Precise Relative and Absolute Germanium Detector Efficiencies for Gamma Rays

Recently, major emphasis has been to develop techniques for generating efficiencies for volume sources for field applications. The present work is aimed at establishing a methodology for laboratories to improve the precision of their detector efficiencies from {approx}0.5 to near 0.1% for both relative and absolute efficiencies. Measurements of sources with gamma rays whose relative intensities are known very accurately are combined with measurement of a precisely calibrated Co-60 source and efficiencies calculated with a Monte Carlo photon and electron transport code. The effects of uncertainties in the dimensions of the sensitive volume of a high-purity Ge detector and its position in the housing are illustrated.