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1 July 1991 Radiation concerns for the Solar-A soft x-ray telescope
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The charge-coupled device (CCD) camera of the Soft X-ray Telescope (SXT) for the Japanese Solar-A Mission utilizes a 1024 X 1024 virtual phase CCD manufactured by Texas Instruments in Japan. This sensor will be subject to radiation in the form of trapped protons from the earth''s radiation belts and soft x-rays (0.2-4 keV) in the solar image. Proton damage produces ''dark spikes'' or pixels of enhanced dark current. This can be characterized in terms of the average increase in dark current as a function of proton fluence and predicted through proton transfer calculations. During the preparation of this camera it has been discovered that exposure to soft x-rays creates ''permanent'' ionization damage in the gate insulator, resulting in flat-band shift, dark current increase, loss of charge transfer efficiency, and, ultimately, total unpinning of the sensor. It has been found that ultra-violet, and to a lesser degree, visible-light flooding photo-emits free electrons into the gate oxide which ''anneals'' the damage, restoring proper operation of the CCD.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Loren W. Acton, Mons D. Morrison, James R. Janesick, and Tom S. Elliott "Radiation concerns for the Solar-A soft x-ray telescope", Proc. SPIE 1447, Charge-Coupled Devices and Solid State Optical Sensors II, (1 July 1991);


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