Efficient emission of positronium negative ions from Cs deposited W(100) surfaces

Abstract

The emission of positronium negative ions from Cs deposited W(100) surfaces has been studied. A dramatic change in the emission efficiency was observed upon coating a W(100) surface with Cs. The conversion efficiency (the fraction of incident slow positrons yielding the ions) of the W(100) target with a 2.2 × 1014 atoms cm-2 Cs coverage, measured over a time interval of 3 × 103 s immediately after deposition, was found to be 1.25%, which is two orders of magnitude higher than that obtained for the clean, uncoated W(100) surface and 45 times greater than the highest efficiency reported thus far. © IOP Publishing Ltd and Deutsche Physikalische Gesellschan.