Neutron Resonance in Samarium

The total neutron cross section of Sm152 has been measured in the energy range from 6.84 to 9.18 ev with the BNL crystal spectrometer using the Be (1231) crystal planes as a monochromator. The resonance at 8.036 ev was fitted to a Breit-Wigner single-level formula by the method of shape analysis. Since the target nucleus is even-even, I = 0, and hence the statistical weight factor g = 1. Consequently all Breit-Wigner parameters can be determined from the total cross section measurements alone. The resonance parameters obtained from the analysis are: E0 = 8.036 ± 0.010 ev, σ0 = 210,000 ± 2000 barns, Γ = 0.201 ± 0.008 ev, Γγ = 0.071 ± 0.010 ev, and Γn = 0.130 ± 0.005 ev.