Development of a radiation resistant neutron carbon mirror

When considering effective induction of ultra cold neutron, because of its much large beam scattering angle, it is necessary to insert top of the neutron conduit at just proximity of cold neutron source, and it is required to actually use a neutron mirror capable of resisting severe radiation environment for realizing this. Here was produced a carbon mirror with very high smoothness of about 10 nm in PV and about 1 nm in rms of surface roughness, to test its neutron reflectivity. The mirror has 130 neV in total reflection critical potential in response to 1.5 g/cm3 in density, and about 1 in reflectivity against neutron with less energy. The mirror is improved in its general performance on smoothness, flatness, radiation resistant strength, easy handling, and large area, in comparison with conventional replica mirror and so forth. It is future expected to be a mirror usable under higher radiation when planning to realize ultra cold neutron conduit. (G.K.)