Thermal neutron capture cross-section measurements of 243Am and 242Pu using the new mini-INCA - and -spectroscopy station

In the framework of the Mini-INCA project, dedicated to the study of Minor Actinide transmutation process in high neutron fluxes, an α - and γ -spectroscopy station has been developed and installed at the High Flux Reactor of the Laue-Langevin Institut. This set-up allows short irradiations as well as long irradiations in a high quasi-thermal neutron flux and post-irradiation spectroscopy analysis. It is well suited to measure precisely, in reference to 59Co cross-section, neutron capture cross-sections, for all the actinides, in the thermal energy region. The first measurements using this set-up were done on 243Am and 242Pu isotopes. Cross-section values, at E n = 0.025 eV , were found to be ( 81.8 ± 3.6 ) b for 243Am and ( 22.5 ± 1.1 ) b for 242Pu. These values differ from evaluated data libraries by a factor of 9% and 17%, respectively, but are compatible with the most recent measurements, validating by the way the experimental apparatus.