Total Neutron Cross Sections of Lanthanum and Praseodymium in the Energy Range from 20 to 240 keV

not registered; not registered; not registered; Nakagawa, Tsuneo

Total neutron cross sections for La and Pr in the energy range from 20 to 240 keV were measured by using monochromatic neutrons, which were produced by the Li(p,n)Be reaction. Theenergy spreads of incident neu- trons were about 18 keV for La and about 8 keV for Pr. The measured total neutron cross sections, with statistical error of 2 - 5% for La and 2 - 3% for Pr, were compared with other available data. The average total neutron cross-section data for both nuclides were interpreted in terms of a spherical optical-model potential. S-wave strength functions S for La and Pr were deduced from the optical-model parameters obtained by fitting to the average total neutron cross-section data; i.e. S = 0.46 10 for La and S = 1.0 10 for Pr. The result of total neutron cross sections for La in the energy range from 70 to 140 keV with the energy spreads of about 2.8 keV is also presented.