Map with the location of the Collider plotted on it

To further combine fundamental interactions in one theory, various approaches are used: string theory, which was developed in M-theory (brane theory), supergravity theory, loop quantum gravity, etc. Some of them have internal problems, and none of them have experimental confirmation. The problem is that to carry out the corresponding experiments, energies are needed that are unattainable at modern particle accelerators.

The LHC will make it possible to conduct experiments that were previously impossible to conduct and will probably confirm or refute some of these theories. So, there is a whole range of physical theories with dimensions greater than four that suggest the existence of "supersymmetry" - for example, string theory, which is sometimes called superstring theory precisely because without supersymmetry it loses its physical meaning. Confirmation of the existence of supersymmetry would thus be an indirect confirmation of the truth of these theories.

Study of top quarks

Construction history

27 km underground tunnel designed to house the LHC booster

The idea for the Large Hadron Collider project was born in 1984 and was officially approved ten years later. Its construction began in 2001, after the completion of the work of the previous accelerator - the Large Electron-Positron Collider.

The accelerator is supposed to collide protons with a total energy of 14 TeV (that is, 14 teraelectronvolts or 14 10 12 electron volts) in the center of mass system of the incident particles, as well as lead nuclei with an energy of 5.5 GeV (5.5 10 9 electron volts) for each pair of colliding nucleons. Thus, the LHC will be the most high-energy elementary particle accelerator in the world, surpassing its closest competitors in energy by an order of magnitude - the proton-antiproton collider Tevatron, which is currently operating at the National Accelerator Laboratory. Enrico Fermi (USA), and the RHIC Relativistic Heavy Ion Collider at the Brookhaven Laboratory (USA).

The accelerator is located in the same tunnel formerly occupied by the Large Electron-Positron Collider. The tunnel with a circumference of 26.7 km was laid at a depth of about one hundred meters underground in France and Switzerland. To contain and correct proton beams, 1624 superconducting magnets are used, the total length of which exceeds 22 km. The last one was installed in the tunnel on 27 November 2006 . The magnets will work at 1.9 K (-271°C). The construction of a special cryogenic line for cooling magnets was completed on November 19, 2006.

Tests

Specifications

The process of accelerating particles in a collider

The speed of particles in the LHC on colliding beams is close to the speed of light in vacuum. Acceleration of particles to such high speeds is achieved in several stages. In the first stage, low-energy Linac 2 and Linac 3 linear accelerators inject protons and lead ions for further acceleration. Then the particles enter the PS booster and then into the PS (proton synchrotron) itself, acquiring an energy of 28 GeV. After that, particle acceleration continues in the SPS (Proton Super Synchrotron), where the particle energy reaches 450 GeV. Then the beam is directed to the main 26.7-kilometer ring and at the collision points, the detectors record the events taking place.

Power consumption

During the operation of the collider, the estimated energy consumption will be 180 MW. Estimated energy costs for the entire Canton of Geneva. CERN does not generate power itself, with only standby diesel generators.

Distributed Computing

To control, store and process data that will come from the LHC accelerator and detectors, a distributed computing network LCG is being created. L HC C omputing G RID ) using grid technology. For certain computing tasks, a distributed computing project will be involved [email protected].

Uncontrolled physical processes

Some experts and members of the public express concern that there is a non-zero probability that the experiments conducted in the collider will get out of control and develop a chain reaction, which, under certain conditions, could theoretically destroy the entire planet. The point of view of supporters of catastrophic scenarios associated with the operation of the LHC is presented on a separate website. Because of these sentiments, the LHC is sometimes deciphered as Last Hadron Collider ( Last Hadron Collider).

In this regard, the theoretical possibility of the appearance of microscopic black holes in the collider, as well as the theoretical possibility of the formation of antimatter clots and magnetic monopoles, followed by a chain reaction of capturing the surrounding matter, is most often mentioned.

