1.
Rev Sci Instrum
; 82(3): 033106, 2011 Mar.
Article
in English
| MEDLINE
| ID: mdl-21456717
ABSTRACT
We briefly report on the performance and stability of periodic multilayer mirrors containing Y(2)O(3) and Al layers designed for normal incidence reflection at the He-II emission line (30.4 nm). We found that Y(2)O(3)∕Al multilayer coatings had higher reflectivity (24.9%) at 30.4 nm and significantly lower reflectivity (1.3%) at 58.4 nm than the conventional coatings such as Mo∕Si. Furthermore, we investigated the temporal stability of the Y(2)O(3)∕Al multilayer coatings. Our sample was kept under vacuum, dry N(2) purge, and normal atmosphere for over three months, and there were no measurable changes in the reflectivity. These results suggest that we can use Y(2)O(3)∕Al multilayer coatings as standard mirrors for the He-II radiation.