NEWS September 2013

Supermirror m = 6 on Super-Polished Aluminum – A Champion Result

SwissNeutronics ran an extensive campaign to refine aluminum substrates for the ILL H5 in-pile guide monolith in July 2013. Raw substrates with dimensions 500 mm × 200 mm × 7.5 mm were super-polished. They were used to extract the required substrates of adequate formats, machined and coated with supermirror m = 3 for the guide assembly. All coated substrates were tested with neutrons showing an excellent reflectivity of R = 88±2%.

A spare part from the production campaign was coated with supermirror m = 6 in order to test ultimately the quality of the super-polished surface. The figure below shows the measured reflectivity profile of the supermirror on aluminum compared to other substrates, which were coated during the same deposition run. The reflectivity on aluminum is R = 66% @ m = 6 and therefore equal to high quality Borofloat glass and silicon wafer.

In conclusion, SwissNeutronics confirmed the possibility to prepare aluminum substrates with outstanding low surface roughness enabling to deposit large-m supermirror with excellent reflectivity. Large-m supermirror on metal substrates offer new possibilities for extracting, transporting and focusing neutrons: Indeed A Champion Result!