Nuclear Techniques ›› 2014, Vol. 37 ›› Issue (07): 70404-070404.

• NUCLEAR ELECTRONICS AND INSTRUMENTATION •

### Study of HPGe detector peak efficiency by disc source

ZHANG Xiaolin1,2 YU Gongshuo2 LI Yuanjing1 XU Qichu2 XIE Feng2 BAI Tao2

1. 1(Department of Engineering Physics, Tsinghua University, Beijing 100084, China) 2(Northwest Institute of Nuclear Technology, Xi’an 710024, China)
• Received:2013-09-05 Revised:2014-04-08 Online:2014-07-10 Published:2014-07-07

Abstract: Background: Calibrating the detection efficiency accurately is the key process to the disc filter sample activity detected by High Purity Germanium (HPGe) gamma spectrometer, and the diameter of the disc filter source is varied with the specification of the sampler filter. Purpose: To study further the relation between detection efficiency and the source size, the HPGe detector peak efficiency (relative detective efficiency is 60%) was performed for disc sources with diameters of ?24mm, ?80mm and ?90mm, respectively. Methods: The efficiency and the solid angle for disc source with diameter ranging ?40–160mm were simulated using the MCNP and the Geant4. Results: The result shows that the detecting efficiency of three sources is consistent, and the efficiency gradually decreases with the increasing size of the disc source with diameter greater than ?90mm. Conclusion: The efficiency for disc sources with diameter less than ?90mm is directly calibrated by the standard point sources, while for disc sources with diameter larger than ?90mm which is needed to be calibrated by the standard disc sources.