The ISO-SWS Detectors: Performance Trends and Space Radiation
Effects
A.M. Heras, E. Wieprecht, H. Feuchtgruber, F. Lahuis, K. Leech, R.
Lorente, P. Morris, A. Salama and B. Vandenbussche
Abstract:
We present a trend analysis of the ISO-SWS detector performance and a
study of the space radiation effects on the SWS detectors. In
particular, dark currents, dark current noise and detector responses
have been checked as a function of time along the mission and as a
function of time in a revolution. The results show that these parameters
were stable in all bands but for band 3 (Si:As), in which the dark
currents, and in some cases the noise, increased during the mission.
Dark currents and responses were found to be higher in the first four
hours following the start of the science window, being this effect
specially important in band 2 (Si:Ga). On the other hand, the noise
level was constant along the revolution in all bands. The space
radiation environment of ISO was dominated by galactic cosmic rays and
trapped electrons and protons. Only an intense solar proton event
occured during the ISO mission, since the satellite was operated during
solar minimum. Bands 4 and 6 (Ge:Be) registered the highest glitch
rates, which showed a correlation with the electron fluxes measured on
GOES 9 for observations executed close to perigee. This fact, together
with the analysis of the glitch height distributions, support the
conclusion that secondary electrons contribute at least as much as
cosmic rays to the glitch rate in the Ge detectors.
Keywords: ISO SWS: glitch trend
Status: Experimental Astronomy accepted
Address: mailto:
ewieprec@mpe.mpg.de
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