NEWS November 2009

SwissNeutronics completes "Grand Slam"

The beamline VISION at the Spallation Neutron Source SNS in Oak Ridge, USA utilizes a converging neutron guide to transport neutrons with energies as high as 200 meV from the moderator to the sample. Initially the complete guide should be equipped with supermirror coatings m = 4. However, the VISION team became encouraged by the recent developments at SwissNeutronics in terms of large-m supermirror (e.g. see News September 2008) and decided to upgrade the guide by employing supermirror with m values 4, 5, 6, and even 7 within distinct sections from the moderator to the sample.

SwissNeutronics performed the coatings in the sequence from m = 4 to 7.  For m = 4 and 5 an excellent reflectivity similarly as in previous projects was reproduced. Subsequently, supermirror with m = 6 were coated with a reflectivity of R ≈ 0.62 at the critical edge. This manifests a significant improvement compared to the first m = 6 mirror in the history of SwissNeutronics. Finally we manufactured our first supermirror with m = 7. After several days of sputtering we measured the reflectivity and were more than excited to see that we have obtained a reflectivity of R ≈ 0.51 at the critical edge.

In conclusion, SwissNeutronics is proud to be first to establish a new benchmark in the history of supermirror. Within the campaign for the VISION project, coatings with four different and challenging m values were successfully produced constituting a supermirror “Grand Slam”.