Heidelberg 2015 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 45: Structure and Dynamics of Nuclei 9
HK 45.1: Gruppenbericht
Mittwoch, 25. März 2015, 14:30–15:00, T/HS2
Low electric dipole response in 120Sn — •Anna Maria Krumbholz1, Peter von Neumann-Cosel1, Atsushi Tamii2, Vladimir Yu. Ponomarev1, and Michael Mathy1 for the EPPS0 collaboration — 1Institut für Kernphysik, TU Darmstadt — 2Research Center for Nuclear Physics, University Osaka
A consistent and powerful method to measure electric and magnetic dipole modes over a broad excitation energy range including energies below and above the neutron separation energy is polarized proton scattering at small scattering angles including 0∘ [1]. Measurements of the 120Sn(p→,p→’) reaction have been performed at RCNP with a beam energy of 295 MeV and an energy resolution of about 25 keV. For the separation of electric and magnetic contributions two different independent methods are applied: a multipole decomposition of the angular distributions and the analysis of the polarization transfer. In the energy region between 5.5 and 6.5 MeV the extracted E1 strength is comparable to results of the (γ,γ’) reaction [2]. Between 7 MeV and 9 MeV significant previously unknown E1 strength is found. The low energy E1 strength distribution shows a resonance-like structure peaking at 8.2 MeV. A comparison with B(E1) strength distributions from various microscopic models is shown. The electric dipole polarizability was determined from the data: It represents an important test of the poorly contrained isovector strength of modern mean field models.
A. Tamii et al., Phys. Rev. Lett. 107, 062502 (2011).
B. Özel-Tashenov et al., Phys. Rev. C 90 024304.
*Supported by DFG under contracts SFB 634 and NE 679/3-1.