These theoretical possibilities were considered by a special CERN group, which prepared a corresponding report, in which all such fears are recognized as unfounded. English theoretical physicist Adrian Kent published a scientific article criticizing the safety standards adopted by CERN, because the expected damage, that is, the product of the probability of an event by the number of victims, is, in his opinion, unacceptable. However, the maximum upper estimate of the probability of a catastrophic scenario at the LHC is 10 -31 .

As the main arguments in favor of the groundlessness of catastrophic scenarios, references are made to the fact that the Earth, the Moon and other planets are constantly bombarded by streams of cosmic particles with much higher energies. The successful operation of previously commissioned accelerators is also mentioned, including the Relativistic Heavy Ion Collider RHIC in Brookhaven. The possibility of the formation of microscopic black holes is not denied by CERN specialists, however, it is stated that in our three-dimensional space such objects can appear only at energies that are 16 orders of magnitude greater than the energy of beams in the LHC. Hypothetically, microscopic black holes can appear in experiments at the LHC in the predictions of theories with extra spatial dimensions. Such theories do not yet have any experimental evidence. However, even if black holes are created by particle collisions in the LHC, they are expected to be extremely unstable due to Hawking radiation and will evaporate almost instantly in the form of ordinary particles.

On March 21, 2008, Walter Wagner filed a lawsuit in the federal district court of Hawaii (USA). Walter L. Wagner) and Luis Sancho (eng. Luis Sancho), in which they, accusing CERN of trying to arrange the end of the world, demand that the launch of the collider be banned until its safety is guaranteed.

Comparison with natural speeds and energies

The accelerator is designed to collide such particles as hadrons and atomic nuclei. However, there are natural sources of particles, the speed and energy of which are much higher than in the collider (see: Zevatron). Such natural particles are found in cosmic rays. The surface of the planet Earth is partially protected from these rays, but, passing through the atmosphere, particles of cosmic rays collide with atoms and molecules of the air. As a result of these natural collisions, many stable and unstable particles are born in the Earth's atmosphere. As a result, the natural radiation background has been present on the planet for many millions of years. The same thing (collision of elementary particles and atoms) will also occur in the LHC, but with lower speeds and energies, and in much smaller quantities.

microscopic black holes

If black holes can be created during the collision of elementary particles, they will also decay into elementary particles, in accordance with the principle of CPT invariance, which is one of the most fundamental principles of quantum mechanics.

Further, if the hypothesis of the existence of stable black micro-holes was correct, then they would be formed in large quantities as a result of the bombardment of the Earth by cosmic elementary particles. But most of the high-energy elementary particles arriving from space have an electric charge, so some black holes would be electrically charged. These charged black holes would be captured by the Earth's magnetic field and, if they were really dangerous, would have destroyed the Earth long ago. The Schwimmer mechanism that makes black holes electrically neutral is very similar to the Hawking effect and cannot work if the Hawking effect does not work.

In addition, any black holes, charged or electrically neutral, would be captured by white dwarfs and neutron stars (which, like the Earth, are bombarded by cosmic radiation) and destroyed them. As a result, the lifetimes of white dwarfs and neutron stars would be much shorter than actually observed. In addition, destructible white dwarfs and neutron stars would emit additional radiation that is not actually observed.

Finally, theories with extra spatial dimensions that predict the emergence of microscopic black holes do not contradict experimental data only if the number of extra dimensions is at least three. But with so many extra dimensions, billions of years must pass before a black hole causes any significant harm to the Earth.

Strapelki

Eduard Boos, Doctor of Physical and Mathematical Sciences from the Research Institute of Nuclear Physics of Moscow State University, holds opposing views, denying the occurrence of macroscopic black holes at the LHC, and, consequently, "wormholes" and time travel.

