The Diffusion Parameters of Heavy Water

Measurements of the diffusion parameters of heavy water were made using a 1 Mev Van de Graaff accelerator utilizing the Be⁹(d, n) reaction under pulsed operation. The measurements were made at temperatures of 10°, 20°, 31°, 40°, and 50°C for buckling values ranging from 0.063 cm⁻² to 0.100 cm⁻². The decay of the neutron density was measured by a BF₃ counter, located under the moderator container, in conjunction with a 26-channel time analyzer. The meanlife for each buckling was computed using Peierls' method; and values of the diffusion parameters were computed by the method of least squares. The value of the diffusion constant, (2.00 ± 0.04) × 10⁵ cm²/sec at 10°C, agreed within the limits of experimental error with that found by Raievski and Horowitz, who used the modulated source method. The coefficient of the B⁴ term, usually referred to as the diffusion cooling coefficient, was found to be (3.72 ± 0.50) × 10⁵ cm⁴/ sec as compared with (3.5 ± 0.8) × 10⁵ cm⁴/sec as reported by Sjostrand in 1959.