Large Handron Collider

INTRODUCTION

The Large Hadron Collider (LHC) is a circular particle accelerator 27 miles circuferencia. It will be used to study the smallest known particles. Two beams of subatomic particles called 'hadrons' - either protons or lead ions - will travel in opposite directions inside the circular accelerator, gaining energy with every lap. Physicists will use the LHC to recreate the conditions just after the Big Bang, by colliding the two beams head-on at very high energy. There are many theories about what will result from these collisions, but what is certain is that a new world of physics will emerge from the new accelerator, as knowledge in particle physics will describe the workings of the Universe. for decades, the Standard Model, which is currently the theoretical framework of particle physics has served physicists as a way of understanding the fundamental laws of nature, but not complete. Only experimental data with the highest energies reached by the LHC can push knowledge forward, challenging those who seek confirmation of established knowledge, and those who dare to dream beyond paradigma.Uno major objective is to find the Higgs boson. largest accelerator ever built, the LHC, is making his final tests. Throttle only requires a power of 120 MW (800,000 MWh / year) to be supplied from French nuclear plants.

LARGE HANDRON COLLIDER

The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. It was built by the European Organization for Nuclear Research (CERN) from 1998 to 2008, with the aim of allowing physicists to test the predictions of different theories of particle physics and high-energy physics, and particularly that of the existence of the hypothesized Higgs boson and of the large family of new particles predicted by supersymmetric theories. The LHC is expected to address some of the most fundamental questions of physics, advancing human understanding of the deepest laws of nature. It contains six detectors each designed for specific kinds of exploration.

The LHC lies in a tunnel 27 kilometres (17 mi) in circumference, as deep as 175 metres (574 ft) beneath the Franco-Swiss border near Geneva, Switzerland. Its synchrotron is designed to collide opposing particle beams of either protons at up to 7 teraelectronvolts (7 TeV or 1.12 microjoules) per nucleon, or lead nuclei at an energy of 574 TeV (92.0 µJ) per nucleus (2.76 TeV per nucleon-pair). It was built in collaboration with over 10,000 scientists and engineers from over 100 countries, as well as hundreds of universities and laboratories.

On 10 September 2008, the proton beams were successfully circulated in the main ring of the LHC for the first time, but 9 days later operations were halted due to a magnet quench incident resulting from an electrical fault. The ensuing helium gas explosion damaged over 50 superconducting magnets and their mountings, and contaminated the vacuum pipe. On 20 November 2009 proton beams were successfully circulated again, with the first recorded proton–proton collisions occurring 3 days later at the injection energy of 450 GeV per beam. On 30 March 2010, the first collisions took place between two 3.5 TeV beams, setting the current world record for the highest-energy man-made particle collisions, and the LHC began its planned research program.

The LHC will operate at 4 TeV per beam until the end of 2012, 0.5 TeV higher than in 2010 and 2011. It will then go into shutdown for 20 months for upgrades to allow full energy operation (7 TeV per beam), with reopening planned for late 2014

Accelerator chainthe Large Hadron Collider (LHC)

LCH Experiments

ATLAS A Toroidal LHC ApparatusCMS Compact Muon SolenoidLHCb LHC-beautyALICE A Large Ion Collider Experiment

TOTEM Total Cross Section, Elastic Scattering and Diffraction Dissociation

LHCf LHC-forward

MoEDALMonopole and Exotics Detector At the LHC

LHC Preaccelerators

p and Pb Linear accelerators for protons (Linac 2) and Lead (Linac 3)

(not marked) Proton Synchrotron BoosterPS Proton SynchrotronSPS Super Proton Synchrotron

HISTORY

The project was officially launched in 1984, with a symposium in Lausanne, Switzerland. Groups were formed to propose a project to accelerate hadrons. In 1989 the first collaborations began and it became the priority project at CERN. In 1992 a meeting in Evian, France marks the beginning for the proposed experiments. The idea was to build a sophisticated accelerator superconductor that worked at very low temperatures. On 16 December 1994 the CERN Council approved the project to be built in two stages. In June 1995 Japan becomes CERN observer and his education minister announced a financial contribution to the project. The opportunity offers a Daruma the Director General of CERN, including all mystical symbol. In October 1996, the technical report with the design of the LHC was published detailing the operation and architecture of the future accelerator. In February, four years after the first technical proposals, CMS and ATLAS experiments are officially approved. Both hope to find the Higgs boson and probe the mysterious dark matter that pervades the universe. FOLLOWING year two detectors are officially approved: ALICE whose task is to study the primordial quark-gluon plasma and that becomes fourth LHCb experiment approved to study the phenomenon known as CP violation that can explain the asymmetry existing in materiaantimateria universe.

Thanks to financial contributions, the India, Russia and Canada, the CERN Council decided in 1997 to build the LHC in one step. In December the U.S. signed a partnership agreement and participate in the project, particularly to produce supercondutores accelerator magnets. In 1998 the French government decreed the LHC as a public utility project thus obtaining consent to build.

In 2000 the LEP, the largest accelerator in the world at the time, since it had major successes, such as the detection of W boson It has to be removed to give the LHC physical space, as this would take advantage of the LEP tunnel, and would save the cost of its construction.

ETYMOLOGY

The term hadron refers to composite particles composed of quarks held together by the strong force (as atoms and molecules are held together by the electromagnetic force). The best-known hadrons are protons and neutrons; hadrons also include mesons such as the pion and kaon, which were discovered during cosmic ray experiments in the late 1940s and early 1950s.

A collider is a type of a particle accelerator with directed beams of elementary particles. In particle physics colliders are used as a research tool: they accelerate particles to very high kinetic energies and let them impact other particles. Analysis of the byproducts of these

collisions gives scientists good evidence of the structure of the subatomic world and the laws of nature governing it. Many of these byproducts are produced only by high energy collisions, and they decay after very short periods of time. Thus many of them are hard or impossible to study in other ways.

OPERATION

The set of facilities constituent LHC several rings of different sizes. In all of these magnets are used to generate an intense magnetic field to accelerate and bend the path of the proton beams within each ring or ring for transfer to the next. The protons process followed is:

Hydrogen is taken from a container. The hydrogen is ionized electrons tearing, which we have only protons. The proton flux passes through the various rings, each of which is accelerated and therefore its power is increased. Then a proton flux is introduced into one of two parallel rings forming the LHC. In a ring protons circulating in the clockwise direction (same clockwise) and the other counterclockwise (reverse of clockwise). Periodically, the flow of the two rings to deviate slightly protons collide frontally.

One of the tasks of 2010 was to reach the LHC luminosity of 1032 particles per square centimeter per second. The brightness is a measure of the efficiency of a particle accelerator. As that goal was reached on October 13 was passed to the next stage.

After extracting the final proton beam of 2010 in the beginning of November, it took just four days to replace it with a lead ion beam which remained stable. On November 7 the LHC began a new phase: the collision of lead ions to study a primary phase of matter. In the lead-ion collisions are simulated conditions in the first microseconds after the Big Bang where matter reaches a temperature greater than 100,000 times that of the center of the Sun ALICE, ATLAS and CMS are the three detectors designed to record data and the recruitment process reaches the 6th of December when then the LHC will shutdown for the period of the maintenance of winter.

The main TAEA LHC is to discover the Higgs, also called "the God particle". Another important task is to understand the current asymmetry between matter and antimatter in the universe since both were paramount in equal amounts. Understand what the universe was still in its first moments and why today 96% of its constitution has nothing to do with the matter observed and another with dark matter and energy that promote an accelerated expansion of the universe are also issues that occupy the minds of many physicists at the LHC. All these questions are not answered by the current Standard Model, because despite being the most tested model of all time is still incomplete. The LHC will search for clues to these answers.

EXPERIMENTS

ALICELarge Ion Collider Experiment. For the experiment ALICE, the LHC will collide lead ions to recreate in the laboratory the conditions that prevailed just after the Big Bang. The data obtained allow to study the evolution of matter from the birth of the universe to the present.A collaboration of more than 1,000 scientists representing 94 institutions and 28 countries working on the ALICE experiment (March 2006).

