A Cascade Mass Spectrometer

Abstract

A cascade spectrometer has been designed and constructed in which the ion beam traverses two successive 180° trajectories. This instrument differs from previous two-stage mass spectrometers in that a large single magnet (rather than tandem magnets) is utilized. Designed as a research rather than an analytical instrument, it provides for not only the analysis of ions from a primary source but also the identification of primary, secondary, or dissociated ions after the primary ion beam has interacted with a suitable target at the focal point of the first 180° 12-in. radius trajectory. Reflected and/or sputtered ions from the target traverse a second 180° trajectory and are detected by a semiconductor magnetic multiplier, which scans the entire focal plane. Isotopically resolved mass spectra of ions sputtered from pure metals and alloys have been obtained.