| Popis: |
TENMAK D.N.3326 For practical measuring purposes in high pure Ge detectors, some useful semiempirical approaches are often used to calculate the peak efficiency (absolute efficiency) for any source-to-detector distance (d) if the efficiency has been measured at one known distance (d1). In all approaches considered, normally, one begins an experimental efficiency calibration for single measuring geometry at a distance (d1), and then derives the efficiency for any other arbitrary distance (d), from the relation ∈(d) = Ω (d) ∈(d1) = Ω (d1) where ∈ denotes the detector efficiency for any gamma ray energy and Ω is solid angle that is subtended by detector to the source position. However, this relation is only valid when the distances used in the relation was corrected for the effective photon interaction depth for any gamma-ray energy (Debertin and Helmer, 1988;Yücel et al.1996) since the efficiency ratio, ∈(d)/∈(d1), is not equal to the inverse ratio, d1-2/d-2. In the present work, the photon interaction depths depending upon gamma- ray energies in the range of about 50-2000 keV for point gamma sources (241Am, 137Cs, 60Co, 133Ba and 152Eu) and a liquid volume (cylindrical) source containing 57Co, 88Y, 113Sn, 137Cs, 109Cd, 139Ce and 60Co radionuclides were measured. Then, the calculation of the peak efficiency of a ptype HPGe detector is experimentally tested for both point and the extended (cylindrical) liquid source at various distances from the surface of the end cap of the detector by introduction of the effective photon interaction for any gamma-ray energy. Turkish Atomic Energy Authority, [v.d.]…. |
