Shizuma K, Iwatani K, Hashi H, Oka T, Morishima H, Hoshi M
Applied Nuclear Physics, Faculty of Engineering, Hiroshima University.
J Radiat Res. 1992 Jun;33(2):151-62. doi: 10.1269/jrr.33.151.
Neutron-induced activities 60Co and 152Eu have been measured for samples collected from the Atomic-Bomb Dome locating at 161 m from the hypocenter of the Hiroshima Bomb. Specific activities 60Co/Co and 152Eu/Eu at the time of the detonation have been determined as 10.0 +/- 1.0 Bq mg-1 (steel sample S4) and 80 +/- 9 Bq mg-1 (granite sample G1), respectively. Detailed measurements of 60Co and 152Eu activities for samples collected from various locations of the Dome show almost no directional dependence whether the sample faced to the epicenter or not, nor vertical height dependence between 17 m height and the ground level. In addition, 152Eu was not detected in the sample collected from the basement. It has been shown that the present 60Co activity value, the nearest steel one to the hypocenter, as well as other short distance data are systematically lower than the calculated values based on the neutron fluence of the DS86.
对从广岛原子弹爆心投影点（距广岛原子弹爆心161米）采集的样本测量了中子诱发的放射性活度60Co和152Eu。已确定爆炸时60Co/Co和152Eu/Eu的比活度分别为10.0±1.0 Bq mg-1（钢样本S4）和80±9 Bq mg-1（花岗岩样本G1）。对从原子弹爆心投影点不同位置采集的样本进行的60Co和152Eu放射性活度详细测量表明，无论样本是否朝向震中，几乎都没有方向依赖性，在17米高度与地面之间也没有垂直高度依赖性。此外，在从地下室采集的样本中未检测到152Eu。结果表明，目前距爆心最近的钢样本的60Co活度值以及其他短距离数据系统地低于基于DS86中子注量计算的值。
