Isomeric yield ratios for the natSb(γ,xn)120m,g,122m,gSb reactions measured at 40-, 45-, 50-, 55-, and 60-MeV bremsstrahlung energies

We measured the isomeric yield ratios for the 120m,gSb and 122m,gSb isomeric pairs produced by natSb(γ,xn)120m,g,122m,gSb photonuclear reactions in the bremsstrahlung energy region from 40 to 60MeV with a step size of ΔE=5MeV by the activation method. The induced γ-activities of the irradiated samples were measured by a coaxial high purity germanium detector coupled to a PC-based multichannel analyzer. The necessary corrections were made to improve the accuracy of the experimental results. The experimental results at bremsstrahlung energies of 40, 45, 50, 55, and 60MeV were 0.045±0.003, 0.046±0.003, 0.048±0.003, 0.050±0.003, and 0.049±0.003 for the 120m,gSb isomeric pair, and 0.341±0.022, 0.362±0.020, 0.374±0.021, 0.371±0.021, and 0.358±0.022 for the 122m,gSb isomeric pair, respectively. The present results are the first measurements at bremsstrahlung energies just above the giant dipole resonance region. The obtained results confirm the dependence of the isomeric yield ratios on the incident energy and the reaction channel effect observed in some earlier experiments.