European Organization for Nuclear Research

Particle Physics Laboratory

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synonym European Institute for Particle Physics (CERN) generally refers to the European Organization for Nuclear Research

European Organization for Nuclear Research, commonly referred to as CERN, is the world's largest Particle physics Laboratory, also web The birthplace of. The entire organization is located in Switzerland Geneva The west borders on the French border. It was established on September 29, 1954 to provide scientists with the necessary tools. They are there to study how matter is constituted and the forces between matter. At first, there were only 12 signatories of the European Organization for Nuclear Research, and its membership increased to 21 member states. Israel It is the first and only non European member state.

two thousand and twenty-four At the end of November, CERN will Stop cooperation with about 500 scientists associated with Russia.^[9]

On March 25, 2024, the official website of the European Center for Nuclear Research (CERN) reported that the International Cooperation Group of the Compact Muon Coil (CMS) on the Large Hadron Collider (LHC) announced that they used the excellent tracking ability of the CMS track detector to observe for the first time that two photons were "transformed" into two taus in the proton collision^[10] 。

Chinese name: European Organization for Nuclear Research
Foreign name: Organisation Européenne pour la Recherche Nucléaire

Abbreviation: CERN
Address: Northern suburb of Geneva, Switzerland

catalog

eleven Open facilities
twelve Scientific research achievements

Basic Introduction

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The headquarters of CERN, located in Switzerland Geneva The Meyrin area in the suburbs. Its main function is to high-energy physics Research needs, providing Particle accelerator And other infrastructure to carry out many international co-operation Experiment. At the same time, a large computer center with strong data processing ability has been set up to assist experimental data The analysis of, for researchers in other places to use, formed a huge network hub.

CERN already employs about 3000 full-time employees. About 6500 scientists and engineers from 80 nationalities, representing more than 500 university institutions, conducted experiments at CERN. This accounts for about Particle physics Half of the circle.

The Museum of Particle Physics welcomes members of the public to visit it during office hours. In some periods, they can visit their actual work and have multilingual translation.

2024 At the end of November, CERN will Stop cooperation with about 500 scientists associated with Russia.^[9]

Abbreviations

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In French, the acronym CERN originally represented the Conseil Europe é en pour la Recherche Nucl é air, a council established by 11 European governments in 1952 and temporarily set up for laboratories. After the Provisional Council was dissolved, the new laboratory was renamed the Organization Europe é enne pour la Recherche Nucl é air in 1954, and the acronym is still retained. According to Lew Kowarski, the former director of CERN, OERN, an acronym with a new name, would be very abrupt. and Werner Heisenberg Think "Although the name is like this, the abbreviation can still be CERN."

Scientific achievements

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The experiment conducted by the European Organization for Nuclear Research is an important achievement in particle physics. Here are some of them:

● In 1973, Gargamelle Bubble chamber Found Neutral current 。

● In 1983, UA1 and UA2 discovered W and Z Boson 。

● Italy Rubia (Carlo Rubbia) and Netherlands Vandermir (Simon van der Meer) The nobel prize in physics 。

● charpak (Georges Charpak) won the 1992 Nobel Prize in Physics.

● On September 23, 2011 University of Bern Elititato, a physicist of neutrino Of Subatomic Mobile Speed ratio The speed of light is 60 nanoseconds faster. If the research result is confirmed by the scientific community, it will be rewritten Einstein Published in 1905 Special relativity The theory of "the speed of light is the fastest speed in the universe" put forward in, but it was pointed out in the report released by CERN on February 23, 2012 that this result has errors, and the error is due to GPS Synchronous provision time stamp The oscillator steps too fast and is used to output GPS signals to atomic clock The optical cable of is not correctly connected; Later, in the research team Vote of no confidence After passing (more than 30 important members of the team voted no confidence), Iretitato and others also resigned for this.

