Fülöp M, Ragan P
Institute of Preventive and Clinical Medicine, Bratislava, Slovakia.
Health Phys. 1997 Jun;72(6):923-30. doi: 10.1097/00004032-199706000-00011.
An improved in-situ spectrometry measurement of 137Cs concentration in soil is introduced. The method uses the information contained in the pulse spectrum in order to forego the need for soil sampling. The approach is based on the unfolding of responses of a collimated and uncollimated HPGe detector to primary 0.662 MeV photons and to photons scattered forward in the soil. The calibration of the in situ equipment has been performed by Monte Carlo calculations and by experiments. For unfolding of experimental detector responses the code SAND II has been found reliable and capable of calculating distribution of 137Cs in soil profile with adequate accuracy for environmental monitoring purposes. The analysis of the spectra indicates that 137Cs concentration in soil 10 y after Chernobyl accident would be measurable using a middle HPGe detector (20-30% relative efficiency) and a counting time on the order of 1 h. Even with smaller detectors, 137Cs concentrations of 5 kBq m(-2) are measurable, and the depth distribution of 137Cs activities above 10 kBq m(-2) in the soil can be estimated by the presented method when a counting time on the order of 3 h is used.
介绍了一种改进的土壤中137Cs浓度原位光谱测量方法。该方法利用脉冲谱中包含的信息，从而无需进行土壤采样。该方法基于对准直和非准直高纯锗探测器对初级0.662 MeV光子以及在土壤中向前散射光子的响应进行解卷积。原位设备的校准已通过蒙特卡罗计算和实验完成。对于实验探测器响应的解卷积，已发现SAND II代码可靠，并且能够以足够的精度计算土壤剖面中137Cs的分布，以用于环境监测目的。光谱分析表明，使用中等高纯锗探测器（相对效率为20 - 30%）和大约1小时的计数时间，可以测量切尔诺贝利事故10年后土壤中的137Cs浓度。即使使用较小的探测器，5 kBq m(-2)的137Cs浓度也可测量，并且当使用大约3小时的计数时间时，所提出的方法可以估计土壤中10 kBq m(-2)以上的137Cs活度的深度分布。
