Measurement of cross sections and isomeric yield ratios for 110m, gIn, 111m, gIn and 112m, gIn from natIn( $\gamma$ γ , xn) reactions in the bremsstrahlung end-point energies of 65-75 MeV

Abstract

The flux weighted average cross sections and the isomeric yield ratios of 110m, gIn, 111m, gIn and 112m, gIn in the natIn( $\gamma$ ,xn) 112-110In reactions with the bremsstrahlung end-point energies of 65, 70 and 75 MeV have been determined by activation and off-line $\gamma$ -ray spectrometric technique using the 100 MeV electron linac at Pohang accelerator laboratory, Korea. It was found that the natIn( $\gamma$ ,xn) 112-110In reaction cross sections increase very fast from the threshold energy to a certain value of the bremsstrahlung energy, where the other reaction channel opens. After a certain energy, it remains constant because the cross section of the other reaction channel starts to increase. This indicates the partition of the excitation energy in different reaction channles. The isomeric yield ratios of 110m, gIn, 111m, gIn and 112m, gIn in the natIn( $\gamma$ ,xn) reactions decrease very fast with the bemsstrahlung end-point energy from the threshold value to 15-30 MeV due to the giant dipole resonance (GDR) effect. Above that, the isomeric yield ratios increase slowly with the bremsstrahlung energy due to the increase of excitation energy.