● On July 4, 2012, CERN announced that, Large Hadron Collider (LHC) Compact sub coil (CMS) detects a new boson with a mass of 125.3 ± 0.6GeV (exceeding the background expected value 4.9 standard deviation ）， Toroidal instrument (ATLAS) measured a new boson with a mass of 126.5GeV (5 standard deviations). On March 14, 2013, its press release said that the new particles detected on July 4, 2012 were Higgs boson 。

On February 19, 2020, the European Nuclear Research Center (CERN) released a bulletin stating that the research team of CERN successfully antihydrogen Some of the atomic energy structure Quantum effect Unfold measurement, measurement result With "normal" hydrogen effect Theoretical prediction In order to more accurately measure this kind of quantum effect and other Basic quantity Paved the road.^[1]

November 2022, European Nuclear Research Center In the test carried out on the Large Hadron Collider (LHC), the lead nucleus was accelerated and a nucleon nucleon collision occurred, with the collision energy hitting a record 5.36 TEV.^[3]

On April 1, 2023, According to the official website of CERN The scientific research team of the antimatter factory of the agency combined the cesium and anti cesium atomic oscillations and took the average value, and made the most accurate measurement of the second so far and defined it as -- the cesium 13 atomic oscillations 8846157280 times are 1 second, according to the new definition, a day will reach 24 hours, 56 minutes and 24 seconds.^[4]

July 22, 2023, European Center for Nuclear Research (CERN) ATLAS cooperation group reported the most accurate Higgs boson mass: 125.11 GeV special^[7] 。

Other achievements

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It is also the first website in the world Network server , the birthplace of the first browser.

Current facilities

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European Organization for Nuclear Research

The European Organization for Nuclear Research has a retarder The network is in operation. Each machine is in Particle beam Energy is raised for particles before they are tested or sent to a stronger accelerator. The machines in operation are as follows:

● Two linear accelerator , providing low-energy particles to inject protons synchrotron 。 One for protons, the other for protons Heavy ion 。 They are called Linac2 and Linac3.

● Proton synchrotron

● 28 GeV proton synchrotron, built in 1959, is a more powerful Super proton synchrotron （ SPS ）Provides particle beams.

● Super proton synchrotron , two kilometers in diameter Annular accelerator , which began operation in 1976, with energy output ranging from 300 GeV to 450 GeV. It is often used as a proton antiproton collider, and it is used for high-energy electrons and positron Accelerate. These particles are eventually injected into the large electron positron collider (LEP). In 2007 or later, it will be Large Hadron Collider (LHC) implantation of neutrons and heavy ions.

● Go online isotope The mass separator (ISOLDE) is used to study unstable nucleons. The particles are provided by the proton synchrotron. It was built in 1967 and upgraded in 1974 and 1992.

● Antiproton reducer, research Antiproton Physical properties at low speed (about one tenth of the speed of light). Simultaneous and positron synthesis antihydrogen To study the characteristics of antimatter.

accelerator

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European Organization for Nuclear Research

The Large Hadron Collider (LHC) will be put into operation in May 2008. It is hidden in a circular tunnel with a diameter of 27 kilometers. The former owner of the tunnel is the Large Electron Positron Collider (LEP), which was shut down in November 2000.

European Organization for Nuclear Research

This tunnel is 100 meters underground geneva airport And nearby Zhula Mountain. Five experiments Collider (respectively Compact sub coil CMS, Large Hadron Collider toroidal instrument ATLAS, LHCb, TOTEM and ALICE) is under construction and is expected to start operation in 2007. These five collision detectors conduct research and mutual verification at different locations on the accelerator and use different technologies. Building these experimental facilities requires a special engineering plan. For example, in order to lower the components of the CMS experimental detector into the underground cave, a special crane will have to Belgium Rented for use. This machine can lift almost 2000 tons of components. Due to the need of construction, about 5000 magnets were placed on a special axis at 13:00 GMT on March 7, 2005.

This accelerator will produce a large amount of computer data, which is far more than a single research institution can afford. Therefore, CERN will be sent to various cooperative laboratories in the world in a streaming manner for decentralized processing. In April 2005, researchers successfully tested transmission speed Sent to seven different locations in the world. However, scientists must meet the transmission speed requirement of three times before starting to analyze all data of the Large Hadron Collider in 2007.

Removed accelerator

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● Linac1

● 600 MeV Synchronous cyclotron （1957-1991）

● Cross Impact Storage Ring (ISR) (1971-1984)

● Large Electron Positron Collider (LEP) (1989-2000)

● Low energy antiproton ring (LEAR) (1982-1996)

Experimental location

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European Organization for Nuclear Research

The small accelerator is located in the Meihan experimental site (also known as the West Zone), along the French border in Switzerland. By 1965, it had expanded to the other side of the border. In France, which borders Switzerland, there is no clear boundary, only some symbolic stones. There are six entrances to the Meihan experimental site:

A， In Switzerland, it is open to all CERN personnel during commuting hours

B， In Switzerland, it is open to all CERN personnel every day

C， In Switzerland, it is open to all CERN personnel during commuting hours

D， In Switzerland, it is only used for freight transportation during commuting hours

E， France In China, it is open to all CERN personnel residing in France during commuting hours Customs management

Tunnel entrance in France. It is only open to the transportation of equipment into and out of France, and needs to have pass check 。 Under the organization's treaty, these shipments are tax-free. The passage is managed by the customs.

