Electron multiplier noise

Dark noise of the ion counter or analog electron multiplier (especially important for the latter, for which the 2c dark noise is typically 10-15 ions/second)... 

The lifetime of channel electron multipliers is ca. 1-2 years. Neutrals or photons hitting the detector also increase the noise of the detection. 

After it emerged from an electron multiplier, the signal was fed into a preamplifier that consisted of four cascaded active bandpass filters (White Instrument Inc., Austin, Texas). Without these filters, the signal-to-noise ratio would have precluded any measurements of the differential cross... 

Poisson counting statistics ultimately limit signal-to-noise ratios in conventional ICP-MS instruments. The improvement achieved by increased intensity is directly proportional to the square root of the counts s . The temptation is, therefore, to work with ever-larger counts. However, the detectors (usually electron multipliers) will have a limit to their linearity and will ultimately saturate. Even over the normal linearity range, typically up to 10 counts s , there will be an influence from the detector s dead time . There is no need to correct for dead time if a matching procedure is being adopted, but in other cases, for very accurate measurements, the multiplier will need to be characterised for dead time. 

Back illuminated, frame transfer electron-multiplying charge coupled device (EMCCD) camera (such as Photometries Cascade II 512, Roper Scientific, Tuscon, AZ). Back illuminated EMCCD cameras capture more than 90% of incoming photons and amplify signals to overcome instrument noise. 

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