The ${}_{}{}^2{}_{}{}^{}\mathrm{H}(\overrightarrow{d},\gamma ){}_{}{}^4{}_{}{}^{}\mathrm{He}$ reaction observables $\sigma \left(\theta \right)$, $A_y\left(\theta \right)$, and $A_{\mathrm{yy}}\left(\theta \right)$ have been measured at six angles at $〈E_d\left(\mathrm{lab}\right)〉=1.2\mathrm{}$ MeV. The data have been compared to a microscopic multichannel resonating group model calculation. According to this calculation, the cross section consists of nearly equal contributions from $E2\mathrm{}$, $E1\mathrm{}$, and $M2\mathrm{}$ radiation, and the tensor analyzing power arises primarily as a consequence of the large $\frac{E1\mathrm{}}{M2\mathrm{}}$ strength.

• Received 29 February 1988

DOI:https://doi.org/10.1103/PhysRevC.38.565