DEUTERON BREAKUP AT EXTREME FORWARD ANGLES - FAILURE OF A PURE COULOMB DISSOCIATION DESCRIPTION

We present an analysis of recent measurement of the 56 MeV deuteron br eakup data on C-12, Ca-40, and Pb-208 targets taken by Okamura et al.. The cross section measured at theta(p) = theta(n) = 0 degrees was cla imed to be a strong evidence of Coulomb breakup, especially in light n uclei. However, the single-step pure Coulomb breakup formalism fails t o describe both the magnitude and the shape of the triple differential cross section even in light nuclei. At 56 MeV incident deuteron energ y, the nuclear interference effect is found to be significant in all t he above nuclei. The prior form distorted-wave Born-approximation calc ulations with unusual optical potentials in the exit channel can repro duce the highly asymmetric shapes of the triple differential cross sec tion at the extreme forward angle, but, fail to give their exact magni tude. The possible role of multistep processes is discussed.