Simulation of radiation damage in detectors on earth observation satellites

This study investigates the radiation damage hardness of SiPIN and MCT detectors using GEANT4 simulations. The aim is to evaluate the long-term radiation resistance of detectors in Earth observation satellites. Simulations were carried out using data from the Landsat-8 and GOES satellites. Detector dimensions and geometries were defined in GEANT4, treating the detector volume as a whole. Energy deposition, dose, Frenkel pairs, and Displacements Per Atom (DPA) values were calculated. Using NIEL (Non-Ionizing Energy Loss), 1 MeV neutron equivalent fluxes were determined. Each energy level was considered separately, followed by an overall evaluation. The detectors were positioned within multilayer insulation (MLI) made of Kapton, Dacron, and aluminum layers. The results showed that protons with energies below 10 MeV and alpha particles with energies below 40 MeV could not penetrate the MLI layers. The energy range for electrons and photons from the GOES satellite was insufficient to penetrate the MLI layers. Since GOES did not provide neutron data, estimates were derived from the STS-36 mission and projected over 7 years. These data offer an estimate of the radiation damage to which the detectors will be exposed. Moreover, data from the GOES satellite indicated that the solar cycle significantly affects particle flux. During periods of solar minimum, the number of particles with energies above 50 MeV tends to increase, potentially due to cosmic rays, as these particles do not show coherence with the solar cycle. Particles below 50 MeV, however, remain consistent with the solar cycle's variations. Furthermore, data analysis reveals that, while radiation-induced damage is present, it has not reached measurable levels. According to findings from Hartmann (2017), measurable radiation damage, such as from 1 MeV neutron fluxes, generally requires flux levels of $10^{14}$ or higher. In our study, we observed fluxes at a much lower level, approximately $10^{11}$ (100 billion), indicating that while damage is occurring, it remains below the threshold of detectability. In conclusion, this study provides a comprehensive analysis of radiation damage hardness in detectors for Earth observation satellites, with significant insights for future satellite missions.