Development of high-reflectivity neutron supermirrors using an ion beam sputtering technique

Neutron supermirrors have increasingly become important devices for transporting, bending, and focusing neutron beams. To produce these optical devices for the new spallation neutron source (Japan Proton Accelerator Research Complex, J-PARC), an ion beam sputtering (IBS) system with an effective deposition area of 0.2 m2 has been installed at the Japan Atomic Energy Agency. We have succeeded in fabricating high-reflectivity supermirrors by adopting NiC/Ti multilayers instead of conventional Ni/Ti multilayers. The neutron reflectivity of the NiC/Ti supermirrors is 0.88 and 0.82 at critical angles 3 and 4 times larger, respectively, than that of nickel. We have also demonstrated that a NiC/Ti supermirror with a reflectivity of 0.40 at a critical angle 6 times larger than that of nickel can be fabricated.