20 research outputs found
Structure and decay properties of spin-dipole giant resonances within a semimicroscopical approach
A semimicroscopical approach is applied to calculate: (i) strength functions
for the charge-exchange spin-dipole giant resonances in the 208Pb parent
nucleus; (ii) partial and total branching ratios for the direct proton decay of
the resonance in 208Bi. The approach is based on continuum-RPA calculations of
corresponding reaction-amplitudes and phenomenological description of the
doorway-state coupling to many-quasiparticle configurations. The only
adjustable parameter needed for the description is found by comparison of the
calculated and experimental total widths of the resonance. Other model
parameters used in calculations are taken from independent data. The calculated
total branching ratio is found to be in reasonable agreement with the
experimental value.Comment: 15 pages, 4 figures, submitted to Phys. Lett.
The strength of the analog and Gamow-Teller giant resonances and hindrance of the 2\nu\beta\beta -decay rate
An approach for describing the hindrance of the nuclear 2\nu\beta\beta-decay
amplitude is proposed. The approach is based on a new formula obtained by a
model-independent transformation of the initial expression for the amplitude.
This formula takes explicitly into account the hindrance of the decay-amplitude
due to the presence of the collective Gamow-Teller state. Calculations are
performed within the simplest version of the approach. Calculated and
experimental 2\nu\beta\beta halve-lives are compared for a wide range of
nuclei.Comment: 11 pages, 1 tabl
Direct-decay properties of Giant Resonances
A semi-microscopic approach based on the continuum-RPA method and a
phenomenological treatment of the spreading effect is developed and applied to
describe direct-decay properties of a few isovector giant resonances.
Capabilities of the approach to describe giant-resonance gross properties are
also checked.Comment: This paper has been presented at 2nd International Conference on
"Collective Motion in Nuclei under Extreme Conditions" (COMEX 2), June 20-23,
2006, Sankt Goar, German
Structure of isobaric analog states in 91Nb populated by the 90Zr(a,t) reaction
Decay via proton emission of isobaric analog states (IAS's) in
was studied using the reaction at =180 MeV.
This study provides information about the damping mechanism of these states.
Decay to the ground state and low-lying phonon states in was
observed. The experimental data are compared with theoretical predictions
wherein the IAS `single-particle' proton escape widths are calculated in a
continuum RPA approach. The branching ratios for decay to the phonon states are
explained using a simple model.Comment: 3 figures. submitted to Phys. Lett.
On direct proton decay of the Gamow-Teller giant resonance
The semi-microscopic approach to the description of giant resonances in medium-heavy mass closed-shell nuclei is implemented to treat partial probabilities of direct-proton decay of the Gamow-Teller giant resonance (GTGR) in 208Bi. The corresponding experimental data are reasonably explained