符合效率外推法绝对测量131Xem活度

放射性气体氙是全面禁止核试验条约组织重点关注的监测对象，准确测量放射性氙的活度是其中的难点之一。本文详细介绍了β-γ符合效率外推法测量放射性核素活度的原理和方法，使用该方法绝对测量了¹³¹Xe^m活度，测量不确定度为0.3%(k=1)。根据外推法原理推导了参数法测量¹³¹Xe^m活度的计算公式，外推法与参数法活度结果相差2.0%。实验中同时用HPGe γ谱仪对¹³¹Xe^m进行了活度比对测量，其结果与符合外推法测量结果相差2.7%，二者结果在置信水平(k=1)区间范围内一致。以上结果表明，β-γ符合效率外推法显著提高了¹³¹Xe^m活度测量的准确度。

Absolute Measurement of 131 Xem Activity with Coincidence Efficiency Extrapolation Method

Radioactive gas xenon is one of the important components for International Monitoring System (IMS) of Comprehensive Nuclear‐Test‐Ban Treaty (CTBT ) .It is a difficult problem that the activity of radioactive xenon can be accurately measured .T he principle of β‐γcoincidence efficiency extrapolation method was described in detail in this paper .The activity of 131 Xem was absolutely determined by β‐γ coincidence efficiency extrapolation method ,and its standard uncertainty of measurement is 0.3% .According to β‐γcoincidence efficiency extrapolation method ,parameter method formula of 131 Xem activity was deduced . And 131 Xem activity result difference of these two methods is 2.0% .In addition ,the activity of 131 Xem was determined by HPGe γspectrometry ,and the discrepancy of measurement results between coincidence efficiency extrapolation method and HPGe γ spectrometry is 2.7% .The above results indicate that the meas‐urement accuracy of 131 Xem activity is improved significantly by β‐γcoincidence efficiency extrapolation method .