This ensures that rays are recorded in their proper place on the plate, producing a clear image. Only rays that are travelling nearly parallel to the holes will pass through them-any others will be absorbed by hitting the plate surface or the side of a hole. This allows energy selection in addition to collimation - the curvature of the collimator and its rotation will present a straight path only to one energy of neutrons. The collimator comprises a first multi-leaf collimator set, a second multi-leaf collimator set at an acute angle to the first, and a third multi-leaf collimator set at an acute angle to the second. If this forms part of a rotating assembly, the sandwich may be curved. A multi-leaf collimator is disclosed which alleviates the problems of inter-leaf leakage and pixellation. or if mechanical strength is needed then aluminium may be used. Gadolinium) with neutron transmitting material. ![]() This may be a sheet of lead or other material opaque to the incoming radiation with many tiny holes bored through it or in the case of neutrons it can be a sandwich arrangement (which can be up to several feet long - see ENGIN-X) with many layers alternating between neutron absorbing material (e.g. ![]() In the lower panel of the figure, a collimator has been added (blue bars).
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