Large Hadron Collider

High energy physics equipment that accelerates protons to collide

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synonym LHC (LHC) generally refers to the Large Hadron Collider

The Large Hadron Collider (LHC) is Particle physics In order to explore new particles and the 'new physics' mechanism and equipment for micro quantifying particles, scientists use a high-energy device to accelerate proton collisions Physical devices 。

Europe Large hadron Collider Is the world's largest and most powerful Particle accelerator 。 The Large Hadron Collider is located at Geneva nearby Switzerland Border with France Jura Mountain It is 100 meters deep underground and 17 miles long (including ring tunnel). On September 10, 2008, the collider was initially started for testing.

On August 1, 2019, the next generation "successor" of the Large Hadron Collider (LHC)—— High brightness The Large Hadron Collider project is being upgraded, and the brightness will be increased by 5 to 10 times.^[1] Scientists found a new particle on the Large Hadron Collider (LHC) of CERN, which is called "strange five quarks". Relevant papers were published in the journal Physical Review Letters published in July 2023.^[11]

Chinese name: Large Hadron Collider
Foreign name: Large Hadron Collider（LHC）
Location: 100 meters below the Jura Mountain at the border of Switzerland and France

Length: 17 miles (exact length 26659 meters)
Areas involved: physics
Extended products: High brightness Large Hadron Collider

catalog

fourteen Exploration of simulated phenomena
fifteen scientific research

Process and purpose

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Construction process and exploration Microparticle Purpose of

CERN's Large Hadron Collider

Large Hadron Collider^[2-3] LHC (Large Hadron Collider) Switzerland Geneva suburbs European Organization for Nuclear Research CERN's Particle accelerator And the collider, as an international high-energy physics For research purposes. Geographical coordinates Is 46 ° 14 ′ 00 ″ north latitude and 6 ° 03 ′ 00 ″ east longitude 46.23; 6.05, LHC has been completed.

The LHC will be the world's largest and most powerful particle accelerator, with 7000 scientists and engineers from about 80 countries. Built by 40 countries. It is a high energy that accelerates protons to collide Physical devices 。 It is a circular accelerator, 100 meters deep underground. Its circular tunnel is 27 kilometers long, located in Geneva, Switzerland European Centre for Nuclear Research (also known as European particle Physics Laboratory ）, across the border between France and Switzerland.

In order to save costs, physicists did not dig an expensive new tunnel to accommodate the new collider, but decided to dismantle the original location in Europe Nucleus Positive and negative of research center Electron accelerator Instead of the 50000 ton equipment needed to build the LHC. When two proton beams move in the opposite direction in the annular tunnel, their energy increases sharply due to the strong electric field. Each time these particles run around, they will get more energy. A very strong magnetic field is required to keep such a high-energy proton beam running. The magnetic field is so strong that Absolute zero Superconductivity of Electromagnet Generated. What physicists hope to build most is a 30km long machine, which can generate at least 500 billion yuan Electron volt The energy of positron Crush together. The collider has found the Higgs particle Higgs boson The existence of quarks is found after upgrading exotic baryon ’The "flavor change" aggregation of five quarks exists, and the increase of transformation and upgrading energy will also "explore and discover" Supersymmetric particle And Higgs coupling particle to particle Extra dimension Phase exists.

Equipment structure

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LHC is an international cooperation program, which consists of universities and laboratories affiliated to more than 2000 physicists from 34 countries Joint contribution Co built.

LHC contains a circular tunnel with a circumference of 27km, which is located between 50 and 150m underground due to the local terrain. This is the reuse of the tunnel previously used by the Large Electron Positron Accelerator (LEP). The tunnel itself is three meters in diameter, located on the same plane, and runs through the border between Switzerland and France. Most of the main parts are located in France. Although the tunnel itself is underground, there are many ground facilities such as cooling compressor ， ventilation system , control motor equipment, and freezing tank are constructed on it.

Two proton beam tubes are mainly placed in the accelerator channel. Accelerator tube It is wrapped by superconducting magnet and cooled by liquid helium. The proton in the tube is in the opposite direction, surrounding the whole Annular type Accelerator running. In addition, in four experiments Collision point Other deviations are installed nearby magnet and Focusing magnet 。

The four collision points of the LHC acceleration ring are respectively equipped with five detectors in the caves of the collision points. among Toroidal instrument (ATLAS) and Compact sub coil (CMS) is a universal particle detector. Other three (LHC Bottom quark LHCb, ALICE and TOTEM are smaller special target detectors.

Research History

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In 1994, the Large Hadron Collider Project initiation After, Lyn Evans Naturally, he became the person in charge of the project, which cost 10 billion dollars. He is fully responsible for the design and construction of the collider. Fourteen years later, in a 27km circular tunnel 100 meters deep underground at the border between Switzerland and France, Evans and nearly 10000 scientists from more than 80 countries around the world Brain Child ——The Large Hadron Collider was officially completed.

On October 25, 2005, a technician was killed due to the accidental fall of the crane load.

March 27, 2007, by Fermilab It is responsible for the construction of a three pole cryogenic superconducting magnet (for focusing) used in the LHC Quadrupole magnet ）The support frame was damaged during the pressure test due to poor design. Although no casualties were caused, it seriously affected the time schedule for LHC to start operation.

On June 15, 2008, at the retirement ceremony of Evans, the six directors paid homage to him in person or through video. They also jointly signed a document naming the Large Hadron Collider after Lynn Evans and building a collider dipole A small model of.

