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HK: Fachverband Physik der Hadronen und Kerne
HK 14: Structure and Dynamics of Nuclei III
HK 14.1: Talk
Tuesday, March 12, 2024, 15:45–16:00, HBR 14: HS 1
Isoscalar Properties of the Pygmy Dipole Resonance in 120Sn — •Michael Weinert, Florian Kluwig, Markus Müllenmeister, Miriam Müscher, and Andreas Zilges — University of Cologne, Institute for Nuclear Physics
A concentration of electric dipole strength below the neutron separation threshold is known to be common in medium to heavy mass nuclei. The established picture of a neutron-skin oscillation being the single cause for this strength was questioned about 15 years ago, when comparing the excitation in bremsstrahlung experiments to results from a hadronic probe, i.e., (α,α′γ) [1]. The evolution of the so-called isospin splitting previously found in 124Sn was recently investigated via a 120Sn(α,α′γ) experiment at Eα= 130 MeV. The experiment was performed at the CAGRA+GR setup at RCNP, Osaka, and is sensitive to both isoscalar properties and the surface character of excitations in the Pygmy Dipole Resonance (PDR) region. This contribution presents the analyzed data set as well as recent theoretical efforts from two state-of-the-art EDF+QPM and RQTBA models coupled to reaction theory. Since the PDR in 120Sn is also known to have significant single-particle character [2], the new theoretical results allow to study the connection between microscopic nuclear structure effects and the macroscopic surface mode probed in the (α,α′γ) experiment. Supported by the DFG (ZI 510/10-1).
[1] J. Endres et al., Phys. Rev. C 80, 034302 (2009)
[2] M. Weinert et al., Phys. Rev. Lett. 127, 242501 (2021)
Keywords: Pygmy Dipole Resonance; Isoscalar E1 Strength; 120Sn(a,a'g)