Deformation on isomeric excitation of Eu isotopes in $(\gamma ,n)$ and $(n,\gamma )$ reactions

Isomeric ratios in $(n,\gamma )$ and $(\gamma ,n)$ reactions in Eu isotopes were measured. Thermal neutrons and bremsstrahlung photons in the giant dipole resonance energy range of 13–22 MeV were used to excite the isomeric states. The isomeric levels $0^{-}$ and $8^{-}$ were excited in the isotopes ${}^{150}\mathrm{Eu},{}^{152}\mathrm{Eu},$ and ${}^{154}\mathrm{Eu}.$ The cross section for the reaction $(\gamma ,n)$ leading to the high-spin isomeric state $8^{-}$ on ${}^{152}{\mathrm{Eu}}^{m2\mathrm{}}$ isotope was measured in the giant-dipole-resonance region by the activation method. Experimental values of the isomeric cross section ratios were compared with the theoretical values. The influence of the nuclei quadropole deformation on the isomeric ratio was described.