Mainz 2012 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 13: Struktur und Dynamik von Kernen
HK 13.7: Talk
Monday, March 19, 2012, 18:15–18:30, P 4
Pygmy dipole resonance and neutron skin in 208Pb* — •Iryna Poltoratska1, Peter von Neumann-Cosel1, Vladimir Yu. Ponomarev1, Atsushi Tamii2, and Sergej Bassauer1 — 1Institut für Kernphysik, TU Darmstadt, Deutschland — 2RCNP, Osaka University, Japan
A benchmark experiment on 208Pb shows that polarized proton inelastic scattering at very forward angles including 0∘ is a powerful tool for studies of electric dipole (E1) and spin magnetic dipole (M1) modes in nuclei over a broad excitation energy range to test up-to-date nuclear models. For the separation of E1/M1 contributions two different independent methods are applied, viz. a multipole decomposition of the angular distribution of the cross sections utilizing DWBA calculations and a model-independent analysis based on polarization transfer coefficients. Such an experiment allows the extraction of the complete electric dipole strength including the pygmy dipole resonance and determine its global features. Utilizing recent theoretical results [1,2] in combination with the extracted electric dipole nuclear polarizability αD one is able to constrin the neutron skin in 208Pb [3] and thereby the symmetry energy relevant for the description of the neutron stars.
[1] P.-G. Reinhard and W. Nazarewicz, Phys. Rev. C 81, 051303(R) (2010).
[2] J. Piekarewicz, Phys. Rev. C 83, 034319 (2011).
[3] A. Tamii et al., Phys. Rev. Lett. 107, 062502 (2011).
⋆ Supported by DFG under contracts SFB 634 and NE 679/3-1.