Large Hadron Collider

3.3816381638068 (1111)
Posted by kaori 05/01/2009 @ 00:07

Tags : large hadron collider, cern, physics, sciences

News headlines
The Large Hadron Collider Delayed Until October 2009 - Soft Sailor
The Large Hadron Collider went live last year in September. It kicked particles for about nine days after a technical problem caused the LHC to stop. Although it was supposed to go live in April, it was delayed until September 2009 because the damages...
Watch the Physics Rapper - New York Times
Her previous rap explaining the physics behind the Large Hadron Collider has been viewed more than 5 million times since its debut on YouTube a year ago. Alpinekat's new rap (above) is about nuclear physics, the field of science that explains why the...
Large Hadron Collider to run through the year in Higgs boson race - Times Online
The Large Hadron Collider (LHC) will start smashing its first protons in October and run through the winter to keep it ahead in the international race to find the elusive “God particle”. The CERN laboratory's decision to operate the £4 billion particle...
Are we witnessing the end of science? -
This may well be because scientists have lacked the right equipment – results from the Large Hadron Collider at Cern could break the logjam. But you do see something similar going on in physicists' attempts to unpack the composition of the universe....
The Daily Engadget: Stadium Screen Gaming, Colbert Unveils 'Ex-Xbox' - Switched
There's been plenty of doom and gloom surrounding the Large Hadron Collider and how it's going to cause a black hole that'll consume the Earth. If you listen to folks that actually know what they're talking about, that's apparently unlikely....
Naples teacher will help test theory at CERN - Stars and Stripes
This summer, she will become the first DODDs teacher to work at the European Organization of Nuclear Research in Switzerland, site of the Large Hadron Collider. She hopes her selection will open opportunities for students to take trips to the lab....
Hadron collider defence lands science prize for particle physicist - Times Online
Tom Whyntie, 25, impressed judges at The Times Cheltenham science festival when he spoke for three minutes on the CERN Large Hadron Collider. He denied that a failure to detect the Higgs boson — or “God particle” — would be a waste of the £5 billion...
University of Toronto's Supercomputer Goes Online Thursday - AHN
Among its planned use will be to examine particle collisions produced by the Large Hadron Collider in Switzerland, which seeks to recreate the condition before the Big Bang. Richard Peltier, scientific director of the project, said ultra powerful...
Overwhelmingly Large Hadron Collider Fired Up In Russia - The Spoof (satire)
Work on this collider has been going on for years now, but the Russians quite sensibly told people that it wasn't actually going to kill people before the media took hold of it. The Large Hadron Collider has terrified a large proportion of the Western...
Black holes on a desktop - Economist
WHEN the Large Hadron Collider, a giant particle accelerator near Geneva, was switched on last September, the press was full of scare stories about the risk of it producing a tiny black hole that would, despite its minuscule size, quickly swallow the...

Large Hadron Collider

Map of the Large Hadron Collider at CERN

The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator, intended to collide opposing particle beams, of either protons at an energy of 7 TeV per particle, or lead nuclei at an energy of 574 TeV per nucleus.

The Large Hadron Collider was built by the European Organization for Nuclear Research (CERN) with the intention of testing various predictions of high-energy physics, including the existence of the hypothesized Higgs boson and of the large family of new particles predicted by supersymmetry. It lies in a tunnel 27 kilometres (17 mi) in circumference, as much as 175 metres (570 ft) beneath the Franco-Swiss border near Geneva, Switzerland. It is funded by and 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. On 19 September 2008, the operations were halted because of a serious fault between two superconducting bending magnets. Due to the time required to repair the resulting damage and to add additional safety features, the LHC is scheduled to be operational again no sooner than September 2009.

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. (see A Large Ion Collider Experiment). This will allow an advancement in the experimental program currently in progress at the Relativistic Heavy Ion Collider (RHIC). The aim of the heavy-ion program is to provide a window on a state of matter known as Quark-gluon plasma, which characterized the early stage of the life of the Universe.

The LHC is the world's largest and highest-energy particle accelerator. 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 underground.

