Properties of ¹⁵²Gd collective states

The decays of ¹⁵²Tb (T_1/2 = 17.5 h) and ₁₅₂Gd excited states have been investigated by the analysis of γ-rays and γγ-coincidences measured with the use of high-resolution HPGe detectors. The source of ¹⁵²Tb was prepared by chromatographic isolation followed by electromagnetic separation from a tantalum target irradiated by an internal proton beam of the LNP JINR phasotron. New and more precise data on the γ-transitions and excited states of ¹⁵²Gd are reported. Using previously published data on internal-conversion electrons many transition multipolarities are suggested, some of them with E0 admixture. The EC/β⁺ ratio was found for a number of low-lying levels, for most of the levels their spins, parities, and log ft are given. The excited levels of ¹⁵²Gd were deduced from the analysis of γγ-coincidences. The experimental level energies and reduced transition probabilities are compared with the calculations by phenomenological formulae as well as in the frameworks of theoretical models.