一种测量~(241)Am溶液比活度的方法

根据符合法原理,利用4πα+4πγ活度测量标准装置,采用改变γ探测效率的方法,外推测量241Am溶液的比活度,解决了电离室测量α源时需进行的自吸收和反散射系数校正问题。双4π-γ效率外推法通过调整测量装置升降机高度来改变NaI(Tl)探测器对放射源所张的立体角,从而达到改变γ探测效率的目的,进而通过γ效率拟合外推得到放射源的活度。经过对两种241Am溶液20多个源的测量,测量结果与2πα屏栅电离室活度测量结果在不确定度范围内符合一致,且其测量不确定度降到了0.4%以内。

A Method for Specific Activity Measurement of 241Am Solution

According to the principle of coincidence theory, the specific activity of ²⁴¹Am solution was determined on 4πα+4πγ counting standard device by γ efficiency extrapolation, and the problems of constant correction coefficients of self-absorption and scattering in α ionization chamber method were solved. The method was based on the alteration of detection efficiency when the height of elevator was altered, and the activity was obtained by γ fitting extrapolation according to detection efficiency. The results of more than 20 alpha radioactive sources by this method in our work are accordant with those of 2πα ionization chamber, and their uncertainties are improved to 0.4%.