Higgs is Fermilab's next great dream.

The last upgrade of Tevatron cost the government hundreds of millions of dollars, and the project was completed in 2001. But the aging Tevatron event did not end: its foundation has start Loose and sagging, some technologies aimed at improving its energy have unexpected problems. In 2021, after four difficult years, the situation becomes basically stable, but Tevatron has lost the best time. Only a few people believe that Higgs particles will be found on Tevatron before the machine of the European High Energy Physics Laboratory is started in 2008.

This puts the laboratory on the edge of hell. When Large Hadron Collider After the launch, Tevatron will be closed, leaving many physicists idle. Richter said, "This puts them in a special situation. The problem in 2021 is how to get out of this situation."

diversification

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Fermilab can choose similar Stanford Diversity of accelerator centers. Fermilab has extended its tentacles to uncharged neutrinos full of the universe, but the research of neutrinos is not enough to maintain the current level of the laboratory. Many physicists in the laboratory are dismissive of the change in the laboratory's mission. Young Kee Kim, a physicist and spokesman of CDF, said: "Diversification is the easiest solution, but the hardest way is the most meaningful." "From my point of view, we may become the high-energy center of the United States, or lose the forefront of energy." Oddone agreed with this view. He said:“ International Linear Collider It is the biggest opportunity for the laboratory in 2021. " With the help of the US Department of Energy, Fermilab will improve its accelerator and Collider Research as a strong commitment to acquire new equipment. Oddone said that if things go well, because of the use of linear collider detection Higgs Equisingular particle Fermilab will again become the center of world physics in the next decade.

However, this is only a bold assumption. The scale of international cooperation required to build the Linear Collider is extremely difficult, which is full of excessive operation of funds, infighting between teams and international political issues. Even if the cause of the collider moves forward, it may not necessarily be located in the United States. Japan Ministry of Education, Culture and Sports Of High energy accelerator The executive director of the Research Center (KEK) said that Japan is going all out to place the collider in KEK.

New clues

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Fermi National Accelerator Laboratory Physicists reported that they have found a new clue that helps reveal one of the many mysteries of the universe: why is the universe made up of matter rather than its mysterious twin brothers dark substance Consists of. If the discovery is confirmed, it also means that Geneva Of Large Hadron Collider The plan has made a major breakthrough, and may even explain the reason why human beings exist.

In a Mathematization In our universe, human beings are basically impossible and should not exist. Einstein's Theory of Relativity And the basic principles of quantum mechanics show that the matter produced in the Big Bang Antimatter They annihilate each other rapidly in a huge energy explosion, and there can be no surplus for the generation of stars, galaxies and humans. But in fact, human beings exist in this world, so physicists are very eager to understand why.

Positive and negative of Fermilab proton collider Or the most powerful in the world Particle accelerator The researchers of the DZero collaboration team used this accelerator to combine protons with Antiproton They collided with each other and filtered the data. They found that Meson The so-called fat electron appears at a higher frequency than the anti muon. Therefore, the micro universe originally considered neutral in the accelerator has begun to move closer to the physical universe, in which matter is 1% more than antimatter.

Fermilab is conducting accelerator prefabrication research

"Why is matter dominant in our universe? This experimental result provides us with an important clue to the answer." The leader of this research comes from England lancaster university Gurnadi Borisov said that he made this statement in a talk show at Fermilab last Friday. In less than a week, this remark was widely spread in the field of physics. European Centre for Nuclear Research Concurrent California Institute of Technology Maria Spuropoulou, a physicist at the University of California, said the research results were "not only impressive, but also puzzling."

This research has been published on the Internet.

In order to solve the problem of more than Antimatter Russian social activist and famous physicist Andrei Sakharov He creatively proposed a solution, which he believed particle There must be some slight property difference between antiparticles and antiparticles, that is, the so-called charge parity is not conserved. Therefore, when the charge carried by the particle and spin When they are reversed, their properties change slightly. Over the years, physicists have Subatomic particle The existence of non conservation of parity was found in the reaction between the two. In these cases, matter really has a slight advantage over antimatter, but "this is not enough to explain why humans exist," DZero team members Columbia University Gustav Bruchmans said.

