Explanation of recent observations of very large electromagnetic dissociation cross sections. II. Higher order corrections.

Abstract

Hill, Wohn, Schwellenbach, and Smith have recently measured very large electromagnetic dissociation cross sections in the collisions of very heavy nuclei. Weizsacker-Williams (WW) theory predicts that these cross sections should be even larger. It has recently been shown that WW theory fails for these reactions because the associated probabilities are too large. However, WW theory is based on first order perturbation theory and an electric dipole approximation. Calculations are presented which show that for those cases where WW theory and experiment disagree, higher order perturbation plus electric quadrupole corrections improve the agreement between theory and experiment. These corrections also imply that multiple electromagnetic excitations occur.