We have previously reported measurements of ultra-shallow boron implants in silicon using a magnetic sector Cameca IMS-6f, and excellent depth resolution and dynamic range were obtained for boron implants down to 1 keV using O-2(+) primary beam. The appropriate impact energy of the primary beam and incidence angle could be easily achieved for an analysis by the choice of several combinations of sample and source voltages, based on calculations governing the penetration depth and incidence angle of the primary ion beam. This article outlines additional low energy analysis results for boron and arsenic implants with either oxygen or cesium low energy beams. Methods for low energy beam alignment have been utilized to allow analysis conditions to be reached quickly while maintaining a good beam shape, and calculations that more accurately describe how the angle of incidence varies with the primary, sample, and deflector voltages are described.