Study of isomer ratios of proton-nucleus reaction cross sections on tin isotopes

The induced-activity method is applied to study the proton-nucleus reactions obtained irradiating the 112Sn, 118Sn, 124Sn enriched isotopes by 660-MeV protons. Cross sections for 35 residual nuclei are measured. Dependences of the isomer ratios of the cross sections and of the behavior of the high-spin and low-spin states on the number of emitted protons are obtained for several residual nuclei. These dependences show that proton-nucleus reactions involve not only the cascade-evaporation process, but as well the absorption of the secondary π- mesons by surface quasideuterons followed by neutron emission. 13 refs., 2 figs., 2 tabs