CALCULATION OF FAST AND THERMAL GROUP CONSTANTS WITH APPLICATIONS TO DIPHENYL

摘要

Fast and thermal diffusion lengths and diffusion coefficients are computed for C12H10 (diphenyl). Comparison is made with measurements at 185°F, performed at Atomics International, of the thermal diffusion length and of the neutron age to indium resonance. Good agreement between calculation and experiment is obtained for the thermal diffusion length. However, the present status of age calculations for diphenyl is comparable to that for water where the Selengut-Goertzel approach yields better agreement with experiment than the rigorous P1 approach.nSeries expansions for extending thermal averages of the diphenyl diffusion length to the case of diphenyl mixtures are presented. (The thermal averages for diphenyl are performed by using a Wigner-Wilkins spectrum). A semi-empirical approach, based on the method of Deutsch, is used to obtain the age for diphenyl mixtures. This procedure is° normalized to the experimental age in diphenyl'. Finally, various methods of calculating fast diffusion coefficients are compared.