Patent ID: 6297501
Filing Date: 2001-10-02
Classification: H01J

Abstract:
An isotopic-ratio multiple-collector mass spectrometer comprising:a) an ionization source for generating from a sample ions having an initial kinetic energy;b) a magnetic sector analyzer that disperses said ions according to their momentum into a plurality of ion beams each of which substantially comprises ions of a different mass-to-charge ratio, and focuses each of said beams to different position in a focal plane, wherein in use said plurality of beams comprises at least a first ion beam and a second ion beam that is more intensive than said first ion beam;c) first ion detection means disposed in said focal plane to receive ions of a first mass-to-charge ratio comprised in said first ion beam;d) second ion detection means disposed in said focal plane to receive ions of a second mass-to-charge ratio comprised in another of said plurality of ion beams, other than said first ion beam; ande) means for determining from signals generated by said first and said second ion detection means the ratio of the number of ions having said first mass-to-charge ratio to the number of ions having said second mass-to-charge ratio;said mass spectrometer characterized in that said first ion detection means comprises an ion-energy filter that allows only ions having substantially said initial kinetic energy to pass to a collection electrode and thereby to generate said signal from said first ion detection means.