Notes

  1. The ultimate guide to the LHC (English) P. 30.
  2. LHC: key facts. "Elements of Big Science". Retrieved September 15, 2008.
  3. Tevatron Electroweak Working Group, Top Subgroup
  4. LHC synchronization test successful
  5. The second test of the injection system was intermittent, but the goal was reached. "Elements of big science" (August 24, 2008). Retrieved September 6, 2008.
  6. LHC milestone day gets off to fast start
  7. First beam in the LHC - accelerating science .
  8. Mission complete for LHC team . physicsworld.com. Retrieved September 12, 2008.
  9. A stable circulating beam is launched at the LHC. "Elements of big science" (September 12, 2008). Retrieved September 12, 2008.
  10. An incident at the Large Hadron Collider delays experiments indefinitely. "Elements of Big Science" (September 19, 2008). Retrieved September 21, 2008.
  11. The Large Hadron Collider will not resume operation until spring - CERN. RIA Novosti (September 23, 2008). Retrieved September 25, 2008.
  12. http://press.web.cern.ch/Press/PressReleases/Releases2008/PR14.08E.html
  13. https://edms.cern.ch/file/973073/1/Report_on_080919_incident_at_LHC__2_.pdf
  14. https://lhc2008.web.cern.ch/LHC2008/inauguration/index.html
  15. Repairing damaged magnets will be more extensive than previously thought. "Elements of big science" (November 09, 2008). Retrieved November 12, 2008.
  16. Schedule for 2009. "Elements of big science" (January 18, 2009). Retrieved 18 January 2009.
  17. CERN press release
  18. The work plan of the Large Hadron Collider for 2009-2010 has been approved. "Elements of Big Science" (February 6, 2009). Retrieved April 5, 2009.
  19. The LHC experiments.
  20. Pandora's Box opens. Vesti.ru (September 9, 2008). Retrieved September 12, 2008.
  21. The Potential for Danger in Particle Collider Experiments
  22. Dimopoulos S., Landsberg G. Black Holes at the Large Hadron Collider Phys. Rev. Lett. 87 (2001)
  23. Blaizot J.-P. et al. Study of Potentially Dangerous Events During Heavy-Ion Collisions at the LHC.
  24. Review of the Safety of LHC Collisions LHC Safety Assessment Group
  25. A Critical Review of the Risks of Accelerators. Proza.ru (May 23, 2008). Retrieved September 17, 2008.
  26. What is the likelihood of a catastrophe at the LHC?
  27. Judgment Day
  28. Asking a Judge to Save the World, and Maybe a Whole Lot More
  29. Explanation of why the LHC will be safe
  30. http://environmental-impact.web.cern.ch/environmental-impact/Objects/LHCSafety/LSAGSummaryReport2008-es.pdf (Spanish)
  31. http://environmental-impact.web.cern.ch/environmental-impact/Objects/LHCSafety/LSAGSummaryReport2008-de.pdf (German)
  32. http://environmental-impact.web.cern.ch/environmental-impact/Objects/LHCSafety/LSAGSummaryReport2008-fr.pdf (fr)
  33. H. Heiselberg. Screening in quark droplets // Physical Review D. - 1993. - T. 48. - No. 3. - S. 1418-1423. DOI:10.1103/PhysRevD.48.1418
  34. M. Alford, K. Rajagopal, S. Reddy, A. Steiner. Stability of strange star crusts and strangelets // The American Physical Society. Physical Review D. - 2006. - T. 73, 114016.
Publication date: 09/17/2012

What is the Large Hadron Collider? Why is it needed? Can it cause the end of the world? Let's break it all down.

What is BAK?

This is a huge annular tunnel, similar to a particle dispersal pipe. It is located at a depth of about 100 meters under the territory of France and Switzerland. Scientists from all over the world participated in its construction.

The LHC was built to find the Higgs boson, the mechanism that gives particles mass. A secondary goal is also to study quarks - the fundamental particles that make up hadrons (hence the name "hadron" collider).

Many people naively believe that the LHC is the only particle accelerator in the world. However, more than a dozen colliders have been built around the world since the 1950s. LHC is considered the largest - its length is 25.5 km. In addition, its structure includes another, smaller in diameter, accelerator.

