The 2H(rvec p,γ)3He and 1H(rvec d,γ)3He reactions below 80 keV

The details of a recent experimental study of the 2H(rvec p,γ)3He and the 1H(rvec d,γ)3He reactions for beam energies below 80 keV are discussed. In this study, both polarized and unpolarized incident beams were used to measure the cross section σ(θ,E), the astrophysical S factor S(θ,E), the vector analyzing power Ay(θ,E), and the tensor analyzing power T20(θ). In addition, the γ-ray linear polarization Pγ(θ) was measured for an unpolarized incident beam. The experimental details of these measurements are discussed and the data are analyzed to obtain the amplitudes and phases of the contributing transition-matrix elements. The results of our measurements are compared with recent ab initio three-body theoretical calculations. This comparison reveals the large sensitivity of the polarization observables, especially the vector analyzing power (Ay), to the presence of meson-exchange current effects and indicates the need for further study. The tensor analyzing power data [T20(θ)] are used to extract a value of the asymptotic D- to S-state ratio, η, for 3He. copyright 1997 The American Physical Society