Prediction of the analyzing power for p+6He elastic scattering at 200 MeV from p+4He elastic scattering at 200 MeV
Abstract
We apply the cluster-folding (CF) model for p+6He scattering at 200 MeV, where the potential between p and 4He is fitted to data on p+4He scattering at 200 MeV. For p+6He scattering at 200 MeV, the CF model reproduces measured differential cross section with no free parameter, We then predict the analyzing power Ay(q) with the CF model, where q is the transfer momentum. Johnson, Al-Khalili and Tostevin construct a theory for one-neutron halo scattering, taking (1) the adiabatic approximation and (2) neglecting the interaction between a valence neutron and a target, and yield a simple relationship between the elastic scattering of a halo nucleus and of its core under certain conditions. We improve their theory with (3) the eikonal approximation in order to determine Ay(q) for 6He from the data on Ay(q) for 4He. The improved theory is accurate, when approximation (1)--(3) are good. Among the three approximations, approximation (2) is most essential. The CF model shows that approximation (2) is good in 0.9 < q < 2.4 fm-1. In the improved theory, the Ay(q) for 6He is the same as that for 4He. In 0.9 < q < 2.4 fm-1, we then predict Ay(q) for p+6He scattering at 200 MeV from measured Ay(q) for p+4He scattering at 200 MeV. We thus predict Ay(q) with the model-dependent and the model-independent prescription. The ratio of differential cross sections measured for 6He to that for 4He is related to the wave function of 6He. We then determine the radius between 4He and the center-of-mass of valence two neutrons in 6He. The radius is 5.77 fm.