Approaching the pygmy dipole resonance in Sn isotopes with the Oslo method

Abstract

Collective resonance phenomena in atomic nuclei are historically one of the first and most plentiful sources of unique information on the intricate nuclear structure and properties of nuclear matter. One of them, the pygmy dipole resonance, is commonly recognised as a potential key to the description of dense neutron-rich matter, thus bridging the gap between heavy, neutron-rich nuclei and massive astrophysical objects, such as neutron stars. In this regard, systematic experimental studies of the pygmy dipole resonance are highly desired to guide future improvements in the theoretical description of its underlying mechanisms.

This dissertation sheds new light on the evolution of the low-lying electric dipole strength, commonly interpreted as the pygmy dipole resonance, based on a systematic analysis of particle-γ coincidence data from the Oslo Cyclotron Laboratory for eleven Sn isotopes using the Oslo method. Through the investigation of their statistical characteristics, such as nuclear level densities and γ-ray strength functions, the properties of the potential pygmy dipole resonance in Sn nuclei and its impact on the production of heavy elements in the astrophysical intermediate neutron-capture process have been investigated.