Si, GaAs and diamond damage in pion fields with application to LHC

The concentration of primary radiation defects induced by charged pions, in the energy range 20 MeV–50 GeV, in the bulk of silicon, GaAs and diamond has been calculated in order to characterise the radiation resistance of these materials. The mechanisms by which pions impart energy to the lattice have been analysed and their contribution has been evaluated starting from the data on pion–nucleus interaction. The energy partition of the primary recoil nuclei between ionisation and displacements has been considered in the frame of the Lindhard theory. The energy dependence of the concentration of primary radiation defects presents two maxima: one in the region of the delta resonance, and another one around 1 GeV. The main conclusion is that diamond is hardner to pion irradiation than both silicon and GaAs in the whole energy range investigated. The pion-induced degradation in the inner detector system at LHC has been evaluated, starting from the simulated spectra, and considering different detector materials: diamond, silicon and GaAs.