History of the construction and operation of the Large Hadron Collider

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 previous accelerator, the Large Electron-Positron Collider ^[1] .

• In October 2006, the construction of a special cryogenic line for cooling magnets was completed ^[1] .
• On April 27, 2007, the last superconducting magnet was installed in the tunnel ^[1] .

2008

On August 11, 2008, the first part of the preliminary tests ^{[2] [3]} was successfully completed. During the tests, a beam of charged particles passed a little more than three kilometers along one of the rings of the LHC. Thus, the scientists were able to verify the synchronization operation of the preliminary accelerator, the so-called proton super synchrotron ( SPS ), and the right-hand beam delivery system. This system transfers the dispersed beams to the main ring in such a way that they begin to move clockwise along the ring. As a result of the tests, it was possible to optimize the system.

On August 24, the second stage of the tests took place ^[3] . The injection of protons into the LHC accelerator ring in the counterclockwise direction was tested ^[4] .

On September 10, the collider was officially launched. At 12:24:30 Moscow time ^[5] (according to official information, at 12:28 Moscow time ^[6] ), the launched proton beam successfully passed the entire perimeter of the collider clockwise. At 17:02 Moscow time ^{[7], a} proton beam launched counterclockwise also successfully passed the entire perimeter of the collider ^[3] .

September 12, at about 00:30 Moscow time, the LHC team was able to start and continuously hold the circulating beam for 10 minutes. A little later, the beam was launched again and circulated continuously, interrupted only if necessary. On this, the task of establishing a circulating beam was completed, and physicists began detailed tests of the magnetic system ^[8] . Also, the computer network of Cern was hacked by a group of hackers from Greece, gaining access to CMS servers ^[3] .

September 19 , at 14:05 Moscow time, during the tests of the magnetic system of sector 3-4 (34), an incident occurred, as a result of which the LHC failed ^[9] . According to a preliminary investigation, confirmed and detailed later, one of the electrical contacts between the superconducting magnets melted under the influence of an electric arc generated due to an increase in the current strength, which broke through the insulation of the helium cooling system (cryogenic system), which led to the release of about 6 tons of liquid helium into the tunnel and, as a result, a sharp increase in temperature. To restore the cryogenic system, it will be necessary to return this part of the accelerator to room temperature, and after repair - to cool it again to operating temperature.

On September 23, an official representative of CERN announced that the LHC would resume work no earlier than spring 2009 ^[10] .

On October 16, CERN issued a press release describing the interim results of an investigation into the incident of September 19 ^[11] . Detailed technical information is presented in a four-page report ^[12] .

On October 21, the official opening ceremony (inauguration) of the LHC took place ^[13] .

On October 29, during the eighth meeting of the LHC Performance Committee, Roberto Saban announced details regarding sector 3-4 of the LHC accelerator ring, which suffered during the September accident. The speaker showed a diagram of the damaged section of the accelerator ring, on which it was noted how much these or those magnets shifted during the accident. A new analysis showed that it would take 2-3 times more magnets to lift to the surface for repairs than was originally stated (we are already talking about at least fifty magnets and the so-called short straight sections). An action plan was developed in order to raise all magnets in need of repair by the end of December 2008. In addition, it turned out that particles of metals (primarily copper and stainless steel) and some other materials (fiberglass) thrown into the vacuum pipe at the time of the accident settled on the inner walls of the vacuum tubes. They are quite large, tens of microns in size, and they need to be disposed of, since they will interfere with the movement of proton beams. Cleaning has been completed and more reliable floor mounts and a new valve network have been developed to prevent too much pressure build-up inside the cryostats in the event of an emergency. It is precisely because of the sharply increased pressure that ultimately the damage to the magnets occurred ^[14] . According to the latest data ^[15] , with a favorable outcome of repair work, the LHC will resume work in July 2009 .

At the next stage of the tests, simultaneous launches of the beams towards each other will be performed in order to observe what happens during their “head-on” collisions. Then the particles will collide at higher energies. The energy output of 14 T eV of the proton-proton collision is scheduled for 2009 .

