The Disintegration of the Nuclei of Nitrogen and Other Light Atoms by Neutrons. I

Disintegration experiments with N, C and Ne.—Thirtyone disintegrations of nitrogen have been found in 7600 pairs of photographs of a Wilson chamber through which neutrons were shot from a Be-Ms Th source. Of these, nineteen were disintegrations in which the neutron was captured according to the reaction ${{\mathrm{N}}_0}^{14}+{n_1}^1\to {{\mathrm{N}}_1}^{15}\to {{\mathrm{B}}_1}^{11}+{{\mathrm{He}}_0}^4.$ The distribution curve which shows the number of disintegrations for each velocity interval of the neutrons at capture exhibits a peak at 3.2×${10}^9$ cm/sec. The lowest velocity which produces such a disintegration is 1.9×${10}^9$ and the highest 5.5×${10}^9$. The form of the curve is explained by the assumption that the probability that a neutron will be effective in producing disintegration increases rapidly with its velocity but that, as the velocity considered lies higher and higher above 3.2×${10}^9$ cm/sec., the number of neutrons present at such a velocity decreases rapidly. The data are too few to show any indication of resonance. The highest energy found for a neutron at capture is 15.8×${10}^6$ electron-volts, while, according to theory, it should be 14.7×${10}^6$ provided the $\alpha$-particle comes from Th C'.