Showing posts with label LHC(Large Hadron Collider). Show all posts
Showing posts with label LHC(Large Hadron Collider). Show all posts

Monday, August 6, 2007

Large Hadron Collider (LHC) -Supercollisions on the horizon?


The project staggers the imagination: a machine that would stretch 20 miles through the bedrock 400 feet beneath Kane, DuPage and perhaps Will Counties. It could help physicists discover mysterious forces of the universe and new dimensions in the fabric of space and time.
But there are other mysteries to resolve before the first spade is turned for a proposed, multibillion-dollar International Linear Collider scientists hope to center under Fermi National Accelerator Laboratory's Batavia campus.
What would the neighbors think about subatomic particles being fired at nearly the speed of light under west suburban homes, back-yard pools and cornfields? And how to accommodate any criticisms in advance and bring folks onboard?
There's no guarantee the collider -- which experts think could be one of the century's great scientific leaps forward -- will be built. Or that it'll be built in Illinois. Even in the best-case scenario, it will be more than a decade before the first particles fly.
But officials are planning ahead, making sure that what happened about 20 years ago -- when criticism from residents helped doom Fermilab's quest to land a superconducting supercollider -- doesn't happen again.
Fermilab has organized a 24-member ILC Citizens' Task Force to help it plan. The Department of Energy facility has included a wide range of volunteers, from village trustees to the same activists who fought Fermilab's proposed supercollider in the 1980s.
Members are asking questions, offering suggestions and learning about the project firsthand from some of the world's leading physicists and engineers. Their job is to draw up recommendations for the project by early next year so the changes can be incorporated into the design.
All this for an international project Europe and Japan might also compete for and that wouldn't be finished until 2019 at the earliest -- and could take until 2030. The project would employ the equivalent of 2,000 people worldwide during each of the seven years the machine is being built.
If completed, however, the machine would assert Fermilab's position on the frontier of science for decades, employing physicists, engineers and others at the lab after its Tevatron particle accelerator's scheduled shutdown in 2009.
But first, Fermilab wants to win over the neighbors.
In a recent meeting, Dan Lobbes, a task-force member and director of land preservation with the Conservation Foundation, said Fermilab had better prepare itself to answer questions such as, "'Will my kids and my dog get radiated?' Or, 'How will we know we'll get treated fairly?' Or, 'Do we get money if the thing goes under my house?'"
Fermilab officials seem to delight in such bruising questions, nodding and scribbling notes when the interrogation gets tough. They genuinely want to be guided by the public, they say, and it is better to get everything out in the open now -- with informed citizens, not folks spooked by 1950s Godzilla scenarios.
"It's just openness," said Craig Jones, who fought the supercollider and now serves on the task force. "That's what we're talking about -- establishing trust, and treating you like you're something other than some bumpkin from Kane County."
The proposed linear collider could help scientists overcome humankind's humbling ignorance of much of the cosmos. Physicists can only account for 5 percent of the components of the universe. The remaining 95 percent are believed to be dark matter and dark energy, which are invisible but can be detected in the mass and rotational speed of galaxies and galaxy clusters.
The collider would hurl billions of electrons and their antiparticles -- positrons -- toward each other at nearly the speed of light, Fermilab said. The collisions would create new particles that could offer hints about the nature and origin of the universe.
"It's a little bit mind-boggling that to study the smallest particles in the universe, you need the largest machines that mankind has ever built," said Kurt Riesselmann, a Fermilab spokesman.
But there is the problem of where to park a machine that would extend miles beyond the 6,800-acre lab campus.
The collider is so vast and so expensive -- rough estimates start at $6.7 billion -- no single government could afford to build it, Riesselmann said.
An international team is designing it, and the cash would come from many countries. A similar collaboration led to the Geneva-based CERN particle physics laboratory's Large Hadron Collider, scheduled to start up in May 2008.
If Fermilab is chosen for the new collider, it could stir up a hornet's nest of local planning issues. Contractors would bore 44 miles of tunnel -- including a parallel service tunnel -- with a diameter of 15 feet or greater. Thirteen access shafts would be spaced every few miles, and 92 new buildings would have to be built above ground, roughly a third of them off-campus on land Fermilab would acquire.

