Direct and resonant breakup of 6He on 269Bi near the Coulomb barrier.

As part of a program to study reactions induced by the two-neutron halo nucleus He-6 on high-Z targets, a neutron-a-particle coincidence experiment was performed for He-6 incident on a Bi-209 target at an energy just above the Coulomb barrier. The experimental setup was optimized for the measurement of projectile breakup. Direct breakup, as well as breakup through the 2(+) excited state of He-6 and also the He-5+n channel, could be distinguished. The total breakup cross section measured in this work compares well with a continuum-discretized coupled-channels calculation that assumes a 50% reduction in the B(E1) computed from a pure He-4+2n cluster configuration. The B(E2 double up arrow) for Coulomb excitation of the (2)+ state in He-6 was also determined.