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 of $sup 197$Au were carried out in the 400- to 3500-keV energy range. Ratios of the capture cross sections of $sup 238$U to $sup 197$Au were measured from 20 to 1200 keV. Values for $sup 238$U were derived by utilizing evaluated and present data for $sup 197$Au. 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 $sup 6$Li-glass detector were used for the measurement and monitoring of the neutron flux. Results support previous measurements of the $sup 238$U capture cross section and resolve some existing discrepancies. The absolute values for the capture cross section of $sup 197$Au agree well with evaluated data and measurements reported relative to the $sup 235$U fission cross section. (7 figures, 3 tables) (auth)