LHC and media

Since the start of construction, many articles have appeared about the high cost and danger of the accelerator. Most people believe that the money was wasted, and do not understand why it was necessary to spend so much money and effort in order to find some kind of particle.

First, the LHC is not the most expensive scientific project in history. In the south of France is the scientific center of Cadarache with an expensive thermonuclear reactor. Cadarache was built with the support of 6 countries (including Russia); at the moment, about 20 billion dollars have already been invested in it. Secondly, the discovery of the Higgs boson will bring many revolutionary technologies to the world. In addition, when the first cell phone was invented, people also met his invention negatively ...

How does the BAC work?

The LHC collides beams of particles at high speeds and monitors their subsequent behavior and interaction. As a rule, one beam of particles is accelerated first on the auxiliary ring, and then it is sent to the main ring.

Many of the strongest magnets hold the particles inside the collider. And high-precision instruments record the movement of particles, since the collision occurs in a fraction of a second.

The organization of the work of the collider is carried out by CERN (Organization for Nuclear Research).

As a result, after huge efforts and financial investments, on July 4, 2012, CERN officially announced that the Higgs boson had been found. Of course, some properties of the boson found in practice differ from theoretical aspects, but scientists have no doubts about the “reality” of the Higgs boson.

Why do you need a BAC?

How useful is the LHC for ordinary people? Scientific discoveries related to the discovery of the Higgs boson and the study of quarks may in the future lead to a new scientific and technological revolution.

First, since mass is energy at rest (roughly speaking), it is possible in the future to convert matter into energy. Then there will be no problems with energy, which means that it will be possible to travel to distant planets. And this is a step towards interstellar travel ...

Secondly, the study of quantum gravity will allow, in the future, to control gravity. However, this will not happen soon, since gravitons are not yet very well understood, and therefore the device that controls gravity can be unpredictable.

Thirdly, there is an opportunity to understand M-theory (a derivative of string theory) in more detail. This theory states that the universe consists of 11 dimensions. M-theory claims to be the "theory of everything", which means that its study will allow us to better understand the structure of the universe. Who knows, maybe in the future a person will learn to move and influence other dimensions.

LHC and the End of the World

Many people argue that the work of the LHC can destroy humanity. As a rule, people who are poorly versed in physics talk about this. The launch of the LHC was postponed many times, but on September 10, 2008, it was nevertheless launched. However, it is worth noting that the LHC has never been accelerated to full power. Scientists plan to launch the LHC at full capacity in December 2014. Let's look at the possible causes of the end of the world and other rumors ...

1. Creating a black hole

A black hole is a star with huge gravity, which attracts not only matter, but also light, and even time. A black hole cannot appear out of nowhere, which is why CERN scientists believe that the chances of a stable black hole appearing are extremely small. However, it is possible. When particles collide, a microscopic black hole can be created, the size of which is enough to destroy our planet in a couple of years (or faster). But humanity should not be afraid, because, thanks to Hawking radiation, black holes quickly lose their mass and energy. Although there are pessimists among scientists who believe that a strong magnetic field inside the collider will not allow the black hole to disintegrate. As a result, the chance that a black hole will be created that will destroy the planet is very small, but there is such a possibility.

2. Formation of "dark matter"

She is also a “strange matter”, a strangelet (a strange droplet), a “strangelet”. This is matter that, when colliding with another matter, turns it into a similar one. Those. when a strangelet and an ordinary atom collide, two strangelets are formed, giving rise to a chain reaction. If such matter appears in the collider, then humanity will be destroyed in a matter of minutes. However, the chance that this will happen is as small as the formation of a black hole.

3. Antimatter

The version related to the fact that during the operation of the collider such an amount of antimatter may appear that will destroy the planet looks the most delusional. And the point is not even that the chances of the formation of antimatter are very small, but that there are already samples of antimatter on earth, stored in special containers where there is no gravity. It is unlikely that such an amount of antimatter will appear on Earth that will be capable of destroying the planet.

findings

Many residents of Russia do not even know how to spell the phrase "Large Hadron Collider" correctly, to say nothing about their knowledge of its purpose. And some pseudo-prophets argue that there are no intelligent civilizations in the Universe because each civilization, having achieved scientific progress, creates a collider. Then a black hole is formed, destroying civilization. From here they explain the large number of massive black holes in the center of galaxies.

