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Title: Low-lying dipole response in the stable {sup 40,48}Ca nuclei with the second random-phase approximation

Abstract

Low-energy dipole excitations are analyzed for the stable isotopes {sup 40}Ca and {sup 48}Ca in the framework of the Skyrme-second random-phase approximation. The corresponding random-phase approximation calculations provide a negligible strength distribution for both nuclei in the energy region from 5 to 10 MeV. The inclusion and the coupling of 2 particle-2 hole configurations in the second random-phase approximation lead to an appreciable dipole response at low energies for the neutron-rich nucleus {sup 48}Ca. The presence of a neutron skin in the nucleus {sup 48}Ca would suggest the interpretation of the low-lying response in terms of a pygmy excitation. The composition of the excitation modes (content of 1 particle-1 hole and 2 particle-2 hole configurations), their transition densities and their collectivity (number and coherence of the different contributions) are analyzed. This analysis indicates that, in general, these excitations cannot be clearly interpreted in terms of oscillations of the neutron skin against the core with the exception of the peak with the largest B(E1) value, which is located at 9.09 MeV. For this peak the neutron transition density dominates and the neutron and proton transition densities oscillate out of phase in the internal part of the nucleus leading to a strongmore » mixing of isoscalar and isovector components. Therefore, this state shows some features usually associated to pygmy resonances.« less

Authors:
 [1];  [2];  [1]
  1. Dipartimento di Fisica e Astronomia and INFN, Via Santa Sofia 64, I-95123 Catania (Italy)
  2. Institut de Physique Nucleaire,Universite Paris-Sud, IN2P3-CNRS, F-91406 Orsay Cedex (France)
Publication Date:
OSTI Identifier:
21596732
Resource Type:
Journal Article
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 84; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevC.84.034301; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2813
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CALCIUM 40; CALCIUM 48; COMPUTERIZED SIMULATION; COUPLING; DENSITY; DIPOLES; DISTRIBUTION; E1-TRANSITIONS; EXCITATION; INCLUSIONS; ISOVECTORS; MEV RANGE 01-10; MIXING; NEUTRON-RICH ISOTOPES; NEUTRONS; OSCILLATIONS; RANDOM PHASE APPROXIMATION; RESONANCE; SKYRME POTENTIAL; ALKALINE EARTH ISOTOPES; APPROXIMATIONS; BARYONS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; CALCIUM ISOTOPES; CALCULATION METHODS; ELEMENTARY PARTICLES; ENERGY RANGE; ENERGY-LEVEL TRANSITIONS; EVEN-EVEN NUCLEI; FERMIONS; HADRONS; INTERMEDIATE MASS NUCLEI; ISOTOPES; LIGHT NUCLEI; MEV RANGE; MULTIPOLE TRANSITIONS; MULTIPOLES; NUCLEI; NUCLEON-NUCLEON POTENTIAL; NUCLEONS; PHYSICAL PROPERTIES; POTENTIALS; RADIOISOTOPES; SIMULATION; STABLE ISOTOPES; TENSORS; VECTORS

Citation Formats

Gambacurta, D, Grand Accelerateur National d'Ions Lourds, Grasso, M, and Catara, F. Low-lying dipole response in the stable {sup 40,48}Ca nuclei with the second random-phase approximation. United States: N. p., 2011. Web. doi:10.1103/PHYSREVC.84.034301.
Gambacurta, D, Grand Accelerateur National d'Ions Lourds, Grasso, M, & Catara, F. Low-lying dipole response in the stable {sup 40,48}Ca nuclei with the second random-phase approximation. United States. https://doi.org/10.1103/PHYSREVC.84.034301
Gambacurta, D, Grand Accelerateur National d'Ions Lourds, Grasso, M, and Catara, F. 2011. "Low-lying dipole response in the stable {sup 40,48}Ca nuclei with the second random-phase approximation". United States. https://doi.org/10.1103/PHYSREVC.84.034301.
@article{osti_21596732,
title = {Low-lying dipole response in the stable {sup 40,48}Ca nuclei with the second random-phase approximation},
author = {Gambacurta, D and Grand Accelerateur National d'Ions Lourds and Grasso, M and Catara, F},
abstractNote = {Low-energy dipole excitations are analyzed for the stable isotopes {sup 40}Ca and {sup 48}Ca in the framework of the Skyrme-second random-phase approximation. The corresponding random-phase approximation calculations provide a negligible strength distribution for both nuclei in the energy region from 5 to 10 MeV. The inclusion and the coupling of 2 particle-2 hole configurations in the second random-phase approximation lead to an appreciable dipole response at low energies for the neutron-rich nucleus {sup 48}Ca. The presence of a neutron skin in the nucleus {sup 48}Ca would suggest the interpretation of the low-lying response in terms of a pygmy excitation. The composition of the excitation modes (content of 1 particle-1 hole and 2 particle-2 hole configurations), their transition densities and their collectivity (number and coherence of the different contributions) are analyzed. This analysis indicates that, in general, these excitations cannot be clearly interpreted in terms of oscillations of the neutron skin against the core with the exception of the peak with the largest B(E1) value, which is located at 9.09 MeV. For this peak the neutron transition density dominates and the neutron and proton transition densities oscillate out of phase in the internal part of the nucleus leading to a strong mixing of isoscalar and isovector components. Therefore, this state shows some features usually associated to pygmy resonances.},
doi = {10.1103/PHYSREVC.84.034301},
url = {https://www.osti.gov/biblio/21596732}, journal = {Physical Review. C, Nuclear Physics},
issn = {0556-2813},
number = 3,
volume = 84,
place = {United States},
year = {Thu Sep 15 00:00:00 EDT 2011},
month = {Thu Sep 15 00:00:00 EDT 2011}
}