The 3.8 m wide concrete-lined tunnel, constructed between 1983 and 1988, was formerly used to house the Large Electron-Positron Collider. 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 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 of each weighing over 27 tonnes. Approximately 96 tonnes of liquid helium is needed to keep the magnets at their operating temperature of 1.9 K, making the LHC the largest cryogenic facility in the world at liquid helium temperature.

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 (2.2 μJ). At this energy the protons have a Lorentz factor of about 7,500 and move at about 99.9999991% of the speed of light. 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, 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.

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.

The LHC will also be used to collide lead (Pb) heavy ions with a collision energy of 1,150 TeV. The Pb 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 then will 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.

The first beam was circulated through the collider on the morning of 10 September 2008. 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. The LHC successfully completed its first 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. 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.

On 19 September 2008, a quench occurred in about 100 bending magnets in sectors 3 and 4, causing loss of approximately six tonnes of liquid helium, which was vented into the tunnel, and a temperature rise of about 100 kelvins in some of the affected magnets. Vacuum conditions in the beam pipe were also lost. 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 it. Subsequently, CERN released a preliminary analysis of the incident on 16 October 2008, and a more detailed one on 5 December 2008. Both analyses confirmed that the incident was indeed initiated by a faulty electrical connection. At most 29 magnets have been damaged in the incident and will have to be repaired or replaced during the winter shutdown.

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 time of the official inauguration on 21 October 2008. However, due to the delay caused by the above-mentioned incident, the collider will not be operational again before the end of September 2009. 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.

Once the supercollider is up and running, CERN scientists estimate that if the Standard Model is correct, a single Higgs boson may be produced every few hours. At this rate, it may take up to three years to collect enough data to discover the Higgs boson unambiguously. Similarly, it may take one year or more before sufficient results concerning supersymmetric particles have been gathered to draw meaningful conclusions.

After some years of running, any particle physics experiment typically begins to suffer from diminishing returns; each additional year of operation discovers less than the year before. The way around the diminishing returns is to upgrade the experiment, either in energy or in luminosity. A luminosity upgrade of the LHC, called the Super LHC, has been proposed, to be made after ten years of LHC 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.

The total cost of the project is expected to be €3.2–6.4 billion. The construction of LHC was approved in 1995 with a budget of 2.6 billion Swiss francs (€1.6 billion), with another 210 million francs (€140 million) towards the cost of the experiments. However, cost over-runs, estimated in a major review in 2001 at around 480 million francs (€300 million) for the accelerator, and 50 million francs (€30 million) for the experiments, along with a reduction in CERN's budget, pushed the completion date from 2005 to April 2007. The superconducting magnets were responsible for 180 million francs (€120 million) 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, and also due to faulty parts provided by Fermilab.

The LHC Computing Grid is being constructed to handle the massive amounts of data produced by the Large Hadron Collider. It incorporates 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.

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 to use their computer 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.

The upcoming experiments at the Large Hadron Collider have sparked fears among the public that the LHC particle collisions might produce doomsday phenomena, involving the production of stable microscopic black holes or the creation of hypothetical particles called strangelets. Two CERN-commissioned safety reviews have examined these concerns and concluded that the experiments at the LHC present no danger and that there is no reason for concern, a conclusion expressly endorsed by the American Physical Society, the world's second largest organization of physicists.

The size of the LHC constitutes an exceptional engineering challenge with unique operational issues on account of the huge energy stored in the magnets and the beams. While operating, the total energy stored in the magnets is 10 GJ (equivalent to one and a half barrels of oil or 2.4 tons of TNT) and the total energy carried by the two beams reaches 724 MJ (about a tenth of a barrel of oil, or half a lightning bolt).

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, an energy equivalent to that of burning eight kilograms of oil, for each of the two beams. These immense energies are even more impressive considering how little matter is carrying it: 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.

On 10 August 2008, computer hackers defaced a website at CERN, criticizing their computer security. There was no access to the control network of the collider.

The Large Hadron Collider has gained a lot of attention from outside the scientific community and its progress is followed by most popular science media. The LHC has also stirred a lot of imagination in works of fiction such as novels, tv series and video games. As is common in fiction, the portrayal is often only vaguely accurate, something that occasionally has caused concern among the 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. 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.

