Photomultiplier tubes multiplication process

DC amplifiers are the simplest and least expensive of the electronic measurement systems. They are most commonly found in commercially available fluorimeters. Ideally, the amplifier stage of a circuit contributes little or no noise to the system the photomultiplier should produce only the noise associated with perfect performance of the photocathode and the electron multiplication process described above. However, the anode dark current of the photomultiplier adds to the noise in the signal, and the amplifier makes its own contribution to the total noise. It is therefore imperative to select the proper photomultiplier tube with low dark current so as to have a higher signal-to-noise ratio. 

CEM Channel Electron Multiplier detects electrons, ions, soft X rays directly. Multiplication of the signal is a similar process to that of a photomultiplier tube. 

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