Task-force member John Carlson of Geneva wanted to know how much blasting would be required."In the Deep Tunnel project, there was a lot of blasting in Chicago, broken windows and that sort of thing," he said. "So I think the objection of the communities will be in the blasting phase."Vic Kuchler, a Fermilab staff member who is part of the collider's global design effort, said most of the tunnels would be drilled, but some blasting would be necessary to create underground rooms and alcoves

Fermilab officials said the machine would meet environmental standards on radiation and other matters. "It's not a nuclear reactor or anything like that," said Riesselmann. The particle collision point would be on Fermilab property, and a power failure would harmlessly shut down the collider, as it does the lab's Tevatron.The surface work could prove more problematic. Fermilab would have to build mini-campuses of an undetermined size where the shafts emerge.Jones, a St. Charles resident who opposed the supercollider in the late 1980s, said the approach now is a far cry from those days. Officials then didn't involve property owners during the design, he said, and were condescending to those who questioned the project.A retired pilot, Jones wrote and distributed a paper disputing the state's claims about the jobs that project would create. He and other opponents undermined it further by gathering 18,000 signatures in opposition.Texas ended up winning the supercollider project, which was later canceled by Congress amid cost overruns.This time, Jones said, Fermilab is going out of its way to listen to citizens. Jones sees his task as not to become an advocate for the linear collider, but to ensure a fair process for the communities it passes under."Am I personally interested in that kind of science?" Jones said. "As a matter of fact, I am. I'm very interested. But I don't want to see people get squashed, having family farms taken and being treated badly, just for the sake of science that I may like."



Large Hadron Collider (LHC) (primary research/costs/upgrades)

Research



When in operation, about seven thousand scientists from eighty countries will have access to the LHC, the largest national contingent (seven hundred) being from the United States. Physicists hope to use the collider to enhance their ability to answer the following questions:



Is the popular Higgs mechanism for generating elementary particle masses in the Standard Model violated? If not, how many Higgs bosons are there, and what are their masses?


Will the more precise measurements of the masses of baryons continue to be mutually consistent within the Standard Model?


Do particles have supersymmetric ("SUSY") partners?


Why are there apparent violations of the symmetry between matter and antimatter?


Are there extra dimensions, as predicted by various models inspired by string theory, and can we "see" them?


What is the nature of dark matter and dark energy?

Why is gravity so many orders of magnitude weaker than the other three fundamental forces?



LHC as an ion collider


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 programme. While lighter ions are considered as well, the baseline scheme deals with lead (Pb) ions.This will allow an advancement in the experimental programme currently in progress at the Relativistic Heavy Ion Collider (RHIC).


LHC proposed upgrade


After some years of running, any particle physics experiment typically begins to suffer from diminishing returns. 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.


COST

The construction of LHC was originally approved in 1995 with a budget of 2600 million Swiss francs (currently about 1.7 billion euro), with another 210 million francs (€140 m) towards the cost of the experiments. However, cost over-runs, estimated in a major review in 2001 at around 480 million francs (€300 m) in the accelerator, and 50 million francs (€30 m) for the experiments, along with a reduction in CERN's budget pushed the completion date out from 2005 to April 2007.180 million francs (€120 m) of the cost increase has been the superconducting magnets. There were also engineering difficulties encountered while building the underground cavern for the Compact Muon Solenoid.


Safety concerns

While many have voiced concerns that the LHC will destroy the Universe, engineers close to the project claim that the possibility is infinitesimally small. As CERN has pointed out, if the Earth were in danger of any such fate, it would have happened billions of years ago from the bombardment of protons the planet receives that are millions of times more energetic than anything that could be produced by the LHC.