2009

• On February 9, 2009, a meeting of the CERN Directorate was held at which the LHC work plan for 2009–2010 was approved ^[16] . In accordance with the approved schedule, the collider will be cooled to operating temperature in August, beams will begin to circulate in late September, proton collisions will begin in October. But in the middle of July 2009, a new malfunction was discovered in sectors 8-1 and 2-3 - insufficient tightness of the helium cryogenic system. Since all other repairs are ongoing on time, it is now expected that the collider will be ready for work in mid-November 2009. The main point of the approved plan: LHC will operate continuously until the fall of 2010, including during the winter (not counting a short Christmas break). In 2010, it is also possible to allocate time for experiments on nuclear collisions ^[17] .

• On August 6, 2009, an official announcement appeared stating that the collider would earn 3.5 TeV per proton on energy. Thus, the total energy of proton-proton collisions will initially be 7 TeV, which is not only lower than the design energy of 14 TeV, but also of the recently discussed initial energy of 10 TeV ^[18] .
• On October 16, 2009, the cooling of all eight sectors of the collider was completed; their temperature was set at 1.9 K ^[19] .
• October 23-25, 2009 - for the first time since the accident, tests of the LHC were conducted. Beams of protons and lead ions were launched into the accelerator ring, along which several kilometers passed. It is expected that by November 19, all tests will be completed and proton beams will pass along the entire ring. The energy of the beams will be 3.5 TeV per proton, which is approximately half of the maximum possible ^[20] .
• November 17, 2009 - the latest tests of superconducting magnets, security systems and the entire infrastructure. 98% of all high-current electric circuits have already been tested to operate on proton energies of 1.2 TeV - physicists plan to limit themselves to such energy in 2009 ^{[21] [22] [23] [24]} .
• November 20, 2009 - for the first time after the accident of September 19, 2008, a proton beam successfully passed along the entire ring of the Large Hadron Collider ^[25] .
• November 23, 2009 - The European Center for Nuclear Research announced that for the first time a collision of proton beams moving at speeds close to the speed of light with total energies of about 900 GeV was carried out at the LHC ^[26] .
• On the night of November 29-30, scientists brought the energy of each of the proton beams to 1180 GeV. Thus, the LHC has become the most powerful proton accelerator in the world ^[27] .
• On the morning of December 7, the LHC was stopped due to problems in the cooling system ^[28] .
• December 9, 2009 - collisions of proton beams at a record energy of 2.36 TeV ^[29] .
• December 16, 2009 - The LHC is stopped for the period of the Christmas holidays ^[30] .

Run 1 session: 2010-2012

The Run 1 session was started at half the proton energy of 3.5 TeV instead of seven ^[31] .

