Nuclear symmetry energy and neutron skins derived from pygmy dipole resonances
- Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany)
- Physics Department, Faculty of Science, University of Zagreb, Bijenicka 32, 10000 Zagreb (Croatia)
- Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain)
- Institut fuer Kernphysik, Johann Wolfgang Goethe-Universitaet, D-60486 Frankfurt am Main (Germany)
- Institut fuer Kernchemie, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany)
- Instytut Fizyki, Uniwersytet Jagiellonski, PL-30-059 Krakow (Poland)
By exploiting Coulomb dissociation of high-energy radioactive beams of the neutron-rich nuclei {sup 129-132}Sn and {sup 133,134}Sb, their dipole-strength distributions have been measured. A sizable fraction of ''pygmy'' dipole strength, energetically located below the giant dipole resonance, is observed in all of these nuclei. A comparison with available pygmy resonance data in stable nuclei ({sup 208}Pb and N=82 isotones) indicates a trend of strength increasing with the proton-to-neutron asymmetry. On theoretical grounds, employing the RQRPA approach, a one-to-one correlation is found between the pygmy strength and parameters describing the density dependence of the nuclear symmetry energy, and in turn with the thicknesses of the neutron skins. On this basis, by using the experimental pygmy strength, parameters of the nuclear symmetry energy (a{sub 4}=32.0{+-}1.8 MeV and p{sub o}=2.3{+-}0.8 MeV/fm{sup 3}) are deduced as well as neutron-skin thicknesses R{sub n}-R{sub p} of 0.24{+-}0.04 fm for {sup 132}Sn and of 0.18{+-}0.035 fm for {sup 208}Pb, both doubly magic nuclei. Astrophysical implications with regard to neutron stars are briefly addressed.
- OSTI ID:
- 21067870
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 76, Issue 5; Other Information: DOI: 10.1103/PhysRevC.76.051603; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA). LAND Collaboration; ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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