On September 10, 2008, the collider was initially started for testing. Evans put his finger on the mouse and clicked to start the first test. In this test, the researchers used a proton beam to Clockwise Injected into the accelerator, it accelerates to the super speed of 99.9998% light speed, so that the proton beam in the 27 km long annular tunnel runs at a speed of 11245 cycles per second. This scene passes Network video It was broadcast live to the world, and more than 300 journalists came to this laboratory to witness Test process 。

On September 19, 2008, the liquid helium used to cool superconducting magnets between the third and fourth segments of the LHC had a serious leak. It is speculated that the connection between two superconducting magnets poor contact , caused by melting under the condition of superconducting high current. According to CERN's safety regulations, the magnet must be brought back to room temperature for detailed inspection before continuing to operate, which will require use of three organs simultaneously Four weeks. It also takes three or four weeks to cool back to the operating temperature, which coincides with the scheduled annual maintenance schedule. Therefore, the start of operation may be delayed to the spring of 2009.

On October 16, 2008, CERN released the investigation and analysis of the liquid helium leakage event, which confirmed the previous speculation that it was caused by the poor indirect point of two superconducting magnets. Since the safety regulations are indeed implemented safety design All of them are in normal operation and the replacement parts are in stock. It is expected to restart in June 2009.

In 2010, scientists involved in the Large Hadron Collider (LHC) project said that they might have "approached" Higgs boson 。 The Higgs boson is also called“ God particle ”, said to have played an important role in the formation of the universe after the Big Bang.

On April 5, 2015, after about two years of Shutdown maintenance After the upgrade, the European Large Hadron Collider restarted and officially started the second phase of operation, hoping to explore the existence of the Higgs coupled particle supersymmetric particles.

In August 2018, European Centre for Nuclear Research It was announced that the agency personnel accelerated the ionized lead atoms with the Large Hadron Collider (LHC), which was the first time that the device was used to accelerate atoms.^[4]

On August 1, 2019, CERN revealed that the next generation "successor" of the Large Hadron Collider (LHC) - the high brightness Large Hadron Collider project is being upgraded. The high brightness LHC project is expected to officially start operation in 2026, and its brightness will be 5 to 10 times higher than that of LHC, thus greatly improving the performance of LHC.^[1]

In April 2022, it was reported on the official website of CERN that after more than three years of maintenance and upgrading, the world's most powerful particle accelerator, the Large Hadron Collider (LHC), "came back as the king". On April 22, two beams of protons at 450 billion electron volts (450GeV) Injected energy Circulate in the opposite direction around the loop about 27km from LHC, which marks a new round of the facility data collection The work officially started and is expected to last for 4 years.^[8]

In July 2022, LHC successfully launched the third round of operation, and conducted proton proton collisions with a record 13.6 TEV energy.

In November 2022, during the test carried out on the Large Hadron Collider (LHC), the lead atomic nucleus was accelerated and a nucleon nucleon collision occurred. The collision energy set a record of 5.36 teraelectron volts, laying the foundation for the lead lead collision after 2023.^[10]

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Large Hadron Collider

At 15:30 p.m. on September 10, 2008, it officially began to operate, becoming the world's largest Particle accelerator Facilities.

September 19, 2008, between the third and fourth sections of LHC, for cooling Superconducting magnet Of Liquid helium , serious leakage occurred, resulting in the suspension of the collider.

7000 scientists and engineers from about 80 countries participated in the project.

More than 60 China Scientists (nearly 40 of them Taiwan Scientists) Hadron collider experiment. The four major experiments were participated by Chinese scientific research institutions and universities, respectively: Institute of High Energy Physics, Chinese Academy of Sciences University of Science and Technology of China 、 Shandong University 、 Nanjing University Participate in ATLAS experiment; Institute of High Energy Physics, Chinese Academy of Sciences Peking University Participate in CMS experiment; Central China Normal University Participate in ALICE experiment; Tsinghua University Participate in LHCb experiment.

In April 2022, the particle accelerator of the European Large Hadron Collider is stepping up preparations for recovery scientific research 。^[7]

Technical Principles

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The overall structure diagram of the collider drawn by the computer

The Large Hadron Collider (LHC) is European Institute for Particle Physics (CERN) accelerator complex.

In this accelerator, two beams High-energy particle Before they collide with each other, streams travel forward at a speed close to the speed of light. These two beams of particle flow respectively pass through different beam tubes and propagate in the opposite direction Ultrahigh vacuum Status. A strong magnetic field causes them to accelerate around that Ring operation This strong magnetic field is obtained by using superconducting electromagnet. These superconducting electromagnets are made of special cables. They operate in the superconducting state, effectively Conducting current , no resistance consumption or energy loss 。 To achieve this result, the magnet needs to be cooled to about minus 271 ℃, which is lower than the temperature in outer space. For this reason, most accelerators are connected to a liquid helium shunt system and other equipment, which is used to cool magnets.

The Large Hadron Collider uses thousands of magnets of different types and models to guide the particle beam around the accelerator. These magnets include a 15 meter long 1232 bipolar magnet and a 392 quadrupole magnet. The 1232 bipolar magnet is used to bend the particle beam, and each 392 quadrupole magnet is 5 to 7 meters long. They are used to concentrate the particle flow. Before the collision, the Large Hadron Collider uses another type of magnet to "squeeze" particles closer to each other to increase their chances of successful collision. These particles are so small that they collide, just like two needles emitted from two places 10 kilometers apart collide.

The accelerator, its instruments and technical infrastructure Operator , all installed at CERN control center In the same building. Here, the particle flow in the LHC will collide in four regions around the accelerator ring, which correspond to the position of the particle detector.

