Production rates of neutrons in soils due to natural radioactivity
Production rates of neutrons in soils due to natural radioactivity
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由于自然放射性而在土壤中产生中子的速率
DOI：
10.1029/jb073i010p03135
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发表时间：
1968
影响因子：
--
通讯作者：
J. Kastner
中科院分区：
文献类型：
--
作者：
Y. Feige;B. G. Oltman;J. Kastner
几个轻元素的目标暴露于单能电离氦束从阿贡串列加速器的相对中子产额被确定为α能量范围从4.8到8.8兆电子伏。我们对5.3 Mev的中子产额的比值与已发表的用Po 210 α粒子获得的厚靶产额的数据一致。根据我们的计算结果，假定铝的（α，n）产额为每108个Po 210 α α粒子75个中子，计算了某些元素和不同土壤成分的天然放射性系列的平均（α，n）产额。如果假定3 ppm的U 238和11 ppm的Th 232代表地球的上地壳，则得到砂中的生产率为6.7 ± 0.7牛顿/克/年，花岗岩中的生产率为13.5 ±1.3牛顿/克/年。由于U238的自发裂变，将产生额外的1.4牛顿/克/年。由于宇宙射线与海平面上的地球表面相互作用产生的中子的产生率约为800 n/g/yr，因此这些（α，n）反应对人口的照射率不可能有任何意义。然而，它们可能会引起地质学家的一些兴趣，并且可能是隧道、深洞或矿井中中子通量的主要贡献者，这些地方的宇宙射线背景非常低。
The relative neutron yield of several targets of light elements exposed to monoenergetic ionized helium beams from the Argonne tandem accelerator was determined for alpha energies ranging from 4.8 to 8.8 Mev. Our ratio of the neutron yields for 5.3 Mev are in agreement with published data on thick target yields obtained with Po210 α particles. The average (α, n) yield per α particle of the natural radioactive series for some elements and for different soil compositions was calculated from our results assuming an (α, n) yield of 75 neutrons per 108 α particles of Po210 α for aluminum. If 3 ppm U238 and 11 ppm Th232 are assumed as representative of the earth's upper crust, a production rate of 6.7 ± 0.7 n/g/yr in sand and 13.5 ±1.3 n/g/yr in granite is obtained. Additional 1.4 n/g/yr will be generated because of the spontaneous fission of U238. As the production rate of neutrons through interactions of cosmic rays with the earth's surface at sea level is of the order of 800 n/g/yr, these (α, n) reactions cannot be of any significance to exposure rates of human populations. They may be of some interest to geologists, however, and may be the main contributors to neutron fluxes in tunnels, deep caves, or mines, where cosmic-ray background is very low.