Total Neutron Cross Section of Thulium in the Energy Region 0.038 to 1.56 ev

Measurements of the total cross section of thulium as a function of neutron energy have been made with the Materials Testing Reactor crystal spectrometer. Twelve cylindrical pellets which contained a total of 2.414 grams of metallic thulium were used as a sample. The low-energy data can be described by the expression $\sigma \mathrm{}\left(E\right)=6.5\mathrm{}\pm 20.1{E_{\mathrm{ev}}}^{-\frac{1}{2}}$ (barns). The extrapolated value for the total cross section at 0.0253 ev is 134±3 barns.