International Conference on Nuclear Data for Science and Technology 2007
DOI: 10.1051/ndata:07113

Measurement of the ²³⁶U(n,f) cross section as a function of the neutron energy

C. Wagemans¹, L. De Smet¹, S. Vermote¹, J. Heyse^{2, 3}, O. Serot⁴ and J. Van Gils<sup>2

1</sup>  Dept. of Subatomic and Radiation Physics, University of Gent, 9000 Gent, Belgium
²  EC-JRC-Institute for Reference Materials and Measurements, 2440 Geel, Belgium
³  SCK°CEN, 2400 Mol, Belgium
⁴  CEA Cadarache, DEN/DER/SPRC/LEPh, 13108 Saint-Paul-lez-Durance, France

cyrillus.wagemans@ugent.be

Published online: 21 May 2008

Abstract
The ²³⁶U(n,f) cross section has been measured in the neutron energy region from 0.5 eV to 25 keV at the GELINA neutron facility of the IRMM in Geel, Belgium. A highly enriched ²³⁶U sample was mounted back-to-back with a ¹⁰B sample in the centre of a Frisch-gridded ionisation chamber; a control measurement was performed with a ²³⁵U sample in the same configuration. Besides a dominant resonance at 5.45 eV, for which a resonance analysis was performed, the next resonance (cluster) only occurs at about 1.3 keV. It is demonstrated that the fission resonance integral and the thermal fission cross section adopted in all commonly used evaluated data libraries are too large by two orders of magnitude.

© CEA 2008