THE NEUTRON MICROGUIDE AS A PROBE FOR MATERIALS ANALYSIS

A system composed of curved totally reflecting nickel mirrors is described for the focusing of neutrons by the superposition of intensities transmitted through many thin-layer films, each of which points individually to the focus. This is achieved by stacking many curved mirrors on top of each other with their ends slightly overlapping, so that the projections of each microguide meet at the focal point. The maximum current density is obtained with a large number of microguide sheets of minimum thickness, a large radius of curvature, and a short focal length, though the thickness of the microguides may be dictated by more practical considerations. The length of the system should be as short as possible (approximately few cm) to reduce both reflection and scattering losses, consistent with the length of direct view. The major loss in transmission is caused by misalignment of the layers which will diffuse the focus from its theoretical maximum.