Momentum distributions forBe12,14fragmentation

Abstract
Data on the fragmentation of Be12,14 on C12 at 56 and 65 MeV per nucleon have been obtained. The Be12 fragments from the breakup of Be14 display both a narrow longitudinal momentum distribution and a distinctive angular distribution that is consistent with an extended neutron ‘‘halo’’ in this nucleus. This is the first experiment in which both longitudinal and transverse fragment momentum distributions of exotic nuclei have been simultaneously measured.