Charge transfer inefficiency in the pre- and post-irradiated Swept Charge Device CCD23

Smith, P. H.; Gow, J. P. D; Pool, P. and Holland, A. D. (2015). Charge transfer inefficiency in the pre- and post-irradiated Swept Charge Device CCD23. Journal of Instrumentation, 10(03), article no. C03041.

DOI: https://doi.org/10.1088/1748-0221/10/03/C03041

Abstract

This paper describes the mapping of spectral response of an e2v technologies Swept Charge Device (SCD) CCD236 pre and post irradiation with a 10 MeV equivalent proton fluence of 5.0 × 10⁸ protons cm⁻². The CCD236 is a large area (4.4 cm²) X-ray detector which will be used in India's Chandrayaan-2 Large Soft X-ray Spectrometer (CLASS) and China's Hard X-ray Modulation Telescope (HXMT). To enable the suppression of surface dark current, clocking is performed continuously resulting in a linear readout. As such the flat field illumination used to measure any change in spectral response over a conventional Charge-Coupled Devices (CCDs) is not possible. An alternative masking technique has been used to expose pinpoint regions of the device to Mn-K_α and Mn-K_β X-rays, enabling a local map of spectral response to be built up over the device. This novel approach allows for an estimation of the Charge Transfer Inefficiency (CTI) of the device to be made by allowing the creation of a CTI scatter plot similar to that typically observed in conventional CCDs.