title: Fast neutrons measured in copper from the Hiroshima atomic bomb dome.
abstract: The first measurements of (63)Ni produced by A-bomb fast neutrons (above approximately 1 MeV) in copper samples from Hiroshima encompassed distances from approximately 380 to 5062 m from the hypocenter (the point on the ground directly under the bomb). They included the region of interest to survivor studies (approximately 900 to 1500 m) and provided the first direct validation of fast neutrons in that range. However, a significant measurement gap remained between the hypocenter and 380 m. Measurements close to the hypocenter are important as a high-value anchor for the slope of the curve for neutron activation as a function of distance. Here we report measurements of (63)Ni in copper samples from the historic Hiroshima Atomic Bomb Dome, which is located approximately 150 m from the hypocenter. These measurements extend the range of our previously published data for (63)Ni providing a more comprehensive and consistent A-bomb activation curve. The results are also in good agreement with calculations based on the current dosimetry system (DS02) and give further experimental support to the accuracy of this system that forms the basis for radiation risk estimates worldwide.
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA. marchetti1@llnl.gov
authors.forename: A A
authors.initials: AA
authors.lastname: Marchetti
authors.forename: J E
authors.initials: JE
authors.lastname: McAninch
authors.forename: G
authors.initials: G
authors.lastname: Rugel
authors.forename: W
authors.initials: W
authors.lastname: Rühm
authors.forename: G
authors.initials: G
authors.lastname: Korschinek
authors.forename: R E
authors.initials: RE
authors.lastname: Martinelli
authors.forename: T
authors.initials: T
authors.lastname: Faestermann
authors.forename: K
authors.initials: K
authors.lastname: Knie
authors.forename: S D
authors.initials: SD
authors.lastname: Egbert
authors.forename: A
authors.initials: A
authors.lastname: Wallner
authors.forename: C
authors.initials: C
authors.lastname: Wallner
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: S
authors.initials: S
authors.lastname: Endo
authors.forename: M
authors.initials: M
authors.lastname: Hoshi
authors.forename: K
authors.initials: K
authors.lastname: Shizuma
authors.forename: S
authors.initials: S
authors.lastname: Fujita
authors.forename: H
authors.initials: H
authors.lastname: Hasai
authors.forename: T
authors.initials: T
authors.lastname: Imanaka
authors.forename: T
authors.initials: T
authors.lastname: Straume
mesh_terms: D003300:Copper / Q000737:chemistry*; D005214:Fast Neutrons; D007564:Japan; D013058:Mass Spectrometry; D009532:Nickel / Q000032:analysis; D054043:Nuclear Weapons; D011868:Radioisotopes / Q000032:analysis
chemical_list: D011868:Radioisotopes; D003300:Copper; D009532:Nickel