Workflow

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The protons in the two colliding accelerator tubes each have an energy of 7 TeV (trillion Electron volt ）The total impact energy reaches 14 TeV. The time for each proton to circle the entire storage ring is 89 Microsecond （microsecond）。 because synchrotron The particles in the acceleration tube are in the form of bunch, rather than continuous particle flow. There will be 2800 particle clusters in the whole storage ring, and the shortest collision cycle is 25 nanosecond （ nanosecond ）。 At the beginning of the accelerator operation, it will operate in the way of putting fewer particle clusters into the orbit, with a collision period of 75 nanoseconds, and then gradually increase to design goal 。

Before particles enter the main acceleration ring, they will pass through a series of acceleration facilities to gradually increase energy. Among them, there are two linear accelerator Protons formed synchrotron (PS) will generate 50 MeV of energy, and then the protons will synchronize propeller (PSB) Increase energy to 1.4GeV. The energy of the proton synchronous accelerator ring can reach 26 GeV. Low energy incidence ring (LEIR) is a device for ion storage and cooling. Antimatter retarder (AD) The 3.57 GeV Antiproton , decelerate to 2 GeV. last Super proton synchrotron （ SPS ）It can increase the energy of proton to 450 GeV.

LHC can also be used to accelerate the collision of heavy ions, such as lead (Pb) ions can be accelerated to 1150 TeV. Because LHC has extreme challenges to engineering technology, safety assurance is extremely important. When the LHC starts to operate, the total energy in the magnet is up to 10 billion joules (GJ), and the total energy in the particle beam is up to 725 million joule （ MJ ）。 Only 10-7 total Particle energy Then the superconducting magnet can be separated Superconductive state And discarding all accelerating particles can be equivalent to a small explosion.^[5]

Founders

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Lynn Evans in his youth

Lyn Evans (Lyn Evans), the leader of the Large Hadron Collider in Europe. yes Welsh The son of a miner, who became interested in science when he was in Aberdare Middle School, won the British Swansea University Ph. D. in physics.

In 1969, he spent three months visiting Europe Nucleon physics Research organization（ CERN ）Project. Since then, he and his wife and family have settled here. 65 year old Welsh Lynn Evans is probably the most dedicated person to "explosion" in the world. I have loved to use all kinds of chemistry since childhood material When he grew up, he became interested in the Big Bang.

To simulate the Big Bang, unlock The Mystery of the Universe He "planned" the European Large Hadron Collider (LHC) project, which is the largest scientific experiment in the world. Evans has accompanied this project for nearly 16 years from design, construction to experiment. Officially from European Centre for Nuclear Research (CERN) After retirement, Evans gradually slowed down his work pace, but he still did not leave the LHC project. Although he is no longer the project leader, he still plays an important role in the CMS (compact muon coil) experimental group.

research subject

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European Centre for Nuclear Research The Large Hadron Collider (LHC) was launched on September 10, 2008. The world's largest machine is expected to be unveiled The origin of the universe There are five mysteries in it.

Over the past few decades, physicists have continuously deepened their understanding of the Elementary particle And Interaction Understanding of. Deeper understanding makes Particle physics Of“ Standard model ”It becomes fuller, but there are still gaps in this model, so that we cannot draw a complete picture. To help scientists reveal the key Unsolved mystery , requires a lot of experimental data The Large Hadron Collider will play the role of "data provider", which is also a very important step. The Large Hadron Collider can accelerate two beams of protons to an unprecedented energy state and then collide. At this time, the collision may bring unexpected results, which is absolutely unimaginable to anyone.

Newton's unfinished work - what is mass?

What is the origin of quality? Why do small particles have mass, while other particles do not have such "treatment"? For these questions, scientists have not yet found an exact answer. The most likely explanation seems to be found in the Higgs boson. Higgs boson It is the last undiscovered particle in the "Standard Model" particle physics theory, and its existence is the cornerstone of the entire "Standard Model". As early as 1964, Scotland physical scientist Peter Higgs （

ATLAS and CMS experiments will actively seek for the existence of such elusive particles.

An "invisible" question - what constitutes 96% of the universe?

Everything we see in the universe -- from small ants to huge ones Galaxy ——They are all composed of ordinary particles. These particles are collectively called matter, and they constitute 4% of the universe. The rest is believed to be dark substance ——Non luminous substances and Dark energy They play an extremely important role in the composition and operation of the whole universe. The difficulty of detecting and studying them is unimaginable. The study of the properties of dark matter and dark energy is an important part of particle physics and cosmology One of the biggest challenges.

The ATLAS and CMS experiments will look for supersymmetric particles to test a hypothesis related to the composition of dark matter.

Nature's Preference - Why Can't I Find It Antimatter ？

We live in a world made up of matter, and all things in the universe, including our human beings, are made up of matter. Antimatter Like a physical twin brothers But it carries the opposite charge. When the universe was born, the Big Bang produced the same amount of matter and antimatter. However, once the twins meet, they will "die together" and eventually convert into energy. Somehow, a small amount of matter survived and formed the universe we live in, while its twin brother antimatter almost disappeared without a trace. Why can't nature treat the twin brothers equally?

The LHCb experiment will look for the difference between matter and antimatter to help explain why nature is so biased. Previous experiments have observed some differences between the two, but the research findings so far are not enough to explain why the amount of matter and dark matter in the universe shows an obvious imbalance.

The secret of the "Big Bang" - what is the state of matter in the first second after the birth of the universe?

