Measuring fast neutrons in Hiroshima at distances relevant to atomic-bomb survivors.

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Bibliographic Details
Title:	Measuring fast neutrons in Hiroshima at distances relevant to atomic-bomb survivors.
Authors:	Straume, T., Rugel, G., Marchetti, A. A., Rühm, W., Korschinek, G., McAninch, J. E., Carroll, K., Egbert, S., Faestermann, T., Knie, K., Martinelli, R., Wallner, A., Wallner, C.
Source:	Nature. 7/31/2003, Vol. 424 Issue 6948, p539-542. 4p.
Subjects:	Neutrons, Atomic bomb, Health risk assessment
Geographic Terms:	Japan
Abstract:	Data from the survivors of the atomic bombs serve as the major basis for risk calculations of radiation-induced cancer in humans[SUP1]. A controversy has existed for almost two decades, however, concerning the possibility that neutron doses in Hiroshima may have been much larger than estimated. This controversy was based on measurements of radioisotopes activated by thermal neutrons that suggested much higher fluences at larger distances than expected[SUP2-6]. For fast neutrons, which contributed almost all the neutron dose, clear measurements validation has so far proved impossible at the large distances (900 to 1,500 m) most relevant to survivor locations.[SUP6]. Here, the first results are reported for the detection of (63)Ni produced predominantly by fast neutrons (above about 1 MeV) in copper samples from Hiroshima. This breakthrough was made possible by the development of chemical extraction methods[SUP7,8] and major improvements in the sensitivity of accelerator mass spectrometry for detection of [SUP63]Ni atoms (refs 8-11). When results are compared with [SUP63]Ni activation predicted by neutron doses for Hiroshima survivors[SUP6], good agreement is observed at the distances most relevant to survivor data. These findings provide, for the first time, clear measurement validation of the neutron doses to survivors in Hiroshima. [ABSTRACT FROM AUTHOR]
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Database:	Psychology and Behavioral Sciences Collection

Description
Abstract:	Data from the survivors of the atomic bombs serve as the major basis for risk calculations of radiation-induced cancer in humans[SUP1]. A controversy has existed for almost two decades, however, concerning the possibility that neutron doses in Hiroshima may have been much larger than estimated. This controversy was based on measurements of radioisotopes activated by thermal neutrons that suggested much higher fluences at larger distances than expected[SUP2-6]. For fast neutrons, which contributed almost all the neutron dose, clear measurements validation has so far proved impossible at the large distances (900 to 1,500 m) most relevant to survivor locations.[SUP6]. Here, the first results are reported for the detection of (63)Ni produced predominantly by fast neutrons (above about 1 MeV) in copper samples from Hiroshima. This breakthrough was made possible by the development of chemical extraction methods[SUP7,8] and major improvements in the sensitivity of accelerator mass spectrometry for detection of [SUP63]Ni atoms (refs 8-11). When results are compared with [SUP63]Ni activation predicted by neutron doses for Hiroshima survivors[SUP6], good agreement is observed at the distances most relevant to survivor data. These findings provide, for the first time, clear measurement validation of the neutron doses to survivors in Hiroshima. [ABSTRACT FROM AUTHOR]
ISSN:	00280836
DOI:	10.1038/nature01815