Reaction Cross Section Of The Two-neutron Halo Nucleus 22C At 235 MeV/nucleon

The reaction cross section (σ R σR ) of the very neutron-rich carbon isotope 22 22 C has been measured on a carbon target at 235 MeV/nucleon. A σ R σR of 1.280±0.023 1.280±0.023 b was obtained for 22 22 C, significantly larger than those for the neighboring isotopes, supporting the halo character of 22 22 C. A 22 22 C root-mean-squared matter radius of 3.44±0.08 3.44±0.08 fm was deduced using a four-body Glauberreaction model. This value is smaller than an earlier estimate of 5.4±0.9 5.4±0.9 fm derived from a σ R σR measurement on a hydrogen target at 40 MeV/nucleon.