Evaluation of radiation dose from atomic bomb (DS86) by measurements

The dosimetry system 86 (DS86) for A-bomb radiation doses was assessed by actual measurements of gamma radiation and Eu-152 neutron which were obtained by thermoluminescent dosimetry. Data of gamma radiation measurements were obtained from 21 measuring points 95 m to 2,030 m from the ground in Nagasaki; and 52 measuring points 140 m to 2,050 m from the ground in Hiroshima. For Eu-152 neutron, data were obtained from 41 measuring points 850 m from the ground in Nagasaki; and 34 measuring points 1,330 m from the ground in Hiroshima. Calculated and measured values for gamma radiation were well correlated with each other in both Nagasaki and Hiroshima. For neutron doses, there was a tendency for greater discrepancy between calculated and measured values at the points farther from the ground in both Nagasaki and Hiroshima. Neutron doses obtained from measured values were 2.0 to 9.7 times larger than those calculated from the DS86 at the points 500 m to 1,500 m from the ground in Nagasaki; 2.1 to 10.0 times larger than the DS86 doses at the points 1,000 m to 2,000 m from the ground in Hiroshima. (N.K.)