Electron multiplier having self-adjusting gain function

Abstract

A method for determining a performance parameter of an electron multiplier (e.g. parameter indicative of gain) comprises comparing an electron flux of a first electron emissive surface with an electron flux of a second electron emissive surface, or of an electron collector. The electron emissive surfaces form part of an electron multiplication chain, and may be discrete dynodes or provided by a single electron emission surface (e.g. a channel of a channel electron multiplier, or a plate of a microchannel plate electron multiplier). The first electron emissive surface may be earlier in the chain and less susceptible to electron flux-mediated gain degradation. A current ratio from the two electron emissive surfaces may be determined and compared with a comparator. An operating parameter (e.g. voltage bias) of the electron multiplier may be altered based on the determined performance parameter or current ratio. The invention may obviate or reduces the need for manual gain adjustment by adjusting the gain continuously and automatically to account for gain instability based on the comparison.

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