An experimentalmeasurement of the high energy gamma rays produced by the slowing down of 14 MeV neutrons in air

During Operation HENRE (High Energy Neutron Reactions Experiment), measurements were made of the gamma-rays produced in air by 14 MeV neutrons. Spectra were obtained for the gamma-rays in the energy interval of 1.5 to 10 MeV at slant ranges of 482 and 571 m. At the greater range, spectra were recorded at angles of 0°, 45°, and 90° with respect to the source-detector line using a collimator that had a conical opening with a 30° total angle. The techniques needed for adequate data reduction are discussed. Agreement with calculated spectra is reasonable, but the measurements have more gamma-rays in the 3–5 MeV region. The difference is thought to be due primarily to insufficient cross section data for the calculations.