Production of the (I = 19/2) high-spin isomer ¹³⁵Cs in photonuclear reactions

Abstract

The yields of ¹³⁵Cs nuclei in a high-spin (19/2) isomeric state and of nuclei neighboring it were measured for photonuclear reactions of the (γ, f) and (γ, α) types. The experiments in question were performed by using bremsstrahlung from a microtron at the maximum electron energy of 25 MeV. The product nuclei were identified by their half-lives and by the lines of gamma radiation emitted in their decay, and the reaction yields R were determined by the ratios of the intensities of these lines to the bremsstrahlung flux. The cross sections for isomer production were calculated, and the angular momenta of product nuclei immediately before the cascade of gamma transitions populating the ground or an isomeric nuclear state were evaluated on the basis of these results. An enhanced yield of the high-spin isomer of ¹³⁵Cs in the fission reaction in relation to the respective (γ, α) reaction and in relation to the results of the calculations is found.