2010

• January 4, 2010 - technical work at the LHC was resumed after the Christmas holidays ^[32] .
• February 28, 2010 - after completing some technical and preventive work in the collider, work resumed at low energies (about 450 GeV) ^[33] .
• On March 18, the proton beam energy was increased to 3.5 TeV ^[34] .
• On March 30, proton collisions with a total energy of 7 TeV took place ^[35] . The first long session of the LHC scientific work has begun.
• On April 22, 2010, statistics were collected that made it possible to clarify for the case of previously inaccessible energy of proton-proton collisions a number of parameters poorly calculated from the first principles. In particular, the number of charged particles generated in the collision, as well as their distribution over pseudo- velocity, was estimated ^[36] . These data will allow more efficient adjustment of the data coming from the detectors.
• June 24 showed the absence of asymmetry of protons and antiprotons ^[37] .
• On August 19, a restriction was obtained on the energy of the excited states of quarks for models where such states exist ^[38] .
• On September 19, the LHCb experiment presented the first data on the production of lovely mesons ^[39] .
• On September 22, a new physical effect was discovered that was not predicted by the existing theory. Among the hundreds of particles that are produced during the collision of protons , pairs were discovered whose motions are related to each other ^[40] . Nevertheless, this effect was not a complete surprise for experimenters, since a very similar effect was discovered in 2007 in a collision of nuclei at the RHIC collider ^[41] . In the case of nuclear collisions, the following explanation is proposed. The nuclei flying at near-light speed are strongly flattened in the longitudinal direction and look more like “pancakes” than “balls”. At the first moment after the collision, two “pancake” nuclei fly through each other, but the collision does not go unnoticed by them, and in the space between them a completely special state of matter arises, which is called “ glasma ”, glasma (English) , and which then produces a lump of quark and gluon fields . Theoretical calculations show that in the "eye" gluon force fields are formed between two flying nuclei in the form of longitudinal tubes. Each such tube is stretched over a wide range of polar angles, but has a fixed azimuthal angle . This tube is extended elongated because it is in this direction that particles move. When it decays into particles, then at the moment of birth they turn out to be automatically correlated in the azimuthal angle ^{[42] [43]} .
• On September 24, the pair production of Z bosons was first recorded on the CMS detector. This event may be related to the Higgs boson , which can be formed during proton collisions. It should decay into a number of other particles, in particular, Z-bosons, which can be detected by collider detectors. Detectors cannot directly capture Z-bosons because of the extremely short lifetime of these elementary particles (about 3⋅10 ⁻²⁵ seconds ), but they can “catch” muons into which Z-bosons turn. CMS recorded the birth of four muons. Nevertheless, as scientists note, one such event is not enough to draw certain conclusions: in order to speak conclusively about the birth of the Higgs boson, it is necessary to register many events of the production of pairs of Z-bosons ^{[44] [45] [46]} .
• On October 4, experiments began with 200 clots per beam. The luminosity of the LHC in this mode of operation exceeded 6 3110 ³¹ cm ⁻² s ⁻¹ , that is, it increased 10,000 times since the first collisions at a total energy of 7 TeV ^[47] .
• November 4 ended the experiments in 2010 in the proton-proton collision mode. During the last week of October, experiments were conducted with 368 clots per beam. Peak luminosity reached values ​​of 2 3210 ³² cm ^{– 2} s ⁻¹ , and the integral luminosity of about 6 picarnes ^{– 1 was} accumulated in one night session of the data set ^[48] . The total integrated luminosity accumulated in the collider’s main detectors by November is approximately 50 pico- barn ⁻¹ , while the first scientific data presented in July at ICHEP- 2010 (the main conference of the year on particle physics) were based on luminosity 0, 2 pico barn ⁻¹ . The statistics accumulated to date are being processed, and the corresponding scientific results will be presented at the 2010–2011 winter and spring conferences. Immediately after the completion of proton-proton collisions, the LHC switched to collisions of heavy ions ( lead ions); In this mode, he will work until about the Christmas holidays, then a stop will follow, and in January 2011 experiments with proton beams will resume ^{[49] [50]} . The first test launches of ionic clots began in the afternoon ^[51] .
• On November 7, collisions of nuclei with a total energy of 5.74 TeV were detected in three main detectors - ATLAS , CMS and the ALICE detector specially adapted for nuclear collisions ^[51] .
• On November 14, the number of clumps in each of the two opposing ion beams was increased to 121 (design value - 592), and the instantaneous luminosity reached 2⋅10 ²⁵ cm ⁻² s ⁻¹ (2% of the design value). Such a rapid increase in the number of clots (per week) is due to the fact that the magnetic system of the accelerator and the security system were carefully tuned and debugged during proton work sessions. On the other hand, the not so high level of luminosity in comparison with the proton-proton mode of operation is not critical for those issues that will be studied in the nuclear collision mode. The most important characteristic is the frequency of interesting collisions ^[48] . In proton collisions, interesting events rarely occur and have a cross section less than a nanobarne , which at luminosities of 10 ³² cm ⁻² s ⁻¹ gives no more than a few events per minute, but almost every direct collision of two nuclei is sufficient to study quark-gluon plasma in nuclear collisions having a cross section of about 8 barn, so the frequency of interesting events reaches a dozen per second ^[52] .
• On November 18th, two articles from the ALICE collaboration appeared on arXiv.org . These articles set forth the first results obtained in collisions of lead nuclei. In one of them, we are talking about the total number of particles generated in head-to-head collisions of nuclei, and in another, the effect arising from an off-center collision of nuclei is studied - an elliptical flow that allows a better understanding of the properties of a quark-gluon plasma . The detection of an elliptical flow in the experiment indicates that a certain fluid state, i.e. a quark-gluon plasma, is formed in the collision of nuclei. As in any solid substance, this state is characterized by the fact that its particles constantly collide with each other, and do not "fly" past. This means that for such a substance one can approximately determine the temperature , entropy , viscosity, and other hydrodynamic and thermodynamic quantities, study phase transitions during cooling, etc. ^[53]
• On December 2, CERN hosted the presentation of the first results obtained in a collision of lead nuclei. Three experimental groups (collaborations of the ATLAS , CMS, and ALICE experiments) made presentations ^[54] . The ATLAS collaboration spoke of a discovered imbalance of hadron jets, which indicates “quenching of jets ” in the quark-gluon plasma ^[55] . The CMS collaboration also presented data on the imbalance of jets and, in addition, presented the results on the production of heavy mesons ( J / ψ and Υ ), as well as Z-bosons , which had never before been recorded in a nuclear collision. The ALICE collaboration, the detector of which is optimized specifically for nuclear collisions, presented the quenching of jets in a slightly different way - through the distribution of hadrons in the transverse momentum. The data on the elliptical flow and the first measurements of physical parameters (volume, lifetime before cooling, viscosity) inside a bunch of a quark-gluon plasma are also presented. In addition, the ALICE detector “saw” some light anti - cores - anti deuterium , anti tritium , anti helium-3 ^[56] .
• December 6 was the last in 2010 session with beams. The collider was stopped on Christmas and New Year holidays, work will resume on January 24, 2011, and proton beams will be re-launched into the accelerator in mid-February ^[57] .
• On December 17, a conference was held at CERN , which presented reports of collaborations of all six collider detectors on the results of the work of the Large Hadron Collider in 2010 ^[58] . From a technical point of view, the work of the collider was unanimously recognized successful, since all the goals set for 2010 were achieved: reaching a luminosity above 10 ³² cm ⁻² s ⁻¹ , successful work with several hundred clots, and a well-functioning collider cycle. An important achievement was the correct tuning of security systems and monitoring of beams: the total energy of all protons circulating in the accelerator reached 28 megajoules , which is an order of magnitude higher than the previous achievement ^[59] . The CMS collaboration presented the first preliminary results on the search for supersymmetric particles. There is no evidence in favor of the existence of these particles in the collected statistics ^[60] .

