Determination of HPGe peak efficiency for voluminous gamma-ray sources by using an effective solid angle method. (October 2016) - Kang, M.Y.
Abstract: A code called EXVol has been developed to obtain the absolute peak efficiency for an extended or voluminous γ-ray source. The method is based on the concept of effective solid angles. Several efficiency curves that have been determined semi-empirically for voluminous sources are compared with the experimental values based on certified reference volume sources. To study the geometric and matrix effects, standard γ-ray sources of several media, volumes and shapes were measured using HPGe detectors with three different efficiencies. For the n-type detector of 32% relative efficiency, the relative deviations are less than ±10%; this performance is similar to that of existing programs for similar purposes. The EXVol code is able to calculate the detection efficiency within approximately five minutes or less. Systematic errors based on EXVol input parameters, which are mainly due to the inherent uncertainty in the detector's characteristic dimensions provided by the vendor, are studied to obtain more accurate specifications of the detectors. Highlights: We use cylindrical sources of large volume and Marinelli beaker sources and a big volume detector, which were not dealt in most previous studies. Comparing with a previous study of similar experimental conditions, we have shown the effects of the detector variables on the relative deviations vs. the γ-energy. The EXVol is versatile in that it can give the detection efficiency for a variety of forms, geometries and distances for a voluminous source and detector.