HIGH-RESOLUTION STUDIES OF GAMMA-RAY SPECTRA USING LITHIUM-DRIFT GERMANIUM GAMMA-RAY SPECTROMETERS

Abstract

This paper describes the use of germanium lithium-drift p-i-n diodes as high-resolution γ-ray spectrometers. With these spectrometers we have obtained γ-ray resolutions of 2.05 keV at 122 keV, 4.0 keV at 1333 keV, and 5.5 keV at 2614 keV. Using the detectors as pair spectrometers for high-energy γ rays, we have obtained a resolution of 9.8 keV on a 7.6-MeV γ ray. The factors affecting the resolution of the detectors are discussed. Fano factors of ~0.4 have been observed. Efficiency curves are given for a 2.5 cm2 × 3.5 mm detector and for a 5 cm2 × 8 mm detector.The detectors have been used to make high-resolution studies of the complex γ-ray spectra from sources of 131Cs, 161Pm, 153Gd, 156Eu, 159Gd, 177Yb, and 226Ra. Results are reported for the energies and intensities of the γ rays observed in these studies.