Spallation neutron emission spectra in medium and heavy target nuclei by a proton beam up to 140 MeV energy

In this study, neutron-emission spectra produced by (p,xn) reactions for some spallation neutron target nuclei such as 65Cu, 204,206,207,208Pb, 209Bi, 232Th and 238U have been calculated by a proton beam up to 140 MeV. Multiple pre-equilibrium mean free path constants from internal transition for 204,208Pb (p, xn) neutron emission spectra have been investigated. In the calculations, pre-equilibrium effects were calculated by using new evaluated hybrid model and geometry dependent hybrid model, full exciton model and cascade exciton model. The reaction equilibrium component was calculated by Weisskopf–Ewing model. The obtained results have been discussed and compared with the available experimental data and found agreement with each other.