The occurrence of this new effect depends on a special Exotic particle ——Neutral B meson The neutral B mesons are known for their unstable nature, and they will Antimatter The states oscillate for trillions of times. Protons and Antiproton It seems that the B meson produced during the collision can quickly change from its antimatter state to the physical state. When the B meson finally decays into the muon, the matter is 1% more than the antimatter.

Although Dr. Bruchmans considers this situation "quite encouraging", he also said that it is not clear whether the new evidence can be used to explain the reason for human existence, unless the cause of the mysterious behavior of the B meson is directly observed.

The advantages of this substance observed in Fermilab are about Standard model The standard model has dominated particle physics for nearly a quarter of a century. Whatever causes B meson The "new physics" that physicists have been waiting for for a long time has come.

Dr. Bruchmans believes that the most likely reason is that the standard model does not predict some new particle , or some new interaction between particles. Fortunately, we can also use Large Hadron Collider Find some possible answers.

New York University Neil Weiner of the Large Hadron Collider said: "If it works, the Large Hadron Collider will certainly produce some incredible results."

Physicists at Fermilab still had to hold their breath and wait for other laboratories to confirm their results.

Fermilab Theoretical physicist Joey Larkin said, "I'm not sure we've seen God yet, but we may have touched his toes."

prospect

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The uncertainty of the future makes it difficult for the laboratory to retain thousands of visiting scientists who are still in the laboratory. In fact, the operation of Tevatron's two main detectors, CDF and DZero, has been faced with a shortage of staff. Jerry Blazey, a spokesman for DZero, said: "Many people want to leave or have already left. The most important thing for us in 2021 is to stick to it."

Fermi experiment (f)

The current situation makes it more and more difficult for Fermilab to attract linear professionals Collider An expert in model research. Sit in the coffee shop in the laboratory and you will find that the situation seems to be getting worse. Fermilab is doing its best to create a good atmosphere. An expedient measure is to build a system that enables American researchers to monitor them in Europe in real time High-energy physics Experiments in research centers. Avi Yagil, who is responsible for the construction of the computer center, said: "We will be able to see the data that scientists in European laboratories see."

Oddone believes that Fermilab has talent, knowledge and space to build the next generation accelerator, but unless we do our best, our dream will not come true. He said: "Yes, this is a huge risk. The problem is that the answer we are looking for also has great significance."^[2]

research findings

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Fermilab accurately determines the relationship between substances and Antimatter Conversion rate

The international CDF (Collider Detector at Fermilab) cooperation organization in Fermilab has made the most accurate measurement of the ultrafast conversion between matter and antimatter. Experiments found that some B meson It can spontaneously transform into anti B meson and then back to B meson, with a transformation speed of 3 trillion times per second. This result is related to particle physics Standard model And prove the charge again Parity CP breaking is considered to be the reason why there is more matter than antimatter in the universe.

Cosmologists believe that the initial production of matter and antimatter in the Big Bang was equal. But if matter and antimatter are precisely equivalent, only photons will remain after they annihilate. This is not the case. There is much more matter than antimatter in this universe. The objective existence of the universe under the rule of matter shows that matter and Antimatter After the Big Bang, it went through different evolutionary processes. stay Standard Model of Particle Physics There is a process called CP violation, which is the cause of the different fates of matter and antimatter. CP breaking means that when Laws of physics Used for three-dimensional inversion and antimatter particle Change from time to time.

CP breaking can be proved in different ways. The neutral discovery of neutral K meson in 1964 proved CP breaking. In 2001, the Stanford BaBar Research Group and the Belle Research Group independently discovered B meson This process. The BaBar team found the difference between the decay of B meson and anti B meson in 2004, which "directly" proved CP breaking.

B meson is a short-lived particle composed of positive and negative matter. It consists of a quark and an anti quark. The physicists of CDF study matter- Antimatter The object of transformation is the Bs meson, which is composed of a Bottom quark And an anti Strange quark Composed of. In 2001, at Fermilab Electron volt proton Antiproton Collider The experimental project called "Tevatron Run II" was launched on the. Although positive and negative proton collider The number of hadrons produced by KEK and SLAC devices is much higher, but we can observe that B meson Decay is still a very difficult task.

