An evaluation of 235U resonance parameters up to 102eV using the program REFIT

In November 1995 an evaluated resonance parameter set for 235U was produced by Dr Leal et al (as part of the activities of NEANSC/IEC Sub-group 18) and sent to Harwell in order to check the consistency of the evaluation with the observed data in the resolved region. The evaluation was carried out using the Oak Ridge least squares fitting program SAMMY on several sets of transmission, capture and fission data. The comparison was carried out using the latest version of the REFIT computer code which can include simple solid state effects at low neutron energies. The initial comparison indicated that there were some discrepancies between the cross-sections calculated from the evaluation and the measured values. These discrepancies initiated a refitting of the measurements up to a neutron energy of 100 eV using the program REFIT. (author)