The effect of protons on the performance of second generation Swept Charge Devices

The e2v technologies Swept Charge Device (SCD) was developed as a large area detector for X-ray Fluorescence (XRF) analysis, achieving near Fano-limited spectroscopy at −15 °C. The SCD was flown in the XRF instruments onboard the European Space Agencyʹs SMART-1 and the Indian Space Research Organisationʹs Chandrayaan-1 lunar missions. The second generation SCD, proposed for use in the soft X-ray Spectrometer on the Chandrayaan-2 lunar orbiter and the soft X-ray imager on Chinaʹs HXMT mission, was developed, in part, using the findings of the radiation damage studies performed for the Chandrayaan-1 X-ray Spectrometer. This paper discusses the factor of two improvements in radiation tolerance achieved in the second generation SCD, the different SCD sizes produced and their advantages for future XRF instruments, for example through reduced shielding mass or higher operating temperatures.