PhD Thesis Defense: Collective Excitations in Transitional Nuclei Studied by Means of gamma-ray Spectroscopy and Lifetime Measurements
Tuesday 25 August 2015
to 14:00 at
Hongjie Li (KTH, Physics Department)
Despite that it is more than 100 years since the atomic nucleus was first dis- covered by Ernest Rutherford and coworkers, many of its features still elude our understanding. The fact that the fundamental interactions between the nuclear constituents; nucleons, and ultimately quarks, are not yet known in detail, and the complexity of the nuclear many-body system compound the great challenges facing theoretical interpretations of experimental data. It is therefore important to focus on distinct phenomena where experimental mea- surements can be compared with theoretical predictions, providing stringent tests of theory. One such area is the nuclear phenomenology of collective excitations related to rotations and vibrations of the nucleus as a whole, and how such modes of excitation may develop from the interactions between a few nucleons occupying single-particle orbits outside closed shells.
This thesis is devoted to experimental studies of excited states in the 99Tc, 162W, and 166Re nuclei. These nuclei lie in “transitional” regions of the Segrè chart, where collective excitation mechanisms start becoming important when adding valence nucleons outside closed neutron and proton shells. Such nuclei are important for testing state-of-the-art theoretical models.