University of Leicester
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The SMILE Soft X-ray Imager (SXI) CCD design and development

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conference contribution
posted on 2019-08-21, 11:15 authored by MR Soman, DJ Hall, AD Holland, R Burgon, T Buggey, J Skottfelt, S Sembay, P Drumm, J Thornhill, A Read, J Sykes, D Walton, G Branduardi-Raymont, T Kennedy, W Raab, P Verhoeve, D Agnolon, C Woffinden
SMILE, the Solar wind Magnetosphere Ionosphere Link Explorer, is a joint science mission between the European Space Agency and the Chinese Academy of Sciences. The spacecraft will be uniquely equipped to study the interaction between the Earth's magnetosphere-ionosphere system and the solar wind on a global scale. SMILE's instruments will explore this science through imaging of the solar wind charge exchange soft X-ray emission from the dayside magnetosheath, simultaneous imaging of the UV northern aurora and in-situ monitoring of the solar wind and magnetosheath plasma and magnetic field conditions. The Soft X-ray Imager (SXI) is the instrument being designed to observe X-ray photons emitted by the solar wind charge exchange process at photon energies between 200 eV and 2000 eV . X-rays will be collected using a focal plane array of two custom-designed CCDs, each consisting of 18 μm square pixels in a 4510 by 4510 array. SMILE will be placed in a highly elliptical polar orbit, passing in and out of the Earth's radiation belts every 48 hours. Radiation damage accumulated in the CCDs during the mission's nominal 3-year lifetime will degrade their performance (such as through decreases in charge transfer efficiency), negatively impacting the instrument's ability to detect low energy X-rays incident on the regions of the CCD image area furthest from the detector outputs. The design of the SMILE-SXI CCDs is presented here, including features and operating methods for mitigating the effects of radiation damage and expected end of life CCD performance. Measurements with a PLATO device that has not been designed for soft X-ray signal levels indicate a temperature-dependent transfer efficiency performance varying between 5×10^−5 and 9×10^−4 at expected End of Life for 5.9 keV photons, giving an initial set of measurements from which to extrapolate the performance of the SXI CCDs.


The authors would like to thank staff of the Payload Technology Validation section (Future Missions Office at ESA’s Directorate of Science) for enabling and performing the measurements and proving the test data into this study for the SMILE programme.



Journal of Instrumentation, 2018, 13

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


11th International Conference on Position Sensitive Detectors (PSD), Open Univ, Milton Keynes, ENGLAND


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Journal of Instrumentation


IOP Publishing



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