气溶胶滤材样品γ探测效率与测量源尺寸的关系  

Relation between γ-ray detection efficiency and the source size of prepared aerosol filter sample

作　　者：张佳媚[1] 师全林[1] 包敏[1] 刘德敏[1] 

机构地区：[1]西北核技术研究所

出　　处：《核电子学与探测技术》2003年第3期212-215,226,共5页Nuclear Electronics & Detection Technology

摘　　要：用22.5cm×45cm的聚丙烯滤材制备了一套含6种单能γ发射体(能量60～1116keV)的直径为30～110mm的八种圆片形测量源,分析其在6种HPGe探测器上的各能量的相对探测效率。实验显示各能量在各探测器上探测效率最高时的源直径在50～60mm之间。分析实验结果还发现:探测器晶体直径增大,测量源最佳直径也趋于增大;相对于高能射线而言,低能射线趋于选择直径稍小但厚一些的圆片测量源,但此趋势对平面型HPGe探测器不如同轴型HPGe探测器显著。用MCNP4B程序模拟计算上述不同尺寸的源在GEM60195-P探测器上分析时各相应能量的探测效率,探测效率最高的源尺寸结果和实验吻合。对同一探测器计算得到:本实验能量范围内,对20cm×25cm和45cm×45cm的滤材,测量源最佳直径分别为40～50mm和50～70mm。滤材面积增大,测量源最佳直径也增大。By adding revolution of known activity, six disk sources with different diameters are prepared with the filter of 22.5cm×45cm. Several HPGe detectors with different crystal dimensions are employed to detect the nuclides in the disk sources and the relative detection efficiencies are calculated from the experiments. The result indicates that the source with the highest efficiency has the diameter between 50mm and 60mm within the energy range from 60keV to 1116keV. It is also found that the diameter of optimum source increases slightly with the crystal diameter of detector. Besides, a relatively thicker source disk with smaller diameter is preferred for lower energy rays, compared with higher energy rays. But this tendency is not as obvious for planar HPGe detector as that for coaxial HPGe detector. For above samples, Monte Carlo Simulations for the measurement of one detector are carried out and the result accords with the experiments. Also, by Monte Carlo Simulating for other different area filters, it is known that the diameter of source with optimum efficiencies increases with the area of filter. 

关 键 词：气溶胶滤材样品 γ探测效率 测量源 尺寸 放射性核素 空气 环境分析 探测器 

分 类 号：X837[环境科学与工程—环境工程] TL817.2[核科学技术—核技术及应用]