Prediction of the analyzing power for $\vec{p}$+$^{6}$He elastic scattering at 200 MeV from $\vec{p}$+$^{4}$He elastic scattering at 200 MeV

Abstract

We apply the cluster-folding (CF) model for p+ 6 He scattering at 200 MeV, where the potential between p and 4 He is fitted to data on p+ 4 He scattering at 200 MeV. For p+ 6 He 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 6 He from the data on Ay(q) for 4 He. 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 6 He is the same as that for 4 He. In 0.9 < q < 2.4 fm −1 , we then predict Ay(q) for p+ 6 He scattering at 200 MeV from measured Ay(q) for p+ 4 He 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 6 He to that for 4 He is related to the wave function of 6 He. We then determine the radius between 4 He and the center-of-mass of valence two neutrons in 6 He. The radius is 5.77 fm.