Unpaired band crossings

Ma, Riley; Jd, Garrett; Simpson, John; Jf, Sharpey-Schafer

doi:10.1103/physrevlett.60.553

Cited by 23 publications

(17 citation statements)

References 17 publications

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“…[24,26]. A further feature was observed at high spin in the band based on the negative-parity ground-state configuration [24], which has been interpreted as an unpaired neutron band crossing [29]. This is a crossing that occurs in the absence of static neutron pairing correlations.…”

Section: Introductionmentioning

confidence: 89%

“…The simple single-particle model, outlined in [29], predicted a similar crossing in band 3, but at a higher rotational frequency. The new high-spin transitions in band 3 indicate a branching in the sequence at 79/2 − withhω ∼ 0.60 MeV, see Fig.…”

Section: Strongly-coupled Structuresmentioning

confidence: 97%

“…20(e)). Indeed, the observation of an isolated band crossing at this frequency in the experimental data led Riley et al [29] to interpret this as an unpaired band crossing. This crossing was described as an exchange of occupation at the crossing of a pair of high-j (i 13/2 ) neutrons.…”

Section: Strongly-coupled Structuresmentioning

confidence: 99%

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Diverse collective excitations in159Erup to high spin

Mustafa¹,

Ollier²,

Simpson³

et al. 2011

Phys. Rev. C

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A spectroscopic investigation of the γ decays from excited states in 159 Er has been performed in order to study the changing structural properties exhibited as ultrahigh spins (I > 60h) are approached. The nucleus 159 Er was populated by the reaction 116 Cd( 48 Ca,5nγ) at a beam energy of 215 MeV and the resulting γ decays were studied using the Gammasphere spectrometer. New rotational bands and extensions to existing sequences were observed, which are discussed in terms of the cranked shell model, revealing a diverse range of quasiparticle configurations. At spins around 50h there is evidence for a change from dominant prolate collective motion at the yrast line to oblate non-collective structures via the mechanism of band termination. A possible strongly deformed triaxial band occurs at these high spins, which indicates collectivity beyond 50h. The high spin data are interpreted within the framework of cranked Nilsson-Strutinsky calculations.

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Section: Introductionmentioning

confidence: 89%

Section: Strongly-coupled Structuresmentioning

confidence: 97%

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Diverse collective excitations in159Erup to high spin

Mustafa¹,

Ollier²,

Simpson³

et al. 2011

Phys. Rev. C

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“…This type of backbending is an effect from pairing, and does not appear in unpaired solutions. Unpaired band-crossings have been observed in the A ∼ 160 mass region at high spin (where pairing plays a minor role) [23,24].…”

Section: Backbendingmentioning

confidence: 99%

Rotational structure of T=0 and T=1 bands in the N=Z nucleus 62Ga

Juodagalvis¹,

Åberg²

2001

Nuclear Physics A

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The rotational behavior of T =0 and T =1 bands in the odd-odd N =Z nucleus 62 Ga is studied theoretically using the spherical shell model (laboratory frame) and the cranked Nilsson-Strutinsky model (intrinsic frame). Both models give a good description of available experimental data. The role of isoscalar and isovector pairing in the T =0 and T =1 bands as functions of angular momentum is studied in the shell model. The observed backbending in the T =0 band is interpreted as an unpaired band-crossing between two configurations with different deformation. The two configurations differ by 2p-2h and are found to terminate the rotational properties at I π =9 + and I π =17 + , respectively. E2-decay matrix elements and spectroscopic quadrupole moments are calculated. From the CNS calculation, supported by shell model results, it is suggested that the low spin parts of the bands with T =0 and T =1 correspond to triaxially deformed states with the rotation taking place around the shortest axis (positive γ) and intermediate axis (negative γ), respectively. At lower spins the configuration space pf 5/2 g 9/2 , used in the shell model calculation, is found sufficient while also f 7/2 becomes important above the backbending.

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“…While paired band crossings are generally seen at low but similar rotational frequencies in sequences of nuclei, unpaired band crossings depend on details of the nuclear spectrum at high angular momenta [1]. They can involve the exchange of one (1p-1h) [2] or two (2p-2h) [3,4] particles and holes. Measuring interaction strengths in 2p-2h crossings provides information on forces beyond the nuclear mean field, i.e., residual interactions.…”

mentioning

confidence: 99%

Ni58: An Unpaired Band Crossing at New Heights of Angular Momentum for Rotating Nuclei

Rudolph

Carlsson²,

Ragnarsson³

et al. 2006

Phys. Rev. Lett.

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High-spin states in 58Ni have been investigated by means of the fusion-evaporation reaction 28Si(32S, 2p)58Ni at 130 MeV beam energy. Discrete-energy levels are observed in 58Ni at record-breaking 42 MeV excitation energy and angular momenta in excess of 30h. The states form regular rotational bands with unprecedented high rotational frequencies. A comparison with configuration dependent cranked Nilsson-Strutinsky calculations reveals an exceptional two-band crossing scenario, the interaction strength of which is strongly shape dependent.

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Unpaired band crossings

Cited by 23 publications

References 17 publications

Diverse collective excitations in159Erup to high spin

Diverse collective excitations in159Erup to high spin

Rotational structure of T=0 and T=1 bands in the N=Z nucleus 62Ga

Ni58: An Unpaired Band Crossing at New Heights of Angular Momentum for Rotating Nuclei

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