Reflectivity enhancement of large -Qc supermirror by ion polishing

Soyama, Kazuhiko  ; Tsunoda, Haruhiko*; Murakami, Katsuhiko*

An ion polishing technique has been applied to supermirror coating in order to enhance neutron reflectivity. A Ni/Ti supermirror with a critical value of 3Qc and the total number of layers of 407 was coated in combination with ion polishing. The dependencies of Ar ion polishing time, ion acceleration energy and incidence angle on the interface roughness were studied and optimized by using X-ray and neutron reflectometry. The reflectivity of the supermirror was measured at the JRR-3 reflectometer of cold beam line. It has reached 90% at the external critical angle, although the non polished one has the reflectivity of 80%.