Extended dynamic range detectors

In order to obtain extended dynamic range, the use of both analog and pulse-counting modes of operation in a single detector has become widespread.  

Inductively Coupled Plasma Mass Spectrometry Handbook 

The maximum linear output current for the analog output of the multiplier is 5 fj,A, so at a gain of 10, this limit corresponds to an equivalent input ion count rate of 10 cps. 

For operation in pulse-counting mode the gain of the second section of the multiplier is set so that the combined gain of both sections of the multiplier is 3x 10. At this gain, the maximum linear count rate of the pulse-counting output of the multiplier (so that its output current is 15/u.A) is 4 X 10 cps. 

The two sections of the multiplier are separated by a special gate electrode. In the presence of very high signal levels, the gate electrode can be activated to gate off the pulse-counting part of the detector to protect it from excessive signal levels and thus extend its operational life. 

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Figure 4.4 Schematic (a) and photograph of ion detector with extended dynamic range (b) in the double-focusing sector field mass spectrometer Element. (Reproduced by permission of Thermo Fisher Scientific, Bremen.)...

Owing to the added constraints of Time of Flight mass filter-based SIMS instm-ments (these only use MCP detectors), additional options have had to be developed. The two most common approaches include the use of the Poisson statistic correction approach and the introduction of the Extended Dynamic Range (EDR) filter. The Poisson correction approach, apphed during data collection, is a statistic method that attempts to correct for the dead time effect suffered. Although effective, this method is applicable only over a limited intensity range, i.e. the maximum... 

A variant of the Plasmaquad PQ2 is the Plasmaquad PQ2 plus instrument. This latter instrument has improved detector technology which incorporates a multimode system that can measure higher concentrations of elements without compromising the inherent sensitivity of the instrument. This extended dynamic range system (Table 1.3) produces... 

EDR An abbreviation for the term extended dynamic range, used in detector... 

EDR An abbreviation for extended dynamic range, used in detector technology, electrodynamic forces Flow of the ion beam through the interface region, where the positively-charged ions of varying mass-to-charge exert no electrical influence on each other. 

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