Gas target of deuterium with an aluminum entrance foil of 1.5 mg/${\mathrm{cm}}^2$ were bombarded by tritons. Straggling and scattering of the tritons by the foil have been carefully considered and found to introduce reasonably small corrections. Energy loss in the entrance foil was determined by assuming that the sharp resonance peak in the reaction occurs at 165-kev triton energy as measured by T. W. Bonner, and then making use of the $\frac{\mathrm{dE}}{\mathrm{dx}}$ curve of S. D. Warshaw. Neutrons from the reaction were observed by means of a B${\mathrm{F}}_3$ long counter whose energy response has been investigated. Angular distributions of the neutrons were measured and found to be isotropic in the c.m. system below 600 kev. Near 1 Mev the distributions deviate from isotropy, more neutrons coming off at the back angles. The maximum cross section is 4.93 barns at the resonance. The limit of error on cross sections is ± 10 percent. A one-level nuclear dispersion formula has been fitted to the experimental curve and the resonance is ascribed to a level in the ${\mathrm{He}}^5$ compound nucleus, arising from an $S$-wave interaction of the $T$ and $D$, with quantum numbers $J=\frac{3}{2}$, $l=2\mathrm{}$.

• Received 2 May 1952

DOI:https://doi.org/10.1103/PhysRev.87.612