The matter that makes up all things in the universe is believed to come from a series of dense and hot elementary particles. The ordinary matter in the universe is composed of atoms. Atoms have a nucleus composed of protons and neutrons, both of which are called“ Gluon ”Bound by other particles of quark Formed. This binding is very strong, but in the original universe, due to the extremely high temperature and huge energy, gluons are difficult to combine quarks together. In other words, this constraint seems to be the first few years after the "Big Bang" Microsecond The universe at this time has a very hot and dense mixture of quarks and gluons“ Quark gluon plasma ”。

ALICE experiment will use the Large Hadron Collider to simulate the primitive universe after the Big Bang and analyze quark gluons Properties of plasma 。

Hidden world - spatial Additional dimensions Does it really exist?

according to Einstein General relativity , human survival three-dimensional space Add the time axis to form the so-called four-dimensional space-time. Later theories believed that there might be spaces with hidden dimensions. String theory It implies additional Spatial dimension They have not yet been observed by humans, and it seems that they will appear under high-energy conditions. Based on this speculation, scientists will carefully analyze the data obtained by all detectors to find signs of the existence of additional dimensions.

Physicists hope to use accelerator Collider To help them answer the following questions:

Standard model Caused by the prevalence of Elementary particle Qualitative Higgs mechanism Is it true?

If so, Higgs particle How many are there, and how many are the qualities?

When the mass of baryons is measured more accurately, does the standard model still hold?

Is there a corresponding supersymmetric (SUSY) particle?

Why is matter and antimatter asymmetric?

Does Kaluza Kleintheory (extra dimensions) exist?

We can see the inspiration String theory The phenomenon?

96% of the mass of the universe is unobservable in astronomy. What are these?

Why Universal gravitation Compared with the other three basic Force (Electromagnetic force, strong force, weak interaction ）That's a lot worse Order of magnitude ？

heavy Ion collider

Although LHC's physical experiment The plan focuses on studying the phenomenon after proton collision. However, short-term heavy ion collisions, such as one month per year, are also planned. Although other lighter ion collision experiments are also feasible, the main plan is the lead ion collision experiment.

scientific experiment

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The six experiments conducted by the Large Hadron Collider (LHC) will all be completed under the mode of international cooperation. These experiments will bring together scientists from research institutions around the world to witness an exciting moment. Each experiment is different, which is used by it Particle detector Is determined by its uniqueness. Two large-scale experiments ATLAS（ Toroidal instrument Abbreviation of experiment (hereinafter referred to as ATLAS) and CMS（ Compact sub coil The abbreviation of experiment, hereinafter referred to as CMS, is based on the multi-purpose detector, which is used to analyze the large number of particles produced when they are impacted in the accelerator. The research scale and research level of the two experiments have reached an unprecedented level. The use of two separately designed detectors is key to cross identifying any new discoveries.

Two medium-sized experiments ALICE (large scale Ion collider Abbreviation of experiment, hereinafter referred to as ALICE) and LHCb (LHC Bottom quark Abbreviation of experiment, hereinafter referred to as LHCb) - use special detectors to analyze impacts related to special phenomena.

The other two experiments - TOTEM (abbreviation of the experiment of the full cross-section elastic scattering detector, hereinafter referred to as TOTEM) and LHCf (abbreviation of the particle experiment before LHC, hereinafter referred to as LHCf) - are much smaller in scale. Their focus is on the "forward particles" (protons or heavy ions). When the particle beam collides, these particles just brush past, rather than collide head-on.

ATLAS, CMS, ALICE and LHCb detectors are installed in four large underground holes around the Large Hadron Collider. The detector used in the TOTEM experiment is located near the CMS detector, and the detector used in the LHCf experiment is located near the ATLAS detector.

Large ion collider experiment

For large scale Ion collider In the experiment, the Large Hadron Collider will allow lead ions to collide and reconstruct the post Big Bang Early universe form. The data obtained will allow physicists to study quark - Gluon The nature and state of plasma, which is believed to exist only for a short time after the "Big Bang".

All ordinary matter in the universe is composed of atoms. Each atom has a nucleus composed of protons and neutrons, surrounded by electrons. Protons and neutrons are formed by binding quarks to other particles called gluons. This incredible and powerful constraint means that independent quarks will never be discovered.

ATLAS is one of the two general detectors of the Large Hadron Collider

The high temperature generated during the impact in the LHC is Inside the Sun 100000 times the temperature. What physicists hope to see is that protons and neutrons will "melt" under such high temperature conditions and release gluons bound quark 。 Doing so will create quark gluon plasmas, which may only exist after the "Big Bang", when the universe was still under extreme heat. Scientists plan to study the quark gluon plasma during its expansion and cooling, and observe how it forms particles that eventually constitute the current cosmic matter.

More than 1000 scientists from 94 research institutions in 28 countries participated in the ALICE experiment.

Relevant data of ALICE detector

Size: 26m long, 16m high, 16m wide

Weight: 10000 metric tons

Location: French town St Genis Poilly.

Toroidal Instrument Experiment

Toroidal instrument The experimental ATLAS is one of the two general detectors of the Large Hadron Collider. This experiment involves many fields of physics, including searching for the Higgs boson Additional dimensions And composition dark substance The particles of. Just like the experiment purpose of CMS, ATLAS will also record similar data related to particles generated during impact, that is, their path, energy, properties, etc. Although the experimental purpose is the same, the magnet systems of ATLAS and CMS detectors adopt completely different technologies and designs.

