The gamma-ray detection efficiency of a 118 cm3 Ge(Li) detector for disc-sources of 7Be

The full energy peak detection efficiency of a 118 cm3, closed end, coaxial Ge(Li) detector has been measured as a function of source to detector separation using disc-sources of 7Be with diameters ranging from 5 to 80 mm. The detector was characterized using a number of point-like sources of different energy placed on axis at different distances from the detector. The combined results were analysed in terms of the point-detector model and the Gaussian radial dependence model. The point-detector-model was found to provide a satisfactory parameterization of the axial variation of efficiency for point-sources. However the method did not predict the radius dependence of the efficiency for disc-sources. The Gaussian model provided much better fits in this case. (Author)