A Second Bias Boost

A Bias Boost in theory clears the LWS detectors of memory effects and was initially scheduled to occur at the beginning of observations during each revolution. (A revolution is a 24 hour periods with 16 hours of observing time.) During a revolution, cosmic ray hits act to increase the detector responsivity and noise and raise the level of the dark current.

It was discovered during PV phase that the increase in responsivity and noise in the detectors grew during the revolution and became unstable before the revolution observing was complete. For this reason a second, mid-revolution bias boost has been added to each revolution.

The 10 ratty plots below show the growth in responsivity for each of the 10 detectors as a function of revolution time. The x-axis is hours with the values 0, 5, 10, 15, 20 given. The y-axis is detector responsivity divided by responsivity imeadiatly after bias boost. While the y-axis appears illegible, the y-axis numbers spanned by almost all of the function are 1.0 to 1.2 (1.0 is marked centered on the y-axis label).

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Disclaimer:These are largely personal notes of S. Lord, and in are in no way complete or intended to be a substitute for the original manuals, etc..

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Last update: August 1998

INFRARED PROCESSING AND ANALYSIS CENTER