Sector mass spectrometer

A sector instrument is a general term for a class of mass spectrometer that uses a static electric or magnetic sector or some combination of the two (separately in space) as a mass analyzer. A popular combination of these sectors has been the BEB (magnetic-electric-magnetic). Most modern sector instruments are double-focusing instruments (first developed by A. Dempster, K. Bainbridge and J. Mattauch in 1936) in that they focus the ion beams both in direction and velocity.