RELATIVE PROBABILITIES OF WORK-FUNCTION AND EPITHERMAL POSITRON REEMISSION FROM SILVER

Experimentally determined values for the relative probabilities for wo rk-function and epithermal positron re-emission from silver are report ed as a function of incident positron energy E. The method involves th e comparison of absolute slow-positron yields from a polycrystalline A g sample with a very small negative work function with the epithermal yields from an Ag(100) sample having a small positive work function. T he results show that the epithermal fraction increases steeply from al most zero as E decreases below 2 keV, tending to almost 100% as E appr oaches 0.