Résumé du preprint DAPNIA-02-342
| DAPNIA-02-342 |
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| Thermal neutron capture branching ratio of $^{209}Bi$ using a gamma-ray technique |
| A.Letourneau, E.Berthoumieux, O.D'{e}ruelle, M.Fadil, G.Fioni, F.Gunsing, F.Marie, L.Perrot, D.Ridikas, H.Boerner, H.Faust, P.Mutti, G.Simpson, P.Schillebeeckx |
A new experimental program concerning the measurement of the neutron capture branching ratio of $^{209}$Bi as a function of neutron energy has been proposed recently. The preliminary results obtained at the high neutron flux reactor of ILL with a thermal neutron flux are presented in this paper.
The neutron capture cross section and the corresponding branching ratio are measured with an on-line gamma-ray spectroscopy method. We find for the capture cross section 35$\\pm$1.75~mb, what is in a good agreement with existing results. For the partial cross sections we get $\\sigma_{210gs}$=17.9$\\pm$2~mb and $\\sigma_{210m}$=17.1$\\pm$2~mb giving a branching ratio of 51\\%$\\pm$5\\%. This value is by 25\\% smaller than values from evaluated libraries.
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