Exit doorway model for nuclear elastic breakup of weakly bound projectiles

Abstract

We develop the exit doorway model for elastic breakup of loosely bound projectiles. We argue that this model could, in principle, supply an alternative simplified version of the continuum discretized coupled-channels (CDCC) model. We show that the cross section for elastic breakup can be generally written as a product of the cross section for inelastic excitation times a factor containing the excitation energy and width of the exit doorway and is generally bombarding energy dependent. The excitation energy of the exit doorway is identified with the Q value of the breakup channel. The width of the exit doorway is a measure of the energy range of the continuum that is discretized. We apply the theory to derive closed expressions for the nuclear breakup cross sections in the adiabatic limit using the Austern-Blair theory. We demonstrate the approximate validity of the scaling law that dictates that the nuclear breakup cross section scales linearly with the radius of the target. We also compare our results for the nuclear breakup cross section of {sup 11}Be, {sup 8}B, and {sup 7}Be on several targets with recent CDCC calculation.