SILICON-CARBIDE - A NEW POSITRON MODERATOR

Observation of copious positron re-emission from crystalline 6H-SiC, w ith no pretreatment and without the need for ultra-high-vacuum conditi ons, suggests that this material may form the basis of an important ne w moderator for the production of monoenergetic positrons. Its positro n work function is measured to be -3.0 +/- 0.2 eV. Its electrical char acteristics point to SiC as a prime candidate for development as a fie ld-assisted positron moderator, producing moderately intense slow-posi tron beams in laboratory-based systems and enabling a new generation o f positron experimentation.