Research Article
Status of the GRANIT Facility
Figure 16
Schematics and pictures of the optical elements. The extraction mirror and the scatterer have the same sizes ( mm3) and each consists of 3 pieces of mm3 glued together. The mean roughness of the extraction mirror (floor) is very low (0.5 nm) to allow for specular bouncing, whereas the mean roughness of the scatterer (ceiling) is intentionally high (5.6 μm) to allow UCNs with too high vertical velocity to be diffused back. The transport mirror ( mm3) has a surface mean roughness of 0.5 nm and a planarity of 80 nm. The absorber mirror is mm3.