2011

• In early February, there were reports that the LHCb detector detected two new decays of B _s - mesons , that is, mesons with both a “strange quark” ( s-quark ) and a “lovely quark” ( b-quark ) . Interest in them is due to the fact that CP decay can be observed in their decay, and possibly traces of new particles or interactions. ^[61]
• On March 13, collisions of stable proton beams with a working energy of 3.5 TeV per beam and luminosity slightly above ⋅10 ³⁰ cm ⁻² s ^{−1 were} resumed at the Large Hadron Collider. ^[62]
• On April 22, the LHC set a world peak luminosity record for hadron colliders - 4.67⋅10 ³² cm ⁻² · sec ⁻¹ . The previous record was set by the Tevatron accelerator in 2010, then the luminosity was 4.02⋅10 ³² cm ⁻² · sec ^{−1 [63]} .
• On June 17, the luminosity gained by ATLAS and CMS for 2010-2011 exceeded 1 fb ⁻¹ . ^{[64] [65]}
• As a result of processing the data of the OPERA experiment ^[66] , collected from 2008 to 2011 at the Gran Sasso laboratory ( English Laboratori Nazionali del Gran Sasso ) together with CERN , a statistically significant indication of the excess of the speed of light by muonic neutrinos is reported . ^[67] The announcement of this, accompanied by the publication of preprints in the archive ^[68] , was made on September 23, 2011 at CERN. The results obtained are questioned, because they do not agree not only with the theory of relativity , but also with other experiments with neutrinos ^[69] . It is planned to double-check the results obtained in the experiments of MINOS ( Fermilab , USA) and T2K ( Kamioka , Japan) (except Gran Sasso, only two laboratories in the world are capable of this). There is an assumption that the "superluminal velocity" was caused by the unaccounted relativistic effects of the movement of GPS satellites relative to the neutrino beam. ^{[70] [71]}
• On October 30, the proton physics program for 2011 was completed. At the time the program was closed, the luminosity was almost 6 fbn ⁻¹ (the luminosity of 5 fbn ⁻¹ was reached on October 18 ) ^[72] .
• On November 15, collisions of lead ions began. At 170 clots in the beam, the peak luminosity is 1.5⋅10 ²⁶ cm ⁻² · sec ⁻¹ , which is 5 times higher than last year. ^{[73] [74]}
• On December 7, the ion physics program was completed. In a collision of 358 clumps, the peak luminosity was 5.0 × 10 ²⁶ cm ⁻² · sec ⁻¹ . As a result of experiments in 2011, the integrated luminosity of 163.6 mcbn ⁻¹ (ATLAS), 143.6 mcbn ⁻¹ (ALICE), and 149.6 mcbn ⁻¹ (CMS) were accumulated ^[75] .
• December 21 announced the discovery of a new elementary particle${\displaystyle {\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\chi </span></span>}}_{\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">b</span></span>}}<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">(</span></span>\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">3</span></span>}\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">S</span></span>}<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">)</span></span>}$ {\ displaystyle \ chi _ {b} (3S)}   consisting of b- and anti-b-quark ( quarkonium ). ^[76]