As with the Relativistic Heavy Ion Collider (RHIC), people both inside and outside of the physics community have voiced concern that the LHC might trigger one of several theoretical disasters capable of destroying the Earth or even our entire Universe. RHIC has been running since 2000 and has generated no major problems; however the Large Hadron Collider is set to create an environment significantly more alien to nature than the RHIC has ever created, and therefore the probability of catastrophe is greater.[citation needed]
Theoretical disasters include:
Creation of a stable black hole inside the earth which would destroy our planet within 4 to 6 minutes.[citation needed]
Creation of strange matter that is more stable than ordinary matter
Creation of magnetic monopoles that could catalyze proton decay
Triggering a transition into a different quantum mechanical vacuum (see False vacuum)
It is possible that the Large Hadron Collider will create tiny black holes within the Earth . Most physicists expect that Hawking Radiation will cause these black holes to dissipate. The primary cause for concern is the fact that Hawking Radiation - the only means by which these black holes could be dissipated, is entirely theoretical.
CERN performed a study to investigate whether such dangerous events as micro black holes, strangelets, or magnetic monopoles could occur. The report concluded, "We find no basis for any conceivable threat." If black holes are produced, they are expected to evaporate almost immediately via Hawking radiation and thus be harmless, although the existence of Hawking radiation is currently unconfirmed. It has been claimed that a strong argument for the safety of colliders such as the LHC comes from the simple fact that cosmic rays with energies up to twenty million times the LHC's 1.4×10¹³ eV capacity have been bombarding the Earth, Moon and other objects in the solar system for billions of years with no such effects.
However many people remain concerned about the safety of the LHC such as the science watchdog group called the Lifeboat Foundation which has covered these dangers in detail. As with any new and untested experiment, it is not possible to say with utter certainty what will happen. John Nelson at the University of Birmingham stated of RHIC that "it is astonishingly unlikely that there is any risk—but I could not prove it."Furthermore, in academia there is some question, albeit among a minority of scientists, of whether the Hawking radiation theory is correct.

Construction accidents
On October 25, 2005, a technician was killed in the LHC tunnel when a crane load was accidentally dropped

On March 27, 2007, there was an incident during a pressure test involving one of the LHC's inner triplet magnet assemblies provided by Fermilab and KEK. No people were injured, but a cryogenic magnet support broke. Analysis revealed that its design, made as thin as possible for better insulation, was not strong enough to withstand the forces generated by a sudden shutdown. Details are available in a statement from Fermilab, with which CERN is in agreementRepairing the broken magnet and reinforcing the eight identical copies used by LHC caused a postponement of the planned November 26, 2007 startup date [19] to May 2008.[20]

[edit] See also
Fermilab
International Linear Collider
http://en.wikipedia.org/wiki/LHC@home
Superconducting Super Collider
Tevatron


Notes and references


^ New start-up schedule for world's most powerful particle accelerator
^ Symmetry magazine, April 2005
^ "...in the public presentations of the aspiration of particle physics we hear too often that the goal of the LHC or a linear collider is to check off the last missing particle of the standard model, this year’s Holy Grail of particle physics, the Higgs boson. The truth is much less boring than that! What we’re trying to accomplish is much more exciting, and asking what the world would have been like without the Higgs mechanism is a way of getting at that excitement." -Chris Quigg, Nature's Greatest Puzzles
^ Ions for LHC
^ PDF presentation of proposed LHC upgrade
^ Maiani, Luciano (16 October 2001). LHC Cost Review to Completion. CERN. Retrieved on 2001-01-15.
^ Feder, Toni (December 2001). "CERN Grapples with LHC Cost Hike". Physics Today 54 (12): 21. Retrieved on 2007-01-15.
^ Tiny Black Holes - Physicist Dave Wark of Imperial College, London reporting for NOVA scienceNOW
^ Dimopoulos, S. and Landsberg, G. Black Holes at the Large Hadron Collider. Phys. Rev. Lett. 87 (2001).
^ American Institute of Physics Bulletin of Physics News, Number 558, September 26, 2001, by Phillip F. Schewe, Ben Stein, and James Riordon
^ Blaizot, J.-P. et al. Study of Potentially Dangerous Events During Heavy-Ion Collisions at the LHC. (PDF)
^ R. A. Mewaldt "Cosmic Rays" — an article accepted for publication in the Macmillan Encyclopedia of Physics in 1996
^ Jonathan Leake:Big Bang machine could destroy Earth, Sunday Times
^ Adam D. Helfer: General Relativity and Quantum Cosmology
^ Hewett, JoAnne (25 October 2005). Tragedy at CERN (Blog). Cosmic Variance. Retrieved on 2007-01-15. author and date indicate the beginning of the blog thread
^ CERN (26 October 2005). Message from the Director-General (in English and French). Press release. Retrieved on 2007-01-15.
^ LHC Magnet Test Failure
^ Updates on LHC inner triplet failure
^ The God Particle. www.bbc.com. Retrieved on 2007-05-22.
^ CERN (2007-06-22). CERN announces new start-up schedule for world’s most powerful particle accelerator. Press release. Retrieved on 2007-07-01.

