Anode luminous sensitivity

In the test sheets of PMTs, the manufacturers occasionally specify the measured anode luminous sensitivity" instead of the cathode sensitivity. The anode sensitivity is the cathode sensitivity (including the electron transfer efficiency) multiplied by the gain of the tube. Because almost any gain can be obtained by increasing the supply voltage, the anode luminous sensitivity cannot be used to compare the photon counting performance of PMTs. 

Fig. 6.27 Measurement of the Cathode Luminous Sensitivity (Ze/f) and the Anode Luminous Sensitivity (right)...

The Anode Luminous Sensitivity" is measured in a similar setup as the Cathode Luminous Sensitivity. However, the PMT is operated in the normal way, i.e. by applying the specified voltage distribution to the dynode chain (Fig. 6.27, right). Of course, a calibrated filter has to be inserted in the light path to attenuate the light of the lamp to a level that does not overload the PMT. As mentioned before, the anode luminous sensitivity is not very useful in characterising a PMT for TCSPC. 

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