Low-spin indentical bands in neighboring odd-Aand even-even nuclei: A challenge to mean-field theories

Identical bands: two steps forward

“…The first example of such pair of bands was found [1] in superdeformed (SD) nuclei of the rare earth region using the TESSA3 gamma-ray spectrometer. This exciting finding was followed by other examples, firstly at SD shapes and, secondly in normally deformed nuclei [2,3,4], raising the question of the influence of nuclear superfluidity. Indeed, due to the presence of an odd particle, the pairing correlations are expected to be reduced leading to an increase of 10-15% in the moments of inertia of odd-A nuclei.…”

Progress report on nuclear spectroscopic studies

“…While it is for strongly deformed configurations that the best examples of identical bands have been observed, it has been found that also at normal deformation some rotational bands in even-even nuclei and their odd-even neighbors are very similar in moment of inertia, and these bands have been also referred to as identical [35,36,37,381. Before trying to find specific explanations for the identical bands, it seems important to clarify, however, if indeed there are more bands in odd nuclei which are very similar to their even neighbors than one would expect from "simple coincidence".…”

Rotational structures inTa177

“…In this work we have used the Hamiltonian [27] H=HO -2'xX Q"'Q~' GM-P'P Gg-X P~P~* (3) calculations. An aligned angular momentum plot for the experimental bands observed in ' Ta is shown in Fig.…”

“…Indeed several odd-Z nuclei around A = 175 (' Ta included) were singled out for special discussion with regard to the remarkable phenomenon of "identical" bands in normal deformed nuclei [1,2]. The finding that certain single (and even higher seniority) quasiparticle (qp) excitations have identical moments of inertia to those of the neighboring ground-state even-even band was at odds with our conventional understanding of the blocking effect [3].An attempt to explain the effect on the moment of inertia in terms of specific cancellations of pairing, mass, alignment, and deformation has been put forward [1,2]. Some initial results from the present study which tended to support this particular explanation of identical bands in ' Ta have already been published [4].…”

“…Identical bands at low spins The occurrence of bands with "identical" moments of inertia in neighboring normal deformed nuclei is currently attracting a great deal of attention; see[35] for a comprehensive discussion and complete list of references. Some of the best cases occur in odd-Z nuclei around A = 175 and include Ta[2,3]. In ' Ta, both signatures of the [402]-', + structure at low spin have "identical" moments of inertia to the ground-state band in the neighboring even-Aligned angular momentum as a function of rotational frequency for (a) the observedbands in ' Ta and the ground-state band in Hf and (b) the results from the PSM calculations.…”