Hybrid Neutron Supermirrors

The Department of Energy's support for neutron facilities, such as the Spallation Neutron Source (SNS) and the Los Alamos Neutron Science Center (LANSCE), has been instrumental in advancing scientific knowledge and innovation. At the heart of these neutron facilities lies the need to enhance the neutron flux probing the sample, which can be achieved with the application of "Neutron Supermirrors" coatings in the conduits where neutrons are transported. Today, neutron supermirrors are manufactured in Europe using physical vapor deposition (PVD) techniques. However, this approach has challenges, including supply-chain vulnerability posed by a non-US manufacturer and the inability to push for cost-effective supermirrors with m>7 reflectivity. RMD proposes to address these challenges with a novel hybrid manufacturing technique that combines the precision of Atomic Layer Deposition (ALD) and efficiency of PVD. This innovative approach leverages ALD's precision in growing the fine features required for high m-value neutron supermirrors and PVD's capacity for depositing the thick layers at a fast rate for an efficient, cost-effective coating process. RMD's expertise in thin films and ongoing work in conformal neutron supermirrors via ALD further empowers the project. In Phase I, RMD will create a sophisticated numerical simulation code to design supermirrors with an "m" value >7, intricately blending ALD metal nitrides, and PVD metals. Additionally, RMD will demonstrate in- house the technical feasibility of growing PVD supermirrors, by growing a simple, aperiodic structure with up to 10 bilayers using a two-target confocal RF sputtering system. As a three target system is required to grow PVD supermirrors without breaking vacuum, RMD will develop a conceptual design for an advanced confocal Ion Beam Sputtering (IBS) deposition system. Thus, at the end of Phase I, RMD will be primed to demonstrate a prototype hybrid mirror using a combination of ALD and IBS and fabricate supermirrors with an "m" value surpassing 7. There are five neutron facilities in the U.S., Oak Ridge National Laboratory (ORNL) in particular plans to replace all of their neutron guides at the High Flux Isotope Reactor (HFIR) and build additional instruments at the SNS. There is no present US producer of supermirrors; the current suppliers for ORNL are European small businesses. Development of a domestic supplier would be useful to ORNL for both competition and capacity reasons. Additionally, aperiodic multilayer interference coatings are of particular interest for a variety of hard x-ray applications, including target diagnostics, astrophysics, high energy physics and free- electron lasers.