However, there are also people who believe that we should launch the LHC as soon as possible, otherwise, at the time of the arrival of aliens, they will capture us, as they consider us savages.

In the end, the only chance to find out what the LHC will bring us is just to wait. Sooner or later, we still find out what awaits us: destruction or progress.


Recent Science & Tech tips:

Did this advice help you? You can help the project by donating any amount you want for its development. For example, 20 rubles. Or more:)

It is the search for ways to combine two fundamental theories - GR (about gravitational) and SM (standard model that combines three fundamental physical interactions - electromagnetic, strong and weak). Finding a solution before the creation of the LHC was hampered by the difficulties in creating a theory of quantum gravity.

The construction of this hypothesis involves the combination of two physical theories - quantum mechanics and general relativity.

For this, several popular and necessary approaches in modern times were used at once - string theory, brane theory, supergravity theory, as well as the theory of quantum gravity. Prior to the construction of the collider, the main problem in conducting the necessary experiments was the lack of energy, which cannot be achieved with other modern particle accelerators.

The Geneva LHC gave scientists the opportunity to conduct previously unfeasible experiments. It is believed that in the near future, with the help of the apparatus, many physical theories will be confirmed or refuted. One of the most problematic is supersymmetry or string theory, which for a long time divided the physical into two camps - "stringers" and their rivals.

Other fundamental experiments carried out as part of the work of the LHC

The research of scientists in the field of studying top quarks, which are the most quarks and the heaviest (173.1 ± 1.3 GeV / c²) of all currently known elementary particles, is also interesting.

Because of this property, even before the creation of the LHC, scientists could only observe quarks at the Tevatron accelerator, since other devices simply did not have enough power and energy. In turn, the theory of quarks is an important element of the sensational Higgs boson hypothesis.

All scientific research on the creation and study of the properties of quarks is carried out by scientists in the top quark-antiquark steam room at the LHC.

An important goal of the Geneva project is also the process of studying the mechanism of electroweak symmetry, which is also related to the experimental proof of the existence of the Higgs boson. If we define the problem more precisely, then the subject of study is not so much the boson itself, but the mechanism of violation of the symmetry of the electroweak interaction predicted by Peter Higgs.

The LHC also conducts experiments to search for supersymmetry - and the desired result will be both the proof of the theory that any elementary particle is always accompanied by a heavier partner, and its refutation.

A few facts about the Large Hadron Collider, how and why it was created, what is the use of it and what potential dangers for humanity it poses.

1. The construction of the LHC, or the Large Hadron Collider, was conceived back in 1984, and began only in 2001. Five years later, in 2006, thanks to the efforts of more than 10 thousand engineers and scientists from different countries, the construction of the Large Hadron Collider was completed.

2. The LHC is the largest experimental facility in the world.

3. So why the Large Hadron Collider?
It was named large due to its solid size: the length of the main ring, along which the particles are driven, is about 27 km.
Hadron - since the installation accelerates hadrons (particles that consist of quarks).
Collider - due to particle beams accelerating in the opposite direction, which collide with each other at special points.

4. What is the Large Hadron Collider for? The LHC is an ultra-modern research center where scientists conduct experiments with atoms, pushing ions and protons together at great speed. Scientists hope with the help of research to lift the veil over the mysteries of the appearance of the universe.

5. The project cost the scientific community an astronomical sum of $6 billion. By the way, Russia has delegated 700 specialists to the LHC, who are still working today. Orders for LHC brought about $120 million to Russian enterprises.

6. Without a doubt, the main discovery made at the LHC is the discovery in 2012 of the Higgs boson, or as it is also called “God particles”. The Higgs boson is the last link in the Standard Model. Another significant event in Bak'e is the achievement of a record collision energy value of 2.36 teraelectronvolts.

