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New results are presented of the intermediate energy neutron- and proton-induced fission cross sections of nuclei in the lead region. These results, together with earlier ones, are used for comparison of the fission probability of nuclei induced by protons and neutrons. Possible physical reasons of observed differences in proton- and neutron-induced fission cross sections are discussed.

A programme to investigate the neutron-proton scattering differential cross section at intermediate energies is active at the The Svedberg Laboratory, Uppsala, Sweden. Up to now, measurements of back angle differential np scattering cross sections have been undertaken at 96 MeV and 162 MeV. These high-precision data are well described by partial-wave analyses of other data sets over a wide angular range, but deviate at the most backward angles. However, they agree well in shape over the full angular range with another recent high-quality measurement from PSI.These results have large consequences for measurements of nuclear data for applications, because back angle np scattering is used as a primary standard. A new setup, SCANDAL (SCAttered Nucleon detection AssembLy), has been developed and installed for measurements aiming at clarifying the situation at back angles, as well as for forward-angle experiments, resulting in a complete angular distribution.

Systematics have been created for neutron spectra from the 7Li(p, n) reaction at 0° in the 50-200 MeV proton energy region. The available experimental data in the continuum part of the spectra show satisfactory overall agreement with a representation based on the phase-space distribution corresponding to the three-body breakup process 7Li(p, n 3He)α, with empirical correction factors, which depend regularly on incident energy. Validation of the systematics included folding of the predicted neutron spectra with standard 238U neutron fission cross section. Modeled in this way distributions of neutron-induced fission events agree reasonably with experimental data.

Activation experiments with quasi mono-energetic neutrons produced by the 7Li(p, n)7Be reaction with proton-energies between 36.4 and 178.8 MeV were performed at UCL and TSL in order to determine cross sections for the production of residual nuclides from 13 target elements. The targets were irradiated in well-characterized neutron fields monitored by various measuring techniques. Residual nuclide abundances were determined by γ-spectrometry. Cross sections were derived from them by an iterative method based on measured and calculated neutron spectra inside the target stacks and starting from “guess” excitation functions calculated by the ALICE-IPPE code. First results for the target element lead are presented.