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Figure 15: Schematic plot of increasing the operation voltage to compensate gain degradation
over time as function of the extracted charge (all values are only exemplary).
It is not unusual that the operation voltage must be increased several times especially in
the first year of operation.
Note
Typically, the final operation voltage at the end of the burn-in period will be close to the recommended
maximum operation voltage. An increase of the operation voltage above the recommended maximum
operation voltage is in principal possible and allowed, as long as there is no significant increase in the dark
count rate, bright spots at the detection area and/or appearance of high voltage sparking.
The operation voltage can be increased even above the recommended maximum
operation voltage. A safe and reliable operation will still be possible as long as there is
no increase in the dark count rate and/or no appearance of high voltage sparking.
Note
It can be sufficient to estimate the correct operation voltage by monitoring the detector results, when
increasing the voltage to compensate the gain degradation. The exact operation voltage can always be
determined by measuring a so called MCP curve. The MCP curve plots the detected count rate as a function
of the operation voltage. Do as follows to measure an MCP curve:
• Start the detector operation with a homogeneous illumination (as good as possible).
• Open the rate meter in the Surface Concept GUI Software to monitor the count rate output of the
detector.
• Decrease the operation voltage until the count rate of the detector is reduced to zero.
DLD4040 R2.55 & R3.54 Manual | Surface Concept GmbH