Dimensions: 26 meters long, 16 meters wide, 16 meters high.

Weight: 10,000 tons

Configuration: barrel muon spectrometer central rather small angle of one arm.

Location: St Genis-Pouilly, France.

ATLASToroidal LHC Apparatus. ATLAS is one of two multi-purpose detectors at the LHC. Explore a wide range of fields of physics, from the search for the Higgs boson to other dimensions, including the search of particles that can constitute the dark matter.ATLAS, which shares the same goals of the CMS physics, comparable data measured on the particles created during collisions: his career, his energy and nature. That said, the technical solutions and the selected settings for magnetic systems of these two detectors are radically different. More than 1,700 scientists, representing 159 institutions and 37 countries, working on the ATLAS experiment (March 2006).

Dimensions: 46 meters long, 25 meters wide, 25 meters high, ATLAS is the largest detector ever built.

Weight: 7,000 tons.

Configuration: barrel and caps.

Location: Meyrin, Switzerland.

CMSCompact Muon Solenoid. The CMS experiment uses a multipurpose detector to explore a wide range of fields of physics, from the search for the Higgs boson to other dimensions including the search of particles that could constitute the dark matter. Although scientists pursuing the same goals as the ATLAS experiment, the CMS collaboration has chosen technical solutions and a different conception magnetic system. More than 2,000 scientists, representing 155 institutions and 37 countries, collaborating on the CMS experiment (October 2006).

Dimensions: 21 meters long, 15 meters wide and 15 meters high.

Weight: 12,500 tons.

Configuration: barrel and caps.

Location: Cessy, France.

LHCb Beauty of the Large Hadron Collider. The LHCb experiment seeks to understand why we live in a universe that seems to consist entirely of matter, without any presence of antimatter.

The experiment will explore the differences between matter and antimatter by studying a type of particles called "beauty quark" or "b quark." The LHC will recreate the moments just after the Big Bang, during which there would have pairs of quarks by antiquarks b.LHCb Collaboration has 650 scientists representing 48 institutions and 13 countries (April 2006).

Dimensions: 21 meters long, 13 meters wide and 10 meters high.

Weight: 5,600 tons.

Configuration: small angle spectrometer with planar detectors.

Location: Ferney-Voltaire, France.

TOTEM Total cross section measurement of elastic and diffractive. The experiment examines the particles TOTEM very small angles, a portion of the physical polyvalent inaccessible to experiments. Among other research TOTEM measured, for example, the dimensions of the protons and accurately evaluate the LHC luminosity.TOTEM supplement the results obtained by the CMS detector and by the other LHC experiments.

The TOTEM experiment has 50 scientists representing 10 institutions and 8 countries (2006).

Dimensions: 440 meters long, 5 meters wide and 5 meters high

Weight: 20 tons.

Configuration: Roman amphorae with GEM detectors and cathode chambers tapes.

Location: Cessy, France (near CMS).

LHCf Large Hadron Collider advanced. The experiment used LHCf small angle particles created inside the LHC to simulate cosmic rays in laboratory conditions, which may help physicists to contrast the huge detectors of cosmic rays experiments (some may cover thousands of kilometers) and to interpret their results. The experiment LHCf has 22 scientists representing 10 institutions and four countries (September 2006).

Dimensions: two switches, each of which measured 30 cm long, 10 cm wide and 80 cm.

Weight: 40 kg each.

Location: Meyrin, Switzerland (near ATLAS).

Answers we expect to find

Physicists hope that the LHC will provide answers to the following questions:

The significance of the mass. If the Higgs boson exists. The origin of the mass of baryons. Total particle number atom. If the particles interact with the Higgs field. 95% of the mass of the universe is made of matter is known and expected to know what is dark matter. The existence of supersymmetric particles. If there are extra dimensions, as predicted by various models inspired by string theory, and, if so, why have not been able to perceive. If more violations of symmetry between matter and antimatter. Recreate the conditions that caused the Big Bang.

BudgetsThe construction of LHC was approved in 1995 with a budget of 2.6 billion Swiss francs (about 1.7 billion euros), with another 210 million francs (€ 140 million) for the experiments. However, this cost was passed in the 2001 revision of 480 million francs (300 million €) in the gas, and 50 million francs (€ 30m) in paragraph for more experiments. Another 180 million francs (€ 120m) more have had to devote to the increased costs of superconducting magnetic coils. And there are still technical problems in the construction of the last tunnel will be located underground where the Compact Muon Solenoid (CMS). The budget of the institution approved for 2008 is EUR 660 515 000 for a total of 53,929,422 euros.Funding cuts planned for 2011 is 15 million Swiss francs in the 1,100 million euro of the total budget, which represent less than 1.5 percent of annual investment and the following year two percent, so to save 262 million euros for 2015.The delegate of Spain scientist at CERN, Carlos Pajares, has said that the Large Hadron Collider or LHC will not be affected by the funding cuts planned by the scientific to the economic crisis.

Purpose

A simulated event in the CMS detector, featuring the appearance of the Higgs boson

Physicists hope that the LHC will help answer some of the fundamental open questions in physics, concerning the basic laws governing the interactions and forces among the elementary objects, the deep structure of space and time, and in particular the interrelation between quantum mechanics and general relativity, where current theories and knowledge are unclear or break down altogether. Data are also needed from high energy particle experiments to suggest which versions of current scientific models are more likely to be correct – in particular to choose between the Standard Model and Higgsless models and to validate their predictions and allow further theoretical development. Many theorists expect new physics beyond the Standard Model to emerge at the TeV energy level, as the Standard Model appears to be unsatisfactory. Issues possibly to be explored by LHC collisions include:[14]

Are the masses of elementary particles actually generated by the Higgs mechanism via electroweak symmetry breaking?[15] It is expected that the collider will either demonstrate or rule out the existence of the elusive Higgs boson, thereby allowing physicists to consider whether the Standard Model or its Higgsless model alternatives are more likely to be correct.[16][17][18]

Is supersymmetry, an extension of the Standard Model and Poincaré symmetry, realised in nature, implying that all known particles have supersymmetric partners?[19][20][21]

Are there extra dimensions,[22] as predicted by various models based on string theory, and can we detect them?[23]

What is the nature of the dark matter that appears to account for 23% of the mass-energy of the universe?

Other open questions that may be explored using high energy particle collisions:

It is already known that electromagnetism and the weak nuclear force are different manifestations of a single force called the electroweak force. The LHC may clarify whether the electroweak force and the strong nuclear force are similarly just different manifestations of one universal unified force, as predicted by various Grand Unification Theories.

Why is the fourth fundamental force (gravity) so many orders of magnitude weaker than the other three fundamental forces? See also Hierarchy problem.

Are there additional sources of quark flavour mixing, beyond those already predicted within the Standard Model?

Why are there apparent violations of the symmetry between matter and antimatter? See also CP violation.

What are the nature and properties of quark-gluon plasma, believed to have existed in the early universe and in certain compact and strange astronomical objects today? This will be investigated by heavy ion collisions in ALICE.

Design

A Feynman diagram of one way the Higgs boson may be produced at the LHC. Here, two quarks each emit a W or Z boson, which combine to make a neutral Higgs.

Map of the Large Hadron Collider at CERN

The LHC is the world's largest and highest-energy particle accelerator.[3][24] The collider is contained in a circular tunnel, with a circumference of 27 kilometres (17 mi), at a depth ranging from 50 to 175 metres (160 to 574 ft) underground.

The 3.8-metre (12 ft) wide concrete-lined tunnel, constructed between 1983 and 1988, was formerly used to house the Large Electron–Positron Collider.[25] It crosses the border between Switzerland and France at four points, with most of it in France. Surface buildings hold ancillary equipment such as compressors, ventilation equipment, control electronics and refrigeration plants.

