Bochum 2009 – wissenschaftliches Programm
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HK: Fachverband Hadronen und Kerne
HK 71: Nuclear Structure and Dynamics I
HK 71.3: Gruppenbericht
Donnerstag, 19. März 2009, 17:30–18:00, H-ZO 40
Complete dipole response in 208Pb from high-resolution polarized proton scattering at 0∘⋆ — •Iryna Poltoratska — Institut für Kernphysik, Technische Universität Darmstadt, Germany
In proton scattering at angles close to 0∘ one can selectively study dipole modes
which, apart from the isovector giant dipole resonance, are poorly
understood. Recent experimental progress at RCNP Osaka, Japan [1],
allows measurements with intermediate-energy polarized beams at very forward angles including 0∘
combined with high energy resolution of the order ΔE/E
≈8·10−5. This new experimental opportunity was
applied to study soft electric dipole modes such as Pygmy Dipole
Resonance (PDR) and the so-called toroidal mode. The preliminary
data analysis indicates that at very forward angles 1− states
are strongly excited via Coulomb interaction. The extracted
B(E1) transition strengths are in a good agreement with data
obtained from a nuclear resonance fluorescence experiment [2]. E1/M1 contributions are separated based on multipole decomposition of a cross section angular distributions and
utilizing spin-transfer observables.
[1] A. Tamii et al.,Nucl. Phys. A 788 (2007) 53c.
[2] N. Ryezayeva et al., Phys. Rev. Lett. 89, 272502 (2002).
⋆ Supported by DFG contracts SFB 634 and 446 JAP 113/26710-2.