Instability of nuclear wobbling motion and tilted axis rotation

Matsuzaki, Masayuki; Ohtsubo, Shin‐Ichi

doi:10.1103/physrevc.69.064317

Cited by 33 publications

(31 citation statements)

References 34 publications

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“…(18) if the relation between γ (pot:Nils) and γ (den) is taken into account. The excitation energy can be expressed in terms of the three moments of inertia in a usual way [7,30], but their γ dependence is not like the irrotational inertia [37,40], which leads to the rather weak γ dependence of the excitation energy. Here we have only shown the example of the wobbling excitation in 163 Lu, but we have confirmed that these properties of the wobbling-like RPA solution are general, and can be applied to other cases in the Lu region.…”

Section: B(e2) Ratio Of the Wobbling Bandmentioning

confidence: 99%

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Parametrizations of triaxial deformation andE2transitions of the wobbling band

2008

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There are various different definitions for the triaxial deformation parameter "γ ". It is pointed out that the parameter conventionally used in the Nilsson (or Woods-Saxon) potential, γ (pot:Nils) [or γ (pot:WS)], is not appropriate for representing the triaxiality γ defined in terms of the intrinsic quadrupole moments. The difference between the two can be as large as a factor two in the case of the triaxial superdeformed bands recently observed in Hf and Lu nuclei, i.e., γ (pot:Nils) ≈ 20 • corresponds to γ ≈ 10 • . In our previous work, we studied the wobbling excitations in Lu nuclei using the microscopic framework of the cranked Nilsson mean-field and the random phase approximation. The most serious problem was that the calculated B(E2) value is about factor two too small. It is shown that the origin of this underestimate can mainly be attributed to the small triaxial deformation parameter γ ≈ 10 • that corresponds to γ (pot:Nils) ≈ 20 • . If the same triaxial deformation parameter is used as in the analysis of the particle-rotor model, γ ≈ 20 • , the calculated B(E2) gives correct magnitude of the experimental data.

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Section: B(e2) Ratio Of the Wobbling Bandmentioning

confidence: 99%

“…[38,39]. The instability of the wobbling excitation was also studied [40] in relation to the tilted axis cranking rotation.…”

Section: Introductionmentioning

confidence: 99%

Parametrizations of triaxial deformation andE2transitions of the wobbling band

2008

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“…Due to the mean-filed approximation, cranking model yields only the yrast sequence for a given configuration, Therefore, in order to describe the wobbling excitations, one has to go beyond the mean-filed approximation. At present, this has been done by incorporating the quantum correlations by means of random phase approximation (RPA) [21][22][23][24][25][26][27][28] or by the generator coordinate method after angular momentum projection (GCM+AMP) based on the cranking intrinsic states [29].…”

Section: Introductionmentioning

confidence: 99%

Collective Hamiltonian for wobbling modes

et al. 2014

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The simple, longitudinal, and transverse wobblers are systematically studied within the framework of collective Hamiltonian, where the collective potential and mass parameter included are obtained based on the tilted axis cranking approach. Solving the collective Hamiltonian by diagonalization, the energies and the wave functions of the wobbling states are obtained. The obtained results are compared with those by harmonic approximation formula and particle rotor model. The wobbling energies calculated by the collective Hamiltonian are closer to the exact solutions by particle rotor model than harmonic approximation formula. It is confirmed that the wobbling frequency increases with the rotational frequency in simple and longitudinal wobbling motions while decreases in transverse wobbling motion. These variation trends are related to the stiffness of the collective potential in the collective Hamiltonian.

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“…[13]. Furthermore, the rotational bands built on the high-K multiquasiparticle states can be interpreted theoretically as a multiphonon excitation of the precession mode, which is the axially symmetric limit of the wobbling mode [14].…”

Section: Introductionmentioning

confidence: 99%

Single-phonon and multi-phonon excitations of theγvibration in rotating odd-Anuclei

Matsuzaki

2014

Phys. Rev. C

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Background: Collective motions in quantum many-body systems are described as bosonic excitations. Multiphonon excitations in atomic nuclei, however, were observed very rarely. In particular, the first two-phonon γ vibrational (2γ ) excitation in odd-A nuclei was reported in 2006 and only a few have been known so far. Two theoretical calculations for the data on 103 Nb were performed, one of which was done by the present author within a limited model space up to 2γ basis states. Quite recently, conspicuously enhanced B(E2)s, reduced E2 transition probabilities, feeding 2γ states were observed in 105 Nb and conjectured that their parent states, called band (4), are candidates of 3γ states. Purpose: In the present work, the model space is enlarged up to 4γ basis states. The purpose is twofold: One is to see how the description of 2γ eigenstates in the previous work is improved, and the other is to examine the existence of collective 3γ eigenstates, and when they exist, study their collectivity through calculating interband B(E2)s. Method:The particle-vibration coupling model based on the cranking model and the random-phase approximation is used to calculate the vibrational states in rotating odd-A nuclei. Interband B(E2)s are calculated by adopting the method of the generalized intensity relation. Results: The present model reproduces well the energy spectra and B(E2)s of 0γ -2γ states in 103 Nb and 105 Nb. For 3γ states, calculated spectra indicate that the most collective state with the highest K at zero rotation feels strong Coriolis force after rotation sets in and consequently is observed with lowered K, where K is the projection of the angular momentum to the z axis. The calculated states account for the observed enhanced B(E2)s within factors of 2-3. Conclusions:The present calculation with the enlarged model space reproduces the observed 0γ -2γ states well and predicts properties of collective 3γ states. The most collective one is thought to be the main component of the observed band (4) from the analyses of the energy spectra and interband B(E2)s although some mixing with states that are not included in the present model would be possible.

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Instability of nuclear wobbling motion and tilted axis rotation

Cited by 33 publications

References 34 publications

Parametrizations of triaxial deformation andE2transitions of the wobbling band

Parametrizations of triaxial deformation andE2transitions of the wobbling band

Collective Hamiltonian for wobbling modes

Single-phonon and multi-phonon excitations of theγvibration in rotating odd-Anuclei

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