The collider tunnel contains two adjacent parallel beamlines (or beam pipes) that intersect at four points, each containing a proton beam, which travel in opposite directions around the ring. Some 1,232 dipole magnets keep the beams on their circular path, while an additional 392 quadrupole magnets are used to keep the beams focused, in order to maximize the chances of interaction between the particles in the four intersection points, where the two beams will cross. In total, over 1,600 superconducting magnets are installed, with most weighing over 27 tonnes. Approximately 96 tonnes of liquid helium is needed to keep the magnets, made of copper-clad niobium-titanium, at their operating temperature of 1.9 K (−271.25 °C), making the LHC the largest cryogenic facility in the world at liquid helium temperature.

Superconducting quadrupole electromagnets are used to direct the beams to four intersection points, where interactions between accelerated protons will take place.

When running at full design power of 7 TeV per beam, once or twice a day, as the protons are accelerated from 450 GeV to 7 TeV, the field of the superconducting dipole magnets will be increased from 0.54 to 8.3 teslas (T). The protons will each have an energy of 7 TeV, giving a total collision energy of 14 TeV. At this energy the protons have a Lorentz factor of about 7,500 and move at about 0.999999991 c, or about 3 metres per second slower than the speed of light (c).[26] It will take less than 90 microseconds (μs) for a proton to travel once around the main ring – a speed of about 11,000 revolutions per second. Rather than continuous beams, the protons will be bunched together, into 2,808 bunches, 115 billion protons in each bunch so that interactions between the two beams will take

place at discrete intervals never shorter than 25 nanoseconds (ns) apart. However it will be operated with fewer bunches when it is first commissioned, giving it a bunch crossing interval of 75 ns.[27] The design luminosity of the LHC is 1034 cm−2s−1, providing a bunch collision rate of 40 MHz.[28]

Prior to being injected into the main accelerator, the particles are prepared by a series of systems that successively increase their energy. The first system is the linear particle accelerator LINAC 2 generating 50-MeV protons, which feeds the Proton Synchrotron Booster (PSB). There the protons are accelerated to 1.4 GeV and injected into the Proton Synchrotron (PS), where they are accelerated to 26 GeV. Finally the Super Proton Synchrotron (SPS) is used to further increase their energy to 450 GeV before they are at last injected (over a period of 20 minutes) into the main ring. Here the proton bunches are accumulated, accelerated (over a period of 20 minutes) to their peak 7-TeV energy, and finally circulated for 10 to 24 hours while collisions occur at the four intersection points.[29]

CMS detector for LHC

The LHC physics program is mainly based on proton–proton collisions. However, shorter running periods, typically one month per year, with heavy-ion collisions are included in the program. While lighter ions are considered as well, the baseline scheme deals with lead ions[30] (see A Large Ion Collider Experiment). The lead ions will be first accelerated by the linear accelerator LINAC 3, and the Low-Energy Ion Ring (LEIR) will be used as an ion storage and cooler unit. The ions will then be further accelerated by the PS and SPS before being injected into LHC ring, where they will reach an energy of 2.76 TeV per nucleon (or 575 TeV per ion), higher than the energies reached by the Relativistic Heavy Ion Collider. The aim of the heavy-ion program is to investigate quark–gluon plasma, which existed in the early universe.

DetectorsSee also: List of Large Hadron Collider experiments

Six detectors have been constructed at the LHC, located underground in large caverns excavated at the LHC's intersection points. Two of them, the ATLAS experiment and the Compact Muon Solenoid (CMS), are large, general purpose particle detectors.[24] A Large Ion Collider Experiment (ALICE) and LHCb, have more specific roles and the last two, TOTEM and LHCf, are very much smaller and are for very specialized research. The BBC's summary of the main detectors is:[31]

Detector Description

ATLASOne of two general purpose detectors. ATLAS will be used to look for signs of new physics, including the origins of mass and extra dimensions.

CMSThe other general purpose detector will, like ATLAS, hunt for the Higgs boson and look for clues to the nature of dark matter.

ALICEALICE is studying a "fluid" form of matter called quark–gluon plasma that existed shortly after the Big Bang.

LHCbEqual amounts of matter and antimatter were created in the Big Bang. LHCb will try to investigate what happened to the "missing" antimatter.

Operational history

Inaugural tests

The first beam was circulated through the collider on the morning of 10 September 2008.[31]

CERN successfully fired the protons around the tunnel in stages, three kilometres at a time. The particles were fired in a clockwise direction into the accelerator and successfully steered around it at 10:28 local time.[32] The LHC successfully completed its major test: after a series of trial runs, two white dots flashed on a computer screen showing the protons travelled the full length of the collider. It took less than one hour to guide the stream of particles around its inaugural circuit.[33] CERN next successfully sent a beam of protons in a counterclockwise direction, taking slightly longer at one and a half hours due to a problem with the cryogenics, with the full circuit being completed at 14:59.

2008 quench incident

On 19 September 2008, a magnet quench occurred in about 100 bending magnets in sectors 3 and 4, causing a loss of approximately six tonnes of liquid helium, which was vented into the tunnel, and a temperature rise of about 100 degrees celsius in some of the affected magnets. Vacuum conditions in the beam pipe were also lost, and mechanical damage was caused.[34] Shortly after the incident CERN reported that the most likely cause of the problem was a faulty electrical connection between two magnets, and that – due to the time needed to warm up the affected sectors and then cool them back down to operating temperature – it would take at least two months to fix.[35] Subsequently, CERN released a preliminary analysis of the incident on 16 October 2008,[36] and a more detailed one on 5

December 2008.[37] Both analyses confirmed that the incident was indeed initiated by a faulty electrical connection. A total of 53 magnets were damaged in the incident and were repaired or replaced during the winter shutdown.[38]

In the original timeline of the LHC commissioning, the first "modest" high-energy collisions at a center-of-mass energy of 900 GeV were expected to take place before the end of September 2008, and the LHC was expected to be operating at 10 TeV by the end of 2008.[39] However, due to the delay caused by the above-mentioned incident, the collider was not operational until November 2009.[40] Despite the delay, LHC was officially inaugurated on 21 October 2008, in the presence of political leaders, science ministers from CERN's 20 Member States, CERN officials, and members of the worldwide scientific community.[41]

Most of 2009 was spent on repairs and reviews from the damage caused by the quench incident, along with two further vacuum leaks identified in July 2009 which pushed the start of operations to November of that year.[42]

Full operation

On 20 November 2009, low-energy beams circulated in the tunnel for the first time since the incident, and shortly after, on 30 November, the LHC achieved 1.18 TeV per beam to become the world's highest-energy particle accelerator, beating the Tevatron's previous record of 0.98 TeV per beam held for eight years.[43]

The early part of 2010 saw the continued ramp-up of beam in energies and early physics experiments towards 3.5 TeV per beam and on 30 March 2010, LHC set the present record for high-energy collisions by colliding proton beams at a combined energy level of 7 TeV. The attempt was the third that day, after two unsuccessful attempts in which the protons had to be "dumped" from the collider and new beams had to be injected.[44] This also marked the start of its main research program.

The first proton run ended on 4 November 2010. A run with lead ions started on 8 November 2010, and ended on 6 December 2010,[45] allowing the ALICE experiment to study matter under extreme conditions similar to those shortly after the Big Bang.[46]

CERN has declared that the LHC will run through to the end of 2012, with a short technical stop at the end of 2011. The energy for 2011 was 3.5 TeV per beam, whereas for 2012 it was decided to run the LHC at 4 TeV per beam. In 2013 the LHC will go into a long shutdown to prepare for higher-energy running starting in 2014.[13]

Timeline of operationsDate Event

10 Sep 2008 CERN successfully fired the first protons around the entire tunnel circuit in stages.

19 Sep 2008 Magnetic quench occurred in about 100 bending magnets in sectors 3 and 4, causing

a loss of approximately 6 tonnes of liquid helium.

