Two-phonon γ -vibrational states in rotating triaxial odd- A nuclei

2014

Phys. Rev. C

Self Cite

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.

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

2014

Phys. Rev. C

Self Cite

Changes in rotational characters of one- and two-phonon gamma-vibrational bands in 105Mo

Progress of Theoretical and Experimental Physics

2015

The γ vibration is the most typical low-lying collective motion prevailing the nuclear chart. But only few one-phonon rotational bands in odd-A nuclei have been known. Furthermore, two-phonon states, even the band head, have been observed in a very limited number of nuclides not only of odd-A but even-even. Among them, that in 105 Mo is unique in that Coriolis effects are expected to be stronger than in 103 Nb and 105 Nb on which theoretical studies were reported. Then the purpose of the present work is to study 105 Mo paying attention to rotational character change of the one-phonon and two-phonon bands. 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. The present model reproduces the observed yrast zero-phonon and onephonon bands well. Emerging general features of the rotational character change from low spin to high spin are elucidated. In particular, the reason why the one-phonon band does not exhibit signature splitting is clarified. The calculated collectivity of the two-phonon states, however, is located higher than observed.

Quadrupole and monopole transition properties of 0⁺₂in Gd isotopes

Prog. Theor. Exp. Phys.

Ueno

2016

Self Cite

The longstanding problem of characterization of the 0 + 2 states in Gd isotopes is revisited by adopting the Nilsson+BCS mean field and the random-phase approximation. The interband electric quadrupole transition strengths varying almost two orders of magnitude are nicely reproduced at the same time as other observables. These results indicate that the 0 + 2 states, in particular, those in lighter isotopes are well described as β vibrations excited on top of deformed ground states without recourse to the shape-coexistence picture.Subject index D12, D13