Development of Metal Substrates for Neutron-focusing Supermirrors

Abstract

In this study, we established a low-cost, high-precision process for fabricating all-metal substrates for supermirrors for neutron focusing. The key material for this substrate is amorphous plating, which can be polished to achieve the sub-nm surface roughness required to fabricate multilayer supermirrors, and is phosphorus-rich electroless Ni-P plating. This fabrication process was established through multiple prototypes of focusing mirrors for the SOFIA neutron reflectometer at J-PARC MLF BL16. This paper describes the technical difficulties overcome in this development.