CERN employee Katherine McAlpine's "Large Hadron Rap" surpassed 5 million YouTube views.

To the top

Safety of particle collisions at the Large Hadron Collider

A simulated particle collision in the LHC.

Concerns have been raised in the media, on the Internet and through the law courts about the safety of the particle physics experiments planned to take place at the Large Hadron Collider (LHC), the world's largest and most powerful particle accelerator to date, built by the European Organization for Nuclear Research (CERN) near Geneva, in Switzerland. The claimed dangers of the LHC particle collisions, which are expected to begin in the summer of 2009, include doomsday scenarios involving the production of stable micro black holes and the creation of hypothetical particles called strangelets.

To address such concerns, CERN mandated a group of independent scientists to review these scenarios. In a report issued in 2003, they concluded that, like current particle experiments such as the Relativistic Heavy Ion Collider (RHIC), the LHC particle collisions pose no conceivable threat. A second review of the evidence commissioned by CERN was released in 2008. The report, prepared by a group of physicists not involved in the LHC experiments, reaffirmed the safety of the LHC collisions in light of further research conducted since the 2003 assessment. It was reviewed and endorsed by a CERN committee of 20 external scientists and by the Executive Committee of the Division of Particles & Fields of the American Physical Society, and was later published in the peer-reviewed Journal of Physics G by the UK Institute of Physics, which also endorsed its conclusions. The report ruled out any doomsday scenario at the LHC: the physical conditions and events that will be created in the LHC experiments occur naturally in the universe without hazardous consequences.

The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator complex, intended to collide opposing beams of protons (one of several types of hadrons) with very high kinetic energy. It was built by the European Organization for Nuclear Research (CERN) near Geneva, in Switzerland. The LHC's main purpose is to explore the validity and limitations of the Standard Model, the current theoretical picture for particle physics. The first particle collisions at the LHC are planned to take place in October 2009, with the full energy 14 TeV (center-of-mass) collisions planned to begin thereafter.

In the run up to the commissioning of the LHC, Walter L. Wagner (an American botanist and former radiation safety officer, as well as an original opponent of the RHIC), Luis Sancho (a Spanish science writer) and Otto Rössler (a German biochemist) have expressed concerns over the safety of the LHC, and have attempted to halt the beginning of the experiments through petitions to the US and European Courts. These opponents assert that the LHC experiments have the potential to create low velocity micro black holes that could grow in mass or release dangerous radiation leading to doomsday scenarios, such as the destruction of the Earth. Other claimed potential risks include the creation of theoretical particles called strangelets, magnetic monopoles and vacuum bubbles.

These risk assessments of catastrophic scenarios at the LHC have sparked fears among the public, and scientists associated with the project have received protests. The Large Hadron Collider team revealed that they had received death threats and threatening emails and phone calls demanding the experiment be halted. On 9 September 2008, Romania's Conservative Party held a protest before the European Commission mission to Bucharest, demanding that the experiment be halted because it feared that the LHC could create dangerous black holes.

The tabloids also covered the safety concerns. The Daily Mail produced headlines such as "End of the world postponed as broken Hadron Collider out of commission until the spring" and "Are we all going to die next Wednesday?" The Sun quoted Otto Rössler saying, "The weather will change completely, wiping out life. There will be a Biblical Armageddon." After the launch of the collider, it had a story entitled, "Success! The world hasn't ended".

On 10 September 2008, a 16-year-old girl from Sarangpur, Madhya Pradesh, India committed suicide, having become distressed about predictions of an impending "doomsday" made on an Indian news channel covering the LHC.

Drawing from research performed to assess the safety of the RHIC collisions, the LHC Safety Study Group, a group of independent scientists, performed a safety analysis of the LHC, and released their findings in the 2003 report Study of Potentially Dangerous Events During Heavy-Ion Collisions at the LHC. The report concluded that there is "no basis for any conceivable threat". Several of its arguments were based on the predicted evaporation of hypothetical micro black holes by Hawking radiation and on the theoretical predictions of the Standard Model with regard to the outcome of events to be studied in the LHC. One argument raised against doomsday fears was that collisions at energies equivalent to and higher than those of the LHC have been happening in nature for billions of years apparently without hazardous effects, as ultra-high-energy cosmic rays impact Earth's atmosphere and other bodies in the universe.

