Use of Crystal Diffraction with Ge Diode Detector for High Resolution Gamma-Ray Spectroscopy

Abstract

The Argonne 7.7 m bent crystal gamma-ray spectrometer is combined with a lithium drifted Ge diode detector to perform high resolution gamma-ray spectroscopy on complicated neutron capture gamma-ray spectra. The system combines the energy precision of the bent crystal spectrometer with the high resolution of the Ge diode. The system is most useful in the 1–3 MeV energy range where both the precision and energy resolution obtained by the combined system frequently are from 3 to 10 times those of either the bent crystal or the Ge diode used individually. A 50-fold improvement in the signal-to-background ratio is obtained through the use of the combined system. The use of the system is illustrated by 113Cd(n,γ)114Cd spectra. The Argonne system is compared with other possible crystal diffraction arrangements and with coincidence and anticoincidence techniques for improving the quality of the (n,γ) measurements. The application of the Argonne system to the comparison of (n,γ) transisions with gamma transitions following radioactive decay is discussed. New values for the strong gamma transition associated with the decay of 137Cs and 60Co are quoted along with a more precise value (1294.35±0.30 keV) for the gamma ray associated with the decay of 41A. Improvements in the Argonne system are described and a proposed extension of the system for precision energy measurements in the 2–5 MeV range is discussed.