In time resolved measurements of neutron emission, the most common practice is to use a plastic scintillator coupled to a fast photomultiplier. There are different ways of coupling the light emitted by the scintillator to the photomultiplier (PM), according to the size and the shape of the scintillator. Some of the more usual coupling geometries are light pipes, Plexiglas cones with silvered walls or mirror ‘‘huts’’ facing the PM window.