7. Some scientists, including those in Russia, believe that thanks to large-scale experiments at CERN (the European Organization for Nuclear Research, where, in fact, the collider is located), scientists will be able to build the world's first time machine. However, most scientists do not share the optimism of colleagues.

8. The main fears of humanity about the most powerful accelerator on the planet are based on the danger that threatens humanity as a result of the formation of microscopic black holes capable of capturing the surrounding matter. There is another potential and extremely dangerous threat - the emergence of strapels (produced from Strange droplet), which, hypothetically, are capable of colliding with the nucleus of an atom to form more and more new strapels, transforming the matter of the entire Universe. However, most of the most respected scientists say that such an outcome is unlikely. But it is theoretically possible

9. In 2008, CERN was sued by two residents of the state of Hawaii. They accused CERN of trying to end humanity through negligence, demanding safety guarantees from scientists.

10. The Large Hadron Collider is located in Switzerland near Geneva. There is a museum at CERN, where visitors are clearly explained about the principles of the collider and why it was built.

11 . And finally, a little fun fact. Judging by the requests in Yandex, many people who are looking for information about the Large Hadron Collider do not know how to spell the name of the accelerator. For example, they write “andron” (and not only write what the NTV reports with their andron collider are worth), sometimes they write “android” (the Empire strikes back). In the bourgeois net, they also do not lag behind and instead of “hadron” they drive “hardon” into the search engine (in Orthodox English, hard-on is a riser). An interesting spelling in Belarusian is “Vyaliki hadronny paskaralnik”, which translates as “Big hadron accelerator”.

Hadron Collider. Photo

The European Center for Nuclear Research, or simply CERN, is a place where a Nobel laureate in physics can easily dine next to you in the dining room. It is known worldwide for the most powerful particle accelerator, the Large Hadron Collider. After almost ten years of work, it's time to take stock - did one of the most ambitious scientific projects of our time justify the hopes of scientists?

In 2008, I was in the tenth grade. Despite the fact that in those years I was still not at all interested in physics, a wave of excitement could not bypass me: from every iron they trumpeted that the “doomsday machine” was about to be launched. That as soon as the Very Important Director raises the switch, a black hole will form and we will all be finished. On the day of the official launch of the Large Hadron Collider, some teachers even allowed to watch a report from the scene in their lessons.

The worst did not happen. By and large, nothing happened - the switch was raised, numbers incomprehensible to a simple layman jumped on the computer screen, and scientists began to celebrate. In general, why they launched it was not clear.

Undoubtedly, without the Large Hadron Collider, scientists would not have been able to make some significant discoveries - including the discovery of the Higgs boson. But will it be possible to implement all of the planned, and whether there are still prospects for the LHC - we will tell about this.

DELPHI experiment at the Large Electron-Positron Collider

Big Brother: Large Electron-Positron Collider

In the late seventies of the XX century, elementary particle physics developed by leaps and bounds. To test the predictions of the Standard Model in 1976, the project of the Large Electron-Positron Collider (BEP or LEP - from the English Large Electron-Positron Collider) was proposed at the European Center for Nuclear Research (CERN, from the French CERN - Conseil Européen pour la Recherche Nucléaire) . Among many different configurations, the location of the future experiment in an underground tunnel 27 kilometers long was chosen. He was supposed to accelerate electrons and positrons to energies of the order of tens and hundreds of gigaelectronvolts: the colliding beams crossed at four points, where the ALEPH, DELPHI, OPAL and L3 experiments were subsequently located.

From the point of view of physicists, energy is never enough: the BEP option chosen for implementation was a compromise between cost and power; tunnels of greater length, capable of accelerating particles more strongly, were also considered. The resulting energy could be used to test the Standard Model, but was too small to search for the so-called "new physics" - phenomena that are not predicted by its laws. Hadron colliders are much better suited for such purposes - accelerators of compound particles like protons, neutrons and atomic nuclei. Back in 1977, at the time of the discussion of the BEP, John Adams, director of CERN at that time, proposed to make the tunnel wider and place both accelerators there at once - both the electron-positron and the hadron accelerator. However, the council that makes the final decisions rejected this idea, and in 1981 the project of the Large Electron-Positron Collider was approved.

