Transition Radiation Detector

In previous non-magnetic particle experiments, the energy of TeV protons was extrapolated from the data of low-energy protons obtained by the test beam and the geo- magnetic cutoff rigidity. A TRD, traditionally as a particle identification detector, is used on HERD for calibrating the incident particle with dedicated energy at which transition radition is generated but not saturated. 

To increase the detection efficiency of the TR photons, the radiator and gaseous detector are integrated in a common chamber. And a novel design, called side-on TRD, is utilized for the separation of photoelectrons generated by TR photons from ionized electrons by incident particle. The radiator and the working gas are also optimized for maximal TR photon yield and higher TR photon efficiency.