New scheme for positron accumulation in ultrahigh vacuum

A new positron accumulation scheme compatible with ultrahigh vacuum conditions has been developed, which is realized by preparing a high density electron plasma as high as approximately 10(11) cm(-3) and an ion cloud as energy absorbers. The present accumulation rate normalized by the intensity of 22Na positron source is (3.6+/-0.3)x10(2)e(+)/s/mCi, which is more than one and a half orders of magnitude higher than other ultrahigh vacuum compatible schemes so far reported.