In 2007, CERN mandated a group of five particle physicists not involved in the LHC experiments — the LHC Safety Assessment Group (LSAG), consisting of John Ellis, Gian Giudice, Michelangelo Mangano and Urs Wiedemann, of CERN, and Igor Tkachev, of the Institute for Nuclear Research in Moscow — to monitor the latest concerns about the LHC collisions. On 20 June 2008, in light of new experimental data and theoretical understanding, the LSAG issued a report updating the 2003 safety review, in which they reaffirmed and extended its conclusions that "LHC collisions present no danger and that there are no reasons for concern". The LSAG report was then reviewed by CERN’s Scientific Policy Committee (SPC), a group of external scientists that advises CERN’s governing body, its Council. The report was reviewed and endorsed by a panel of five independent scientists, Peter Braun-Munzinger, Matteo Cavalli-Sforza, Gerard 't Hooft, Bryan Webber and Fabio Zwirner, and their conclusions were unanimously approved by the full 20 members of the SPC. On 5 September 2008, the LSAG's "Review of the safety of LHC collisions" was published in the Journal of Physics G: Nuclear and Particle Physics by the UK Institute of Physics, which endorsed its conclusions in a press release that announced the publication.

Following the July 2008 release of the LSAG safety report, the Executive Committee of the Division of Particles and Fields (DPF) of the American Physical Society, the world's second largest organization of physicists, issued a statement approving the LSAG's conclusions and noting that "this report explains why there is nothing to fear from particles created at the LHC". On 1 August 2008, a group of German quantum physicists, the Committee for Elementary Particle Physics (KET), published an open letter further dismissing concerns about the LHC experiments and carrying assurances that they are safe based on the LSAG safety review.

On 20 June 2008, Steven Giddings and Michelangelo Mangano issued a research paper titled the "Astrophysical implications of hypothetical stable TeV-scale black holes", where they develop arguments to exclude any risk of dangerous black hole production at the LHC. On 18 August 2008, this safety review was published in the Physical Review D, and a commentary article which appeared the same day in the journal Physics endorsed Giddings' and Mangano's conclusions. The LSAG report draws heavily on this research.

Strangelets are small fragments of strange matter—a hypothetical form of quark matter—that contain roughly equal numbers of up, down, and strange quarks and that are more stable than ordinary nuclei (strangelets would range in size from a few femtometers to a few meters across). If strangelets can actually exist, and if they were produced at the LHC, they could conceivably initiate a runaway fusion process in which all the nuclei in the planet would be converted to strange matter, similar to a strange star.

The probability of the creation of strangelets decreases at higher energies. As the LHC operates at higher energies than the RHIC or the heavy ion programs of the 1980s and 1990s, the LHC is less likely to produce strangelets than its predecessors. Furthermore, models indicate that strangelets are only stable or long-lived at low temperatures. Strangelets are bound at low energies (in the range of 1-10 MeV), whilst the collisions in the LHC release energies in the range of 14 TeV. The second law of thermodynamics precludes the formation of a cold condensate that is an order of magnitude cooler than the surrounding medium. This can be illustrated by the example of trying to form an ice cube in boiling water.

Otto Rössler, a German chemistry professor at the University of Tübingen, argues that micro black holes created in the LHC could grow exponentially. On 4 July 2008, Rössler met with a CERN physicist, Rolf Landua, at the LHC, with whom he discussed his safety concerns. Following the meeting, Landua asked another expert, Hermann Nicolai, Director of the Albert Einstein Institute, in Germany, to examine Rössler's arguments. Nicolai reviewed Otto Rössler's research paper on the safety of the LHC and issued a statement highlighting logical inconsistencies and physical misunderstandings in Rössler's arguments. Nicolai concluded that "this text would not pass the referee process in a serious journal." Domenico Giulini also commented with Hermann Nicolai on Otto Rössler's thesis, concluding that "his argument concerns only the General Theory of Relativity (GRT), and makes no logical connection to LHC physics; the argument is not valid; the argument is not self-consistent." On 1 August 2008, a group of German physicists, the Committee for Elementary Particle Physics (KET), published an open letter further dismissing Rössler's concerns and carrying assurances that the LHC is safe. Otto Rössler was due to meet Swiss president Pascal Couchepin in mid August to discuss this concern, but it was later reported that the meeting had been canceled as it was believed Rössler and his fellow opponents would have used the meeting for their own publicity.

