Development of low cost method for fabrication of metal neutron guides

Neutron scattering is one of the most useful methods of studying the structure and dynamics of matter. Therefore, a number of new large neutron facilities have recently being constructed, upgraded or planned around the world. Examples include the new, 1.4 billion-dollars Spallation Neutron Source (SNS) at DOEs Oak Ridge National Laboratory and upgrades of ORNLs High- Flux Isotope Reactor and NIST Center for Neutron Research, where a number of new instruments are being constructed. Elsewhere in the world, new neutron research facilities include those in Japan, Australia and Germany, while future European and Chinese sources are at advanced stages of planning. In spite of recent developments of neutron sources, most, if not all, neutron techniques are limited by the flux illuminating the samples. Therefore, much effort is spent on improving neutron instrumentation, striving to preserve neutron source brilliance. One crucial component is neutron transport devices, or guides, which must efficiently deliver neutron beams for tens of meters to samples. Thus, guides are crucial components of neutron instruments. This project aims of producing more cost-effective guides, while improving their performance. In successful, this would be the first US-based company producing neutron guides. An MIT/NASA collaboration has recently demonstrated neutron-focusing mirrors and serves as an inspiration for this project in which we propose to fabricate neutron guides using the same technology. This technology, electroformed nickel replication, was developed at NASA for producing x-ray mirrors for astronomical applications, with substantial participation of Darell Engelhaupt, the PI of this proposal. The promise of the replication technology is that only one mandrel (master) needs to be super-polished for replication of a large number of identical guide segments, without the additional, and costly, polishing of each individual element. The Phase I proposal will demonstrate the capability of Dawn Research, Inc., for the task. The guides will be produced at Dawn Research, Inc., by electroforming guide segments from a precisely finished and polished rectangular cross-section Zerodur (glass ceramic) mandrel provided by collaborators at the Smithsonian Astrophysical Observatory (SAO). The electroformed segments will be made of Ni, an element especially suitable for reflecting neutrons. Collaborators at SAO will also coat the mandrels with a chromium release layer, and test the resulting guides in x-rays, and the group at MIT will develop the specifications for practical neutron guides. The result of future phases will be production of guides for SNS and, possibly, other facilities. By demonstrating commercial production of neutron guides, Dawn Research will introduce a novel technology by a US company, which will help recapture the leading position of American neutron-scattering facilities. These guides will result in better-performing instruments, leading to new insights into materials behavior by a large number of materials scientists using national neutron facilities.