The thermal neutron diffusion cooling coefficient in polyethylene

The diffusion cooling coefficient C for thermal neutrons in polyethylene at 20 degrees C has been determined theoretically. Granada's Synthetic Model of the scattering law has been applied to describe the interaction of neutr ons with polyethylene. Two approximations of the neutron energy distributio n in finite homogeneous systems have been used. The result of the calculati on using a rough approximation is C-B = 2160 cm(4) s(-1). According to a mo re advanced formalism which follows Nelkin's analysis of the neutron pulse decay in a finite medium, applying the diffusion theory with transport corr ection, the value obtained is C = 2916 cm(4) s(-1). (C) 1999 Elsevier Scien ce Ltd. AII rights reserved.