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HK: Fachverband Physik der Hadronen und Kerne
HK 52: Kernphysik / Spektroskopie
HK 52.3: Talk
Thursday, March 15, 2007, 17:30–17:45, B
High-Resolution γ spectroscopy of the Odd-N Fission Isomer 237fPu* — •T. Morgan1, A. Blazhev2, B. Bruyneel2, L. Csige1, D. Habs1, T. Kotthaus2, H.J. Maier1, P. Reiter2, C. Schürmann1, W. Schwerdtfeger1, P.G. Thirolf1, N. Warr2, K. Wimmer1, and MINIBALL Collaboration1,2 — 1LMU und Maier-Leibnitz Laboratorium München — 2IKP Universität zu Köln
While so far spectroscopic studies of fission isomers concentrated on even-even nuclei, high-resolution γ spectroscopy of odd-N fission isomers may allow to identify Nilsson orbitals in heavy actinide nuclei. As the first case ever studied for odd-N nuclei, the fission isomer in 237Pu (t1/2= 110ns/1.1 µs) was investigated using the 235U(α,2n) reaction with a pulsed α beam (Eα=24 MeV, pulse distance 400 ns) from the Cologne Tandem accelerator. A self-supporting thick metallic 235U target (3.7 mg/cm2) was used, where the 237Pu reaction products were stopped and fission products were emitted in opposite directions. The rare γ-rays from the second potential well in delayed coincidence with fission products were measured with the MINIBALL spectrometer. Due to the small population cross section of about 2 µb a large solid angle coverage both for the γ-rays as well as for the fission fragments was required. A very compact 4π parallel plate detector array (diameter ca. 15 cm) was used for the fission fragment detection, allowing for a discrimination between the dominant prompt fission products and the rare isomeric fission events. Results, such as the identification of rotational bands, isomeric lifetimes and angular distributions etc., will be presented. *Supported by DFG under contract no. HA1101/12-1