108 research outputs found
Parity shift and beat staggering structure of octupole bands in a collective model for quadrupole-octupole deformed nuclei
We propose a collective model formalism which describes the strong parity
shift observed in low-lying spectra of nuclei with octupole deformations
together with the fine rotational band structure developed at higher angular
momenta. The parity effect is obtained by the Schroedinger equation for
oscillations of the reflection asymmetric (octupole) shape between two opposite
orientations in an angular momentum dependent double-well potential. The
rotational structure is obtained by a collective quadrupole-octupole rotation
Hamiltonian. The model scheme reproduces the complicated beat staggering
patterns observed in the octupole bands of light actinide nuclei. It explains
the angular momentum evolution of octupole spectra as the interplay between the
octupole shape oscillation (parity shift) mode and the stable
quadrupole-octupole rotation mode.Comment: 16 pages, 7 figure
Symmetries and staggering effects in nuclear rotational spectra
We study the fine structure of nuclear rotational spectra on the basis of
both dynamical and discrete symmetry approaches. In this framework we show that
the odd--even (Delta I = 1) staggering effects observed in various rotational
bands carry detailed information about the collective band-mixing interactions
and the collective shape properties of heavy nuclei.Comment: LaTeX, 4 pages plus 1 figure (.ps). To appear in the proceedings of
the European Conference on the Structure of the Nucleus at the Dawn of the
Century (Bologna, Italy, 29/5/00-3/6/00), ed. G. Bonsignori et a
Staggering behavior of the low lying excited states of even-even nuclei in a Sp(4,R) classification scheme
We implement a high order discrete derivative analysis of the low lying
collective energies of even-even nuclei with respect to the total number of
valence nucleon pairs N in the framework of F- spin multiplets appearing in a
symplectic sp(4,R) classification scheme. We find that for the nuclei of any
given F- multiplet the respective experimental energies exhibit a Delta N=2
staggering behavior and for the nuclei of two united neighboring F- multiplets
well pronounced Delta N=1 staggering patterns are observed. Those effects have
been reproduced successfully through a generalized sp(4,R) model energy
expression and explained in terms of the step-like changes in collective modes
within the F- multiplets and the alternation of the F-spin projection in the
united neighboring multiplets. On this basis we suggest that the observed Delta
N=2 and Delta N=1 staggering effects carry detailed information about the
respective systematic manifestation of both high order alpha - particle like
quartetting of nucleons and proton (neutron) pairing interaction in nuclei.PACS
number(s):21.10.Re, 21.60.FwComment: 22 pages and 6 figures changes in the figure caption
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