Boson Jonas, Plamboeck Agneta H, Ramebäck Henrik, Agren Göran, Johansson Lennart
Swedish Defence Research Agency, FOI CBRN Defence and Security, SE-901 82 Umeå, Sweden.
J Environ Radioact. 2009 Nov;100(11):935-40. doi: 10.1016/j.jenvrad.2009.06.006. Epub 2009 Jul 14.
The aim of this work was to evaluate the use of Monte Carlo-based calibrations for in situ gamma-ray spectrometry. We have performed in situ measurements at five different sites in Sweden using HPGe detectors to determine ground deposition activity levels of (137)Cs from the 1986 Chernobyl accident. Monte Carlo-calculated efficiency calibration factors were compared with corresponding values calculated using a more traditional semi-empirical method. In addition, results for the activity ground deposition were also compared with activity densities found in soil samples. In order to facilitate meaningful comparisons between the different types of results, the combined standard uncertainty of in situ measurements was assessed for both calibration methods. Good agreement, both between the two calibration methods, and between in situ measurements and soil samples, was found at all five sites. Uncertainties in in situ measurements for the given measurement conditions, about 20 years after the fallout occurred, were found to be in the range 15-20% (with a coverage factor k=1, i.e. with a confidence interval of about 68%).
这项工作的目的是评估基于蒙特卡罗方法的校准在原位伽马射线能谱分析中的应用。我们使用高纯锗探测器在瑞典的五个不同地点进行了原位测量，以确定1986年切尔诺贝利事故中(137)Cs的地面沉积活度水平。将蒙特卡罗计算的效率校准因子与使用更传统的半经验方法计算的相应值进行了比较。此外，还将地面沉积活度的结果与土壤样品中的活度密度进行了比较。为了便于对不同类型的结果进行有意义的比较，对两种校准方法都评估了原位测量的合成标准不确定度。在所有五个地点，两种校准方法之间以及原位测量与土壤样品之间均发现了良好的一致性。在沉降发生约20年后的给定测量条件下，原位测量的不确定度在15% - 20%范围内（包含因子k = 1，即置信区间约为68%）。
