INVESTIGATION OF THE SHAPE OF THE 235U(n,f) CROSS-SECTION WITH VERY COLD NEUTRONS

INVESTIGATION OF THE SHAPE OF THE ²³⁵U(n,f) CROSS-SECTION WITH VERY COLD NEUTRONS

C. Wagemans*, A.J. Deruytter, R. Barthélémy

Commission of the European Communities
Joint Research Centre - Gael-Establishment
Central Bureau for Nuclear Measurements, 2440 Geel, Belgium

W. Mampe, P. Ageron, A. Michaudon

Institut Laue-Langevin, 156X, F-38042 Grenoble, France

At the Very Cold Neutron Source of the Institut Laue-Langevin at Grenoble, the shape of the ²³⁵U(n,f) cross-section has been measured in the meV-neutron energy region. For this purpose, a slow chopper has been installed at the end of the very cold neutron guide. Very thin ²³⁵UF₄ and ⁶LiF samples and PIPS-detectors were used for the detection of the ²³⁵U(n,f) fragments and for the determination of the neutron flux via the ⁶Li(n,α)t reaction. Within the experimental accuracy, the present results do not show a significant deviation of the ²³⁵U(n,f) cross-section from a 1/v-shape.

KEYWORDS: ²³⁵U, fission cross-section shape, neutron energy 6-60 μeV