title: Measurement of residual 152Eu activity induced by atomic bomb neutrons in Nagasaki and the contribution of environmental neutrons to this activity.
abstract: Residual 152Eu activities induced by neutrons from the Nagasaki atomic bomb were measured for nine mineral samples located up to 1,061 m in the slant range and one control sample at 2,850 m from the hypocenter. A chemical separation to prepare europium-enriched samples was performed for all samples, and gamma ray measurements were carried out with a low background well-type germanium detector. In this paper, the measured specific activities of 152Eu are compared with activation calculations based on the DS86 neutron fluence and the 93Rev one. The calculated-to-measured ratios are also compared with those of 60Co and 36Cl. The present results indicate that the measurements agree to the calculation within a factor of three as observed in the nuclear tests at Nevada. The activation level of environmental neutrons and the detection limit for 152Eu are also discussed.
mesh_terms: D001417:Background Radiation; D005063:Europium / Q000032:analysis*; D007564:Japan; D009502:Neutrons; D009689:Nuclear Warfare; D011868:Radioisotopes / Q000032:analysis*; D011874:Radiometry
chemical_list: D011868:Radioisotopes; D005063:Europium