Measurement of isomeric yield ratios in the photo-production of 133m,g;137m,gCe from natCe using 55-, 60-, and 65-MeV bremsstrahlung.

The isomeric yield ratios of 133m,g Ce and 137m,g Ce produced from the nat Ce(γ,xn) reactions were determined by using the activation and the off-line γ-ray spectrometric technique with the end-point bremsstrahlung energies of 55-, 60-, and 65-MeV at 100-MeV electron linac of the Pohang accelerator laboratory. The induced activities in the irradiated foils were measured by using an energy- and efficiency-calibrated HPGe 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 55-, 60-, and 65-MeV were 0.324 ± 0.089, 0.331 ± 0.086, and 0.403 ± 0.089 for the 133m,g Ce, and 0.210 ± 0.062, 0.221 ± 0.061, and 0.262 ± 0.061 for the 137m,g Ce, respectively. The present results for nat Ce(γ,xn) 133m,g;137m,g Ce in this energy region were obtained for the first time which has no comparable literature data. The obtained isomeric yield ratios are compared with the calculated values based on the statistical model code TALYS 1.6. [ABSTRACT FROM AUTHOR]