Berlin 2005 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 32: Kernphysik/Spektroskopie

HK 32.4: Talk

Tuesday, March 8, 2005, 17:45–18:00, TU MA005

Binary fission-fragment yields from the reaction 251Cf(nth, f) — •S. Oberstedt¹, E. Birgersson^1,2, A. Oberstedt², F.-J Hambsch¹, D. Rochman³, and I. Tsekhanovitsch⁴ — ¹EC-JRC Institute for Reference Materials and Measurements, B-2440 Geel — ²Dept. of Natural Sciences, Örebro University, SE-70182 Örebro — ³Los Alamos National Laboratory, Los Alamos, New Mexico 87545 — ⁴Institut Laue-Langevin, F-38042 Grenoble Cedex

The interpretation of fission-fragment properties in terms of so-called fission modes has been successfully applied to describe mass yield and total kinetic energy distributions as a function of incident neutron energy. There, the asymmetric standard I (S1) and standard II (S2) modes as well as the symmetric superlong (SL) mode have been used. In the case of spontaneous fission of 252Cf the number of traditional fission modes is not sufficient to properly describe the experimental fission-fragment distributions. Additional theoretically obtained fission modes have to be included into the analysis to improve the description of the data. In order to achieve experimental confirmation of the number of fission modes, neutron-induced fission of 252Cf*, using 251Cf as target material, has been investigated at thermal excitation, using the recoil mass-separator LOHENGRIN of the ILL, Grenoble. Light post-neutron fission-fragment kinetic energy distributions were measured for A = 80 to 124 for the first time ever, and relative emission yields together with mean kinetic energies as a function of A have been determined. Data analysis and final experimental results will be presented.