STUDY OF ISOMERIC RATIOS OF PROTON-NUCLEUS CROSS-SECTIONS ON TIN ISOTOPES

The method of induced activity is used to study proton-nucleus reactio ns resulting from the irradiation of enriched Sn-112, Sn-118, and Sn-1 24 isotopes by 660-MeV protons. The cross sections are measured for 35 residual nuclei. The isomeric ratios of the cross sections and the be havior of the high- and low-spin states are obtained as functions of t he number of emitted protons for several residual nuclei. These depend ences show that, as is the case with photonuclear reactions, proton-nu cleus reactions involve not only a cascade-evaporation process, but al so the absorption of secondary pi(-) mesons by surface quasideuterons followed by neutron emission.