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HK: Fachverband Hadronen und Kerne
HK 67: Poster Session
HK 67.51: Poster
Donnerstag, 19. März 2009, 14:00–16:00, Audi-Max
Experimental Setup for Conversion Electron Spectroscopy of Shape Isomers in 239Pu† — •P.G. Thirolf1, D. Habs1, C. Lang1, T. Morgan1, W.C. Parker2, and W. Schwerdtfeger1 — 1LMU München, Garching, Germany — 2Univ. of Arizona, Tuscon, USA
Investigating shape isomers in odd-A actinide nuclei probes the nuclear single-particle structure of heavy nuclei at large deformations, thus allowing to refine nuclear models. Besides γ-spectroscopic studies, conversion electron spectroscopy is an indispensable tool to complement the experimental spectroscopic information. Fission isomers in 239Pu were populated via the 238U(α, 3n) reaction (Eα= 33 MeV) at the Garching Tandem accelerator. A recoil shadow technique was used to selectively detect only fission fragments from shape isomeric decays at backward angles. For the detection of conversion electrons three Mini-Orange spectrometers (i.e. magnetic transport and filter systems with a toroidal magnetic field from permanent magnet wedges in conjuction with lN2-cooled Si(Li) detectors) were used at forward angles. Due to the long lifetime of 8 µs of the fission isomer in 239Pu an annular catcher foil was placed behind the target to stop the recoiling isomers prior to their isomeric fission decay. In order to optimize the solid angle coverage for delayed fission fragment detection, a large array of silicon solar cells (15 modules, each 4x2 cm2) was used at backward angles. Delayed fission fragments were detected in coincidence with electrons detected in the Si(Li) detectors of the Mini-Orange spectrometers.
†Supported by the DFG Cluster of Excellence UNIVERSE and by DAAD via the RISE program.