Fast Neutron Dose Measurements for a D–D Neutron Source in Water

The penetration of D–D neutrons in water has been studied through measurements of first collision dose. A relative measurement of first collision dose as a function of distance from the neutron source was made at 0°. At large penetrations the results appear to approach asymptotically the slope predicted by the theoretical calculations of Goldstein et al. [0] for a monoenergetic, isotropic 4.0-Mev neutron source in water. However as expected, the measurements close to the source where the average neutron spectrum is relatively soft indicate a steeper slope than the theoretical calculation. Further calculations will be required to obtain an explicit check of this experiment.