摘要：Residual radioactivity data of 152 Eu, 60 Co and 36 Cl have been accumulated and it has been revealed in the thermal neutron region that a systematic discrepancy exists between the measured data and activation calculation based on the DS86 neutrons in Hiroshima. Recently 63 Ni produced in copper samples by the fast neutron reaction 63 Cu(n,p) 63 Ni has been of interest for evaluation of fast neutrons. Reevaluation of atomic-bomb neutrons and prospects based on residual activity measurements have been discussed.
