Pairing fluctuations in rapidly rotating nuclei

Journal Article · Sun Jan 01 04:00:00 EST 1989 · Rev. Mod. Phys.; (United States)

DOI:https://doi.org/10.1103/RevModPhys.61.131· OSTI ID:6535108

Shimizu, Y R; Garrett, J D; Broglia, R A; Gallardo, M; Vigezzi, E

Empirical evidence for the existence of pair fluctuations in rapidly rotating nuclei in connection with the pair gap is reviewed. The quantities considered are single-particle energies (routhians) and alignments. While the cranked shell model in the presence of static pair correlations provides an accurate description of data at rotational frequencies below the critical frequency corresponding to the collapse of the static pair gap, conspicuous discrepancies are found in the region of and above the pairing phase transition. In particular, a group of excitations is observed displaying lower excitation energies and smaller alignments than those predicted by the cranked shell model. Such excitations can be characterized as behaving as if the correlations induced by the presence of a pairing condensate were not totally obliterated after the ''phase transition.'' A theoretical model, based on the renormalization of the single-particle motion mixed by the coupling to pairing vibrations, is quite successful in explaining the overall trend of the data at rotational frequencies larger than the critical frequency. Smaller alignments and excitation energies are correlated with configurations displaying particle coupling schemes which profit most from fluctuations of the pair gap about its zero equilibrium value. While this model reproduces many of the experimental features, it still overpredicts the alignments by 2--3 units of (h/2..pi..) in the crossing region. Thus other degrees of freedom (both static and dynamic), e.g., deformations, also must play a role at large rotational frequencies.

• Research Organization: The Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen OX, Denmark
• OSTI ID: 6535108
• Journal Information: Rev. Mod. Phys.; (United States), Journal Name: Rev. Mod. Phys.; (United States) Vol. 61:1; ISSN RMPHA
• Country of Publication: United States
• Language: English

Related Subjects

653001* -- Nuclear Theory-- Nuclear Structure
Moments
Spin
& Models
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COLLECTIVE MODEL
DEFORMED NUCLEI
DOCUMENT TYPES
ENERGY LEVELS
EXCITED STATES
FUNCTIONS
INTERACTIONS
ISOTOPES
MATHEMATICAL MODELS
NUCLEAR MODELS
NUCLEI
PAIRING INTERACTIONS
PARTICLE MODELS
RARE EARTH ISOTOPES
RESPONSE FUNCTIONS
REVIEWS
ROTATIONAL STATES
SINGLE-PARTICLE MODEL
YTTERBIUM ISOTOPES