  We propose to use a 13 KeV antiproton beam passing through a dense cloud of
positronium (Ps) atoms to produce an H+ beam. These ions can be slowed down and
captured by a trap. The process involves two reactions with large cross
sections under the same experimental conditions. These reactions are the
interaction of p with PS to produce H and the e+ capture by H reacting on PS to
produce H+. Once decelerated with an electrostatic field and captured in a trap
the H+ ions could be cooled and the e+ removed with a laser to perform a
measurement of the gravitational acceleration of neutral antimatter in the
gravity field of the Earth.
