Activation Measurements of the Doppler Effect in Uranium-238 and Thorium-232 at High Surface-to-Mass Values

The Doppler effect in ²³⁸U and ²³²Th metal has been measured by the activation technique in a 1/E spectrum. The samples consisted of foils (or packets of foils) irradiated under cadmium near the center of the Stanford University Pool Reactor. All the measurements were performed at a heated sample temperature of 500 °K. The values of the surface-to-mass ratio (S/M) of the uranium samples ranged from 1 to 20 cm²/g; two values of S/M in the same range were used for thorium. Experimental values of the Doppler ratio, R, defined as the ratio of heated sample activity to unheated sample activity, are shown to be in good agreement with ratios of resonance integrals calculated by ZUT-TUZ and/or GAROL.