Impact of magnetic storms on the dark current of the space infrared camera ISO/ISOCAM

The two detectors of the ISOCAM camera on board the ISO spacecraft have performed nominally for the entire duration of the mission. Their main properties (dark current level, noise and responsivity) have been monitored on a daily basis in order to perform their trend analysis. The dark current level averaged over the whole detectors sometimes significantly increased during one or several days before going back to its nominal value. This occurred only when the spacecraft was approaching the external radiation belt and we observed that the dark current level was strongly correlated with the fluence of ambient electrons. This paper gives the interpretation of the dark current variations, which are attributed to magnetic storms.