Research On The Mechanism Of Irradiation Effect Of X-ray Detector

X-ray detectors plays an important role in improving the accuracy of X-ray pulsar navigation systems.The traditional X-ray detectors are no longer able to meet the high precision requirements of X-ray pulsar navigation systems,and there are certain limitations in performance.Therefore,the world's major space powers are actively developing high-performance detectors that can satisfy the X-ray pulsar navigation system.Based on the investigation of X-ray detectors at home and abroad,this paper carried out simulation study on the irradiation effect of the X-ray detector developed by the project,and provided theoretical support for the development of the detector.In this paper,the Geant4 simulation software based on Monte Carlo method is used to establish the irradiation effect model of SDD,which mainly includes the definition of SDD model,particle source and possible physical processes.After the construction of irradiation effect model,the displacement damage and ionization damage caused by different energy neutrons and gamma photons irradiation SDD were simulated.Made the following conclusions:1)The displacement damage caused by different energy neutron irradiation SDD detectors is simulated.By extracting the spatial coordinates of PKA and reconstructing it three-dimensionally,the spatial distribution map of PKA in SDD detector is obtained,and the neutron is obtained in SDD.The probability of generating PKA at each location in the detector is the same,and the PKA is approximately evenly distributed in the SDD detector.By extracting the energy spectrum of PKA,it is found that PKA is mainly concentrated in the low energy region,mainly due to low energy transmission events.According to the scattering angle distribution of PKA,the scattering angles are all concentrated from 0 to 90 degrees,indicating that only one collision occurs in the SDD detector.By analyzing the other secondary particles produced by the neutrons in the SDD detector,the neutrons have a large energy loss in the inelastic scattering and fission reactions,and the neutrons have a significant nuclear reaction.The relationship between the vacancy defects generated by neutrons in the SDD detector and its energy is simulated.The number of PKA and the total number of vacancy defects are basically consistent with the neutron energy.By calculating the non-ionizing energy deposition and ionization energy deposition generated by the neutron in the SDD detector,it is found that it is approximately linear with the thickness of the SDD detector.2)The displacement damage caused by gamma photon irradiation SDD detectors with different energies is simulated.It is concluded that the displacement damage caused by gamma photons in SDD detectors is basically negligible.Gamma photons mainly cause ionization damage in SDD detectors.The ionization energy deposition caused by gamma photons in the SDD detector is approximately linear with the thickness of the SDD detector.Gamma photons generate a large amount of secondary electrons in the SDD detector.The energy distribution of the secondary electrons ranges from a few eV to the incident particle energy,and as the secondary electron scattering angle increases,the number of secondary electrons decreases.