Transition radiation detector
At each interface between materials, the probability of transition radiation increases with the relativistic gamma factor.The passage of the particle is observed through many thin layers of material put in air or gas.The radiated photon gives energy deposition by photoelectric effect, and the signal is detected as ionization.TRD detectors are used in ALICE and ATLAS experiment at Large Hadron Collider.The ALICE TRD operates together with a big TPC (Time Projection Chamber) and TOF (Time of Flight counter) to do particle identification in ion collisions.The ATLAS TRD is called TRT (Transition Radiation Tracker) which serves also as a tracker measuring particles' trajectory simultaneously.