CROSS SECTIONS OF (p,pxn) REACTIONS IN Au197

Abstract

Cross sections of (p,pn), (p,p2n), and (p,p3n) reactions in Au¹⁹⁷ have been measured by the activation method for incident proton energies up to 86 Mev. The curves of cross section as a function of energy have similar shapes for the three reactions. They rise from apparent thresholds at about 16, 21, and 30 Mev, respectively, to peak values of 180, 145, and 150 mb at proton energies about 30 Mev higher than the apparent threshold energies. The cross sections are much larger than those predicted from the statistical and cascade-evaporation theories, and they are interpreted in terms of two-body collisions in the diffuse surface of the target nucleus. A combination of these results with measured (p,xn) cross sections yields an approximation to the total reaction cross section of a heavy nucleus.