Comparison of the measured gamma ray dose and the DS86 estimate at 2.05 km ground distance in Hiroshima.

The gamma ray dose at 2.05 km ground distance from the Hiroshima atomic bomb hypocenter was measured from roof tile samples by a thermoluminescence technique. Two tile samples collected at 2.45 km also were analyzed to check the reliability of the background estimates. The result for the 2.05 km distance was 129 +/- 23 mGy for five-tile sample average. This value is 2.2 times larger than the corresponding DS86 estimate. These results and those in the literature show the DS86 estimate is 50% or less of the measured value 2.05 km from the Hiroshima hypocenter.