München 2006 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 29: Kernphysik/Spektroskopie
HK 29.5: Vortrag
Mittwoch, 22. März 2006, 15:15–15:30, C
High-Resolution γ spectroscopy of the Odd-N Fission Isomer 237fPu* — •T. Morgan1, B. Bruyneel2, D. Habs1, L. Csige1, R. Hertenberger1, H. Hübel3, R. Lutter1, H.-J. Maier1, P. Reiter2, C. Schürmann1, W. Schwerdtfeger1, T. Striepling2, P.G. Thirolf1, and N. Warr2 — 1LMU München — 2Universität zu Köln — 3Universität Bonn
While so far spectroscopic studies of fission isomers concentrated on even-even nuclei, high-resolution γ spectroscopy of odd-N fission isomers will 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, width ca. 4 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 be 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, consisting of 24 sixfold segmented Ge detectors. 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 is required. A very compact 4π parallel plate detector array (diameter ca. 15 cm) consisting of 8 trapezoidal detector modules was used for the fission fragment detection, allowing for a discrimination between the dominant prompt fission products and the rare isomeric fission events. First results of the analysis will be presented. *Supported by DFG under contract no. HA1101/12-1