Patent ID: 8692188

Claim:
A mass spectrometer comprising: an ion source operable to provide an ion beam comprising a plurality of ions, each having a mass-to-charge ratio; a mass filter arranged to receive the ion beam from the ion source and configured to eject ion packets in each of which the ions have nominally equal velocities irrespective of their mass-to-charge ratios, wherein the ion packets are ejected along a beam axis; and an ion detector arranged in the beam axis so as to receive the ion packets from the mass filter, wherein the ion detector comprises a lens arrangement operable to deflect ions away from the beam axis by a distance from the beam axis inversely proportional to their mass-to-charge ratios, and further comprises a position-sensitive sensor having a plurality of channels which lie at different distances away from the beam axis, so as to detect the mass-to-charge ratios of the ions according to their distances from the beam axis.