Measurement of x-ray photogeneration in amorphous selenium

The use of low-mobility photoconductors in x-ray imaging, especially amorph ous selenium (a-Se), is currently of great interest. Detailed measurements of the photoconversion gain factor W+/- and gain fluctuations sigma have be en obtained to facilitate applications using a-Se and to provide a better u nderstanding of the charge formation process. The measurements were made wi th an x-ray spectrometer constructed using a-Se as the x-ray absorber. Puls e height spectra of known monoenergetic x-ray sources were measured to dete rmine the response of the a-Se. Both the gain and fluctuations calculated f rom the data were found to depend on the x-ray energy epsilon, and the appl ied field E, indicating the recombination of a larger amount of charge that was created initially. (C) 1999 American Institute of Physics. [S0021-8979 (99)07410-1].