Abstract
Background: Collective motions in quantum many-body systems are described as bosonic excitations. Multi-phonon excitations in atomic nuclei, however, were observed very rarely. In particular, the first two-phonon vibrational excitation in odd- nuclei was reported in 2006 and only a few have been known so far. Two theoretical calculations for the data on were performed, one of which was done by the present author within a limited model space up to basis states. Quite recently, conspicuously enhanced , reduced transition probabilities, feeding states were observed in and conjectured that their parent states, called band (4), are candidates of states.
Purpose: In the present work, the model space is enlarged up to basis states. The purpose is twofold: One is to see how the description of eigenstates in the previous work is improved, and the other is to examine the existence of collective eigenstates, and when they exist, study their collectivity through calculating interband .
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- nuclei. Interband are calculated by adopting the method of the generalized intensity relation.
Results: The present model reproduces well the energy spectra and of states in and . For states, calculated spectra indicate that the most collective state with the highest at zero rotation feels strong Coriolis force after rotation sets in and consequently is observed with lowered , where is the projection of the angular momentum to the axis. The calculated states account for the observed enhanced within factors of 2–3.
Conclusions: The present calculation with the enlarged model space reproduces the observed states well and predicts properties of collective 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 although some mixing with states that are not included in the present model would be possible.
3 More- Received 12 June 2014
DOI:https://doi.org/10.1103/PhysRevC.90.044313
©2014 American Physical Society