Measurement ofp+d→He3+γand Comparison with the Inverse Reaction

Seven differential cross sections of the reaction $p+d\to {}_{}{}^3{}_{}{}^{}\mathrm{He}+\gamma$ have been measured at $T_p=450\mathrm{} \mathrm{and} 550$ MeV between 52° and 92° (${\theta }_{\gamma }$ c.m.). ${}_{}{}^3{}_{}{}^{}\mathrm{He}$'s were analyzed by the SPES I spectrometer in coincidence with photons detected by Cherenkov counters. The results are about twice the cross sections of the inverse reaction measured recently by Hegerath et al. and by Argan et al. The data are consistent, however, with the $\gamma +{}_{}{}^3{}_{}{}^{}\mathrm{He}\rightleftarrows p+d$ data of Heusch et al.