Transition Radiation Detector

  • Posted on: 23 July 2014
It is the main electron detector in the GeV/c momentum range in ALICE. Electrons and positrons coming out of the collision points of heavy-ions can be distinguished from other charged particles by the emission of transition radiation.

The identification of electrons and positrons is achieved by a transition radiation detector (TRD). In a similar manner to the muon spectrometer, this system enables detailed studies of the production of vector-meson resonances, but with extended coverage down to the light vector-meson ρ and in a different rapidity region. Inside such a radiator, fast charged particles cross the boundaries between materials with different dielectric constants, which leads to the emission of TR photons with energies in the X-ray range. The effect is tiny and the radiator has to provide hundreds of material boundaries to achieve a high enough probability to produce at least one photon.

The ALICE TRD was designed to derive a fast trigger for charged particles with high momentum and can significantly enhance the recorded yields of vector mesons and jets.

Read more about TRD.