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6.4 Detector Dark Currents

The dark signals and the noise on the dark signals measured after the helium boil-off are not significantly different from those measured during the nominal mission. Figure 6.4 shows the mean of the detector signals during the dark current measurements in the calibration observations during every revolution in the Post-Helium Phase. There is no distinct trend with the temperature increase. This is not so surprising, since the output signal of the instrument with closed shutter is dominated by the JFET amplifier offsets rather than the detector dark currents.

Figure 6.4: The variation of the mean detector dark signals during the Post-Helium Phase
\resizebox {\hsize}{!}{\includegraphics{posthe_darkchange.ps}}



ISO Handbook Volume V (SWS), Version 2.0.1, SAI/2000-008/Dc