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Seminar | Physics Division

The Pygmy Dipole Resonance: Its Structure and Significance for Nuclear Astrophysics

PHY Seminar

Abstract: In atomic nuclei, the term pygmy dipole resonance” (PDR) has been commonly used for the electric dipole (E1) strength around and below the neutron-separation energy. It has been shown that the PDR strength strongly impacts neutron-cap­ture rates in the s- and r-process, which synthesize the majority of heavy elements in our universe. A precise understanding of the PDR’s microscopic structure is essential to pin down how it con­tributes to the gamma-ray strength function (γSF) often used to calculate the neutron-cap­ture rates. In fact, the different responses to isovector and isoscalar probes proved the complex” structure of the PDR and emphasized that different underlying structures would indeed need to be disentangled experimentally if stringent comparisons to microscopic mod­els wanted to be made.

In this seminar talk, I will present an overview on current experimental work and results on the PDR, which will also feature our recent study of the PDR in 208Pb via one-neutron transfer and inelastic proton scattering via isobaric analog resonances. I will close with an outlook including an experi­mental program starting at Florida State University, and possible ways forward for experiments at the Facility for Rare-Isotope Beams and other facilities.