30 Sep 2008 First "modest" high-energy collisions planned but postponed due to accident.

16 Oct 2008 CERN released a preliminary analysis of the accident.

21 Oct 2008 Official inauguration.

 5 Dec 2008 CERN released detailed analysis.

20 Nov 2009 Low-energy beams circulated in the tunnel for the first time since the accident.[47]

23 Nov 2009 First particle collisions in all four detectors at 450 GeV.

30 Nov 2009LHC becomes the world's highest-energy particle accelerator achieving 1.18 TeV per beam, beating the Tevatron's previous record of 0.98 TeV per beam held for eight years.[43]

28 Feb 2010The LHC continues operations ramping energies to run at 3.5 TeV for 18 months to two years, after which it will be shut down to prepare for the 14 TeV collisions (7 TeV per beam).[48]

30 Mar 2010The two beams collided at 7 TeV (3.5 TeV per beam) in the LHC at 13:06 CEST, marking the start of the LHC research program.

8 Nov 2010 Start of the first run with lead ions.

6 Dec 2010 End of the run with lead ions. Shutdown until early 2011.

13 Mar 2011 Beginning of the 2011 run with proton beams.[49]

21 Apr 2011LHC becomes the world's highest-luminosity hadron accelerator achieving a peak luminosity of 4.67·1032 cm−2s−1, beating the Tevatron's previous record of 4·1032 cm−2s−1 held for one year.[50]

17 Jun 2011 The high luminosity experiments ATLAS and CMS reach 1 fb -1 of collected data.[51]

14 Oct 2011 LHCb reaches 1 fb-1 of collected data.[52]

23 Oct 2011 The high luminosity experiments ATLAS and CMS reach 5 fb-1 of collected data.

5 Apr 2012First collisions with stable beams in 2012 after the winter shutdown. The energy is increased to 4 TeV per beam (8 TeV in collisions).[53]

4 July 2012Announcement of observation of a new boson consistent with the theorized Higgs boson.

Findings

CERN scientists estimated that, if the Standard Model is correct, a single Higgs boson may be produced every few hours, and that over a few years enough data to confirm or disprove the Higgs boson unambiguously and to obtain sufficient results concerning supersymmetric particles would be gathered to draw meaningful conclusions.[3] On the other hand, some extensions of the Standard Model predict additional particles, such as the heavy W' and Z' gauge bosons, whose existence might already be probed after a few months of data collection.[54]

The first physics results from the LHC, involving 284 collisions which took place in the ALICE detector, were reported on 15 December 2009.[55] The results of the first proton–proton collisions at energies higher than Fermilab's Tevatron proton–antiproton collisions were published by the CMS collaboration in early February 2010, yielding greater-than-predicted charged-hadron production.[56]

After the first year of data collection, the LHC experimental collaborations started to release their preliminary results concerning searches for new physics beyond the Standard Model in proton-proton collisions.[57][58][59][60] No evidence of new particles was detected in the 2010 data. As a result, bounds were set on the allowed parameter space of various extensions of the Standard Model, such as models with large extra dimensions, constrained versions of the Minimal Supersymmetric Standard Model, and others.[61][62][63]

On 24 May 2011, it was reported that quark–gluon plasma (the densest matter besides black holes) has been created in the LHC.[64]

Between July and August 2011, results of searches for the Higgs boson and for exotic particles, based on the data collected during the first half of the 2011 run, were presented in conferences in Grenoble[65] and Mumbai.[66] In the latter conference it was reported that, despite hints of a Higgs signal in earlier data, ATLAS and CMS exclude with 95% confidence level (using the CLs method) the existence of a Higgs boson with the properties predicted by the Standard Model over most of the mass region between 145 and 466 GeV.[67] The searches for new particles did not yield signals either, allowing to further constrain the parameter space of various extensions of the Standard Model, including its supersymmetric extensions.[68][69]

On 13 December 2011, CERN reported that the Standard Model Higgs boson, if it exists, is most likely to have a mass constrained to the range 115-130 GeV. Both the CMS and ATLAS detectors have also shown intensity peaks in the 124–125 GeV range, consistent with either background noise or the observation of the Higgs boson.[70]

On 22 December 2011, it was reported that a new particle had been observed, the χb (3P) bottomonium state.[71]

On 4 July 2012, both the CMS and ATLAS teams announced the discovery of a boson in the mass region around 125-126 GeV, with a statistical significance at the level of 5 sigma.

This meets the formal level required to announce a new particle which is "consistent with" the Higgs boson, but scientists are cautious as to whether it is formally identified as actually being the Higgs boson, pending further analysis.[72]

Proposed upgradeMain article: Super Large Hadron Collider

After some years of running, any particle physics experiment typically begins to suffer from diminishing returns: as the key results reachable by the device begin to be completed, later years of operation discover proportionately less than earlier years. A common outcome is to upgrade the devices involved, typically in energy, in luminosity, or in terms of improved detectors. A luminosity upgrade of the LHC, called the Super LHC, has been proposed,[73] to be made in 2018 after ten years of operation.

The optimal path for the LHC luminosity upgrade includes an increase in the beam current (i.e. the number of protons in the beams) and the modification of the two high-luminosity interaction regions, ATLAS and CMS. To achieve these increases, the energy of the beams at the point that they are injected into the (Super) LHC should also be increased to 1 TeV. This will require an upgrade of the full pre-injector system, the needed changes in the Super Proton Synchrotron being the most expensive. Currently the collaborative research effort of LHC Accelerator Research Program, LARP is conducting research into how to achieve these goals.[74]

CostSee also: List of megaprojects

With a budget of 7.5 billion euros (approx. $9bn or £6.19bn as of Jun 2010), the LHC is one of the most expensive scientific instruments[75] ever built.[76] The total cost of the project is expected to be of the order of 4.6bn Swiss francs (approx. $4.4bn, €3.1bn, or £2.8bn as of Jan 2010) for the accelerator and SFr 1.16bn (approx. $1.1bn, €0.8bn, or £0.7bn as of Jan 2010) for the CERN contribution to the experiments.[77]

The construction of LHC was approved in 1995 with a budget of SFr 2.6bn, with another SFr 210M towards the experiments. However, cost overruns, estimated in a major review in 2001 at around SFr 480M for the accelerator, and SFr 50M for the experiments, along with a reduction in CERN's budget, pushed the completion date from 2005 to April 2007.[78] The superconducting magnets were responsible for SFr 180M of the cost increase. There were also further costs and delays due to engineering difficulties encountered while building the underground cavern for the Compact Muon Solenoid,[79] and also due to faulty parts provided by Fermilab.[80] Due to lower electricity costs during the summer, it is expected that the LHC will normally not operate over the winter months,[81] although an exception was made to make up for the 2008 start-up delays over the 2009/10 winter.

Computing resources

Data produced by LHC, as well as LHC-related simulation, was estimated at approximately 15 petabytes per year (max throughput while running not stated).[82]

The LHC Computing Grid [83] was constructed to handle the massive amounts of data produced. It incorporated both private fiber optic cable links and existing high-speed portions of the public Internet, enabling data transfer from CERN to academic institutions around the world.[84]

The Open Science Grid is used as the primary infrastructure in the United States, and also as part of an interoperable federation with the LHC Computing Grid.

The distributed computing project LHC@home was started to support the construction and calibration of the LHC. The project uses the BOINC platform, enabling anybody with an Internet connection and a computer running Mac OSX, Windows or Linux,[85] to use their computer's idle time to simulate how particles will travel in the tunnel. With this information, the scientists will be able to determine how the magnets should be calibrated to gain the most stable "orbit" of the beams in the ring.[86] In August 2011, a second application went live (Test4Theory) which performs simulations against which to compare actual test data, to determine confidence levels of the results.

Safety of particle collisionsMain article: Safety of particle collisions at the Large Hadron Collider

The experiments at the Large Hadron Collider sparked fears among the public that the particle collisions might produce doomsday phenomena, involving the production of stable microscopic black holes or the creation of hypothetical particles called strangelets.[87] Two CERN-commissioned safety reviews examined these concerns and concluded that the experiments at the LHC present no danger and that there is no reason for concern,[88][89][90] a conclusion expressly endorsed by the American Physical Society.[91]

Operational challenges

The size of the LHC constitutes an exceptional engineering challenge with unique operational issues on account of the amount of energy stored in the magnets and the beams.[29][92] While operating, the total energy stored in the magnets is 10 GJ (2,400 kilograms of TNT) and the total energy carried by the two beams reaches 724 MJ (173 kilograms of TNT).[93]

Loss of only one ten-millionth part (10−7) of the beam is sufficient to quench a superconducting magnet, while the beam dump must absorb 362 MJ (87 kilograms of TNT) for each of the two beams. These energies are carried by very little matter: under nominal operating conditions (2,808 bunches per beam, 1.15×1011 protons per bunch), the beam pipes contain 1.0×10−9 gram of hydrogen, which, in standard conditions for temperature and pressure, would fill the volume of one grain of fine sand.

