Rotation of an Eight-Quasiparticle Isomer

Purry, C.S.; Walker, P. M.; Dracoulis, George; Kibédi, T.; Bayer, S.; Bruce, A. M.; Byrne, Aidan; Dasgupta, M.; Gelletly, W.; Kondev, F. G.; Regan, P. H.; Thwaites, C.

doi:10.1103/physrevlett.75.406

Cited by 28 publications

(10 citation statements)

References 19 publications

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“…Solid line: TAC calculation. Dashed line: experiment [13][14][15][16]. Upper panel: bands in 178 W. Lower panel: bands in 178 Hf and 179 W. Moments of inertia can be obtained from the graphs, as J/ω (kinematic value) and dJ/dω (dynamic value).…”

Section: The Tilted-axis-cranking Modelmentioning

confidence: 99%

“…In the present study we address the inertial behavior of a different class of nuclear excitations: high-seniority states in well deformed A≈180 nuclei (see also the earlier work by Andersson et al [12]). Recently, rotational bands have been observed in, for example, 178 Hf, 178 W and 179 W [13][14][15][16] that are built on configurations with up to four broken pairs (that is, seniority eight) and high K values, where K is the angular momentum with respect to the body-fixed deformation axis. It is found (see the empirical data in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Moments of inertia for multiquasiparticle configurations

et al. 2000

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Section: The Tilted-axis-cranking Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Moments of inertia for multiquasiparticle configurations

et al. 2000

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“…The current experiments are able to find evidences for 6-or 8-qp isomers (see, for example, Refs. [14,15]), and discoveries of more high-K isomers are expected from modern facilities such as the storage ring [16]. These data provide us with valuable information on the single-particle structure in deformed potentials.…”

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confidence: 99%

Toward extremes of angular momentum: Application of the Pfaffian algorithm in realistic calculations

et al. 2014

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In a calculation of rotated matrix elements with angular momentum projection, the generalized Wick's theorem may encounter a practical problem of combinatorial complexity when the configurations have more than four quasi-particles (qps). The problem can be solved by employing the Pfaffian algorithm generally applicable to calculations of matrix elements for Hartree-Fock-Bogoliubov states with any number of qps. This breakthrough in many-body techniques enables studies of high-spin states in a shell-model framework. As the first application of the Pfaffian algorithm, the configuration space of the Projected Shell Model is expanded to include 6-qp states for both positive and negative parities. Taking 166 Hf as an example, we show that 6-qp states become the main configuration of the yrast band beyond spin I ≈ 34 , which explains the observed third back-bending in moment of inertia. Structures of multi-qp high-K isomers in 176 Hf are analyzed as another example.PACS numbers: 21.10. Re, 21.60.Cs, 23.20.Lv, 27.70.+q All nucleons of even-even nuclei couple pairwise in their ground state. Nuclear rotation brings an effect into the system that tends to break the nucleon pairs. This effect due to the rotation of nuclei was suggested in 1960 [1] in analogy to the electron pair breaking in superconductivity due to the existence of external magnetic fields. However, it was soon after realized that a sharp phase transition with pair collapse does not occur in nuclear systems due to the fact that nuclei have a finite size [2]. Another reason is that nucleons have an orbital angular momentum in addition to spin. The nucleons in the vicinity of the Fermi surfaces belong to subshells with rather different j-values, and therefore, they feel the Coriolis force very differently. Pairs in those orbitals with the highest angular momentum j, as for instance the neutron i 13/2 shell in the rare earth region, feel a strong Coriolis force, and therefore, break first (the Stephens-Simon effect [3]). They contribute to formation of 2-quasiparticle (qp) state as the main configuration of the yrast state. The Stephens-Simon effect [3] successfully explained the experimental observations of backbending in moment of inertia for rotating nuclei [4]. As a nucleus rotates faster and faster, subsequent pair-breakings can occur for the pairs from the next highest j orbitals. In the rare earth region, proton pairs in the h 11/2 shell are expected to break next, which was observed experimentally [5]. Measurements for further pair breakings at higher angular momenta are difficult. However, there have been early [6] and recent evidences [7,8] of breaking of three nucleon pairs, which form 6-qp states as the main configuration of the yrast sequence.Pair-breaking in nuclei can lead to formation of another special group of excited states: nuclear isomers. In a deformed potential a j-shell splits up into 2 j+1 K-states. Two or more states with high K quantum numbers can couple to form a high-K multi-qp configuration. The selection rules of elec- * El...

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“…A related thrust of the collaborative studies has been the effort to iden- tify, and characterise, high-seniority multi-quasiparticle states. This has resulted in the assignment in 178W of the highest-seniority multiparticle state with an associated collective band yet found [14]. The band is seen clearly in the spectrum obtained by selecting transitions feeding the 25-isomer7 as shown in Figure 4.…”

Section: Nuclear Spectroscopy and Nuclear Structurementioning

confidence: 94%

Heavy Ion Accelerator Facility Department of Nuclear Physics Australian National University

Dracoulis¹

1999

Nuclear Physics News

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Rotation of an Eight-Quasiparticle Isomer

Cited by 28 publications

References 19 publications

Moments of inertia for multiquasiparticle configurations

Moments of inertia for multiquasiparticle configurations

Toward extremes of angular momentum: Application of the Pfaffian algorithm in realistic calculations

Heavy Ion Accelerator Facility Department of Nuclear Physics Australian National University

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