Speaker
Description
The electromagnetic dipole response of 242Pu was studied for the first time using the nuclear resonance fluorescence (NRF) method, hence with real photons. The experiment was performed at TU Darmstadt, where monoenergetic electrons are provided by the superconducting Darmstadt linear electron accelerator S-DALINAC to produce bremsstrahlung by impinging on a gold radiator target. A sample of PuO2 with a total mass of about 1 g was irradiated by a bremsstrahlung beam, having a continuous energy distribution up to 3.7 MeV. Resonantly scattered photons were detected with two high-purity Germanium detectors at angles of 90◦ and 130◦ relative to the direction of the incident photon beam, which allows us to distinguish between dipole and quadrupole transitions based on their different angular distributions. The highly-enriched 242Pu target was placed in a special con- tainer taking into account the sample’s total radioactivity of about 370 MBq. To identify the NRF signals originating from the target, NRF spectra of an empty target container, γ-ray spectra of the sample’s radioactivity and background measurements were compared. Evidence for decays of photo- excited states of 242Pu was found – making 242Pu the heaviest nuclide for which NRF data is available for the moment. The experiment was the first step towards characterizing dipole excitation modes of transuranium actinides by means of real photons. Details of the experiment, γ-ray spectra and preliminary results will be presented.
We thank the Institute of Resource Ecology of HZDR for providing the 242Pu sample. This work was supported by the State of Hesse within the LOEWE program and by the Deutsche Forschungsge- meinschaft (DFG, German Research Foundation) under project-ID 499256822 – GRK 2891 ”Nuclear Photonics”.
