A Monte Carlo calculation of neutron reflection from various curved surfaces

Plane parallel neutron beams normally incident upon the curved surface of a solid reflector are studied with the Monte Carlo method. The geometries studied are cylindrical, parabolic, and hemispherical. It is shown that when the curved surface is cylindrical, a small focusing effect occurs in the reflected neutron beam. Parabolic and hemispherical surfaces do not show focusing . A study of the factors which determine the spatial dependence of the reflected flux shows that the probability of emergence of a neutron, traveling a fixed distance from a point inside the reflector, depends upon the curvature of the surface. It is only for cylindrical geometry that this probability as a function of distance shows a peak which results in focusing --Abstract, page ii