Nir-El Y
Soreq Nuclear Research Centre, Yavne, Israel.
Health Phys. 2000 Oct;79(4):396-401. doi: 10.1097/00004032-200010000-00007.
The objective of this study was to examine the feasibility of an accurate in situ measurement of radioactive hot spots by a HPGe detector located at a height of 0.1 m above the surface, thus sparing the awkward use of a heavy collimator required at the standard 1 m height. Radioactivity concentrations of primordial naturally occurring 40K, 232Th, 238U and of anthropogenic 137Cs in a sand plot were measured in situ at the two heights. Independently, six fractions of a soil profile collected in the site were measured in the laboratory. Good agreement was found between the results of the two geometries and the soil samples. Good agreement between measured and predicted radioactivity concentration values was obtained for hot spots simulated by uniform planar sources of 40K, 60Co and 137Cs having a circular pattern 0.5 m in diameter. The study shows that an in situ measurement without a collimator but close to a hot spot can provide a reliable result.
本研究的目的是检验使用置于地表上方0.1米高处的高纯锗探测器对放射性热点进行精确原位测量的可行性，从而避免使用标准1米高度所需的笨重准直器带来的不便。在这两个高度对沙地中天然存在的原生40K、232Th、238U以及人为的137Cs的放射性浓度进行了原位测量。另外，对在该地点采集的六个土壤剖面样本进行了实验室测量。两种测量方式的结果与土壤样本之间达成了良好的一致性。对于由直径0.5米的圆形图案的40K、60Co和137Cs均匀平面源模拟的热点，测量值与预测的放射性浓度值之间也取得了良好的一致性。该研究表明，无需准直器但靠近热点进行原位测量能够提供可靠的结果。
