Speaker
Description
Experiments were performed at the Berkeley Lab Laser Accelerator (BELLA) facility, where $^{81}$Br targets were irradiated using 15 MeV electron beams. The associated bremsstrahlung radiation served as a control for the measurements. The experiments were conducted under a range of spatially and temporally focused and defocused beam conditions, enabling a systematic investigation of their impact on nuclear excitation pathways.
The resulting photonuclear reactions populated both the isomeric and ground states of
$^{80}$Br via feeding from the quasi-continuum. Using the activation technique, combined with high-resolution γ-ray spectroscopy, isomer-to-ground-state population ratios were measured under the different irradiation conditions. The results demonstrate clear dependencies of the isomeric yield ratios on the temporal and spatial characteristics of the electron beam. These measurements provide new insights into the role of the quasi-continuum in isomer population mechanisms and offer important benchmarks for reaction modeling.
The work that will be presented establishes a framework for controlled studies of isomer production using laser-accelerated electron beams and contributes to broader efforts to quantify nuclear excitation and decay pathways.
This material is based upon work supported by the Defense Advanced Research Projects Agency (DARPA), the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-05CH11231 and by the US Nuclear Data Program.