Rebar from the Aioi Bridge

These pieces of reinforcing rod (rebar) come from the Aioi Bridge in Hiroshima. The bridge was referred to as the ‘T’ bridge by the crew of the Enola Gay because it looked like a T when viewed from the air. It was used by the bombardier as his target because of its distinct shape. 

The rebar, as well as metal from surrounding buildings, was collected in order to determine its Co-60 content. The latter, produced by neutron activation, was used to provide information about the neutron flux. This, in turn, was used to estimate the neutron exposures to the survivors. Perhaps the biggest problem in estimating the neutron exposures of the survivors is reconciling differences between the actual measure activation and what was predicted theoretically.

Donated by George Kerr.