Efficiency calibration of a Ge detector in the 0.1–11.0 MeV region

An efficiency curve was constructed for a large-volume Ge detector located at the thermal-neutron beam line of the JRR-3M reactor at the Japan Atomic Energy Research Institute (JAERI). The calibrations for γ-ray energies below 2754 keV were accomplished with a large number of radioactive sources and above 2754 keV with the 12C(n,γ) and 14N(n,γ) reactions. This detector and its efficiency curve were subsequently used to determine accurately the photon emission probabilities of γ rays from the decays of 56Co (T1/2=77 d) and 66Ga (9.5 h) and from the 35Cl(n,γ) reaction. These radiation sources can serve as secondary standards for efficiency calibrations.