X-Ray Photoelectric Detectors with Conical Cathodes: Sensitivity to Beam Divergence

摘要

The sensitivity of x-ray photoelectric detectors (PED's) with conical cathodes to the divergence of an incident x-ray beam has been studied theoretically. Using finite element zoning, a simple model has been constructed for computing the net effective yield with typical source-detector geometries. Parameter studies reveal that strong averaging of the local photoelectron yield occurs when no apertures are interposed between the source and the cone, rendering the net yield nearly insensitive to any off-axis tilt of the cone up to 10 deg. However, with apertures the net yield becomes a strong function of cone tilt. Lastly, the net yield requires no more than a 6% correction when realistic calibration and fielding geometries are compared. 14 figs. (ERA citation 12:046117)