Compton Backscattered Photons in Precision Proportional Counter Spectrometry

摘要

The importance of Compton backscattering in gas proportional spectrometry in the energy range 10 to 100 kev is pointed out. If the backscattered photons are unresolved from the main peak, a large error may be introduced under certain conditions in absolute and relative intensity measurements based on theoretical quantum efficiency (geometry×absorption); if the backscattered peak is resolved, failure to recognize its origin may result in the ``discovery'''' of a new gamma ray. The effect is especially pronounced when a collimator is used to establish geometry; for example, the intensity of backscattered photons can amount to as much as half the intensity of the main peak at 46.5 kev with a ¼‐in. diameter collimator.