Located near Cessy, France (which is close to the Swiss border), researchers, headed by physicist Tejinder (Jim) S. Virdee from the Department of Physics at the Imperial College in London, England, will be investigating physical processes at the energy level of tera-electron-Volts (TeV)—where one tera-electron-Volt equals one trillion (10**12) electron-Volts (eV), and one eV equals one volt times the charge (in coulombs) of a single electron.

At this extremely large energy level, the scientists will study collisions of protons at a center-of-mass energy of 14 TeV. They are hoping to be able to answer some of nature’s most fundamental questions. Specifically, some of the goals of these scientists are to discover previously unknown particles (such as the Higgs boson), find evidence of supersymmetry, study properties of top quarks, identify mini-black holes, investigate substructures of leptons and quarks, and explain other universal mysteries such as the origin of mass, the number of dimensions, and characteristics of dark matter (a major part of the universe still unexplored). If such things can be realized, it may dramatically help scientists further explain a unified theory of all physical phenomena, what is sometimes called The Theory of Everything.

The heart of the CMS is a magnet system—the largest magnet of its type ever constructed—to measure the momenta (the products of the mass and velocity) of charged particles. One large superconducting solenoid is used (in fact, the largest solenoid ever made), with a length of about 12 meters (39.4 feet) and an inside diameter of about 6 meters (19.7 feet). (A solenoid is basically a coil of wire that surrounds a metallic core, which generates a magnetic field under the presence of an electrical current.)

The solenoid possesses a magnetic field of 4 Tesla, which is about one-hundred thousand times stronger than the magnetic field of the Earth and capable of storing about 2.5 gigajoules of energy. The temperature of the solenoid’s coil is dropped to a temperature of nearly absolute zero (0 Kelvin) so that almost all electrical resistance is eliminated. Under such conditions superconductivity is achieved.

Because of its huge size, all of its tracking devices and the electromagnetic calorimeter (ECAL, an instrument for measuring the energy of incident particles) can be placed inside the solenoid’s coil—which is why it is called compact. Outside of the solenoid’s coil is a steel return yoke that consist of muon detectors positioned between layers. This configuration permits the momentum of muons to be measured outside of the coil (by the muon chambers) and inside the coil (by the tracking devices). (A muon is an elementary particle with a negative electric charge and a spin of 1/2.)

In September 2006, CMS scientists announced that the solenoid magnet had been successfully tested at full magnetic field strength. Sometime on or after November 2007, the proton-proton Large Hadron Collider (LHC) particle accelerator of Geneva, Switzerland’s CERN (European Organization for Nuclear Research)—the world’s largest particle physics laboratory—is scheduled to begin operations. At that time, it will begin to accelerate beams of particles around a 27-kilometer (16.8-mile circumference), 21-meter (68.9-foot length), 16-meter (52.5-foot diameter), and 12,500-ton (weight) cylindrical underground chamber to energies never before generated on the Earth. The particles will then collide with each other as they pass through the CMS particle detector. While within the CMS, the energy and momentum of electrons, photons, muons, and other particles produced by  the collision will be measured.

With the much-awaited results of the CMS experiment, 2007 should be an exiting year of discovery for physics. For more information, the Web home page of CMS is: http://cms.cern.ch/.

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Physics  Research  Science  Space  William Atkins