On 10 August 2008, Rainer Plaga, a German astrophysicist, posted a research paper on the arXiv Web archive concluding that LHC safety studies have not definitely ruled out the potential catastrophic threat from microscopic black holes, including the possible danger from Hawking radiation emitted by black holes. In a follow-up paper posted on the arXiv archive on 29 August 2008, Steven Giddings and Michelangelo Mangano, the authors of the research paper "Astrophysical implications of hypothetical stable TeV-scale black holes", responded to Rainer Plaga's concerns. They pointed out what they see as a basic inconsistency in Plaga's calculation, and argued that their own conclusions on the safety of the collider, as referred to in the LHC safety assessment (LSAG) report, remain robust. Giddings and Mangano also referred to another research paper posted on arXiv on 22 July 2008, titled Exclusion of black hole disaster scenarios at the LHC, which summarizes proofs intended to rule out any possible black hole disaster at the LHC.

On 21 March 2008, a complaint requesting an injunction to halt the LHC's startup was filed by Walter L. Wagner and Luis Sancho against CERN and its American collaborators, the US Department of Energy, the National Science Foundation and the Fermi National Accelerator Laboratory, before the United States District Court for the District of Hawaii. The plaintiffs demanded an injunction against the LHC's activation for 4 months after issuance of the LHC Safety Assessment Group's (LSAG) most recent safety documentation, and a permanent injunction until the LHC can be demonstrated to be reasonably safe within industry standards. The US Federal Court scheduled trial to begin 16 June 2009.

The LSAG review, issued on 20 June 2008 after outside review, found "no basis for any concerns about the consequences of new particles or forms of matter that could possibly be produced by the LHC". The US Government, in response, called for summary dismissal of the suit against the government defendants as untimely due to the expiration of a six-year statute of limitations (since funding began by 1999 and has essentially been completed already), and also called the hazards claimed by the plaintiffs "overly speculative and not credible". The Hawaii District Court heard the government's motion to dismiss on 2 September 2008, and on, 26 September, the Court issued an order granting the motion to dismiss on the grounds that it had no jurisdiction over the LHC project.

On 26 August 2008, a group of European citizens, led by a German biochemist Otto Rössler, filed a suit against CERN in the European Court of Human Rights, in Strasbourg, alleging the Large Hadron Collider poses grave risks for the safety of the 27 member states of the European Union and their citizens. The request for an injunction was summarily rejected on 26 August, leaving the case that it violates the right to life still pending.

To the top

Super Large Hadron Collider

The Super Large Hadron Collider (SLHC) is a proposed upgrade to the Large Hadron Collider to be made around 2012. The upgrade aims at increasing the luminosity of the machine by factor of 10 to 1035 cm−2s−1, providing a better chance to see rare processes and improving statistically marginal measurements. Many different paths exist for upgrading the collider. A collection of different designs of the high luminosity interaction regions is being maintained by the European Organization for Nuclear Research (CERN). A workshop was held in 2006 to establish which are the most promising options. A comprehensive press article on this workshop can be found at the CERN Courier. A summary of the possible machine parameters can be found at Machine parameters collection.

Increasing LHC luminosity involves reduction of beam size at the collision point and either reduction of bunch length and spacing, or significant increase in bunch length and population. The maximum integrated luminosity increase of the existing options is about a factor of 4 higher than the LHC ultimate performance, unfortunately far below the LHC upgrade project's initial ambition of a factor of 10. However at the latest LUMI'06 workshop, several suggestions were proposed to boost the LHC peak luminosity by another factor of 10 beyond nominal towards 1035 cm−2s−1.

The resultant higher event rate poses important challenges for the particle detectors located in the collision areas.

To the top

Source : Wikipedia