The {sup 58,60}Ni(n,xalpha) reactions from threshold to 50 MeV

The {sup 58,60}Ni(n,xalpha) reactions have been studied at the fast neutron spallation source at the Los Alamos Neutron Science Center (LANSCE) for neutron energies from threshold to 50 MeV. Alpha particles were observed at four angles by detectors consisting of low-pressure proportional counters and silicon surface-barrier detectors. Cross sections and emission spectra agree fairly well with data in the literature for experiments where alpha particles are detected. The cross sections for the {sup 58}Ni(n,alpha) reaction are significantly lower than those determined by activation in the region from threshold to 10 MeV. The cross sections for both isotopes are lower than the ENDF/B-VI evaluations from threshold to 12 MeV. The data are interpreted in terms of the Hauser-Feshbach reaction model with precompound emission