A novel technique for detection efficiency determination of HPGe

In this work, we present an experimental method to determine the detection efficiency of HPGe when the reference source according to the geometry of interest is not accessible. We use known activity point sources (PS) of 152Eu, 137Cs, 241Am and 133Ba to find the detection efficiency for disc source (DS) geometry. It can be assumed that a DS consists of several PS's. Mapping the detector surface by means of 137Cs PS shows that there is radial symmetry for detection efficiency vs. energy. Each radial distance on the detector surface contains some points, which can be considered as a PS. By selecting two points in two different radii and central point, the DS efficiency is obtained. To ensure that the method is correct, we measure the activity of a known activity DS considering DS efficiency obtained by PS's. The DS comprises 137Cs, 133Ba and 60Co. The relative difference between the measured and the reported activity of DS in most energies is less than 5%.