Benchmarking of evaluated nuclear data for bismuth by spherical shell transmission experiments with central T(d,n) and Cf-252 neutron sources

The results of neutron transmission experiments on a spherical bismuth shell of 9.0 cm wall thickness with T(d,n) and Cf-252 point neutron sources at its center are reported. The neutron leakage spectra were measured by the time-of-flight method from 14 MeV down to 100 keV. Descriptions of the experimental arrangement, time-of-flight spectrometer, measurements and data reduction procedures are given. The measured data are compared with results of three-dimensional Monte-Carlo calculations with the MCNP code, using the ENDF/B-VI, EFF-2.4 and JENDL-FF nuclear data libraries. For all three libraries, the calculated neutron leakage deviates significantly from the measured one in case of the T(d,n) source, whereas for the Cf-252 source good agreement is found.