Spatial Distribution in Water at Indium Resonance of Neutrons from a 1.4 Mev D-D Source

The distribution in water of indium resonance neutrons from a 1.4 Mev D-D source has been measured in planes perpendicular to the deuteron beam up to 28 cm in the forward direction from the source. The values of the integrated activities over the planes (including the extrapolated region beyond the range of measurements in each plane) are presented. In addition, a method is described for inferring an age from a D-D source by finding an angle where the distribution is equivalent to that from an isotropic and monoenergetic source. The age of indium resonance neutrons obtained for an equivalent source at 4.3 Mev is 54.4 ± 1.4 cm². Comparison is made with calculated values of the age.