Construction accidents and delaysWikinews has related news: CERN says repairs to LHC particle accelerator to cost €16.6 million

On 25 October 2005, José Pereira Lages, a technician, was killed in the LHC when a switchgear that was being transported fell on him.[94]

On 27 March 2007 a cryogenic magnet support broke during a pressure test involving one of the LHC's inner triplet (focusing quadrupole) magnet assemblies, provided by Fermilab and KEK. No one was injured. Fermilab director Pier Oddone stated "In this case we are dumbfounded that we missed some very simple balance of forces". This fault had been present in the original design, and remained during four engineering reviews over the following years.[95] Analysis revealed that its design, made as thin as possible for better insulation, was not strong enough to withstand the forces generated during pressure testing. Details are available in a statement from Fermilab, with which CERN is in agreement.[96][97] Repairing the broken magnet and reinforcing the eight identical assemblies used by LHC delayed the startup date, then planned for November 2007.

Problems occurred on 19 September 2008 during powering tests of the main dipole circuit, when an electrical fault in the bus between magnets caused a rupture and a leak of six tonnes of liquid helium. The operation was delayed for several months.[98] It is currently believed that a faulty electrical connection between two magnets caused an arc, which compromised the liquid-helium containment. Once the cooling layer was broken, the helium flooded the surrounding vacuum layer with sufficient force to break 10-ton magnets from their mountings. The explosion also contaminated the proton tubes with soot.[37][99] This accident was thoroughly discussed in a 22 February 2010 Superconductor Science and Technology article by CERN physicist Lucio Rossi.[100]

Two vacuum leaks were identified in July 2009, and the start of operations was further postponed to mid-November 2009.[42]

Popular culture

The Large Hadron Collider gained a considerable amount of attention from outside the scientific community and its progress is followed by most popular science media. The LHC has also sparked the imaginations of authors of works of fiction, such as novels, TV series, and video games, although descriptions of what it is, how it works, and projected outcomes of the experiments are often only vaguely accurate, occasionally causing concern among the general public.

The novel Angels & Demons, by Dan Brown, involves antimatter created at the LHC to be used in a weapon against the Vatican. In response CERN published a "Fact or Fiction?" page discussing the accuracy of the book's portrayal of the LHC, CERN, and particle physics in general.[101] The movie version of the book has footage filmed on-site at one of the experiments at the LHC; the director, Ron Howard, met with CERN experts in an effort to make the science in the story more accurate.[102]

The novel FlashForward, by Robert J. Sawyer, involves the search for the Higgs boson at the LHC. CERN published a "Science and Fiction" page interviewing Sawyer and physicists about the book and the TV series based on it.[103]

CERN employee Katherine McAlpine's "Large Hadron Rap"[104] surpassed 7 million YouTube views.[105][106] The band Les Horribles Cernettes was founded by female members of CERN. The name was chosen so to have the same initials as the LHC.[107][108]

National Geographic's "World's Toughest Fixes," Season 2 (2010) Episode 6 "Atom Smasher" features the replacement of the last superconducting magnet section in the repair of the supercollider after the 2008 quench incident. The episode includes actual footage from the repair facility to the inside of the supercollider, and explanations of the function, engineering, and purpose of the LHC.[109]

Gran colisionador de hadronesSaltar a: navegación, búsqueda

Para la hormona GCH, véase Gonadotropina coriónica humana.

Coordenadas: 46°14′N 06°03′E (mapa)

Cadena de aceleradoresdel Gran colisionador de hadrones (LHC)

Experimentos

ATLAS Aparato Toroidal del LHC

CMS Solenoide de Muones Compacto

LHCb LHC-beauty

ALICE Gran Colisionador de Iones

TOTEMSección de Cruce total, diseminaciónelástica y disociación por difracción

LHCf LHC-delantero

Preaceleradores

p y PbAcelerador linealde protones y Plomo

(no marcado) Lanzador de Protones del Sincrotrón

PS Sincrotrón de protones

SPS Supersincrotrón de protones

El Gran Colisionador de Hadrones, GCH (en inglés Large Hadron Collider, LHC) es un acelerador y colisionador de partículas ubicado en la Organización Europea para la

Investigación Nuclear (CERN, sigla que corresponde a su antiguo nombre en francés: Conseil Européen pour la Recherche Nucléaire), cerca de Ginebra, en la frontera franco-suiza. Fue diseñado para colisionar haces de hadrones, más exactamente de protones, de hasta 7 TeV de energía, siendo su propósito principal examinar la validez y límites del Modelo Estándar, el cual es actualmente el marco teórico de la física de partículas, del que se conoce su ruptura a niveles de energía altos.

Dentro del colisionador dos haces de protones son acelerados en sentidos opuestos hasta alcanzar el 99,99% de la velocidad de la luz, y se los hace chocar entre sí produciendo altísimas energías (aunque a escalas subatómicas) que permitirían simular algunos eventos ocurridos inmediatamente después del big bang.

El LHC es el acelerador de partículas más grande y energético del mundo.1 Usa el túnel de 27 km de circunferencia creado para el Gran Colisionador de Electrones y Positrones (LEP en inglés) y más de 2000 físicos de 34 países y cientos de universidades y laboratorios han participado en su construcción.

Una vez enfriado hasta su temperatura de funcionamiento, que es de 1,9 K (menos de 2 grados por encima del cero absoluto o −271,15 °C), los primeros haces de partículas fueron inyectados el 1 de agosto de 2008,2 y el primer intento para hacerlos circular por toda la trayectoria del colisionador se produjo el 10 de septiembre del año 2008.3 Aunque las primeras colisiones a alta energía en principio estuvieron previstas para el 21 de octubre de 2008,4 el experimento fue postergado debido a una avería que produjo la fuga del helio líquido que enfría uno de los imanes superconductores.n. 1

A fines de 2009 se volvió a poner en marcha, y el 30 de noviembre del 2010 se convirtió en el acelerador de partículas más potente al conseguir energías de 1,18 TeV en sus haces, superando el récord anterior de 0,98 TeV establecido por el Tevatrón estadounidense.5 El 30 de marzo de 2010 las primeras colisiones de protones del LHC alcanzaron una energía de 7 TeV (al chocar dos haces de 3,5 TeV cada uno) lo que significó un nuevo récord para este tipo de ensayos. En 2012 el LHC empezó a funcionar a 4 TeV por haz y al finalizar ese año entrará en parada durante 20 meses para realizar las mejoras necesarias para la operación a la energía máxima de 7 TeV por haz; la reapertura está prevista para finales de 2014.6

Este instrumento permitió confirmar la existencia de la partícula conocida como bosón de Higgs el 4 de julio del 2012, a veces llamada “partícula de la masa”. La observación de esta partícula confirmaría las predicciones y "enlaces perdidos" del Modelo Estándar de la física, pudiéndose explicar cómo las otras partículas elementales adquieren propiedades como la masa.7

Diseño del CMS collaboration.

Verificar la existencia del bosón de Higgs sería un paso significativo en la búsqueda de una teoría de la gran unificación, que pretende relacionar tres de las cuatro fuerzas fundamentales conocidas, quedando fuera de ella únicamente la gravedad. Además este bosón podría explicar por qué la gravedad es tan débil comparada con las otras tres fuerzas.n. 2 Junto al bosón de Higgs también podrían producirse otras nuevas partículas cuya existencia se ha predicho teóricamente, y para las que se ha planificado su búsqueda,9 como los strangelets, los micro agujeros negros, el monopolo magnético o las partículas supersimétricas.10

Contenido

1 Experimentos 2 Red de computación 3 Presupuesto 4 Alarmas sobre posibles catástrofes 5 Línea de tiempo del colisionador 6 Véase también 7 Notas 8 Referencias 9 Enlaces externos

Experimentos

Parte del túnel del LHC situada debajo del LHC P8, cerca del LHCb.

