Mitigation of He permeation in microfabricated vapor cells with alumino-silicate glass and Al2O3 coatings

Abstract

International audienceWe study helium permeation in micro-fabricated Cs vapor cells built with alumino-silicate glass (ASG) or borosilicate (BSG) windows, coated or not with Al2O3 layers. Gas permeation rate is derived from long-term measurements of the pressure-shifted clock hyperfine transition frequency in a coherent population trapping (CPT) clock setup. We find that the use of ASG windows reduces, in comparison with BSG, He permeation by more than two orders of magnitude whereas cells with Al2O3 coated BSG exhibit permeation rates up to 100 times smaller than those measured with bare BSG