Measurements of the Neutron Capture Cross Sections of Gold-197 and Uranium-238 Between 20 and 3500 keV

Absolute measurements of the capture cross section of¹⁹⁷Au were carried out in the 400- to 3500-keV energy range. Ratios of the capture cross sections of ²³⁸U to ¹⁹⁷Au were measured from 20 to 1200 keV. Values for σn,y(²³⁸U) were derived by utilizing evaluated and present data for σ n,γ(¹⁹⁷Au). The time-of-flight technique and a large liquid scintillator were used for the detection of the prompt capture gamma rays, and the Grey Neutron Detector, the Black Neutron Detector, and a ⁶Li-glass detector were used for the measurement and monitoring of the neutron flux. The present results support previous measurements of the ²³⁸U capture cross section and resolve some existing discrepancies. The absolute values for the capture cross section of ¹⁹⁷Au agree well with evaluated data and measurements reported relative to the ²³⁵U fission cross section.