MASS SPECTROMETER

摘要

An ion detector for a mass spectrometer is provided wherein a mask (10) is provided between a first microchannel plate (2a) and a second microchannel plate (2b). The mask (10) prevents ion arrival events causing a cloud of secondary electrons to be from the second microchannel plate (2b) which woul d illuminate two collection anodes (5,6) at substantially the same time. The mask (10) also prevents electron clouds emitted which would otherwise vary significantly in intensity.