Tunnel of the Large Hadron Collider

Replaced by LHC

BEP worked for more than ten years: from 1989 to 2000. A number of significant experiments belong to this time, such as the confirmation of the predicted masses of the carriers of the weak interaction - W- and Z-bosons, as well as the measurement of various parameters of the Standard Model with unprecedented accuracy. And already in 1984, the conference "Large Hadron Collider in the LEP Tunnel" was held, dedicated to the issue of building a new collider after the cessation of the work of its predecessor.

In 1991, the project of the Large Hadron Collider (LHC or LHC - from the English Large Hadron Collider) was finally approved, with the help of which it was planned to achieve a total energy of colliding particles of 14 teraelectronvolts, that is, a hundred times greater than that developed by the Large Electron-Positron Collider .

In 1992, a meeting was held on the scientific program of the Large Hadron Collider: in total, twelve applications were received for various experiments that could be built at the site of four beam collision points. During the following years, two general experiments were approved - ATLAS and CMS, the ALICE experiment for the study of heavy ions and LHCb, dedicated to the physics of particles containing b-quarks. The construction of the Large Hadron Collider began in 2000, and the first beams were received already in 2008: since then and to this day, in addition to the scheduled shutdown, the LHC has been accelerating particles and collecting data in the operating mode.

Russia at CERN

The Russian Federation has been an observer country at CERN since 1993, which gives its representatives the right to attend meetings, but does not give them the right to vote when making important decisions. In 2012, on behalf of the Government of the Russian Federation, a statement was made of the intention of the Russian Federation to become an associate member of CERN, which has not yet been supported.

In total, about 700 Russian scientists from twelve scientific organizations, such as the Joint Institute for Nuclear Research, the Russian Research Center Kurchatov Institute, the Institute for Nuclear Research of the Russian Academy of Sciences and Moscow State University named after M.V. Lomonosov.

Injection circuit of the Large Hadron Collider

What is the advantage of accelerating particles?

The scheme of work of the Large Hadron Collider consists of many stages. Before getting directly into the LHC, the particles go through a series of pre-acceleration stages: in this way, they gain speed faster and at the same time with less energy. First, in the linear accelerator LINAC2, protons or nuclei reach an energy of 50 megaelectronvolts; then they alternately enter the Booster Synchrotron (PSB), Proton Synchrotron (PS) and Proton Super Synchrotron (SPS), and at the moment of injection into the collider, the total particle energy is 450 gigaelectronvolts.

In addition to the main four experiments in the tunnel of the Large Hadron Collider, the pre-accelerator system is the site for more than ten experiments that do not require such a large particle energy. These include, in particular, the NA61/SHINE experiment, which investigates the parameters of the interaction of heavy ions with a fixed target; the ISOLDE experiment, which studies the properties of atomic nuclei; and AEGIS, which studies the Earth's gravitational acceleration using antihydrogen.

The search for a particle of God and new physics

Even at the very beginning, at the development stage, the ambitious scientific program of the Large Hadron Collider was announced. First of all, due to the indications received at the BEP, it was planned to search for the Higgs boson, a still hypothetical component of the Standard Model at that time, responsible for the mass of all particles. Including the plans of scientists included the search for the supersymmetric Higgs boson and its superpartners, which are included in the minimal supersymmetric extension of the Standard Model.

In general, as a separate direction, it was planned to search for and test models of the "new physics". To test supersymmetry, in which each boson is associated with a fermion, and vice versa, it was supposed to search for the corresponding partners for particles of the Standard Model. To test theories with additional spatial dimensions, such as string theory or M-theory, the possibility of setting limits on the number of dimensions in our world was announced. It is the search for deviations from the Standard Model that was considered and is still considered one of the main tasks of the LHC.

