Investigation of radiation damage due to particle irradiation on Silicon Drift Detector for Chandrayaan-2 mission

This paper presents the work carrie dout in support of Silicon Drift Detector (SDD) characterization for the Chandrayaan-2 instruments namely Solar X-ray Monitor (XSM) and Alpha Particle X-ray Spectrometer (APXS). The XSM and APXS instruments use SDD to detect X-rays from the Sun and fluorescent X-rays from the lunar surface respectively. The aim of this study is to understand and quantify any spectroscopic performance degradation of these X-ray spectrometers due to space radiation in the SDD during its operational period. Any radiation damage to the SDD leads to increase in the detector leakage current and thus degrades the spectroscopic performance, mainly the energy resolution. The expected end-of-life (EOL) 10 MeV equivalent proton fluence was modeled using SPENVIS simulation software. The Silicon Drift Detector was irradiated with 10 MeV protons for the doses up to 24 krad in logarithmic steps and measured the energy resolution and the leakage current at each dose. The spectrometer energy resolution degraded from ~ 142 eV at 5.9 keV to ~ 250 eV for the cumulative proton dose of ~ 11 krad for the mission life of one year. This satisfies the performance requirement of the SDD based X-ray spectrometers onboard Chandrayaan-2 mission.