[edit] External links

Wikimedia Commons has media related to:
Large Hadron Collider
LHC - The Large Hadron Collider webpage
Challenges in Accelerator Physics
LHC UK webpage
UK Science Museum, London Exhibition supported by the Science and Technology Facilities Council
The Alice experiment
Compact Muon Solenoid (CMS) Main Page
Compact Muon Solenoid Page (U.S. Collaboration)
Energising the quest for 'big theory'
LCG - The LHC Computing Grid webpage
The Large Hadron Collider ATLAS Experiment - Virtual Reality (VR) photography panoramas (requires QuickTime)
LHC startup plan. Includes dates, energies and luminosities
Seed short film - Lords of the Ring
symmetry magazine LHC special issue
BBC Horizon, The six billion dollar experiment
New Yorker: Crash Course. The world’s largest particle accelerator (ca. 6 500 words)
NYTimes: A Giant Takes On Physics’ Biggest Questions (ca. 4 300 words)
Beam Parameters and Definitions. The chapter of the LHC Technical Design Report (TDR) that



lists of all the beam parameters for the LHC.
by www.24hoursnews.blogspot.com

Large Hadron Collider (LHC) (about/technical desing)


LHC
The Large Hadron Collider (LHC) is a particle accelerator and collider located at CERN, near Geneva, Switzerland (46°14′N, 6°03′E). Currently under construction, the LHC is scheduled to begin operation in May 2008.[1] The LHC is expected to become the world's largest and highest energy particle accelerator. The LHC is being funded and built in collaboration with over two thousand physicists from thirty-four countries, universities and laboratories.
When switched on, it is hoped that the collider will produce the elusive Higgs boson particle — often dubbed the God Particle — the observation of which could confirm the predictions and 'missing links' in the Standard Model of physics, and explain how other elementary particles acquire properties such as mass.


Technical Desing

Technical DesignThe collider is contained in a 27 kilometre (17 mi) circumference tunnel located underground at a depth ranging from 50 to 175 metres.[2] The tunnel was formerly used to house the LEP, an electron-positron collider.
The three metre diameter, concrete-lined tunnel actually crosses the border between Switzerland and France at four points, although the majority of its length is inside France. The collider itself is located underground, with many surface buildings holding ancillary equipment such as compressors, ventilation equipment, control electronics and refrigeration plants.
The collider tunnel contains two pipes enclosed within superconducting magnets cooled by liquid helium, each pipe containing a proton beam. The two beams travel in opposite directions around the ring. Additional magnets are used to direct the beams to four intersection points where interactions between them will take place.
The protons will each have an energy of 7 TeV, giving a total collision energy of 14 TeV. It will take around ninety microseconds for an individual proton to travel once around the collider. Rather than continuous beams, the protons will be "bunched" together into approximately 2,800 bunches, so that interactions between the two beams will take place at discrete intervals never shorter than twenty-five nanoseconds apart. When the collider is first commissioned, it will be operated with fewer bunches, to give a bunch crossing interval of seventy-five nanoseconds. The number of bunches will later be increased to give a final bunch crossing interval of twenty-five nanoseconds.
Prior to being injected into the main accelerator, the particles are prepared through a series of systems that successively increase the particle energy levels. The first system is the linear accelerator Linac2 generating 50 MeV protons which feeds the Proton Synchrotron Booster (PSB). Protons are then injected at 1.4 GeV into the Proton Synchrotron (PS) at 26 GeV. The Low-Energy Injector Ring (LEIR) will be used as an ion storage and cooler unit. The Antiproton Decelerator (AD) will produce a beam of anti-protons at 2 GeV, after cooling them down from 3.57 GeV. Finally the Super Proton Synchrotron (SPS) can be used to increase the energy of protons up to 450 GeV.
Six detectors are being constructed at the LHC. They are located underground, in large caverns excavated at the LHC's intersection points. Two of them, ATLAS and CMS are large, "general purpose" particle detectors. The other four (LHCb, ALICE, TOTEM, and LHCf) are smaller and more specialized.
The LHC can also be used to collide heavy ions such as lead (Pb) with a collision energy of 1,150 TeV.
The size of the LHC constitutes an exceptional engineering challenge with unique safety issues. While running, the total energy stored in the magnets is 10 GJ, and in the beam, 725 MJ. Loss of only 10−7 of the beam is sufficient to quench a superconducting magnet, while the beam dump must absorb an energy equivalent to a typical air-dropped bomb. For comparison, 725 MJ is equivalent to the detonation energy of approximately 157 kg (347 pounds) of TNT, and 10 GJ is about 2.5 tons of TNT.

