High accuracy measurements and Monte Carlo calculations of the relative efficiency curve of an HPGe detector from 433 to 2754 keV

The relative full-energy peak efficiency curve of a 280-cm(3) coaxial HPGe detector was determined to an accuracy of about 0.1% over the energy range from 433 to 2754 keV from pairs of gamma-ray lines whose emission probabili ties are very accurately known. The curve was extended from previous studie s by the addition of lines from (108)mAg and Na-24. Ratios of full- energy peak efficiencies were also determined by Monte Carlo calculations using th e CYLTRAN code. The measured ratios and the Monte Carlo values were in exce llent agreement (0.03-0.19 %). The relative efficiency was defined by a pai r of functions, one for 433-1332 and one for 614-2754 keV. Monte Carlo valu es were used to supplement the measured values, resulting in a more accurat e fit. The stability of the relative efficiency curve for a 94-cm(3) HPGe d etector was studied and it was found that there was no statistically signif icant change over a period of 3 years. (C) 2000 Elsevier Science B.V. All r ights reserved.