Excitation study of high-lying states of differently shaped heavy nuclei by the method of two-step cascades

Recently obtained primary transition intensities from two-step gamma-ray cascade investigations of 14 heavy nuclei: ^137,138,139Ba, ¹⁴⁶Nd, ¹⁵⁰Sm, ^156,158Gd, ¹⁶⁰Tb, ¹⁶⁴Dy, ¹⁶⁸Er, ¹⁷⁴Yb, ¹⁸¹Hf, ¹⁹⁶Pt and ¹⁹⁸Au are analysed. Experiments based on thermal neutron capture were undertaken mainly at the Frank Laboratory of Neutron Physics. Comparing these measured intensities and statistical model predictions, some properties of compound-state depopulation were derived. For the spherical nuclei of ^137,138,139Ba, ¹⁴⁶Nd, ¹⁹⁶Pt and ¹⁹⁸Au very intense cascades with high-energy primary transitions were observed. Rather different is the behaviour of the cascade intensity in the strongly deformed nuclei of ^156,158Gd, ¹⁶⁰Tb, ¹⁶⁴Dy, ¹⁶⁸Er and in the transitional nucleus of ¹⁵⁰Sm - where the intensity of primary γ-rays E₁ ∼ 2-3 MeV exceeds the calculated value.