Nathan Cooper

Photon strength of nuclei has been a topic of recent intrigue due to postulated exotic modes of excitation, such as a neutron skin resonance, as well as the difficulty of its measurement near the neutron separation energy. The large number of levels up to the neutron separation energy, a region of particular interest in the calculation of nuclear reaction probabilities, causes detailed and accurate measurements to be close to the threshold of current experimental limits. This talk will begin with the history of photon strength measurement and theory. The results of six nuclear resonance fluorescence experiments on stable A = 76 nuclei will presented along with a comparison between the results of these experiments and many others with the combined theories of Bethe, Brink, and Dyson. The significance of the analysis in relation to the measurements of photon strength below the neutron separation energy will be discussed in light of the current efforts to improve the amount of information extracted from experiment. The predictions of observables such as total gamma-ray spectra from hot nuclei will also be discussed. The second part of the talk will consist of results from a gamma-gamma angular correlations experiment performed on 76As at WNSL, and how the results of this experiment may influence nuclear structure calculations of the matrix element of the 76Ge neutrinoless double-beta decay mode. Finally, the results from fast-timing experiments on rare-earth nuclei will be presented.