EFFECT OF CRYSTALLITES ON SURFACE-POTENTIAL VARIATIONS OF AU AND GRAPHITE

Surfaces made of the nonreactive materials Au and graphite exhibit low surface potential variations after a low-temperature ultrahigh vacuum bake. The variations (due to the finite size crystallites of these materials) may be reduced to a minimum by using Au surfaces of grain size less than 10 nm and graphite surfaces with highly aligned c-axis orientation. Procedures where this may be accomplished are described. Application to the Los Alamos antiproton gravity experiment is presented.