Speaker
Description
The 1975 Nobel prize in Physics was awarded to Bohr, Mottelson, and Rainwater for the discovery of the connection between nucleon motion and the emergent collective behavior. They described nuclei geometrically as a shape and the oscillations of the nucleus around that shape. In deformed nuclei, they predicted low-lying quadrupole oscillations of the deformed shape with respect to projections on the symmetry axis as “$\beta$” and “$\gamma$” vibrations.
The “$\gamma$” vibration seems to be well characterized and exhibits a systematic behavior across the region of deformed nuclei with typical B(E2; 2+ γ → 0+ g.s. ) values of a few Weisskopf units (W.u.). The discussion on the “$\beta$” vibration however still continues today some forty years later and remains an open challenge to nuclear structure studies to large part to the lack of experimental data on the identification and characterization of 0$^+$ states. This has been changing recently with the discovery of numerous 0$^+$ states well below the pairing gap in several isotopes of Sm, Gd, Dy, Er and Hf in the rare earth region. We have been measuring lifetimes of low-lying excited states of K$_{\pi}$ = 0$^+$, 2$^+$, 4$^+$ states in this region of deformation and will present our results along with expected levels of collectivity.
This work was supported by the US National Science Foundation under contract number PHYS- 1419765.
