Speaker
Description
The giant dipole resonance (GDR) is one of the most fundamental nuclear excitations and it dominates the dipole response of all nuclei. Its evolution from a single-humped structure to a double-humped one is considered as one of the prime signatures of nuclear deformation. Yet, its $\gamma$-decay behavior, despite being a key property, is still poorly characterized.
Recently, novel data on the γ-decay of the GDR of the well-deformed nuclide $^{154}$Sm and the spherical $^{140}$Ce were obtained through photonuclear experiments at the HI$\gamma$S facility. Individual regions of the GDR were selectively excited by intense, linearly-polarized and quasi-monochromatic $\gamma$-ray beams provided by HI$\gamma$S. This enabled an excitation-energy resolved determination of the GDR's $\gamma$-decay behavior. For $^{154}$Sm, in particular, the newly obtained data allow for a first experimental test of the commonly accepted K-quantum-number assignments to the double-humped GDR observed in deformed nuclei. First results of the analysis will be presented and discussed with respect to the textbook interpretation of the GDR in deformed nuclei.
This research is supported in part by the State of Hesse through the LOEWE research grant Nuclear Photonics and the cluster project ELEMENTS and by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under grant numbers DE-FG02-97ER41041 and DE-FG02-97ER41033.
