Interaction cross sections (${\sigma }_I$) for all known Li isotopes (${}_{}{}^6{}_{}{}^{}\mathrm{Li}$-${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$) and ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, and ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ on targets Be, C, and Al have been measured at 790 MeV/nucleon. Root mean square radii of these isotopes as well as He isotopes have been deduced from the ${\sigma }_I$ by a Glauber-type calculation. Appreciable differences of radii among isobars (${}_{}{}^6{}_{}{}^{}\mathrm{He}$-${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^8{}_{}{}^{}\mathrm{He}$-${}_{}{}^8{}_{}{}^{}\mathrm{Li}$, and ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$-${}_{}{}^9{}_{}{}^{}\mathrm{Be}$) have been observed for the first time. The nucleus ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ showed a remarkably large radius suggesting a large deformation or a long tail in the matter distribution.

• Received 11 July 1985

DOI:https://doi.org/10.1103/PhysRevLett.55.2676