Timed source of slow protons.

Alpha particle bombardment of a Si surface-barrier detector in vacuum causes the release of several species of ions from the contaminant layer on the detector surface. The charge- to-mass ratios of the ions, M/Q, are determined by time-of- flight spectroscopy. The principal ions emitted are H(+) with a yield of 4x10(-5) H(+) per alpha particle and an emission energy of less than 70eV. This ion source is expected to be useful for testing slow mu(+) collection optics and possibly for studying the diffusion of H atoms in liquid He.