Development of low cost method for fabrication of metal neutron guides

National neutron scattering facilities serve a large and diverse community of users in science and engineering. We propose to improve the performance of one of the most basic and critical components of these facilities, neutron guides, by utilizing a novel fabrication method. The guides are neutron-transport optical devices, which are made of hundreds of meters of state-of-the-art mirrors. Currently, each section of guide sides is polished to fractions of a nanometer (called superpolishing). Due the effort required for superpolishing, guides cost contributes a significant portion of instrument construction and operation budget. In addition, glass substrates of commonly used guides are susceptible to radiation damage if placed near (~5 m) the neutron source. We recognized an opportunity to fabricate metal neutron guides at a lower cost and much more stable against radiation damage. Our fabrication technology involves replication of multiple nickel sides from one superpolished mandrel by electroplating. Our electroforming technology produces tens of Ni replica mirrors, preserving the surface quality of the mandrel. Thus, we can produce sides for a long guide for the cost of one or two existing guide sides. Our production method can accommodate all the parameters, which are required of modern guides, in terms of the surface quality, complex geometrical shapes, and multilayer coatings (produced by sputtering, the same method as existing guides). In addition, the electroform replication could be used to supply other neutron optical components, such as focusing and bending mirrors. During the Phase I we fabricated a small prototype section of Ni guide to show the feasibility of our method. During the Phase II, we will fabricate a guide section of the size required by neutron facilities, fabricate multilayer coating, and test with neutron beam. Our new approach to fabrication will immensely benefit neutron-scattering facilities by supplying affordable guides of very high quality.