Relativistic impulse approximation analysis of elastic proton scattering from He isotopes

Recent relativistic mean field (RMF) calculations have provided nuclear distributions of some isotopes whose mass numbers are much larger than atomic numbers. For helium isotopes, the RMF calculation seems to be inappropriate because of the small mass numbers; however, applicable results are obtained for ${}^{6,8}$He nuclei. The author calculates observables of proton elastic scattering from the helium isotopes and discusses relations between observables and nuclear distributions of the isotopes by comparison of the calculated results with experimental data. The calculations are based on relativistic impulse approximation (RIA) at incident proton energy: 71 MeV for ${}^{4,6,8}$He, 300 and 500 MeV for ${}^{4}$He, and 0.7 GeV for ${}^{6}$He. Scattering observables are predicted for ${}^{6,8}$He at 200 MeV.