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CMS Detector Began the Descent into its Underground Experimental Cavern in Preparation for the Start-up of CERN’s LHC this Summer
:: 23 January, 2008
In the early hours of the morning the final element of the Compact Muon Solenoid (CMS)detector began the descent into its underground experimental cavern in preparation for the start-up of CERN’s Large Hadron Collider (LHC) this summer. This is a pivotal moment for the CMS collaboration, as the experiment is the first of its kind to be constructed above ground and then lowered, element by element, 100 metres below. It marks the culmination of eight years of work in the surface hall, and moves CMS into final commissioning before registering proton-proton collisions at the LHC.
The journey started 14 months ago, when the first of 15 elements of the CMS detector was carefully lowered, with just a few centimetres of leeway, by a huge gantry crane, custom-built by the VSL group. The final element is an asymmetrical cap that fits into the barrel element of the experiment and weighs around 1430 tonnes. It includes fragile detectors that will help identify and measure the energy of particles created in LHC collisions.
“CMS is unique in the way that the detector was constructed in very large elements in a surface assembly building and then lowered underground”, explained Austin Ball, CMS Technical Coordinator. “This is likely to become a model for future experiments, as the technique can now be considered proven.”
There are many advantages to planning an experiment in this way, such as the ability to save time by working simultaneously on the detector while the experimental cavern was being excavated. There were also fewer risks when working on the surface, and elements of detector could be tested together before lowering them.
Experiments at the LHC will allow physicists to take a big leap on a journey that started with Newton's description of gravity. Gravity is ubiquitous since it acts on mass, but so far science is unable to explain why particles have the masses they have. Experiments such as CMS may provide the answer. LHC experiments will also probe the mysterious missing mass and dark energy of the Universe, they will investigate the reason for nature's preference for matter over antimatter, probe matter as it existed close to the beginning of time and look for extra dimensions of spacetime.
“This is a very exciting time for physics,” said CMS spokesman Tejinder Virdee, “the LHC is poised to take us to a new level of understanding of our Universe.”
About Compact Muon Solenoid
The Compact Muon Solenoid (CMS) experiment is one of two large general-purpose particle physics detectors being (as of 2007) built on the proton-proton Large Hadron Collider (LHC) at CERN in Switzerland. Approximately 2600 people from 180 scientific institutes form the collaboration building it. It will be located in an underground chamber at Cessy in France, just across the border from Geneva. The completed detector will be cylindrical, 21 metres long and 16 metres diameter and weigh approximately 12,500 tonnes.
CMS is designed as a general-purpose detector, capable of studying many aspects of proton collisions at 14 TeV, the center-of-mass energy of the LHC particle accelerator. It contains subsystems which are designed to measure the energy and momentum of photons, electrons, muons, and other products of the collisions. The innermost layer is a silicon-based tracker. Surrounding it is a scintillating crystal electromagnetic calorimeter, which is itself surrounded with a sampling calorimeter for hadrons. The tracker and the calorimetry are compact enough to fit inside the CMS solenoid which generates a powerful magnetic field of 4 T. Outside the magnet are the large muon detectors, which are inside the return yoke of the magnet.
Note for Large Hadron Collider
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. 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 as well as hundreds of universities and laboratories.
When activated, it is hoped that the collider will produce the elusive Higgs boson, the observation of which could confirm the predictions and 'missing links' in the Standard Model of physics and could explain how other elementary particles acquire properties such as mass. The verification of the existence of the Higgs boson would be a significant step in the search for a Grand Unified Theory, which seeks to unify three of the four fundamental forces: electromagnetism, the strong force, and the weak force. The Higgs boson may also help to explain why the remaining force, gravitation, is so weak compared to the other three forces.
The collider is contained in a circular tunnel with a circumference of 26.659 kilometres (16.5 miles), at a depth ranging from 50 to 175 metres underground. The tunnel was formerly used to house the LEP, an electron-positron collider.
The 3.8 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.
About CERN
The European Organization for Nuclear Research is the world's largest particle physics laboratory, situated in the northwest suburbs 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.
The main site at Meyrin also has a large computer centre containing very powerful data processing facilities primarily for experimental data analysis, and because of the need to make them available to researchers elsewhere, has historically been (and continues to be) a major wide area networking hub.
CERN currently has approximately 2600 full-time employees. Some 7931 scientists and engineers (representing 500 universities and 80 nationalities), about half of the world's particle physics community, work on experiments conducted at CERN.
As an international facility, the CERN sites are not officially under Swiss or French jurisdiction, and some company vehicles have diplomatic number plates. This includes the organization's fleet of fire trucks.
Tags: Compact Muon Solenoid (CMS) , CERN , Large Hadron Collider , CMS detector , Austin Ball , gravity , Universe , Tejinder Virdee , ,
