Neutron Yields from Photo-Disintegration by Gamma-Rays from Lithium

The relative neutron yield of 33 elements has been studied using the gamma-ray spectrum which arises from proton bombardment of Li. The samples which were to be irradiated were placed in a block of paraffin. The neutrons were detected using four boron trifluoride proportional counters. Absolute gamma-ray and neutron intensity measurements yielded the value (0.055\ifmmode\pm\else\textpm\fi{}0.012) barn for the ($\ensuremath{\gamma},n$) cross section of copper. Rough indications were also obtained concerning the relative neutron energy distribution from the samples.