Study of a neutron radiography system using Cf-252 neutron source

This paper presents a study about moderation and collimation of a neutron r adiography system using Cf-252. A Monte Carlo Code, MCNP4B, has been used t o obtain a maximum and more homogeneous thermal neutron flux in the collima tor outlet next to the image plane. Among the various moderator materials i nvestigated, high density polyethylene proved to be the most efficient, wit h a thermalization factor of 56 cm. Using a collimator design assembly it w as possible to obtain a normalized thermal neutron flux, at the image plane of 6 x 10(-6) n cm(-2) s(-1) at an effective collimator ratio of 7.5, or 3 .2 x 10(-7) n cm(-2) s(-1) at an effective collimator ratio of 50. (C) 2001 Elsevier Science Ltd. All rights reserved.