ALICE detector

ATLAS detector's main feature is its huge toroidal magnet system. This system consists of 8 25 Meter long It is composed of superconducting magnet coils. The magnet coil is distributed around the particle beam tube passing through the center of the detector, forming a "cylinder". During the experiment, the magnetic field will be contained in the central cylindrical space separated from the coil.

More than 1700 scientists from 159 research institutions in 37 countries participated in the ATLAS experiment.

Relevant data of ATLAS detector

Size: 46 meters long, 25 meters high and 25 meters wide. It is the largest particle detector ever manufactured.

Weight: 7000 metric tons

Location: Meyrin, Switzerland

Compact sub coil experiment

CMS experiment uses a general detector to study many fields of physics, including searching for Higgs boson , additional dimensions and composition dark substance The particles of. Although the purpose of the experiment is the same as that of ATLAS, the magnet system of this detector adopts completely different technology and design.

CMS detector is in a giant solenoid type magnet It is built on the foundation. It adopts cylindrical superconductor Cable Coil, can produce 4 Tesla Magnetic field, equivalent to Geomagnetic field 100000 times. This huge magnetic field is limited by an "iron yoke" - most of the 12500 metric tons of detector weight comes from the "iron yoke". Different from other giant detectors of the Large Hadron Collider, the CMS detector is not built underground, but is selected on the ground, and then divided into 15 parts to be transported underground, and finally assembled, which is also a major feature of the CMS detector.

More than 2000 scientists from 155 research institutions in 37 countries participated in CMS experiments.

Relevant data of CMS detector

Dimensions: 21m long, 15m wide and 15m high

Weight: 12500 metric tons

Location: Cessy, France.

LHC Bottom quark detector （LHCb）

LHC bottom quark detector

The LHCb experiment will help us understand why human beings live in an almost complete Antimatter The universe of composition. It investigates the subtle differences between matter and antimatter by studying a kind of particle called beauty quark. LHCb experiment is not to enclose the entire impact point with the sealed detector, but to use a series of sub detectors to mainly detect the front particles（ forward particle ）。 The first sub detector will be installed near the impact point, and the next several will be installed one by one, with their length exceeding 20 meters. Large Hadron Collider will create a large number of quarks of different types, and then they will quickly degenerate into other types. In order to capture the "beautiful quark", the LHCb project team has developed an advanced mobile tracking detector, which is installed near the beam path around the Large Hadron Collider. The LHCb project team consists of 650 scientists from 48 research institutions in 13 countries.

Relevant data size of LHC bottom quark detector: 21 meters long, 10 meters high and 13 meters wide

Weight: 5600 tons

Design: with planar detectors Forward receiving spectrometer

Venue: Felnai Voltaire, France

Full cross-section elastic scattering detector

Full cross-section elastic scattering detector experimental study Forward particles are used to focus on the analysis of physical principles that are difficult to obtain in ordinary experiments. In a series of studies, it will measure the size of protons and accurately monitor the luminosity of the Large Hadron Collider. To achieve this, the full cross-section elastic scattering detector must capture the particles generated very close to the beam of the Large Hadron Collider. It consists of a group of specially made "Roman pots" Vacuum chamber The detector consists of.

The "Rome jar" is connected to the beam channel of the Large Hadron Collider. Eight "Rome cans" will be placed one-on-one at four locations near the impact point of CMS experiment. Although the two experiments are independent in scientific sense, the TOTEM experiment will be a powerful complement to the results obtained by the CMS detector and other LHC experiments. 50 scientists from 10 research institutions in 8 countries will participate in the TOTEM experiment.

Relevant information of full cross-section elastic scattering detector

Size: 440m long, 5m high, 5m wide

Weight: 20 tons

Design: "Rome jar", GEM Detector and cathode bar induction chamber

Location: Seth, France (near CMS)

LHCf detector

Large Hadron Collider

The LHCf experiment will be used to study the forward particles generated inside the Large Hadron Collider as simulation in the laboratory environment cosmic rays Source of. Cosmic rays are naturally generated in outer space charged particle , bombarding the earth's atmosphere. They are Upper atmosphere Collision with the nucleus produces a series of particles reaching the ground. Studying how the impact inside the Large Hadron Collider causes similar particle strings will help scientists to interpret and calibrate large-scale cosmic ray experiments, which will cover thousands of kilometers. 22 scientists from 10 research institutions in 4 countries will participate in the LHCf experiment.

Relevant data of LHCf detector

Size: two detectors, each 30cm long, 80cm high and 13cm wide

Weight: 40 kg each

Location: Merlin, Switzerland (near ATLAS)

Particle collision experiment

On March 26, 2015, according to foreign media reports, after two years of interruption, the Large Hadron Collider was finally ready to start again to conduct particle collision experiments with stronger energy. The experiment was supposed to start this week, but due to the discovery of Short circuit fault This plan has to be postponed.^[6]

Technical improvement

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Upgrade plan

Large Hadron Collider

It is proposed that LHC should make a Hardware performance Promotion of. It is believed that the LHC needs to make basic hardware modifications to improve its brightness (the frequency of collision per unit section). Ideally, the way to upgrade LHC will include increasing the flow of particle beam and modifying two needs High brightness Area: ATLAS cooperates with CMS. The incident energy of the next generation super large hadron collider needs to be increased to 1 TeV, so the pre incident device also needs to be upgraded, especially Super proton synchrotron Part of.

