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Дата изменения: Fri Aug 30 15:55:09 1996 Дата индексирования: Tue Oct 2 11:52:40 2012 Кодировка: Поисковые слова: universe |
Conventional CCDs are illuminated through a
front-surface electrode structure which may be 
m thick. This severely
limits the sub-keV detection efficiency.
They also have a detection volume defined by the depletion layer depth of
m. This should be compared with, for example, the 1/e
attenuation length for 6keV photons which is 
m; hence CCD
sensitivity falls rapidly with increasing energy.
The use of back-illumination technology to enhance soft X-ray response has benefitted from developments for similar requirements to minimize the entrance dead layer thickness for blue/UV wavelengths. However the development of CCDs with deeper depletion depths to maximize the detecting volume has been a pre-occupation unique to the X-ray community. (This method would be useful for the near-IR wavelenghts, but has not been widely adopted)