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Proceedings Paper

The impact of radiation damage on photon counting with an EMCCD for the WFIRST-AFTA coronagraph
Author(s): Nathan Bush; David Hall; Andrew Holland; Ross Burgon; Neil Murray; Jason Gow; Matthew Soman; Douglas Jordan; Richard Demers; Leon Harding; Michael Hoenk; Darren Michaels; Bijan Nemati; Pavani Peddada
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Paper Abstract

WFIRST-AFTA is a 2.4m class NASA observatory designed to address a wide range of science objectives using two complementary scientific payloads. The Wide Field Instrument (WFI) offers Hubble quality imaging over a 0.28 square degree field of view, and will gather NIR statistical data on exoplanets through gravitational microlensing. The second instrument is a high contrast coronagraph that will carry out the direct imaging and spectroscopic analysis of exoplanets, providing a means to probe the structure and composition of planetary systems. The coronagraph instrument is expected to operate in low photon flux for long integration times, meaning all noise sources must be kept to a minimum. In order to satisfy the low noise requirements, the Electron Multiplication (EM)-CCD has been baselined for both the imaging and spectrograph cameras. The EMCCD was selected in comparison with other candidates because of its low effective electronic read noise at sub-electron values with appropriate multiplication gain setting. The presence of other noise sources, however, such as thermal dark signal and Clock Induced Charge (CIC), need to be characterised and mitigated. In addition, operation within a space environment will subject the device to radiation damage that will degrade the Charge Transfer Efficiency (CTE) of the device throughout the mission lifetime. Here we present our latest results from pre- and post-irradiation testing of the e2v CCD201-20 BI EMCCD sensor, baselined for the WFIRST-AFTA coronagraph instrument. A description of the detector technology is presented, alongside considerations for operation within a space environment. The results from a room temperature irradiation are discussed in context with the nominal operating requirements of AFTA-C and future work which entails a cryogenic irradiation of the CCD201-20 is presented.

Paper Details

Date Published: 11 September 2015
PDF: 15 pages
Proc. SPIE 9605, Techniques and Instrumentation for Detection of Exoplanets VII, 96050E (11 September 2015); doi: 10.1117/12.2189818
Show Author Affiliations
Nathan Bush, The Open Univ. (United Kingdom)
David Hall, The Open Univ. (United Kingdom)
Andrew Holland, The Open Univ. (United Kingdom)
Ross Burgon, The Open Univ. (United Kingdom)
Neil Murray, The Open Univ. (United Kingdom)
Jason Gow, The Open Univ. (United Kingdom)
Matthew Soman, The Open Univ. (United Kingdom)
Douglas Jordan, e2v technologies (UK) Ltd. (United Kingdom)
Richard Demers, Jet Propulsion Lab. (United States)
Leon Harding, Jet Propulsion Lab. (United States)
Michael Hoenk, Jet Propulsion Lab. (United States)
Darren Michaels, Jet Propulsion Lab. (United States)
Bijan Nemati, Jet Propulsion Lab. (United States)
Pavani Peddada, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 9605:
Techniques and Instrumentation for Detection of Exoplanets VII
Stuart Shaklan, Editor(s)

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