Compact Muon Solenoid

  • ATLAS
  • CMS
  • LHCb
  • ALICE
  • MoEDAL
  • Linear accelerators for protons (p ) or lead nuclei (Pb)
  • Proton Synchrotron Booster (PSB )
  • Proton Synchrotron (PS )
  • Super Proton Synchrotron (SPS )

The Compact Muon Solenoid (CMS ) experiment is a particle detector at the Large Hadron Collider ( LHC) at CERN in Switzerland. The site of the experiment is an underground hall in the accelerator ring at Cessy in France, just across the border near Geneva.

The main objectives of the experiment are:

  • The discovery of the Higgs boson
  • The search for evidence of supersymmetry
  • Studying the collision of heavy ions.

The group consists of about 3,200 people from 200 scientific institutes.

The name of the detector describes the design:

  • Its relatively small size ( cylindrical shape, 21 m long, 16 m in diameter, about 12,500 tons )
  • Identify his ability muon tracks
  • Its strong solenoid magnet (13 meters long, 6 meters in diameter, flux density of the cooled superconducting niobium-titanium coil max. 4 Tesla).

The latter allows - as in most other detectors: - the determination of the ratio of charge to mass by measuring the curvature of the particle track in the magnetic field, similar to a mass spectrometer.

Spokesman of the experiment is currently (2012 ) Joe Incandela ( University of California, Santa Barbara ) and were previously Michel Della Negra (Imperial College London ), Tejinder Virdee (Imperial College London ) and Guido Tonelli (Pisa). 2012, the CMS collaboration was involved, together with the operationally independent second major collaboration ATLAS at the discovery of a new boson, which is compatible with the Higgs boson. The exact properties need to be further explored.

Construction

CMS - detector is constructed in multiple layers, which allow a precise measurement of all formed in the proton collisions particles.

From inside the detector consists of the following components to the outside:

  • A silicon pixel detector, i.e. a semiconductor detector which very small silicon structures are used to detect charged particles. The spatial resolution is in the range of 0.01 mm.
  • A silicon strip detector as the pixel detector used exactly as proof silicon material, but with a worse - absolutely but still very good - much better than spatial resolution of 0.1 mm.
  • An electromagnetic calorimeter lead tungstate crystals for the detection of photons and electrons (or positrons)
  • A hadronic calorimeter with brass plates, alternating with layers of scintillators to measure hadrons, such as protons, pions or kaons can.
  • In the return yoke of the magnet coil are muon chambers, which are specially designed for the detection of muons.

Assembly

The detector was initially largely assembled and tested at the surface and then lowered into individual parts into the cavern. The lowering of the great parts was completed on 22 January 2008.

The substructures of the silicon tracking detector were assembled and tested on the CERN site. The transport to Cessy was carried out in December 2007.

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