H2(p,γ)He3reaction using polarized and unpolarized protons

The 90° yield curve for the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$($p$,$\gamma$)${}_{}{}^3{}_{}{}^{}\mathrm{He}$ reaction has been studied over the excitation region in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ of approximately 7 to 15 MeV. Both polarized and unpolarized proton beams were used to measure the angular distributions of cross section and analyzing power at $E_x=8.83, 9.83, \mathrm{and} 10.83$ MeV. If only the four non-spin-flip $E1$ and $E2\mathrm{}$ $T$-matrix elements are considered, their amplitudes and relative phases can be extracted. The $E2\mathrm{}$ cross section obtained from this analysis is found to be (12±5)% of the total cross section. The detailed balanced differential (${\theta }_{\mathrm{lab}}=90\mathrm{}°$) and total cross sections at $E_x=10.83\mathrm{}$ MeV are found to be (117±11) μb/sr and (1.07±0.11) mb, respectively; the quoted errors represent the total uncertainties in the cross sections obtained in this experiment. The results are also compared with recent $E1$ and $E2\mathrm{}$ calculations.