The HPGe as a defined-solid-angle detector for low-energy photons

HPGe detectors now available are well suited for use as defined-solid-angle spectrometers in the low-energy range, 25 to 80 keV. The calculation of efficiency, as defined by an external collimator, to very high accuracy seems possible if account is taken of the various mechanisms through which photons can be lost from the full-energy peak. Compton scattering is important in this energy range and its effect on peak shape and detection efficiency has been investigated for the 59.5 keV γ-ray from 241Am and compared with calculation. The close agreement found suggests that an uncertainty of less than 1% is attainable. (orig.)