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Proceedings Paper

Performance tests of a DIVA-CCD: before and after proton irradiation
Author(s): Klaus Reif; Henning Poschmann; Karl-Heinz Marien; Philipp Mueller
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Paper Abstract

The E2V CCD42-20 NIMO type CCD was tested in view of its use for the german astrometric satellite mission DIVA. As in other astrometric missions (FAME, GAIA) the CCDs will be operated in TDI mode synchronous with the stars drifting across the detectors. At the expected operating temperature, around -30C to -50C, the dark current performance is an important parameter. Radiation induced degradations with respect to dark current and CTE are of particular concern, too. We find that TDI operation reduces the dark current by a factor of ≈30 near the DIVA satellite TDI clock rate (1.4 msec). The detector was irradiated with soft protons, in a first run, with rather weak doses of up to an equivalent 10 MeV fluence of 1.6×108 protons/cm2. The increase in dark current is quite small (4% to 5% maximum at -40C) but seems to vary with temperature (e.g. 2% at -60C). The CTE degradation shows a linear dependance on the radiation dose and the CTE gets worse if the detector temperature gets lower (e.g. for the highest dose: 0.999 98 at -60C and 0.999 95 at -100C). Vertical and horizontal deferred charge patterns show a significant difference. The total mission dose will be about 10x higher and the dark current and CTE values are tentatively extrapolated. The results of this study shall serve as a basis for further irradiation experiments combined with laboratory simulations and numerical modelling. During the course of this study the DIVA project had to be stopped due to lack of funding. But our results are applicable equally well to the proposed SMEX mission AMEX which is based on the DIVA concept.

Paper Details

Date Published: 12 January 2004
PDF: 12 pages
Proc. SPIE 5167, Focal Plane Arrays for Space Telescopes, (12 January 2004); doi: 10.1117/12.507128
Show Author Affiliations
Klaus Reif, Sternwarte Univ. of Bonn (Germany)
Henning Poschmann, Sternwarte Univ. of Bonn (Germany)
Karl-Heinz Marien, Max-Planck Institut für Astronomie (Germany)
Philipp Mueller, Radioastronomical Institute Univ. of Bonn (Germany)

Published in SPIE Proceedings Vol. 5167:
Focal Plane Arrays for Space Telescopes
Thomas J. Grycewicz; Craig R. McCreight, Editor(s)

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