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Probing the Nuclear Neutron Skin by Low-Energy Dipole Modes

N. Tsoneva·H. Lenske·Ch. Stoyanov
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Abstract

Dipole excitations below the neutron threshold in neutron rich Sn isotopes are studied theoretically in the Quasiparticle-Phonon Model with HFB single particle input. Of special interest are the low-lying two-phonon 1- states and the Pygmy Dipole Resonance (PDR). The evolution of low-energy dipole excitations with neutron excess is investigated over the Sn isotopic chain including the experimentally unknown regions close to 132Sn. A dependence of the PDR strengths and centroid energies on the neutron skin thickness is found. Despite significant multi-phonon contributions to mean energies and transition strengths, the PDR states retain their one-phonon character. The fragmentation pattern is reduced with increasing neutron excess towards the N=82 shell closure which will be of advantage for future experimental work.

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N. Tsoneva, H. Lenske, Ch. Stoyanov. 2004-04-02. Probing the Nuclear Neutron Skin by Low-Energy Dipole Modes. https://doi.org/10.1016/j.physletb.2004.02.024

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