The 3He(d,p)α reaction at astrophysical energies

We have performed a microscopic study of the 3He(d,p)α reaction at astrophysical energies within the framework of the Resonating Group Method adopting three different effective nucleon-nucleon interactions. The calculations suggest that the low-energy 3He(d,p)α cross section is in good approximation given by the contribution arising from the 3/2+ resonant state at ER=245 keV. In fact, the low-energy data can be better (and more physically) described by a single Breit-Wigner resonance parametrization than by a polynomial fit. Our fit to the 3He(d,p)α cross section results in a noticeable reduction in the uncertainties of the resonance parameters of the 3/2+ resonant state as well as in a significantly improved extrapolation of the data to astrophysically important energies. On the basis of this extrapolation we were able to quantitatively deduce the enhancement of the low-energy cross section due to electron screening effects from the data of Krauss et al. and Engstler et al. These experimental enhancement factors were compared with various theoretical models which are all based on the Born-Oppenheimer approximation. As the models underestimate the observed enhancement we suggest that the theoretical study of electron screening effects requires a dynamical treatment. (orig.)