Measurement of isomeric yield ratios for the Ho-nat(gamma,xn)Ho-164m,Ho-g;162m,Ho-g reactions in the bremsstrahlung energy region from 45 to 65 MeV

Abstract

We have measured the isomeric yield ratios for the Ho-164m,Ho-g and the Ho-162m,Ho-g isomeric pairs formed via photonuclear reactions Ho-165(gamma,n)Ho-164m,Ho-g and Ho-165(gamma,3n)Ho-162m,Ho-g in the bremsstrahlung energy region from 45 to 65 MeV in steps of a dagger E = 5 MeV by the activation method. The induced gamma-activities of the irradiated holmium foils were measured by a coaxial high-purity germanium detector coupled to a PC-based multichannel analyzer. In order to improve the accuracy of the experimental results the necessary corrections were made. The experimental results at bremsstrahlung energies of 45, 50, 55, 60, and 65 MeV are 0.408 +/- A 0.027, 0.413 +/- A 0.027, 0.427 +/- A 0.029, 0.452 +/- A 0.032, and 0.448 +/- A 0.031 for the Ho-164m,Ho-g isomeric pair, and 0.587 +/- A 0.041, 0.624 +/- A 0.044, 0.652 +/- A 0.045, 0.637 +/- A 0.045, and 0.668 +/- A 0.046 for the Ho-162m,Ho-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 isomeric ratios on the incident photon energy as observed in some earlier experiments.