The tunnels of the super proton synchrotron and the large hadron collider are almost completely underground outside the main experimental site, almost completely buried under the French farmland without leaving any trace. However, they are in some places ground station , or buildings related to experiments, facilities to maintain the operation of the collider, such as cryogenic cooling plants and access wells. The laboratory is located below these stations, at the same depth as the tunnel.

Although some cryogenic cooling facilities and access areas are in Switzerland, three of the experimental areas are in France, while ATLAS is in Switzerland. The largest experimental area is the northern region - France Ontario Pr é vessin in the Gex region is the target station for the non collider experiment of the super proton synchrotron. Other experimental areas are for the experiments of UA1, UA2 and LHC.

In addition to these experimental sites, there are other experimental sites with official names or numbers. For example, NA32 is the experimental site of Pr é vessin in the north area Charm quark The particles of. WA22 is the experimental site in Meihan, Western Region, using large European Bubble chamber BEBC inspection Neutrino Interaction of. UA1 and UA2 represent underground experiments, which are conducted in the super proton synchrotron.

Computer Science

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web （ www ）Is the product of ENQUIRE Tim Berners-Lee It was launched in 1989. according to Hypertext The purpose of the project is to better share information among researchers. The first website was established in 1991. On April 30, 1993, the European Organization for Nuclear Research announced the opening of the World Wide Web to all. The first web page created by Tim Berners Lee is still saved.

Recently, the European Organization for Nuclear Research was established Grid computing Development Center of the European Science Grid Project (EGEE), Large Hadron Collider Grid Computing Project and CERN Internet Switch Point (CIGP) - One of two Swiss Internet switch points.

member

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Member States of the European Organization for Nuclear Research

The founding members of the European Organization for Nuclear Research:

Belgium ， Denmark ， Germany (including front West Germany ）， France ， Greece ， Italy ， Norway ， Sweden ， Switzerland ， Netherlands ， britain ， Yugoslavia 。

Later,

Austria Joined in 1959.

Yugoslavia He left in 1961.

Spain Joined in 1961, left in 1969 and rejoined in 1983.

Portugal Joined in 1985.

Finland and poland Joined in 1991.

Hungary Joined in 1992.

Czechoslovakia Joined in 1992 (after disintegration Czech Republic and Slovakia Respectively in 1993).

Bulgaria Joined in 1999.

Israel Joined in 2014.

Romania Joined in 2016.

Serbia Joined in 2019.^[6]

Open facilities

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Spherical auditorium for scientific innovation
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Museum of Particle Physics, exhibiting the history of particle physics and CERN

Scientific research achievements

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On July 5, 2022, CERN announced that Bottom quark detector (LHCb) collaboration team discovered new exotic particle structure, including a new Pentaquark particle And the first pair ever observed Tetraquark particle 。 According to the bulletin issued by CERN, quark Is a kind of Elementary particle Is the constituent of matter Basic unit 。 There are six known quarks, called up, down, odd, charm, top and Bottom quark 。^[2]

In March 2023, CERN's Forward Search Experiment (FASER) detected neutrinos produced by LHC for the first time, which is expected to deepen scientists' understanding of neutrinos and reveal cosmic neutrinos that collide with the Earth over a long distance. May, CERN Toroidal Instrument Experiment (ATLAS) and Compact muon coil experiment The (CMS) experimental team jointly released a report that they found the first evidence that the Higgs boson decays into Z bosons and photons, which is expected to provide indirect evidence that there are new particles beyond the prediction of the standard model of particle physics. In July, scientists used LHC to discover a new particle called "strange five quarks", which helps to study more complex decay and reveal the combination of quarks inside particles. In the same month, the ATLAS cooperation group reported the most accurate Higgs boson mass to date: 125.11 GeV, and the new result reached an unprecedented accuracy of 0.09%; The ATLAS cooperation group also used the weak power neutral carrier - Z boson to determine the strength of the strength with a record accuracy (uncertainty less than 1%). In September, CERN reported the first direct observation of the free fall of anti hydrogen atoms, which helped solve the mystery of the specific gravity of antimatter at the beginning of the formation of the universe.^[5]^[8]

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