We present a theoretical analysis of recently published experimental data for the elastic scattering of protons from the helium isotopes ${}^6\mathrm{He}$ and ${}^8\mathrm{He}$ at energies near 700 MeV per nucleon. The analysis treats the few-body degrees of freedom of these light neutron-rich nuclei explicitly and is developed in terms of three- and five-body wave functions for ${}^6\mathrm{He}$ and ${}^8\mathrm{He}$, respectively. Comparisons of calculations with the data show that the sizes of the He nuclei consistent with such an analysis are larger by about 0.2 fm than those deduced from a more approximate procedure in which the structure of the weakly bound nuclei enters only through an assumed nuclear matter density.

• Received 18 November 1997

DOI:https://doi.org/10.1103/PhysRevC.57.1846