International Intercomparison of Fast Neutron Fluence-Rate Measurements Using Fission Chamber Transfer Instruments

Fluence measurements made with accelerator-based neutron fields in standards laboratories have been compared at neutron energies of 0,144, 0,565, 2,5, 5,0 and 14,8 MeV. The method used was to compare the neutron sensitivities of a pair of fission chambers, one containing 235U and the other containing 238U fissile deposits. The uncertainty contribution from the transfer method is generally smaller than the uncertainty in the fluence determination, and the results of the intercomparison are in satisfactory agreement. The weighted least squares estimates of the measured chamber neutron sensitivities at each energy confirm the ENDF/B-VI evaluations of the fission cross-sections.