High-precision thermal neutron diffusion parameters for Plexiglass

The thermal neutron diffusion parameters for Plexiglass have been determined with high accuracy. The classic pulsed neutron experiment based on the concept of variable geometric buckling has been performed (the buckling B² being from 0.036 to 1.234 cm^-2). Details on the treatment of data are given. The following values of the parameters have been obtained at the temperature of 20 degrees C: v Sigma _a=(4120+or-30) s^-1, D₀=(37312+or-100) cm² s^-1, C=(6192+or-457) cm⁴ s^-1, F=(1203+or-400) cm⁶ s^-1. They are compared with the values reported by other authors. The influence of experimental conditions on the final results as well as some theoretical problems concerning diffusion cooling are discussed.