Dipole Response of Medium-Mass Nuclei

• Applicant: Professor Dr. Andreas Zilges
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 460150577

The electromagnetic interaction between photons in the MeV energy range and atomic nuclei is governed by the nuclear dipole response. It has been shown that a precise knowledge of the dipole response is important to understand the nucleosynthesis in the universe, is connected to the symmetry parameter in the equation of state of nuclear matter, and shows a correlation with the neutron skin of nuclei. Because of the increasing asymmetry between neutrons and protons, further enhancement of electric dipole strength at low energies is expected in exotic, neutron-rich nuclei. In spite of the enormous general progress in models for nuclear structure, a robust prediction of the properties of dipole strength is still a challenge.The goal of the project is to measure various observables of the dipole response in medium-mass nuclei at the Z=20 and Z=28 shell closures with complementary experimental probes. Such nuclei are an ideal testing ground because the level density up to the particle threshold is low enough for a detailed analysis due to the closed proton shell and the rather low mass number. On the other hand, theoretical calculations in those nuclei are very well developed and it will be important to see, how reliable they can predict properties of the excitations. For this purpose, we plan a combination of experiments using photon, proton, and alpha beams at different national and international experimental facilities and to compare the results with state-of-the-art theoretical calculations. These measurements will fill the gaps in the knowledge, providing additional points in the mid-mass systematics, and will give a very much needed feedback to theoreticians.

• DFG Programme: Research Grants