The gamma decay in the quasicontinuum is used to study the order-to-chaos transition in the thermally excited Er-163 nucleus. The experimental analysis is performed on high-statistics EUROBALL data, focusing on the spin region I approximate to(20-40)h, and internal excitation energy up of approximate to 2.5 MeV. The results are compared to cranked shell model calculations for this nucleus, taking into account the dependence on the K quantum number. Two main topics are investigated. First, the validity of the selection rules associated with the K quantum number are studied as a function of the internal energy U above yrast. K-selection rules are found to be obeyed in the decay along discrete unresolved rotational bands up to U approximate to 1.2 MeV, whereas in the interval U approximate to 1.2-2.5 MeV, where the order-to-chaos transition is expected to take place, selection rules are found to be only partially valid. Second, the line-shape analysis of gamma-gamma coincidence spectra provides a direct experimental measurement of the rotational and compound damping widths (Gamma(rot) and Gamma(mu)), yielding values of 200 and 20 keV, respectively, in good agreement with theory.
|Titolo:||Damping mechanisms and order-to-chaos transition in the warm rotating Er-163 nucleus|
|Parole Chiave:||K-QUANTUM NUMBER; GAMMA-DECAY; STATES; CASCADES; EUROBALL; YB-164; BANDS; RAYS; SPIN|
|Settore Scientifico Disciplinare:||Settore FIS/04 - Fisica Nucleare e Subnucleare|
Settore FIS/01 - Fisica Sperimentale
|Data di pubblicazione:||set-2005|
|Digital Object Identifier (DOI):||10.1103/PhysRevC.72.034307|
|Appare nelle tipologie:||01 - Articolo su periodico|