Glancing angle scattering and neutralization of a positron beam at metal surfaces

Abstract

We have formed an energetic (10--100 eV) beam of positronium (Ps) by scattering a well-collimated, small-diameter beam of 30--400 eV positrons off surfaces of Al(110) and clean and oxygen-coated Cu(100) at glancing angles of 6\ifmmode^\circ\else\textdegree\fi{}--42\ifmmode^\circ\else\textdegree\fi{} with respect to the surface. We determined the angular distribution (FWHM \ensuremath{\approxeq}20\ifmmode^\circ\else\textdegree\fi{}) of the Ps beam and measured the relative Ps formation efficiency (3%--5%) as a function of incident positron beam energy and angle. Future uses of the Ps beam in atomic and surface physics will be discussed.