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HK: Fachverband Physik der Hadronen und Kerne
HK 8: Structure and Dynamics of Nuclei II
HK 8.2: Talk
Monday, March 28, 2022, 14:15–14:30, HK-H7
The Systematic Study of Pygmy Dipole States in 40,44,48Ca Induced in the (p,p′γ) Reaction — •Barbara Wasilewska, Anna Bohn, Sarah Prill, Michael Weinert, and Andreas Zilges — University of Cologne, Institute for Nuclear Physics, 50937 Cologne, Germany
The calcium nuclei form a unique isotopic chain. It is the only element with two stable doubly-magic isotopes and the masses spread over a wide range of N/Z ratios.
The second feature is especially interesting for studies of the Pygmy Dipole Resonance (PDR). This additional E1 strength in the region of the neutron separation energy (S n ) has been shown to increase with the N/Z ratio, but its nature is a subject of discussion [1].
The recent progress in nuclear physics theory enabled ab-initio calculations in the medium-mass region [2], making calcium isotopes a perfect probe to examine the states forming the PDR.
In a series of experiments at the Institute for Nuclear Physics, University of Cologne, the isotopes 40 Ca, 44 Ca and 48 Ca were studied in the (p,p′ γ ) reaction at E p = 12, 15 MeV. Employment of the SONIC@HORUS set-up allowed a high-precision measurement of the excitations near S n .
In the talk, the experimental set-up and the analysis process will be briefly described. The obtained relative excitation cross-sections close to S n will be shown and compared with other experiments. The attempt to extract spins of observed states will also be discussed.
Supported by the DFG (ZI 510/10-1).
[1] D. Savran et al., Prog. Part. Nucl. Phys. 70 (2013) 210.
[2] S.G. Pickstone et al., Nucl. Inst. Meth. A875 (2017) 104.