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PRECISE AND HIGHLY PRECISE MEASUREMENT OF GAMMA-RAY EMISSION PROBABILITY

精确、高精度测量伽马射线发射概率

基本信息

批准号：
10680487
负责人：
MIYAHARA Hiroshi
金额：
$ 1.66万
依托单位：
NAGOYA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10680487/
关键词：
HPGe DETECTOR STANDARD SOURCES EMITTING TWO CASCADE γ-RAYS HIGHLY PRECISE RELATIVE DETECTION EFFICENCY CURVE RELATIVE γ-RAY INTENSITY HIGHLY PRECISE ABSOLUTE DETECTION EFFICIENCY CURVE DISINTEGRATION RATE γ-RAY EMISSION PROBABILITIES カスケードγ放

项目摘要

Gamma-ray emission probabilities have been precisely measured by a4πβ-γ coincidence apparatus using a live-time two-dimensional data-acquisition system, and the certainties of those for ^<76>As, ^<159>Gd, ^<169>Yb, ^<182>Ta, ^<186>Re, ^<187>W and ^<188>Re have been improved by two factors or more. Furthermore, it becomes clear that the reported values for ^<76>As and ^<169>Yb are overestimated by 10% and 2%, respectively, and that those for ^<159>Gd, ^<187>W and ^<188>Re are underestimated by 5%, 20% and 3-10%, respectively.Highly precise determination of γ-ray detection efficiency curve for an HPGe detector with relative efficiency of 25% have been tried Standard sources emitting two cascade γ-rays with high probabilities were measured at 30 cm of source-detector distance under the condition of small correction for absorption and cascade summing. The sources were ^<24>Na, ^<46>Sc, ^<48>Sc, ^<60>Co, ^8Y, ^<94>Nb, ^<108>Ag and ^<111>In. The relation between energy and detection efficiency was analysed and the least-squares method using covariance matrix was applied for normalised those data. The relative detection efficiency curve was obtained with uncertainty of 0.1% between 171 and 2754 keV, whereas the uncertainty was about 0.3% in the range of lower energy and near 2754 keV.The relative γ-ray intensity of the 1643 to 2167 keV γ-rays for ^<38>Cl was very precisely determined to be 0.7496±0.0011 by using this curve. Also, the emission probabilities of the 844 and 1014 keV γ-rays for ^<27>Mg were measured to be 0.7186±0.0008 and 0.2820±0.0008, respectively. Furthermore, the highly precise relative detection efficiency curve was converted to the highly precise absolute detection efficiency curve by determining the disintegration rate of ^<60>Co source with uncertainty of 0.03%. By using this curve, γ-ray emission probabilities of ^<134>Cs and ^<152>Eu used as multi-γ ray standard source are measured and will be compared to the evaluated values.

A4πβ-γ符合装置使用实时二维数据采集系统精确地测量了伽马射线发射几率，并且^&lt；76&gt；As，^&lt；159&gt；Gd，^&lt；169&gt；Yb，^&lt；182&gt；Ta，^&lt；186&gt；Re，^&lt；187；W和^&lt；188；Re的确定性提高了两倍或更多。此外，很明显，报告的^&lt；76；As和^&lt；169&>Yb的价值分别被高估了10%和2%，^&lt；159&>；Gd，^&lt；187&>W和^&lt；188&>的价值被高估了。分别低估了5%、20%和3-10%的Re。对相对效率为25%的高纯锗探测器的γ-射线探测效率曲线进行了高精度测量。在小吸收校正和级联求和的条件下，在源-探测器距离30 cm处测量了发射两个高概率级联γ射线的标准源。来源是^&lt；24；Na，^&lt；46&gt；SC，^&lt；48&gt；SC，^&lt；60&gt；Co，^8y，^&lt；94&gt；Nb，^&lt；108&gt；Ag和^&lt；111&gt；In。分析了能量与检测效率的关系，并采用协方差矩阵的最小二乘法对数据进行归一化处理。相对探测效率曲线在171keV和2754keV之间的不确定度为0.1%，而在低能区和2754keV附近的不确定度约为0.3%。利用该曲线非常精确地测量了~1t；38&gt；Cl的1643~2167keVγ射线的相对γ-射线强度为0.7496±0.0011。此外，还测得~(27)和~(27)Mg的844keV和1014keVγ辐射几率分别为0.7186±0.0008和0.2820±0.0008。此外，通过测定不确定度为0.03%的60Co源的衰减率，将高精度的相对探测效率曲线转换为高精度的绝对探测效率曲线。利用这一曲线，测量了~(134)Cs和~(152)Eu作为多γ标准射线源的γ射线发射几率，并与评估值进行了比较。