Los protones se acelerarán hasta tener una energía de 7 T eV cada uno (siendo el total de energía de la colisión de 14 TeV). Se están construyendo 5 experimentos para el LHC. Dos de ellos, ATLAS y CMS, son grandes detectores de partículas de propósito general. Los otros tres, LHCb, ALICE y TOTEM, son más pequeños y especializados. El LHC también puede emplearse para hacer colisionar iones pesados tales como plomo (la colisión tendrá una energía de 1150 TeV). Los físicos confían en que el LHC proporcione respuestas a las siguientes cuestiones:

El significado de la masa (se sabe cómo medirla pero no se sabe qué es realmente). La masa de las partículas y su origen (en particular, si existe el bosón de Higgs). El origen de la masa de los bariones. Número de partículas totales del átomo. A saber el por qué tienen las partículas elementales diferentes masas (es decir, si

interactúan las partículas con un campo de Higgs). El 95% de la masa del universo no está hecha de la materia que se conoce y se espera

saber qué es la materia oscura. La existencia o no de las partículas supersimétricas. Si hay dimensiones extras, tal como predicen varios modelos inspirados por la Teoría de

cuerdas, y, en caso afirmativo, por qué no se han podido percibir. Si hay más violaciones de simetría entre la materia y la antimateria. Recrear las condiciones que provocaron el Big Bang.11

El LHC es un proyecto de tamaño inmenso y una enorme tarea de ingeniería. Mientras esté encendido, la energía total almacenada en los imanes es 10 giga julios y en el haz 725 mega julios .

El detector CMS del LHC.

Tanques de helio.

Red de computación

La red de computación (Computing Grid en inglés) del LHC es una red de distribución diseñada por el CERN para manejar la enorme cantidad de datos que serán producidos por el Gran Colisionador de Hadrones. Incorpora tanto enlaces propios de fibra óptica como partes de Internet de alta velocidad.

El flujo de datos provisto desde los detectores se estima aproximadamente en 300 Gb/s, que es filtrado buscando "eventos interesantes", resultando un flujo de 300 Mb/s. El centro de cómputo del CERN, considerado "nivel 0" de la red, ha dedicado una conexión de 10 Gb/s.

Se espera que el proyecto genere 27 Terabytes de datos por día, más 10 TB de "resumen". Estos datos son enviados fuera del CERN a once instituciones académicas de Europa, Asia y Norteamérica, que constituyen el "nivel 1" de procesamiento. Otras 150 instituciones constituyen el "nivel 2".

Se espera que el LHC produzca entre 10 a 15 Petabytes de datos por año. Para controlar la configuración primaria para las máquinas de la red de ordenadores del LHC se utiliza una distribución científica del sistema operativo Linux llamada Scientific Linux. Esta red se utiliza para recibir y distribuir los datos a los 100.000 CPU de todo el mundo que constituyen los niveles 1 y 2 de procesamiento.12

Presupuesto

La construcción del LHC fue aprobada en 1995 con un presupuesto de 2600 millones de Francos suizos (alrededor de 1700 millones de euros), junto con otros 210 millones de francos (140 millones €) destinados a los experimentos. Sin embargo, este coste fue superado en la revisión de 2001 en 480 millones de francos (300 millones de €) en el acelerador, y 50 millones de francos (30m €) más en el apartado para experimentos.13 Otros 180 millones de francos (120m €) más se han tenido que destinar al incremento de costes de

las bobinas magnéticas superconductoras. Y todavía persisten problemas técnicos en la construcción del último túnel bajo tierra donde se emplazará el Solenoide compacto de muones (CMS). El presupuesto de la institución aprobado para 2008, es de 660.515.000 euros para un total de 53.929.422 euros.

El recorte de fondos previsto para el año 2011 es de 15 millones de francos suizos dentro de los 1.100 millones de euros del presupuesto total, lo que representaría menos del 1,5 por ciento de inversión anual; al año siguiente un dos por ciento; así hasta ahorrar 262 millones de euros para 2015.14 15

El delegado científico de España en el CERN, Carlos Pajares, ha asegurado que el Gran Colisionador de Hadrones o LHC no se verá afectado por el recorte de fondos previsto por la institución científica ante la crisis económica.14 15

"Todos los países dijimos que no había que tocar el programa del LHC y es lo que se hizo. El director general ha enviado un mensaje a toda la comunidad científica diciendo que el CERN se ha apretado el cinturón igualmente pero el LHC no va a sufrir", ha señalado Carlos Pajares.14 15

Alarmas sobre posibles catástrofes

Desde que se proyectó el Gran Colisionador Relativista de Iones (RHIC), el estadounidense Walter Wagner y el español Luis Sancho16 denunciaron ante un tribunal de Hawái al CERN y al Gobierno de Estados Unidos, afirmando que existe la posibilidad de que su funcionamiento desencadene procesos que, según ellos, serían capaces de provocar la destrucción de la Tierra. Sin embargo su postura es rechazada por la comunidad científica, ya que carece de cualquier respaldo matemático que la apoye.

Los procesos catastróficos que denuncian son:17

La formación de un agujero negro estable. La formación de materia extraña supermasiva, tan estable como la materia ordinaria. La formación de monopolos magnéticos (previstos en la teoría de la relatividad) que

pudieran catalizar el decaimiento del protón. La activación de la transición a un estado de vacío cuántico.

A este respecto, el CERN ha realizado estudios sobre la posibilidad de que se produzcan acontecimientos desastrosos como microagujeros negros 18 inestables, redes, o disfunciones magnéticas.19 La conclusión de estos estudios es que "no se encuentran bases fundadas que conduzcan a estas amenazas".20 21

Resumiendo:

En el hipotético caso de que se creara un agujero negro, sería tan infinitamente pequeño que podría atravesar la Tierra sin tocar ni un solo átomo, ya que el 95% de estos son

espacios vacíos. Debido a esto, no podría crecer y alcanzaría el espacio, donde su probabilidad de chocar contra algo y crecer, es aún más pequeña.[cita requerida]

El planeta Tierra está expuesto a fenómenos naturales similares o peores a los que serán producidos en el LHC.

Los rayos cósmicos alcanzan continuamente la Tierra a velocidades (y por tanto energías) enormes, incluso varios órdenes de magnitud mayores a las producidas en el LHC.

El Sol, debido a su tamaño, ha recibido 10.000 veces más. Considerando que todas las estrellas del universo visible reciben un número

equivalente, se alcanzan unos 1031 experimentos como el LHC y aún no se ha observado ningún evento como el postulado por Wagner y Sancho.

Durante la operación del colisionador de iones pesados relativistas (RHIC) en Brookhaven (EE. UU.) no se ha observado ni un solo strangelet. La producción de strangelets en el LHC es menos probable que el RHIC, y la experiencia en este acelerador ha validado el argumento de que no se pueden producir strangelets.

Estos argumentos no impidieron que hubiera revueltas e incluso un suicidio por temor al fin del mundo cuando LHC lanzó su primera partícula el 10 de septiembre del 2008.22

Línea de tiempo del colisionadorLínea de tiempo

Fecha Evento

2008-09-10

CERN disparó con éxito los primeros protones en el circuito del túnel por etapas.

2008-09-19

Se produjo amortiguación magnética en alrededor de 100 imanes de flexión en los sectores 3 y 4, causando una pérdida de aproximadamente 6 toneladas de helio líquido.

2008-09-30

Se tenía prevista la primera colisión, pero fue pospuesta por el accidente.

2008-10-16

CERN dio a conocer un análisis preliminar del incidente.

2008-10-21

Inauguración oficial.