Less high-profile problems: the study of quark-gluon plasma and violation of CP invariance

The top quark, the heaviest of the six quarks in the Standard Model, was only observed before the Large Hadron Collider at the Tevatron accelerator at the Enrico Fermi National Accelerator Laboratory in the United States due to its extremely large mass of 173 gigaelectronvolts. During collisions in the LHC, due to its power, the birth of a large number of top quarks was expected, which interested scientists in two aspects. The first was related to the study of the hierarchy of particles: at the moment there are three generations of quarks (the top quark completed the third), but it is possible that there are still more of them. On the other hand, the production of the Higgs boson during the decay of the top quark was considered the main method for its experimental detection.

In 1964, a violation of the combined CP invariance (from the English "charge" - charge and "parity" - parity) was discovered, which corresponds to the mirror image of our world with the complete replacement of all particles by the corresponding antiparticles. This fact plays an important role in theories of the formation of the Universe, which try to explain why all of our matter consists of matter, and not of antimatter. Among other things, CP-parity violation is manifested in the behavior of B-mesons - particles, the active production of which was assumed in the process of collisions in the LHC, and with their help, scientists hoped to shed light on the causes of this phenomenon.

The operation of the Large Hadron Collider in the mode of collision of heavy nuclei should have led to the reconstruction of the state of quark-gluon plasma, which, according to modern concepts, is observed 10-5 seconds after the Big Bang - a state so "hot" that quarks and gluons do not interact with each other. another, and do not form particles and nuclei, as occurs in the normal state. Understanding the processes of origin and cooling of quark-gluon plasma is necessary for studying the processes of quantum chromodynamics, the branch of physics responsible for describing strong interactions.

Schematic of the discovery of the Higgs boson in the ATLAS experiment

Discovery of new particles at the LHC

So, what can the Large Hadron Collider boast of for a whole decade of its work?

First, of course, the most famous of the discoveries is the discovery in July 2012 of the Higgs boson with a mass of 126 gigaelectronvolts. Just a year later, Peter Higgs and François Engler were awarded the Nobel Prize in Physics for theoretically predicting the existence of a "God particle" responsible for the mass of all matter in the universe. Now, however, physicists are faced with a new task - to understand why the desired boson has such a mass; the search for supersymmetric partners of the Higgs boson also continues.

In 2015, the LHCb experiment discovered stable pentaquarks - particles consisting of five quarks, and a year later - candidates for the role of tetraquarks - particles consisting of two quarks and two antiquarks. Until now, it was believed that the observed particles consist of no more than three quarks, and physicists have yet to refine the theoretical model that would describe such states.

Still within the Standard Model

Physicists hoped that the LHC would be able to solve the problem of supersymmetry - either completely refute it, or clarify in which direction it is worth moving, since there are a huge number of options for such an extension of the Standard Model. So far, it has not been possible to do either one or the other: scientists put various restrictions on the parameters of supersymmetric models, which can weed out the simplest options, but definitely do not solve global issues.

There were also no explicit indications of physical processes outside the Standard Model, which, perhaps, most scientists counted on. However, it is worth noting that the LHCb experiment also showed that the B-meson, a heavy particle containing a b-quark, does not decay in the way that the Standard Model predicts. Such behavior in itself can serve, for example, as an indication of the existence of another neutral carrier of the weak interaction, the Z' boson. So far, scientists are working on a set of experimental data that will limit various exotic scenarios.

Possible scheme of the future 100-kilometer collider

Time to start digging a new tunnel?

Could the Large Hadron Collider justify the efforts and funds invested in it? Undoubtedly, although not all of the goals set for the decade have been achieved so far. At the moment, the second stage of the accelerator operation is underway, after which the planned installation will be carried out and the third stage of data collection will begin.

Scientists do not lose hope to make the next great discoveries and are already planning new colliders, for example, with a tunnel length of as much as 100 kilometers.