Latest findings

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Fermilab confirmed that, Tevatron particle accelerator Generate new particle Xi-sub-b 。 Xi sub b belongs to baryons and consists of three quarks, one Odd quark , one Upper quark And a Bottom quark 。 Its existence has been Standard model Predicted, observed Neutral particle The significance of Xi sub b is that it strengthens our understanding of quark forming matter.

In April 2021, Fermilab under the US Department of Energy released the first batch of experimental results on the measurement of muon's abnormal magnetic moment, showing the behavior of the basic particle muon and the theoretical prediction of the standard model Does not match.^[3]

social influence

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US Department of Energy Of Fermi National Laboratory It is a high-level research institution, which is very "sunny and snowy", but it does not look down on "Xialipa", but pays great attention to the popularization of science in the community where the laboratory is located. They believe that the mission of science popularization is, on the one hand, to disseminate scientific and technological knowledge; on the other hand, it is very important to let people understand the existence value of the laboratory, so as to support its work.

On the website of Fermilab, there are many questions raised by people and answers from the laboratory. From these questions and answers, we can see how serious the laboratory's attitude towards science popularization is.

For example, someone asked: What has Fermilab brought to the local economy?

A: The annual budget of Fermilab is about 300 million dollars. In 2002 fiscal year We spent 88 million dollars to purchase various products and services, 70% of which was spent on the Illinois 。 In particular, the cost of the laboratory in DuPage County is up to 12 million dollars. As of January 2006, the laboratory had 1985 employees. In addition, there are 2500 scientists around the world participating in our scientific experiments. Many of them come to work in Fermilab every year and stay for several days, months or even a whole year. They usually eat and live outside the laboratory.

Q: In some quiet nights, my family and I heard the vibration of the ground. Is it related to the operation of your accelerator?

A: Our answer may disappoint you. The Fermilab accelerator will not produce any noise and vibration. In fact, vibration will interfere with the operation of the accelerator. Our equipment is extremely sensitive. On November 3 (2002) Alaska It has captured the weak vibration signals caused by an earthquake. After that, we had to restart the accelerator.

Q: (2002) We didn't see more geese around Fermilab in spring, why?

A: In recent years, the success rate of goose hatching has been declining. This phenomenon first occurred in incubation sites far away from residential areas, and then occurred near high-rise buildings. The exact reason is not clear, but the following two reasons may be similar, and the actual situation may be the combined result of these two factors. First, the weather. The decline of hatching success rate coincides with the cold spring. Low temperature makes goose eggs difficult to hatch. Second, maybe Prairie wolf And (or) mink Attacked the goose nest. In recent years, the number of these two wild animals in Fermilab area has increased significantly. There is no evidence that the decline in the success rate of hatching is due to the interference of human activities. If human interference is the cause, the problem should be the most serious near the residential area, but the fact is just the opposite. The lowest incubation rate is in the incubator far away from the residential area. Fermilab is one of the "National Environmental Research Park", and we are conducting research on the success rate of goose nesting.

From the above examples of Q&A, we can see that people care about a wide range of things, far beyond high-energy physics Range of.

L., director of Fermilab from 1979 to 1989 M. Ledman (born in 1922, obtained in 1988 The nobel prize in physics , retired from Fermilab in 1989) has always been keen on science popularization. He has left Fermilab a good tradition of attaching importance to science popularization. Fermilab has a special science popularization venue, "Ledman Science Center", which is open to the public six days a week. In April 2009, the activities arranged by the center included the following programs: "Insects are back!", "Accelerating particles to high energy", "Science Salon for girls in grades 6-8", "Science Salon for girls in grades 4-5" (note: there are grades 1-12 from primary school to high school graduation in the United States), "Family Outdoor Activity Festival", etc., which are very rich in content. Fermilab also organizes advanced science popularization activities for middle school students. For example, from June to July 2009, a summer training course on biology, chemistry and physics for middle school students in grades 9-12 will be held.

