Charge dispersion and recoil properties atA=131from the interaction ofAu197with 11.5- and 300-GeV protons

Cross sections and thick-target recoil properties of five nuclides with $A=131\mathrm{}$ as well as those of a number of neighboring nuclides have been determined for the interaction of ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ with 11.5-GeV protons. The charge dispersion at $A=131\mathrm{}$ has a single peak at $Z_A-Z=-3.5\mathrm{}$ and the total isobaric cross section is 8.9 ± 0.8 mb. The ranges indicate that only ∼2% of this value can be ascribed to fission, the bulk of the cross section involving a deep spallation process. Similar data have been obtained at 300 GeV. Within the limits of error the results are the same at both energies. The systematics of deep spallation reactions are examined.