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 Florescence (XRF) analysis, achieving near Fano-limited spectroscopy at -15 °C. The SCD was flown in the XRF instruments on board the European Space Agency's SMART-1 and the Indian Space Research Organisation's 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 China's 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 improvement 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

Comparison of proton irradiated P-channel and N-channel CCDs

Charge transfer inefficiency and dark current effects are compared for e2v technologies plc. p-channel and n-channel CCDs, both irradiated with protons. The p-channel devices, prior to their irradiation, exhibited twice the dark current and considerable worse charge transfer inefficiency (CTI) than a typical n-channel. The radiation induced increase in dark current was found to be comparable with n-channel CCDs, and its temperature dependence suggest the divacancy is the dominant source of thermally generated dark current pre and post irradiation. The factor of improvement in tolerance to radiation induced CTI varied by between 15 and 25 for serial CTI and 8 and 3 for parallel CTI, between −70 °C and −110 °C respectively