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The impact of radiation damage on photon counting with an EMCCD for the WFIRST-AFTA coronagraph

Bush, Nathan; Hall, David; Holland, Andrew; Burgon, Ross; Murray, Neil; Gow, Jason; Soman, Matthew; Jordan, Doug; Demers, Richard; Harding, Leon K.; Hoenk, Michael; Michaels, Darren; Nemati, Bijan and Peddada, Pavani (2015). The impact of radiation damage on photon counting with an EMCCD for the WFIRST-AFTA coronagraph. In: Proceedings of SPIE, Society of Photo-Optical Instrumentation Engineers (SPIE), 9605, article no. 96050E.

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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.

Item Type: Conference or Workshop Item
Copyright Holders: 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)
ISSN: 1996-756X
Project Funding Details:
Funded Project NameProject IDFunding Body
Simulation and Measurement of Charge Transfer in Advanced Semiconductor Imaging Sensors. (SP-12-121-DH)ST/K005634/1STFC (Science & Technology Facilities Council)
Keywords: coronagraphy; electron multiplying charge coupled devices; radiation; photon counting; equipment and services; exoplanets; electrons; sensors; spectrographs; spectroscopy
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Centre for Electronic Imaging (CEI)
Related URLs:
Item ID: 44421
Depositing User: Nathan Bush
Date Deposited: 24 Sep 2015 09:10
Last Modified: 08 Dec 2018 14:03
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