Patent ID: 6864479

Claim:
A mass spectrometer comprising an ion source to produce ions from a substance to be detected and detector means to detect a quantity of ions incident on said detector means wherein the said detector means includes at least two detector elements, each of which elements detect at least a part of said quantity of ions from the ion source, attenuation means and means for generating secondary electrons from said ions, wherein the attenuation means are placed before any of the means for generating secondary electrons and act to attenuate the quantity of ions reaching at least one said detector element relative to another of the at least two detector elements, and wherein at least one of said detector elements is connected to a time-to-digital converter (TDC) to allow counting of detected ions and at least one of said detector elements is connected in parallel to both a time-to digital converter (TDC) and an analogue-to digital converter (ADC) for ion detection.