2012

• On March 14, the cooling of all magnets was completed, the first beams appeared in the collider. It was decided to increase the energy of the beams to 4 TeV ^[77] .
• On March 16, protons were first accelerated to an energy of 4 TeV ^[77] .
• On April 5, the first collisions of proton beams at an energy of 4 TeV began ^[78] .
• On April 10, Yandex launched a search for CERN for use in LHCb ^[79] .
• On April 26, the CMS collaboration announced the discovery of a theoretically predicted particle Ξ _b ^{* 0} with a mass difference of 14.84 ± 0.74 ± 0.28 MeV compared to the sum of the masses of Ξ _b ^- and π ⁺ as a result of processing statistics of 5.3 fbn ^{−1 [80] [81]} .
• May 15 LHCb collaboration announced particle detection${\displaystyle {\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\Lambda </span></span>}}_{\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">b</span></span>}}^{\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">0</span></span>}<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\ast </span></span>}<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">(</span></span>\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">5912</span></span>}<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">)</span></span>}$ {\ displaystyle \ Lambda _ {b} ^ {0 *} (5912)}   ( statistical significance 4.9σ) and${\displaystyle {\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\Lambda </span></span>}}_{\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">b</span></span>}}^{\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">0</span></span>}<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\ast </span></span>}<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">(</span></span>\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">5920</span></span>}<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">)</span></span>}$ {\ displaystyle \ Lambda _ {b} ^ {0 *} (5920)}   (10.1σ) during the processing of statistics, 1.0 fbn ^{−1 [81] [82]} .
• On July 4, ATLAS and CMS collaborations announced the discovery of a boson with a mass of 125.3 ± 0.6 GeV . The characteristics of this particle correspond rather accurately to the Higgs boson predicted earlier. Whether this particle is a Higgs boson remains in doubt. ^[83]
• On December 17, the proton physics program was completed in 2012; the ATLAS and CMS detectors scored 23.27 fbn ^{−1 of} integrated luminosity. ^[84]

Technical Pause LS1: 2013–2015

2013

• On February 14, the collider was stopped for the planned upgrade of the accelerator and detectors. By the end of 2014, the energy of accelerated proton beams is expected to increase from 4 to 6.5–7 TeV ^[85] .
• On February 15, a proton-ion collision session was completed, as a result of which an integrated luminosity of about 31 nb ^{−1 was} acquired at the ATLAS, CMS, and ALICE detectors and 2.1 nb ⁻¹ at the LHCb ^[86] .

The collider worked until February 2013, when it was closed for long-term repairs ^[87] . Repair and improvement tooktwo years (the rest of 2013 and the whole of 2014) ^{[1] [88]} .

2014

• At the end of November 2014, test launches of protons in the LHCb detector began ^[89] .

Run 2 Session: 2015-2018

During the Run 2 session, it is planned to collect at least 120 fb-1 in the ATLAS and CMS detectors ^[90] .