2008-12-05

CERN publicó un análisis detallado.

2009-10-29

El LHC reanudó su operación a 3,5 TeV por haz.

2009-11-20

El LHC reinició sus operaciones.

2009-11-23

Los cuatro detectores captan las primeras colisiones a 450 GeV.

2009-11-30

El LHC rompe récord en ser el acelerador de partículas más potente del mundo, creando colisiones a 2.36 TeV (1.18 TeV por haz).

2009-12-16

El LHC es apagado para realizarse en él los ajustes necesarios para que pueda funcionar a 7 TeV.

2010-02-28

El LHC reanuda sus actividades, haciendo circular dos haces de partículas en sentidos contrarios con una energía de 450 GeV por haz.

2010-03-19

El LHC alcanza un nuevo récord haciendo circular los dos haces de protones, cada uno a 3.5 TeV.

2010-03-30

El LHC inicia exitosamente las colisiones de partículas a 7 TeV (3.5 TeV por haz). Se mantendría así hasta finales de 2011, para realizar los ajustes necesarios para ponerlo a funcionar a toda potencia (14 TeV).

2010-09-18

Se cierra junta de miembros del CERN, anunciandose que se pospondrá el experimento a 14 TeV para 2016.

2010-11-08

el Gran Colisionador de Hadrones (LHC), recreó con gran éxito un "mini Big Bang" provocado por el choque de iones, anunció el Centro Europeo de Física Nuclear (CERN, por siglas en francés).

2012-07-04

El 4 de julio de 2012 se presentaron en el CERN los resultados preliminares de los análisis conjuntos de los datos tomados por el LHC en 2011 y 2012. Los dos principales experimentos del acelerador (ATLAS y CMS) anunciaron la observación de una nueva partícula «compatible con el bosón de Higgs», con una masa de unos 125 GeV/c2.

Zoo de partículas en la supersimetría.

Convergencia de las tres fuerzas. Se marca la energía máxima del LHC.

Véase también

Hadrón DESY Fermilab Bosón de Higgs (uno de los entes más buscados con el GCH/LHC). Microagujero negro (probablemente se puedan sintetizar en el GCH). Observatorio Pierre Auger

Notas

1. ↑ Cada vez que el LHC sufre alguna avería, es necesario calentarlo hasta temperatura ambiente, reparar la avería y volver a enfriarlo a temperaturas cercanas al cero absoluto. El proceso completo conlleva aproximadamente unos tres meses.

2. ↑ Stephen Hawking apostó 100 dólares a que la partícula bosón de Higgs no existe, y mencionó que sería más interesante el no encontrarla.8

Historia:

El inicio oficial del proyecto fue en 1984, con un simposio organizado en Lausanne, Suiza. Se formaron grupos para proponer un proyecto que acelerase hadrones. En 1989 las primeras colaboraciones comenzaron y en él se tornó el proyecto prioritario del CERN. En 1992 un encuentro en Evian, Francia marca el inicio para las propuestas de experimentos. La idea era construir un acelerador supercondutor sofisticado que funcionase a bajísimas temperaturas. El 16 de diciembre de 1994 el consejo del CERN aprobó el proyecto para ser construido en dos etapas. En junio de 1995 Japón se torna observador del CERN y su ministro de educación anuncia una contribución financiera al proyecto. En la oportunidad ofrece un Daruma al Director general del CERN, incluyendo toda la mística del símbolo. En octubre de 1996 el informe técnico con el design del LHC fue publicado detallando la operación y la arquitectura del futuro acelerador. En febrero, cuatro años después de las primeras propuestas técnicas, los experimentos CMS y ATLAS son aprobados oficialmente. Ambos esperan encontrar el bosón de Higgs y sondear la misteriosa materia oscura que permea el universo. Al año seguiente otros dos detectores son aprobados oficialmente: ALICE cuya tarea es estudiar el plasma quark-gluón primordial y el LHCb

que se torna cuarto experimento aprobado para estudiar el fenómeno conocido como violación de CP que puede llegar a explicar la asimetría materiaantimateria existente en el universo.

Gracias a las contribuiciones financieras de la India, Rusia y Canadá, el consejo del CERN decide en 1997 construir el LHC en una etapa. En diciembre los Estados Unidos firman un acuerdo de colaboración y participan del proyecto, en particular para producir los magnetos supercondutores del acelerador. En 1998 el gobierno francés decreta el LHC como un proyecto de utilidad pública obteniendo así el consentimiento para construir.

En 2000 el LEP, el mayor acelerador del mundo en su época, ya que en él se habían obtenido éxitos importantes, como la detección del bosón W. Tiene que ser desmontado para dar espacio físico al LHC, ya que así se aprovecharía el túnel del LEP, y se ahorraría el coste de su construcción.FUNCIONAMIENTO:El conjunto de las instalaciones del LHC lo constituyen varios anillos de distintos tamaños. En todos ellos se emplean imanes para generar un campo magnético intenso que acelere y curve la trayectoria de los haces de protones dentro de cada anillo o para transferirlos al anillo siguiente. El proceso que siguen los protones es el siguiente:

Se toma hidrógeno de un recipiente. El hidrógeno es ionizado arrancándole los electrones, con lo que nos quedan sólo protones. El flujo de protones va pasando por los distintos anillos, en cada uno de los cuales es acelerado, y por tanto se va incrementando su energía. Entonces un flujo de protones es introducido en uno de los dos anillos paralelos que forman el LHC. En un anillo los protones circulan en el sentido dextrógiro (el mismo que las agujas del reloj) y en el otro levógiro (inverso al de las agujas del reloj). Periódicamente, los flujos de los dos anillos se desvían ligeramente para que los protones choquen frontalmente.

Una de las tareas de 2010 del LHC era llegar a la luminosidad de 1032 partículas por centímetro cuadrado por segundo. La luminosidad da una medida de la eficiencia de un acelerador de partículas. Como esa meta fuealcanzada el 13 de octubre se pasó a la próxima etapa. Después de extraer el haz de protones final de 2010 en el inicio de noviembre, fueron necesarios apenas cuatro días para substituirlo por un haz de iones de plomo que permaneció estable. El siete de noviembre el LHC inició una nueva fase: la colisión de iones de plomo para estudiar una fase primordial de la materia. En la colisión de iones de plomo se simulan las condiciones existentes en los primeros microsegundos después del Big Bang donde la materia alcanza una temperatura mayor que 100.000 veces la del centro del Sol. ALICE, ATLAS y CMS son los tres detectores diseñados para registrar datos y ese proceso de captación llega hasta el día 6 de diciembre cuando a continuación el LHC será apagado para el período de manutención técnica de invierno.La principal taea del LHC es descubrir el Higgs, también denominada "La partícula de Dios". Otra tarea importante es entender la actual asimetría entre materia y antimateria dado que en el universo primordial ambas existían en cantidades iguales. Entender aún como era el Universo en sus primeros instantes y por qué hoy en día 96% de su

constitución nada tiene que ver con la materia observada y sí con energía y materia oscuras que promueven una expansión acelerada del universo también son asuntos que ocupan la mente de muchos físicos en el LHC. Todas esas cuestiones no son respondidas por el actual Modelo Estándar, pues a pesar de haber sido este el modelo más testeado de todos los tiempos está aún incompleto. El LHC permitirá buscar pistas para tales respuestas.

History:

The project was officially launched in 1984, with a symposium in Lausanne, Switzerland. Groups were formed to propose a project to accelerate hadrons. In 1989 the first collaborations began and it became the priority project at CERN. In 1992 a meeting in Evian, France marks the beginning for the proposed experiments. The idea was to build a sophisticated accelerator superconductor that worked at very low temperatures. On 16 December 1994 the CERN Council approved the project to be built in two stages. In June 1995 Japan becomes CERN observer and his education minister announced a financial contribution to the project. The opportunity offers a Daruma the Director General of CERN, including all mystical symbol. In October 1996, the technical report with the design of the LHC was published detailing the operation and architecture of the future accelerator. In February, four years after the first technical proposals, CMS and ATLAS experiments are officially approved. Both hope to find the Higgs boson and probe the mysterious dark matter that pervades the universe. FOLLOWING year two detectors are officially approved: ALICE whose task is to study the primordial quark-gluon plasma and that becomes fourth LHCb experiment approved to study the phenomenon known as CP violation that can explain the asymmetry

existing in materiaantimateria universe.

