Delayed neutron yields and time spectra from 1-GeV protons interacting with natFe, natPb and 209Bi targets

This paper presents the experimental results on the DN yields and time spectra from 1-GeV protons interacting with the natPb, 209Bi and natFe targets of variable thicknesses from 5 cm to 55 cm. Both absolute yields and time constants are reported. In parallel, the MCNPX and PHITS codes were used to predict the DN precursors and construct the theoretical DN tables. Different model parameters are examined and show significant dependence on the choice of the infra-nuclear cascade and fission evaporation models used. Finally, the above experiment allowed the determination of the production cross-sections of a number of DN precursors such as 87'Br, 88Br and 17N. These results permit the examination of two different reaction mechanisms, namely fission and fragmentation, implemented in high-energy transport codes. These data and modelling are of great importance for the new generation spallation neutron sources based on liquid metal technologies. (authors)