Quadrupole Contribution to Two Neutron Removal in Heavy Ion Collisions

Abstract

In this report, electric quadrupole corrections to the two neutron removal cross section measured in heavy ion collisions are estimated for $^{197}$Au and $^{59}$Co targets. The quadrupole process is assumed to proceed primarily through excitation of the giant isovector quadrupole resonance, which then decays by neutron emission. For $^{59}$Co, the contribution from E2 radiation is found to be small, while for $^{197}$Au we find the quadrupole contribution resolves the discrepancy between experiment and the simple predictions of the Weissacker-Williams virtual photon method.