CAJ | 학술논문

介绍了中国计量科学研究院用于测量放射性核素活度的4πγ井型NaI（ Tl）晶体装置。通过分析测量得到的60 Co放射源发射的γ射线能谱发现，采用4πγ井型NaI（ Tl）晶体对衰变纲图较为复杂的核素进行测量时存在相加峰效应。当放射源从井型NaI（ Tl）晶体井口附近逐渐移至井底的过程中，相加峰的计数率逐渐增加，从而使得对60 Co特征γ射线全能峰探测效率逐渐降低；此外，由于在井口附近探测器对放射源所张立体角相对较小，对γ射线的探测效率也较低；放射源在井型晶体内的位置发生变化也会对探测器的能量刻度带来影响。
개소료중국계량과학연구원용우측량방사성핵소활도적4πγ정형NaI（ Tl）정체장치。통과분석측량득도적60 Co방사원발사적γ사선능보발현，채용4πγ정형NaI（ Tl）정체대쇠변강도교위복잡적핵소진행측량시존재상가봉효응。당방사원종정형NaI（ Tl）정체정구부근축점이지정저적과정중，상가봉적계수솔축점증가，종이사득대60 Co특정γ사선전능봉탐측효솔축점강저；차외，유우재정구부근탐측기대방사원소장입체각상대교소，대γ사선적탐측효솔야교저；방사원재정형정체내적위치발생변화야회대탐측기적능량각도대래영향。
A 4πγ well-type NaI( Tl ) crystal counting device for gamma-ray detection at NIM is introduced. By analyzing the detected gamma spectrum of 60 Co,it is found that the sum-peak counting effect is inevitable for nuclei with complex decay scheme using 4πγ well-type NaI( Tl ) crystal. Further,a series of test experiments are carried out to investigate the performance of detector by changing the depth of 60 Co source in the well. The results reveal that the sum-peak counting rate increases as the source moved to the bottom of the well,and the efficiency for full-energy peak has a slight reduction for the increasing sum-peak effect. Besides,the efficiency is reasonable lower at the mouth of the well-type NaI( Tl)crystal for the smaller solid angle coverage. Moreover,the energy calibration is also effected by the variation of source position.