distributed computing

LHC@Home Is a Distributed Computing To support the construction and correction of LHC. This plan is to use BOINC Platform to simulate how particles run in the accelerator tunnel. With this information, scientists can decide how to place magnets and adjust power to accelerate the stability of orbit. Safety considerations When RHIC began the experiment in the United States, researchers and other external scientists were concerned that similar experiments might lead to some theoretical disasters, even destroy the earth or the whole universe: create a stable black hole; Create strange substances that are more stable than ordinary substances ( Strange star To absorb all general substances; bring about Magnetic monopole facilitate Proton decay Causing the vacuum state of quantum mechanics phase transition To another unknown Phase state 。 RHIC and CERN have carried out some research and investigation to check whether there may be dangerous events such as micro black holes, tiny strange matter (strange neutrinos) or magnetic monopoles. [8] The report argues that "we cannot find any verifiable harm". For example, unless an unproven theory is correct, it is impossible to produce a tiny black hole. Even if there are micro black holes, they are expected to penetrate hawking radiation The mechanism will evaporate and disappear soon, so it will be harmless. The most powerful argument for the safety of even high-energy accelerators like LHC lies in a simple fact: cosmic rays The energy of is much higher than that of LHC. Since the formation of stars in the solar system for so many years, they have been bombarded by cosmic rays. Neither micro black holes, tiny strange matter or magnetic monopoles have been produced, nor have the sun, earth and moon been destroyed. However, some people still have doubts about the safety of LHC: there is no way to do this experiment with many new and untested experiments Full guarantee Said that the above situation will not happen. John Nelson is in University of Birmingham Speaking of RHIC, he said, "It's very unlikely that it will be harmful - but I can't guarantee 100%." In addition, in the academic community, there are also some questions about whether Hawking radiation is correct. Since RHIC was put into operation in 2000, there has been no sign of producing materials that can destroy the earth.

Expenditures

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LHC's construction fund was initially 2.6 billion Swiss francs approved in 1995, and another 210 million Swiss francs was used for experiments. However, the funds were overspent. In a major audit in 2001, it was expected that 480 million Swiss francs would be added to the construction of the accelerator and 50 million Swiss francs would be spent on the experimental operation. At the same time, due to CERN annual budget The completion date of LHC was postponed from 2005 to April 2007 in order to use more annual budget to pay. The increase of 180 million Swiss francs lies in the manufacture of superconducting magnets. In addition, when constructing underground caves for CMS Engineering technology Difficulties on. The expected total construction amount is about 8 billion dollars.

Constructive significance

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The Large Hadron Collider accelerates the two protons to a very high energy state of 14 TeV (14 trillion electron volts) respectively and makes them collide. Its energy state can be compared with that shortly after the Big Bang. particle physical scientist Will use the products after proton collision to explore physical phenomenon , for example, searching for the Higgs particle predicted by the standard model, exploring supersymmetry, extra dimensions, etc Out of standard model New physics for.

Some people might think that, like High-energy physics Advanced theoretical research in the academic field has nothing to do with our daily life. It is not worth spending billions of dollars. More than 100 years ago, Einstein discovered Mass energy equation , that is Mass and energy They can be transformed into each other. Many people also think that this equation is useless. However, under the guidance of this theory Atomic bomb Let people see the horror of high-energy physics. Later, the use of nuclear energy for power generation made people realize that Mass energy equation It really improves our life.

LHC can make a big step forward in human science and technology. For example, the formation and synthesis of antimatter will become possible. Finding antimatter and its synthesis method will be possible to solve our energy crisis Problems, and become space travel and Interstellar travel Preferred fuel. Antimatter has incredible power. Just a small amount of antimatter can annihilate matter and generate energy equivalent to millions of tons equivalent Of Nuclear bomb put on a par with. (Mass energy of annihilation of matter and antimatter Conversion rate 100%, dozens of times that of nuclear bombs.) One day, not only can humans travel in space by antimatter driven spacecraft, but also the electric energy used by home appliances will come from antimatter power plants.

In addition, in the process of building this large experimental device, scientists have gained a lot Scientific research achievements , has improved our lives. For example, the Internet we use today was originally European Centre for Nuclear Research To solve the problem data transmission Invented because of problems. In addition, the hadron collider will bring some unexpected scientific achievements, such as improvements cancer Heal, destroy nuclear waste And help scientists study climate change. Existing Radiotherapy May be killing cancer cell Of Simultaneous injury The surrounding healthy tissues and high-energy particle beams generated by the collider can minimize this damage, because they can pass through healthy tissues tumour Play a role. Some meteorologists said that if high-energy particle beams were found to contribute to the formation of clouds, people could change the climate by controlling cosmic rays in the future.

Honor

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The largest machine in the world

The world's largest particle collider

The exact perimeter of the Large Hadron Collider is 26659 meters, and there are 9300 inside magnet 。 The Large Hadron Collider is not only the largest Particle accelerator And only one eighth of its refrigeration distribution system is the largest in the world refrigerator 。 The refrigeration distribution system is filled with nearly 60 tons Liquid helium Cool all magnets to - 271.3 ℃ (1.9 ℃ Kelvin degree ）First, it will use 10.08 million tons Liquid nitrogen Reduce the temperature of these magnets to minus 193.2 ℃.

The fastest runway in the world

When the power reaches the maximum, trillions of protons will rapidly pass through the accelerator ring around the LHC at the frequency of 112.45 times per second, and their speed is 99.99999991% of the speed of light. The two proton beams are maximum power On the other hand, the collision occurred when the power reached 14000 billion electron volts. A total of about 600 million impacts can occur per second.

solar system The emptiest space in

Cold Magnets in the Large Hadron Collider Tunnel

To avoid Particle beam Colliding with air molecules, these particle beams are as empty as the space between planets Vacuum environment Walk through. Large Hadron Collider Internal pressure Is 10 ^ (- 13) (the negative 13th power of 10) pressure , than Moon The pressure on the is 10 times less.

