Mixing activity-calibrated and uncalibrated gamma-ray sources in efficiency calibration

A method to calibrate the absolute efficiency of HPGe detectors in a large energy range using both activity-calibrated and uncalibrated multienergy ga mma-ray radioactive sources is presented. The adopted efficiency calibratio n function epsilon(E) has the simple form In epsilon(E) = a(0) + a(1) In(E/ E-B)+ a(2) In-2(E/E-B). Different parameters a(0) are simultaneously fitted to the activity-calibrated and uncalibrated sources experimental efficienc y data by the least-squares method. As an application example, the calibrat ion of a HPGe detector in the 500 to 3500 keV energy range using a Bi-207 a ctivity calibrated source and one uncalibrated Co-56 source is described. ( C) 1999 Elsevier Science Ltd. All rights reserved.