The Livermore 90-in. variable-energy cyclotron has been used to measure the excitation function for the $\mathrm{T}(p, \gamma ){\mathrm{He}}^4$ reaction for proton energies between 5.8 and 9.2 Mev at a laboratory angle of 90°. The $\gamma$ radiation was produced in a 0.12-Mev-thick tritium gas target and detected in a 5-in.-diam by 6-in.-long NaI(Tl) crystal. Gamma-ray angular distributions were measured at $E_p=5.8, 6.4, 7.7, 8.4, \mathrm{and} 9.2$ Mev and were found to be peaked at angles less than 90°, the asymmetry increasing with proton energy. No evidence was found for excited states of ${\mathrm{He}}^4$ previously reported by Milone.

• Received 8 September 1961

DOI:https://doi.org/10.1103/PhysRev.125.626