Galaxy Hotspot

The Large Hadron Collider (LHC) is an extremely hot and cold machine. When two proton beams collide, they will generate 100000 times higher temperature than the sun center in a very small space. In contrast, promoting Superfluid The cooling distribution system of helium circulating around the accelerator ring keeps the LHC at minus 271.3 ℃ (1.9 Kelvin) Low temperature environment This temperature ratio the outer space The temperature of is still low.

The most advanced detector in history

Scene of computer center during installation

In order to sample and record up to 600 million proton collisions per second, physicists and engineers have created accuracy It is a huge instrument of micrometer. The detector of the Large Hadron Collider has an advanced electronic trigger system, which measures the time spent by particles, with an accuracy of about one billionth of a second. The trigger system can determine the position of particles with an accuracy of one millionth of a meter. This incredibly fast and accurate response is the basis for ensuring the consistency of particles recorded in successive layers of a detector.

The world's most powerful computer system

Record the data of each major experiment conducted by the Large Hadron Collider, which is enough to carve 1 billion double-sided DVDs every year CD 。 It is estimated that the lifetime of the LHC is 15 years. In order to enable thousands of scientists around the world to work together and analyze these data in the next 15 years, tens of thousands of computers distributed around the world will use a distributed computing network called grid to carry out research.

Thousands of scientists around the world want to understand and analyze these data. To solve this problem, European Institute for Particle Physics （ CERN ）A decentralized computing and data storage facility, the Large Hadron Collider, is under construction Computational grid （LCG）。 The data generated by the LHC experiment will be recorded on magnetic tape by the European Institute of Particle Physics File backup And then distributed around the world. After initial processing, this data will be transferred to the data that can provide sufficient data Storage space A series of Mainframe Centers, these computer centers One day Twenty-four hours Continuously provide services for the Large Hadron Collider computing grid.

China Taiwan He also participated in the research and development of two important systems and handled huge experimental data. Asia Our computer center is located in the Chinese Academy of Sciences in Taiwan. About 40 scientists from Taiwan participated in this international experiment, responsible for the research and development of the world's largest and heaviest detector, and the "grid computer" relied on to process huge experimental data was located in Taiwan's Chinese Academy of Sciences.

After processing by these computer centers, other equipment can use these data. Each of the other equipment is composed of one or several joint computer centers that perform special analysis tasks. As a scientist, you can use the LAN or personal computer Knowing these devices, these people may often check the LHC computing grid.

Exploration of simulated phenomena

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Large Hadron Collider

The energy generated by the Large Hadron Collider (LHC) is other Particle accelerator It can't be reached before, but in nature Cosmic light The collision produced higher energy. Over the years, this High-energy particle The safety of the energy generated by the collision has always been a concern. According to new experimental data and new understanding of relevant theories, the Large Hadron Collider Safety Assessment Group (LSAG) has recalibrated an investigation and analysis made by the group in 2003. This security assessment mission was conducted by Neutralist Scientists.

In 2003, relevant reports said that there was no risk of LHC collision, so there was no reason to safety problem Too much attention. The LHC safety assessment team reviewed and supplemented these conclusions. No matter what the Large Hadron Collider will do, nature has done this many times in the life of the Earth and other celestial bodies. European Institute for Particle Physics Science policy The CERN's Scientific Policy Committee has reviewed the report of the Large Hadron Collider Safety Assessment Mission again, and agrees with its views. The Scientific Policy Committee of CERN is composed of the academic surgeons who make suggestions for the board of directors, the governing body of CERN. European Institute for Particle Physics The main arguments summarized can support the views of the Large Hadron Collider safety assessment team. Anyone who is interested in more details is encouraged to directly discuss this issue and its implications Technical science Thesis.

cosmic rays

Looking for Higgs boson

With others Particle accelerator Similarly, the Large Hadron Collider reproduces the cosmic ray natural phenomena , which enables scientists to conduct more detailed research on cosmic rays. Cosmic rays are outer space The generated particles, some of which are accelerated, generate energy far more than the energy generated by the Large Hadron Collider. In about 70 years of experiments, cosmic rays spread to Earth's atmosphere The energy and speed of has been monitored. In the past few billion years, the number of particle collisions in the nature of the earth has been equivalent to about 1 million LHC experiments, but the earth still exists. Astronomers have observed a large number of larger objects in the universe, which are bombarded by cosmic rays. The operation of the universe is like an experiment like the Large Hadron Collider, which runs more than ten billion times per second. The possibility of any dangerous outcome contradicts what astronomers have seen, because stars and galaxies still exist.

Miniature black hole

When certain stars larger than our sun occur in the final stage of life During explosion Black holes will form in nature. They will Substance concentration In a very small space. Suppose that during the process of proton collision in the Large Hadron Collider to produce particles, a tiny black hole is formed, and the energy of each proton can match that of a flying mosquito Sub equivalent. Astronomical black holes weigh more than anything produced by the Large Hadron Collider. According to Einstein relativity Described by the gravity property, it is impossible to generate a small black hole in the LHC. However, some pure theories predict that the Large Hadron Collider can produce such particle products. All these theories predict that such particles produced by the Large Hadron Collider will decompose immediately. Therefore, the black hole it produces will have no time to concentrate matter, producing results visible to the naked eye.

