Dispersion relations and low-energy elastic scattering of charged particles from nuclei. (II). Application to N-4He scattering

A "Coulomb-modified" dispersion relation is applied to low-energy p-4He forward elastic scattering. To check the validity of the modification, the results are compared with those deduced from n-4He elastic scattering. Completely analogous information is obtained for the two processes. The exchange of three bound nucleons is found to contribute strongly to N-4He forward scattering. The corresponding 4He-3H-p and 4He-3He-n coupling constants are evaluated as Rp = 3.8±0.3 and Rn = 3.0±0.3, respectively. These constants are related to the strength of the asymptotic wave function of nucleons in 4He and thus to the tail of the nucleon distribution. A comparison of Rp with the empirical proton distribution in 4He as deduced from e-4He elastic scattering shows excellent agreement. From Rp and Rn the effective ranges of the singlet 3H-p and 3He-n interactions in the ground state of 4He are determined to be equal, in accordance with charge symmetry, and to have a value of reff = 1.072±0.006 fm. © 1973.