抄録
A relationship between the Doppler and the self-shielding effects has been experimentally studied by measuring the effective average total cross sections of the metal and sintered dioxide of 232Th for 24keV Fe-filtered neutrons. The relationship is a theoretical prediction that the apparent value of the total cross section measured with the neutrons of an adequate energy spread is expressed by a single parameter N/√θ in the high temperature limit, N being the thickness and θ the effective temperature of the samples. The temperature has been varied from room-temperature to 1, 173K and the thickness from about 0.3cm to about 3.8cm. The results of the measurements support the theoretical prediction for both cases of the metal and dioxide samples. The Doppler and the self-shielding effects for the metal and dioxide agree within the experimental errors though some dependence on atomic binding was expected.
