Cascade?-decay of compound-state of the nuclei163Dy,167Er and179Hf

Abstract

An attempt has been made to reveal the general characteristics of two-quanta cascades, populating the low-lying states of an excitation energy E< 1 MeV. The difference observed between the experimental cascade intensities and statistical model calculations has been analysed. Qualitative explanation of the measured two-quanta cascade intensities was achieved in the framework of a quasi-particle phonon model description of highly excited states. A considerable enhancement was revealed of the radiative strength function of the E2-transitions in the studied nuclei.

Experimental estimates on radiative strength function of low-energy ?-quanta following even-odd heavy nuclei decay

“…It may be, for instance, the dependence of the partial widths on the structure of the levels connected by these transitions. This dependence was clearly observed, for example, in [19,20,34].…”

“…Strong nonstatistical effects were observed (see also [12,13,19,20,34,41]) reflecting mainly the shell structure effects. The most probable reason for a certain part of transitions to become enhanced is the 4 S= 3 P single particle transition.…”

“…For 181Hf there are the primary transitions in cascades with the energy E 1 = 3.7 MeV and high-energy primary transitions, E 1 = 5.5 MeV [24]. According to [40] Earlier [34] we have already made notes on the correlation between the cascades intensity to final singleparticle states of deformed nuclei and the single-particle component of the compound-state wave function. In accordance with [42] the reduced neutron width Fo ~ is the measure of this correlation.…”

“…In accordance with [42] the reduced neutron width Fo ~ is the measure of this correlation. This aspect of the research considering two-step y-cascades is discussed in more detail in [34].…”

Study of the187W states excited in the (n, ?) reaction

“…The cascade intensity calculations made analogously to [21] under the assumption that: a) the energy dependence of the widths of transitions of given multipolarities is known; b) all nuclear decay modes at an excitation energy E,,,~ 1.1 MeV are known to allow the prediction and comparison with the experiment of cascade intensities I~,y summed over all their possible intermediate levels.…”