2015

• It was planned that in March 2015 the collider will be restarted, scientists are going to concentrate on searching for dark matter particles and supersymmetry ^[91] , but on March 21, during tests to supply voltage to superconducting magnets, it was found that a short circuit to “is present in the power circuit of one of the magnets” earth ”, which arose due to the smallest metal fragment, the problem is being solved ^[92] .
• On April 11, protons were dispersed to 6.5 TeV, technicians will continue testing equipment and beam controllability ^[93] .
• On May 21, there was a collision of oncoming proton beams with an energy of 6.5 TeV, and collimators were tuned to ensure parallel beams. ^[94] .
• On June 3, the collection of scientific data at a total collision energy of 13 TeV began, which began a new phase of the Run 2 collider ^[95] .
• On July 14, LHCb announced the discovery of a particle class known as pentaquark . ^{[96] [97]}
• On November 2, work in the proton collision mode was completed ^[98] .

2016

On March 25, after stopping for the winter, proton beams were launched into the collider ^[99] .

With a break for the winter, the collection of statistics of proton-proton collisions took place until October 2016, after which the collider in November and early December spent about a month colliding protons with lead nuclei ^[100] . Then the collider was again stopped for the winter (a long stop for repairs and updates).

2017 (plan and reality)

Technical work will take the first half of the year. The collection of statistics will begin only at the beginning of summer and will last until winter. There will be no increase in proton energy in beams (from 13 TeV to 14 TeV) in 2017 and 2018, since the transition to 14 TeV will require a longer magnet training campaign ^[102] and is planned only in the Run 3 session ^[103] . Contrary to the emerging tradition, according to which a month is allocated for nuclear collisions, they will not be held this year ^[104] .

On April 18, the problem with lepton universality was confirmed ^[1] .

As it became known on August 29, episodes have been happening in the cell of the accelerator ring with code number 16L2 (16 cells to the left of point 2) for three weeks now, when protons suddenly start to escape from the beams, which causes a sharp energy release , and the collider’s security system gives beam reset signal ^[105] .

In October, xenon nuclei first collided to study a quark-gluon plasma : determining the critical energy necessary for its formation ^[106] .

In 2017, 5 hadrons were discovered ^[107] .

2018 (plan and reality)

It is planned to accumulate an integrated luminosity of at least 50 fb-1 in ATLAS and CMS detectors in 2018 ^[108] .

At the end of the year, a month was allocated for nuclear collisions ^[109] .

Technical Pause LS2: 2019–2020

The technical pause of Long Shutdown 2 is the second long break for accelerator optimization and an increase in proton energy to design 7 TeV ^[1] .

Future plans starting in 2015.

After restarting the collider in the spring of 2015, scientists are going to concentrate on searching for dark matter particles and supersymmetry ^[91] . This phase is planned until December 2017. From January to December 2018, it is planned to stop the accelerator optimization ^[1] . Further, after gaining an integral luminosity of 300 fb ^{−1 by the} current LHC, approximately from the beginning of 2024, in fact, the modernization of the collider under the HL-LHC project will begin, which will take 2.5 years. The stated goal of the modernized collider is to set 3000 fb ⁻¹ over 10 years ^[110] . It is believed that the project will work until 2034 , but already in 2014, CERN physicists began preparations for the implementation of other colliders, their capacity will be 10 times greater ^[111] . The study of the possibility of building a collider with a perimeter of up to 100 km ^{[111] [112] has begun} . The project is called FCC (Future Circular Collider), it combines the sequential creation of an electron-positron machine (FCC-ee) with an energy of 45-175 GeV in the beam to study Z-, W-, Higgs bosons and t-quark, and then, in the same tunnel, the hadron collider (FCC-hh) for energy up to 100 TeV ^[113] .

For 2019, Russia and Cern are interested in Russia's participation in the modernization of the collider ^[114] .

• LHC: chronology of creation and work (neopr.) . Elements.ru . Date of treatment June 14, 2014. Archived on February 9, 2014.
• CERN Topics / The Large Hadron Collider
• Video: what the robot sees inside the Large Hadron Collider
• The Large Hadron Collider. Chronicle of events (neopr.) . RIA News . Date of treatment June 28, 2019. Archived June 28, 2019.