Nuclear Shape Transition, Triaxiality and Energy Staggering of -Band States for Even–Even Xenon Isotopic Chain
The positive-parity states of even–even Xe nuclei are inspected within the framework of modified (6) limit of the interacting boson model (IBM). The effective three-body interaction where is the IBM (6) quadrupole operator is introduced to exhibit the triaxiality nature. The shape of nuclear surface...
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Veröffentlicht in: | Physics of atomic nuclei 2023-08, Vol.86 (4), p.356-369 |
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Sprache: | eng |
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Zusammenfassung: | The positive-parity states of even–even Xe nuclei are inspected within the framework of modified
(6) limit of the interacting boson model (IBM). The effective three-body interaction
where
is the IBM
(6) quadrupole operator is introduced to exhibit the triaxiality nature. The shape of nuclear surface is quantified by the deformation parameters
,
by using the intrinsic coherent state. For each nucleus, the potential energy surfaces (PES) of the transition
(5)–Triaxiality–
(6) are resolved and analyzed and the critical phase transition points are identified. For each nucleus a fitting procedure is adopted to get the best model parameters by fitting some selected calculated energy levels and
transition rate ratios with experimental ones. These ratios are analyzed because they serve as effective order parameters in the shape phase transition. The nuclei in Xe isotopic chain evolve from spherical vibrator
(5) to
-soft rotor
(6) by increasing the boson number from
(heavy isotope
Xe) to
(light isotope
Xe) and the isotope
Xe represents the critical nucleus. The nucleus
Xe has triaxial nature. To transact with high spin states in
-band in
Xe isotopic chain to investigate and exhibit the odd–even-spin energy staggering, we introduce the two-parameter collective nuclear softness rotor model (CNS2). Three different staggering indices are considered depending on the dipole transitions linking the two families of spins while the quadrupole transitions are within each spin family. Strong odd–even-spin energy staggering has been seen. As a link between the IBM and CNS2 models we observed that the energy difference
between the
-band and ground state band normalized to
decreases with increasing the mass number. |
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ISSN: | 1063-7788 1562-692X |
DOI: | 10.1134/S1063778823040208 |