Isomeric yield ratios for the formation of 44m,gSc in the 45Sc(γ,n), natTi(γ,xnp), natFe(γ,xn5p) and natCu(γ,xn8p) reactions with 2.5 GeV bremsstrahlung

We measured the isomeric yield ratios for the Sc-44m,Sc-g isomeric pairs produced from four different photo-nuclear reactions Sc-45(gamma,n)Sc-44m,Sc-g, Ti-nat(gamma,xn1p)Sc-44m,Sc-g, Fe-nat(gamma,xn5p)Sc-44m,Sc-g, and Cu-nat(gamma,xn8p)Sc-44m,Sc-g by using the activation method. The high purity natural Sc, Ti, Fe, and Cu metallic foils in disc shape were irradiated with uncollimated 2.5 GeV bremsstrahlung beams of the Pohang Accelerator Laboratory. The induced activities in the irradiated foils were measured by the high-resolution gamma-ray spectrometry with a calibrated high-purity Germanium (HPGe) detector. In order to improve the accuracy of the experimental results the necessary corrections were made in the gamma activity measurements and data analysis. The obtained isomeric yield ratios for the Sc-45(gamma,n)Sc-44m,Sc-g. Ti-nat(gamma,xn1p)Sc-44m,Sc-g, Fe-nat(gamma,xn5p)Sc-44m,Sc-g and Cu-nat(gamma,xn8p)Sc-44m,Sc-g reactions are 0.25 +/- 0.03, 0.43 +/- 0.05, 1.38 +/- 0.14, and 1.89 +/- 0.21, respectively. The present result for the Cu-nat(gamma,xn8p)Sc-44m,Sc-g reaction is in good agreement with the existing data. Our results for the Sc-45(gamma,n)Sc-44m,Sc-g, Ti-nat(gamma,xn1p)Sc-44m,Sc-g, and Fe-nat(gamma,xn5p)Sc-44m,Sc-g reactions are the first measurements at 2.5 GeV bremsstrahlung. The obtained results are compared with the corresponding values found in the literature. The relation between the isomeric yield ratios and the complexity of the photo-nuclear reactions is discussed. (C) 2008 Elsevier B.V. All rights reserved.