Proton irradiation of swept-charge devices for the Chandrayaan-1 X-ray Spectrometer (C1XS)

Abstract

This paper presents work carried out in support of swept-charge device (SCD) characterisation for the Chandrayaan-1 X-ray Spectrometer (C1XS) instrument. A brief overview of the C1XS instrument is presented, followed by a description of SCD structure and operation. The SCD test facility and method of device characterisation using two different drive sequencers to assess leakage current and spectroscopy performance (FWHM and noise at Mn-Kα) are then described. The expected end-of-life (EOL) 10 MeV equivalent proton fluence for the SCDs of C1XS was modelled using Monte Carlo simulation software and used in a subsequent proton irradiation study involving eight SCDs. The irradiation study was carried out at the Kernfysisch Versneller Instituut (KVI) in the Netherlands and characterised the impact of 50 % and 100 % of the expected Chandrayaan-1 EOL proton fluence on the SCD operational characteristics. The radiation environment modelling, irradiation methodology and post-irradiation characterisation of the devices are presented in this paper and recommendations about the planned C1XS operational temperature and shielding are given.