Sunday, July 22, 2007

CERN believes that the LHC will let scientists re-create how the universe behaved immediately after the Big Bang,Search for God (Particles) Drives Mas


About CERN (the European Organization for Nuclear Research) and its massive particle accelerators in Angels & Demons by Dan Brown of The Da Vinci Code fame. In that book, the lead character travels to the cavernous research institute on the border of France and Switzerland to help investigate a murder. In real life, one of CERN's grisliest problems is finding storage for the massive amounts of data derived from its four high-profile physics experiments making use of the institute's large hadron collider (LHC). Due for operation in May 2008, the LHC is a 27-kilometer-long device designed to accelerate subatomic particles to ridiculous speeds, smash them into each other and then record the results.



The LHC experiments will study everything from the tiniest forms of matter to the questions surrounding the Big Bang. The latter subject provided Pierre Vande Vyvre, a project leader for data acquisition for CERN, with a particularly thorny challenge: He had to design a storage system for one of the four experiments, ALICE (A Large Ion Collider Experiment). It's one of the biggest physics experiments of our time, boasting a team of more than 1,000 scientists from around the world.


For one month per year, the LHC will be spitting out project data to the ALICE team at a rate of 1GB per second. That's 1GB per second, for a full month, "day and night," Vande Vyvre says. For this month, that data rate is an entire order of magnitude larger than each of the other three experiments being done with the LHC. In total, the four experiments will generate petabytes of data.CERN believes that the LHC will let scientists re-create how the universe behaved immediately after the Big Bang. At that time, everything was a "sort of hot dense soup...composed of elementary particles," the project's webpage explains. The LHC can trigger "little bangs" that let ALICE scientists study how the particles act and come together, helping answer questions about the actual structure of atoms.

"The data is what the whole experiment is producing," Vande Vyvre says. "This is the most precious thing we have.”Vande Vyvre is charged with managing the PCs, storage equipment, and custom and homegrown software surrounding the ALICE project's data before it hits the data center and gets archived. The ALICE group's experiments will start running in May 2008, but the storage rollout began in September 2006.

The ALICE experiment grabs its data from 500 optical fiber links and feeds data about the collisions to 200 PCs, which start to piece the many snippets of data together into a more coherent picture. Next, the data travels to another 50 PCs that do more work putting the picture together, then record the data to disk near the experiment site, which is about 10 miles away from the data center. "During this one month, we need a huge disk buffer,


" News Inside News,The European Organization for Nuclear Research (French: Organisation européenne pour la recherche nucléaire), commonly known as CERN (see Naming), pronounced [sɝn] (or [sɛʀn] in French), is the world's largest particle physics laboratory, situated just northwest of Geneva on the border between France and Switzerland. The convention establishing CERN was signed on 29 September 1954. From the original 12 signatories of the CERN convention, membership has grown to the present 20 member states. Its main function is to provide the particle accelerators and other infrastructure needed for high-energy physics research. Numerous experiments have been constructed at CERN by international collaborations to make use of them.