Cold neutron effects in graphite diffusion measurements

Abstract

Diffusion-length measurements have been made in AGOT graphite as a function of transverse buckling. For bucklings greater than 3·5 x 10^-3 cm⁻² spectral equilibrium is not attained between a predominantly thermal neutron group and a cold neutron group beyond the Bragg cut-off. The presence of cold neutrons cause a distinct increase in the measured extrapolation length. A treatment is given for the variation of the steady-state diffusion length with buckling for a Maxwellian spectrum whose temperature is modified by leakage.