Although the stable theory of micro black holes is not tenable, the results of studying the micro black holes generated by cosmic rays show that they are harmless. The impact in the Large Hadron Collider is different from that in the Earth and other celestial bodies and cosmic rays Collision process The new particles produced in the running speed More slowly. A stable black hole is either charged or neutral. No matter the particles produced by cosmic rays or the particles produced by the Large Hadron Collider, if they are charged, they can combine with ordinary matter, and this process occurs when particles pass through Earth time Will stop. The fact that the Earth still exists precludes the possibility that cosmic rays or the Large Hadron Collider can produce electrically charged and dangerous small black holes. If a stable tiny black hole dead The interaction between them and the earth will be very weak. Those black holes generated by cosmic rays can pass through it and enter space without causing any harm to the Earth, so those black holes generated by the Large Hadron Collider can also continue to stay on the Earth. However, there are larger and denser celestial bodies in the universe than the Earth. Cosmic rays and neutron star or White dwarf The black hole generated by collision of other celestial bodies can be located at Sleep state 。 The fact that such compact bodies as the Earth continue to exist precludes the possibility of any dangerous black holes generated by the Large Hadron Collider.

Strange Microns and 'Angel Particles'

The existence of Mayolana fermion 'Angel particle'

Strange neutrinos are tiny particles“ Exotic matter ”The term produced by strange matter includes almost Strange quark The number of particles is the same, and the 'angel particles' are exploration‘ Mayolana fermion ’A 'independent' particle lattice with positive and negative particles in the same body. According to the research with the highest theoretical composition, strange neutrinos can be transformed into ordinary matter in one millionth of a millionth of a second. But can strange neutrinos combine with ordinary matter and become strange matter? 2000 Relativistic heavy ion collider (RHIC) When it first appeared in the United States, people raised this question. A research at that time showed that people had no reason to pay attention to this problem. The relativistic heavy ion collider had been running for 8 years. It had been looking for strange neutrinos, but it still had nothing. Strange neutrinos may be a heavy mass‘ Sterile neutrino ’The exists of. Sometimes the LHC, like the relativistic heavy ion collider, needs to run through heavy nucleon beams. The beam of the Large Hadron Collider will have more energy than the beam of the Relativistic Heavy Ion Collider, but this situation makes it less likely that strange neutrinos will form. Just as ice cannot be formed in hot water, the high temperature generated by such colliders makes it difficult for strange substances to combine. In addition, quarks are weaker in the Large Hadron Collider than in the Relativistic Heavy Ion Collider, which makes it difficult to gather strange matter. Therefore, the possibility of producing strange neutrinos in the Large Hadron Collider is smaller than that in the Relativistic Heavy Ion Collider. This result has confirmed the argument that strange neutrinos cannot be produced.

Strange neutrinos -- the existence of inert neutrinos

Vacuum foam

It was speculated that the universe was not in its most stable state Perturbation It will enable it to enter a more stable state, which is called a vacuum bubble. In this state, human beings will no longer exist. If the Large Hadron Collider can do this, can't cosmic ray collisions achieve this effect? Since there is no such vacuum bubble anywhere in the visible universe, the LHC will not be able to produce such a substance.

Magnetic monopole

The magnetic monopole is a particle with monopolar magnetic charge in the hypothesis, each of which only has the North Pole or antarctic 。 Some pure theories point out that if they do exist, magnetic monopoles will cause protons to disappear. These theories also indicate that such magnetic monopoles are too heavy to be generated in the LHC. However, if the weight of magnetic monopoles is enough to appear in the LHC, cosmic rays hitting the Earth's atmosphere would have produced such substances long ago. If they did exist, the Earth could very effectively stop and capture them, and now people should have found them. The fact that the Earth and other celestial bodies continue to exist precludes the possibility that the dangerous magnetic monopoles that can swallow protons are light enough to be generated in the LHC.

Simulated explosion

On November 8, 2010, scientists began to use Switzerland The European Large Hadron Collider on the border with France created a small "Big Bang" to simulate the instantaneous process of the formation of the universe nearly 14 billion years ago.

This is the first time that the machine collides with lead ions, and protons have been used in previous experiments. Lead ion and proton“ hadron ”, but the former is larger and heavier than the latter. The experiment started on the 8th was named "ALICE", which is the abbreviation of "Large Hadron Collider Experiment". The first phase of the experiment will be completed in December 2010.

In the 27 km long annular orbit, the two lead ion beams move in the opposite direction. Each time they run, they will gain more energy and speed. The high temperature generated at the moment of collision is equivalent to Solar core 100000 times the temperature, or 10 trillion degrees. It is believed that this temperature was just a few millionths of a second after the Big Bang 13.7 billion years ago. At this temperature“ Quark gluon plasma ”。 According to the existing physical theory, a matter called "quark gluon plasma" once existed in the universe within a few millionths of a second after the birth of the universe. Scientists hope to solve the mystery of the formation of the universe through the mini "Big Bang" experiment.

scientific research

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In October 2022, the Large Hadron Collider (LHC) Compact sub coil （CMS） international co-operation In the latest issue of Nature Physics, the group pointed out that Higgs boson Of mass distribution ——"Width" has made the most accurate measurement so far: 3.2 trillion Electron volt 。^[9]

Scientists found a new particle on the Large Hadron Collider (LHC) of CERN, which is called "strange five quarks". Relevant papers were published in the journal Physical Review Letters published in July 2023. In the latest research, scientists discovered this new particle by colliding two protons with extremely high energy. The newly discovered five quark particle contains a strange quark.^[11]

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