magnetic analyzer

A magnetic analyzer creates a magnetic field  perpendicular to the ion path and, in conjunction  with entrance and exit slits along the flight path, selects and  focuses ions of a selected momentum (and, nominally, then,  with the same mass-to-charge ratio) through to the detector.  A magnetic analyzer is also called a magnetic sector. An  instrument that includes magnetic or electric analyzers is  called a sector mass spectrometer.