Development of neutron supermirrors with large critical angle

Maruyama, Ryuji   ; Yamazaki, Dai  ; Ebisawa, Toru*; Hino, Masahiro*; Soyama, Kazuhiko  

The development of neutron supermirrors is important for neutron scattering experiments since it offers a considerable increase in the available neutron intensity. Up to now, many studies have been carried out to realize high reflectivity and large , where is the ratio of the effective critical angle of the supermirror to that of natural nickel. We have developed neutron supermirrors by employing the ion beam sputtering (IBS) technique because it enables the production of layers with high density and small grain size. Although the IBS technique produces high quality layers, its disadvantage is that the deposition area is relatively small. In order to produce the optical devices using supermirrors, which is planned in the project of a new spallation neutron source (Japan Proton Accelerator Research Complex, J-PARC), a new IBS instrument with a large deposition area whose diameter is 500 mm has been designed and installed at the Japan Atomic Energy Agency. The deposition rate has been confirmed to be almost uniform over the entire deposition area. We have carried out the development of Ni/Ti supermirror with large . In this presentation, the performance of those supermirrors fabricated with the IBS instrument is discussed.