[Previous] | [Session 22] | [Next]
M. Bautz, C. Grant, S. Kissel, B. LaMarr, G. Prigozhin (MIT CSR), S. Brown (NASA/GSFC), J. Hill (PSU)
We report results of laboratory soft-proton irradiation of a cold ACIS CCD. We performed this experiment in an attempt to reproduce the effect of the September, 1999 room-temperature bakeout of the flight ACIS detectors on detector performance, and to gain understanding of the effects of future ACIS bakeouts. Following irradiation of a cold (-100C) detector by 120 keV protons, simulating the 1999 irradiation of the ACIS flight detectors, an initial eight-hour bakeout to +30C increased charge transfer inefficiency (CTI) by a factor of roughly 2.5. Following additional irradiations to simulate the dose received by the flight instrument since its 1999 bakeout, a bakeout of the laboratory device for 8 hours at -60C produced no degradation in CTI. However, a subsequent bakeout of the laboratory device for 8 hours at +30C produced an additional increase in CTI of roughly 15%. We compare these results to in-flight experience, and discuss mechanisms by which bakeouts to room temperature may change CTI.
This work was supported by NASA through contract NAS-8-37716.
Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.