Thanks to financial contributions, the India, Russia and Canada, the CERN Council decided in 1997 to build the LHC in one step. In December the U.S. signed a partnership agreement and participate in the project, particularly to produce supercondutores accelerator magnets. In 1998 the French government decreed the LHC as a public utility project thus obtaining consent to build.

In 2000 the LEP, the largest accelerator in the world at the time, since it had major successes, such as the detection of W boson It has to be removed to give the LHC physical space, as this would take advantage of the LEP tunnel, and would save the cost of its construction.OPERATION:The set of facilities constituent LHC several rings of different sizes. In all of these magnets are used to generate an intense magnetic field to accelerate and bend the path of the proton beams within each ring or ring for transfer to the next. The protons process followed is:cern3.jpg

Hydrogen is taken from a container. The hydrogen is ionized electrons tearing, which we have only protons. The proton flux passes through the various rings, each of which is accelerated and therefore its power is increased. Then a proton flux is introduced into one of two parallel rings forming the LHC. In a ring protons circulating in the clockwise direction (same clockwise) and the other counterclockwise (reverse of clockwise). Periodically, the flow of the two rings to deviate slightly protons collide frontally.

One of the tasks of 2010 was to reach the LHC luminosity of 1032 particles per square centimeter per second. The brightness is a measure of the efficiency of a particle accelerator. As that goal wasreached on October 13 was passed to the next stage. After extracting the final proton beam of 2010 in the beginning of November, it took just four days to replace it with a lead ion beam which remained stable. On November 7 the LHC began a new phase: the collision of lead ions to study a primary phase of matter. In the lead-ion collisions are simulated conditions in the first microseconds after the Big Bang where matter reaches a temperature greater than 100,000 times that of the center of the Sun ALICE, ATLAS and CMS are the three detectors designed to record data and the recruitment process reaches the 6th of December when then the LHC will shutdown for the period of the maintenance of winter.The main TAEA LHC is to discover the Higgs, also called "the God particle". Another important task is to understand the current asymmetry between matter and antimatter in the universe since both were paramount in equal amounts. Understand what the universe was still in its first moments and why today 96% of its constitution has nothing to do with the matter observed and another with dark matter and energy that promote an accelerated expansion of the universe are also issues that occupy the minds of many physicists at the LHC. All these questions are not answered by the current Standard Model, because despite being the most tested model of all time is still incomplete. The LHC will search for clues to these answers.

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ExperimentsALICE: Large Ion Collider ExperimentFor the experiment ALICE, the LHC will collide lead ions to recreate in the laboratory the conditions that prevailed just after the Big Bang. The data obtained allow to study the evolution of matter from the birth of the universe to the present.A collaboration of more than 1,000 scientists representing 94 institutions and 28 countries working on the ALICE experiment (March 2006).Imagen1.pngDimensions: 26 meters long, 16 meters wide, 16 meters high.Weight: 10,000 tonsConfiguration: barrel muon spectrometer central rather small angle of one arm.Location: St Genis-Pouilly, France.ATLAS: Toroidal LHC ApparatusATLAS is one of two multi-purpose detectors at the LHC. Explore a wide range of fields of physics, from the search for the Higgs boson to other dimensions, including the search of particles that can constitute the dark matter.ATLAS, which shares the same goals of the CMS physics, comparable data measured on the particles created during collisions: his career, his energy and nature. That said, the technical solutions and the selected settings for magnetic systems of these two detectors are radically different.More than 1,700 scientists, representing 159 institutions and 37 countries, working on the ATLAS experiment (March 2006).Imagen2.pngDimensions: 46 meters long, 25 meters wide, 25 meters high, ATLAS is the largest detector ever builtWeight: 7,000 tonsConfiguration: barrel and capsLocation: Meyrin, Switzerland.CMS: Compact Muon SolenoidThe CMS experiment uses a multipurpose detector to explore a wide range of fields of physics, from the search for the Higgs boson to other dimensions including the search of particles that could constitute the dark matter. Although scientists pursuing the same goals as the ATLAS experiment, the CMS collaboration has chosen technical solutions and a different conception magnetic system.

More than 2,000 scientists, representing 155 institutions and 37 countries, collaborating on the CMS experiment (October 2006).2.jpgDimensions: 21 meters long, 15 meters wide and 15 meters highWeight: 12,500 tonsConfiguration: barrel and capsLocation: Cessy, France.

LHCb: Beauty of the Large Hadron ColliderThe LHCb experiment seeks to understand why we live in a universe that seems to consist entirely of matter, without any presence of antimatter.The experiment will explore the differences between matter and antimatter by studying a type of particles called "beauty quark" or "b quark." The LHC will recreate the moments just after the Big Bang, during which there would have pairs of quarks by antiquarks b.LHCb Collaboration has 650 scientists representing 48 institutions and 13 countries (April 2006).Imagen31.jpgDimensions: 21 meters long, 13 meters wide and 10 meters highWeight: 5,600 tonsConfiguration: small angle spectrometer with planar detectorsLocation: Ferney-Voltaire, France.

TOTEM: Total cross section measurement of elastic and diffractiveThe experiment examines the particles TOTEM very small angles, a portion of the physical polyvalent inaccessible to experiments. Among other research TOTEM measured, for example, the dimensions of the protons and accurately evaluate the LHC luminosity.TOTEM supplement the results obtained by the CMS detector and by the other LHC experiments.The TOTEM experiment has 50 scientists representing 10 institutions and 8 countries (2006).200807311052_totem.jpgDimensions: 440 meters long, 5 meters wide and 5 meters highWeight: 20 tonsConfiguration: Roman amphorae with GEM detectors and cathode chambers tapesLocation: Cessy, France (near CMS)LHCf: Large Hadron Collider advancedThe experiment used LHCf small angle particles created inside the LHC to simulate cosmic rays in laboratory conditions, which may help physicists to contrast the huge detectors of cosmic rays experiments (some may cover thousands of kilometers) and to interpret their results.The experiment LHCf has 22 scientists representing 10 institutions and four countries (September 2006).

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Dimensions: two switches, each of which measured 30 cm long, 10 cm wide and 80 cm

Weight: 40 kg eachLocation: Meyrin, Switzerland (near ATLAS)

Answers we expect to find

Physicists hope that the LHC will provide answers to the following questions:

The significance of the mass. If the Higgs boson exists. The origin of the mass of baryons. Total particle number atom. If the particles interact with the Higgs field. 95% of the mass of the universe is made of matter is known and expected to know what is dark matter. The existence of supersymmetric particles. If there are extra dimensions, as predicted by various models inspired by string theory, and, if so, why have not been able to perceive. If more violations of symmetry between matter and antimatter. Recreate the conditions that caused the Big Bang.

BudgetsThe construction of LHC was approved in 1995 with a budget of 2.6 billion Swiss francs (about 1.7 billion euros), with another 210 million francs (€ 140 million) for the experiments. However, this cost was passed in the 2001 revision of 480 million francs (300 million €) in the gas, and 50 million francs (€ 30m) in paragraph for more experiments. Another 180 million francs (€ 120m) more have had to devote to the increased costs of superconducting magnetic coils. And there are still technical problems in the construction of the last tunnel will be located underground where the Compact Muon Solenoid (CMS). The budget of the institution approved for 2008 is EUR 660 515 000 for a total of 53,929,422 euros.Funding cuts planned for 2011 is 15 million Swiss francs in the 1,100 million euro of the total budget, which represent less than 1.5 percent of annual investment and the following year two percent, so to save 262 million euros for 2015.The delegate of Spain scientist at CERN, Carlos Pajares, has said that the Large Hadron Collider or LHC will not be affected by the funding cuts planned by the scientific to the economic crisis.