Abstract：A 4πγ well-type NaI(Tl) crystal counting device for gamma-ray detection at NIM is introduced. By analyzing the detected gamma spectrum of 60Co, 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 60Co 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.
2014, Vol. 35 
