Measurement and Resonance Analysis of the ²³²Th Total Neutron Cross Section

Using the Oak Ridge Electron Linear Accelerator pulsed neutron source and a 1-mm-thick lithium glass detector, neutron transmission spectra through ²³²Th have been measured at 22- and 40-m flight paths. At 22 m, transmission spectra through samples of five thicknesses were measured from 7 meV to 15 eV. At 40 m, spectra through samples of eight thicknesses were measured from 15 eV to 4 keV. The resulting total cross section from 0.1 to 20.0 eV is smaller than that given by the ENDF/B-V evaluation. Least-squares shape analysis of the transmissions up to 2.0 keV gives larger neutron widths above 0.5 keV than those previously reported. An average radiation width of 25.2 meV is obtained for 19 low-energy s-wave resonances.