Transition Radiation Detector

  • Posted on: 23 July 2014
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 this detector, 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.