Measurement of isomeric yield ratios for the Sc-44m,Sc-g isomeric pairs produced from Sc-45 and Ti-nat targets at 50-, 60-, and 70-MeV bremsstrahlung

Abstract

We measured the isomeric yield ratios for the Sc-44m,Sc-g isomeric pairs produced from different reaction channels Sc-45(gamma,n)Sc-44m,Sc-g and Ti-nat(gamma,xnp)Sc-44m,Sc-g by using the activation method and gamma-ray spectroscopic methods at 50-, 60-, and 70-MeV bremsstrahlung energies. The high-purity natural Sc and Ti foils in disc shape were irradiated with uncollimated bremsstrahlung beams generated from an electron linear accelerator at Pohang Accelerator Laboratory. The induced activities in the irradiated foils were measured by the high-resolution gamma-ray spectrometric system which consists of a high-purity Germanium detector and a multichannel analyzer. In order to improve the accuracy of the experimental results the necessary corrections were made in the gamma-ray activity measurements and data analysis. The measured isomeric yield ratios for the Sc-45(gamma,n)Sc-44m,Sc-g reaction are 0.20 +/- A 0.02, 0.21 +/- A 0.02, and 0.21 +/- A 0.02 and those for the Ti-nat(gamma,xnp)Sc-44m,Sc-g reaction are 0.063 +/- A 0.012, 0.079 +/- A 0.014, and 0.124 +/- A 0.022 at 50-, 60-, and 70-MeV bremsstrahlung energies, respectively. The obtained results are compared with the corresponding values found in the literature. We observed that the isomeric yield ratios for the Sc-45(gamma,n)Sc-44m,Sc-g reaction increase rapidly with the increasing bremsstrahlung energies from the reaction threshold up to giant resonance region, and then those are almost constant in the energy range from about 30 to 2.5 GeV. The isomeric yield ratios for the Ti-nat(gamma,xnp)Sc-44m,Sc-g reaction increase with increasing bremsstrahlung energies in a wide range of bremsstrahlung energies from 50 to 2.5 GeV.