Reevaluation of the dosimetry system 1986 (DS86) according to the US-Japan joint study and the analysis of the radiation effects

广岛和长崎原子弹爆炸对幸存者的剂量是根据美日联合研究批准的剂量测定系统1986 （DS86）估计的。该系统被用于辐射效应研究基金会（RERF）和广岛大学辐射生物学和医学研究所（RIRBM），并在他们自己的队列研究中评估幸存者的器官剂量。通过对DS86的测定，我们发现中子活化数据与基于DS86的计算结果不一致。同样，在Eu-152、Co-60、Cl-36和P-32的所有数据中都发现了这种差异。最大的差异出现在广岛的数据中。例如，在1500米的地面距离上，数据是DS86的5到10倍。我们的研究就是要找出原因并找到解决办法。问题包括：(1)数据采集过程中的问题；(2)中子输运计算中的问题；(3)爆炸过程的计算和推导出新的源项的问题。我们核实了在近地距离采集的数据和运输计算没有问题。关于远距离采集的数据可能会有一些问题，因为测量到的伽马射线水平很低？对于这个问题，我们使用随机数进行了模拟计算，发现可能存在污染，包括伽马射线。从最近发生的东海村事故的金活化和监测站数据中，验证了在2000m地面范围内，热、首中子数据与计算的一致性较好。因此我认为问题出在广岛原子弹的中子源项上。我以复制广岛原子弹的模型原子弹为基础进行了多次计算，发现数据和计算一致，假设(1)原子弹底部脱落，好像有3cm左右的平行间距，(2)中子发射高度约90m高程（发射弹下落90m后形成火球），(3)增加产量约20%。美国集团不接受这样的假设。然而，2000年5月，Dr.Kaul在ref的研讨会上同意，如果没有这样的假设，我们无法调整计算和数据。我们将于2001年5月再次举行会议。一个美国集团承诺，他们将拿出自己的办法来解决这个问题。我们将在那里讨论这个问题，并希望我们将达成全面协议，我们将为原子弹幸存者获得新的剂量测定系统。少

Atomic bomb doses for the survivors in Hiroshima and Nagasaki have been estimated according to the Dosimetry system 1986 (DS86), which was approved by the effort of US-Japan joint study. The system was used in Radiation Effects Research Foundation (RERF) and Research Institute for Radiation Biology and Medicine, Hiroshima University (RIRBM) and evaluated organ doses of the survivors in their own cohort study. After the determination of DS86 we found discrepancy between the data obtained from neutron activation data and calculation based on DS86. The discrepancy was found in all of the Eu-152, Co-60, Cl-36 and P-32 data, similarly. The largest discrepancy was found in the Hiroshima data. For example, data are 5 to 10 times larger than DS86 at the 1500 m ground distance. Our study was to find its reason and to get a solution. The problem include (1) problems in data taking process, (2) in neutron transport calculation and (3) in the calculation of the process of explosion and deduced neu … More tron source term. We verified that there were no problems in the data taken at short ground ranges and in the transport calculation. About the data taken at long range may have some problems, since gamma rays measured were very low level? For that problem we made simulation calculation using random numbers and found there may be contamination gamma rays included. From the gold activation and monitoring post data taken at Tokai-mura accident, which recently happened, it was verified that thermal and first neutron data and calculation had good agreement until 2000m ground range. Therefore I considered that the problem is in the neutron source term at Hiroshima atomic bomb. I made many calculation based on the model atomic bomb, which reproduce the Hiroshima type atomic bomb, and found the data and calculation agrees if I assume (1) bottom of the atomic bomb came off as if it had about 3cm parallel spacing, (2) about 90m elevation of the neutron emission height (after the emission bomb fell down 90m and formed fire ball), (3) increase the yield about 20%. US group did not accept such assumptions. However, Dr.Kaul in May 2000 at the workshop held at RERF, agreed that we couldn't adjust the calculation and data without such assumptions. We will have a meeting again this May 2001. US-group promised that they would bring their way to solve the problem. There we will discuss this problem and hope that we will have our whole agreement and that we will obtain new dosimetry system for the atomic bomb survivors. Less