Small-Angle Scattering Observed in the Formation of Neutral Atoms from 10- to 55-keV Positive Ion Beams

Abstract

Beams of ${\mathrm{H}}^{+}$, ${\mathrm{D}}^{+}$, ${\mathrm{He}}^{+}$, and ${\mathrm{N}}^{+}$ from 10-55 keV were passed through a small aperture at the entrance of a charge-changing gas target, where neutral atoms were formed by electron attachment. The attachment scattering was measured by scanning the neutral beam beyond the target cell. The increase in beam diameter was measured as a function of the target thickness. It was found that the scattering approximated a normal distribution, and the half-width at half-maximum was used to describe the attachment scattering angle. This angle, which was about one milliradian, was measured as a function of the energy and target thickness for a number of scattering gases.