The Dependence of RBE on the Energy of Fast Neutrons: 1. Physical Design and Measurement of Absorbed Dose

Abstract

Groups of 5 mice each were exposed at 5 neutron energies ranging from 0.43 to 1.8 Mev. These were obtained at different angles with respect to the proton beam in the H3 (p,n) He3 reaction. Bilateral exposure is ensured by rotation of the cage containing the mice. The distance between each group of mice and the target was pre-calculated to provide substantially equal dose rates at all energies. Measurements of the first collision dose were found to require tissue equivalent ionization chambers having minimal wall thickness. The dose distribution in the irradiated mice was determined utilizing a small chamber in a tissue equivalent phantom.