摘要
实验刻度了GEM60P4型高纯锗(High Purity Germanium,HPGe)探测器在H=250mm处对三种圆形面源(φ24 mm、φ80 mm和φ90 mm)的峰探测效率,结果表明,这三种源的效率基本一致。采用MCNP模拟了φ40–160mm内的圆形面源效率,研究了探测效率随样品直径的变化关系,并采用Geant4计算了圆形面源对同轴探测器的有效立体角。对φ90mm以上的样品源,探测效率随源直径的增大在逐渐减小,且高能γ射线效率减小程度较快,需采用标准源进行效率刻度。
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 Ф24 mm, Ф80 mm and Ф90 mm, respectively. Methods： The efficiency and the solid angle for disc source with diameter ranging Ф40-160mm 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 v90mm. Conclusion： The efficiency for disc sources with diameter less than Ф90 mm is directly calibrated by the standard point sources, while for disc sources with diameter larger thanФ90 mm which is needed to be calibrated by the standard disc sources.
出处
《核技术》
CAS
CSCD
北大核心
2014年第7期53-57,共5页
Nuclear Techniques
