CERN — the European Organization for Nuclear Research

The TOTEM detectors: Telescopes

The rate of the inelastic scattering is measured by the Telescopes T1 and T2, two charged particle trackers situated in the CMS cavern at distances of about 10.5m and 13.5m on both sides of the interaction point. By providing a full coverage around the beam line, these telescopes will be able to reconstruct the tracks of the charged particles coming out from the proton-proton collisions and to allow the determination of the primary interaction vertex. Each tracker T1 is made up of 5 sub-detector planes perpendicular to the beam line.

The tracker T2 is based on the GEM (Gas Electron Multiplier) technology, which combines a good spatial resolution with a very high rate capability and a good resistance to radiation. In each T2 arm, 20 semi-circular GEM planes, with overlapping regions, are interleaved on both sides of the beam vacuum chamber to form ten detector planes with a full coverage.