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

Abstract

We measured the isomeric yield ratios for the Sb-120m,Sb-g and Sb-122m,Sb-g isomeric pairs produced by Sb-nat(gamma,xn)Sb-120m,Sb-g,Sb-122m,Sb-g photonuclear reactions in the bremsstrahlung energy region from 40 to 60 MeV with a step size of Delta E = 5 MeV by the activation method. The induced gamma-activities of the irradiated samples were measured by a coaxial high purity germanium detector coupled to a PC-based multi-channel 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 60 MeV were 0.045 +/- 0.003, 0.046 +/- 0.003, 0.048 +/- 0.003, 0.050 +/- 0.003, and 0.049 +/- 0.003 for the Sb-120m,Sb-g 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 Sb-122m,Sb-g 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. (C) 2012 Elsevier B.V. All rights reserved.