Measurement of residual 60Co activity induced by atomic-bomb neutrons in Nagasaki and background contribution by environmental neutrons.
Residual 60Co activity in five steel samples induced by neutrons from the Nagasaki atomic bomb has been measured within about 1000 m from the hypocenter. The chemical separation of cobalt and nickel from steel samples was performed, and cobalt-enriched samples were prepared for all samples. Gamma-ray measurements were carried out with a low-background well-type germanium detector. The gamma-ray spectra for five samples were compared with the spectrum of a control sample to ensure that the observed 60Co was actually induced by A-bomb neutrons. The activation of cobalt by environmental neutrons was also investigated. It has been shown that the present 60Co data are consistent with earlier Hashizume's data.
Shizuma
Kiyoshi
K
Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan. shizuma@hiroshima-u.ac.jp
Endo
Satoru
S
Hoshi
Masaharu
M
Takada
Jun
J
Iwatani
Kazuo
K
Hasai
Hiromi
H
Oka
Takamitsu
T
Shimazaki
Tatsuya
T
Okumura
Yutaka
Y
Fujita
Shoichiro
S
Watanabe
Tadaaki
T
Imanaka
Tetsuji
T
D001417:Background Radiation; D003036:Cobalt Isotopes / Q000528:radiation effects*; D003037:Cobalt Radioisotopes / Q000032:analysis* / Q000302:isolation & purification; D003252:Construction Materials / Q000032:analysis; D003359:Cosmic Radiation; D005720:Gamma Rays; D006207:Half-Life; D006785:Hospitals, University; D006798:Housing; D007564:Japan; D009502:Neutrons; D009689:Nuclear Warfare; D011848:Radioactive Pollutants / Q000032:analysis* / Q000302:isolation & purification; D011874:Radiometry; D012574:Schools; D013232:Steel / Q000737:chemistry
D003036:Cobalt Isotopes; D003037:Cobalt Radioisotopes; D011848:Radioactive Pollutants; D013232:Steel