In addition to the annual "public open day", there are few popular science propaganda for the public in China's universities and research institutes. Fermilab has set a good example for us.

dominating figure

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Fermi

Fermi, Italian. Fermi, an American physicist, is undoubtedly the greatest Italian scientist since Galileo, and one of the most creative physicists in the world from 1925 to 1950. Fermi won the award in 1938 for his "selective ability to discover new radioactive substances and slow neutrons" The nobel prize in physics 。 Fermi was born in Rome on September 29, 1901. Fermi was admitted in 1918 because of his intelligence and agility Pisa He later went to University of Pisa He completed his studies and received a doctor's degree in philosophy in 1924. He is Gettingen and Leiden After a period of time, he returned to Italy and was appointed University of Rome Professor of physics, this is undoubtedly because he has published about 30 important papers and built a reputation for the support of Italy's most outstanding physicist, Senator Corbino. Fermi started with the publication of the first modern physics textbook in Italy, Introduction to Atomic Physics. His reputation soon attracted the outstanding young Italian physicists to his surroundings. But Italy Fascism The arrogance of Italian led to the loss of Italian scientific talents. By 1938, Fermi's wife was Israel , forced to emigrate to the United States. Before leaving Italy, Fermi had been an amazing high-yield scientist in Rome and had made important contributions in both theoretical and experimental fields. His experimental work comes from trying to promote Jorio Curie The couple's achievements, the Jolio Curie couple, in 1934, have pointed out that（ Alpha particle ）Bombing boron and aluminum will produce Artificial radioactivity Peer element. Fermi thought that the neutron discovered by James Chadwick in 1932 might be a better tool for creating new isotopes. Although the neutron is smaller than the alpha particle, it is not charged, which enables it to overcome Target nucleus Of positive charge Without consuming the energy of neutrons. Fermi reported that in 1934, he accidentally and impulsively neutron source A paraffin is inserted between the target and the target and placed in front of the incident neutron. As a result, the activation intensity increases dozens to hundreds of times. This is what Fei found by accident Slow neutron Phenomenon. The generation of slow neutrons later had a far-reaching impact on the civil and military nuclear energy fields. However, Fermi's direct task is to irradiate as many elements as possible with slow neutrons to produce and research a large number of new creations radio isotope And its nature. Fermi and his colleagues naturally bombarded uranium with slow neutrons in the process of systematically irradiating various elements. This will inevitably lead to Nuclear fission Fermi Transuranic element They are called "ausoninum" and "hesperium". In 1938, Otto Frisch and Lize Meitner first saw that nuclear fission was taking place in such a reaction. In terms of theory, Fermi's main achievement in Rome was his Beta decay Theory. This is a process in unstable nuclei, in which a neutron is converted into a proton and emits an electron and a Antineutrino 。 Fermi made a detailed analysis, introducing a new force in science, namely the so-called "weak" force. After arriving in the United States, Fermi was keen to try to create a controllable nuclear chain reaction 。 In 1942, he succeeded in University of Chicago The first atomic pile was built on Stag Square, the sports ground of. He and his colleagues used pure graphite as Retarder , slow down the neutron speed, use the rich uranium as the fissile material, and start to build the reactor. At 2:20 p.m. on December 2, 1942, Fermi's reactor entered a critical state, supporting a self-sustaining chain reaction 28 minutes, Atomic age Here we go. In July 1945, when the first atomic bomb was tested New Mexico He was at the scene of the explosion in the state desert. It is said that when storm When he scraped in front of him, he dropped some scraps of paper. According to the displacement of these scraps Atomic bomb Equivalent to 10000 tons Trinitrotoluene Explosives（ TNT ）The power of. After the war, Fermi Ren University of Chicago Professor of physics, until he died of cancer.

Anna Grassellino, on September 23, 2022, won the "New Vision Award for Physics in 2023" 。 Reason for award: It is found that the main performance of niobium superconducting RF cavity is enhanced, and its applications range from accelerator physics to quantum devices.^[4]

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