• Step-By-Step Selection Guide
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• Step 6

have you considered signal / background?

Background is the unwanted output from the photomultiplier when operating in the absence of signal - that is in the dark.

Dark current or dark count is always a consideration in low light level applications or where the dynamic range exceeds 10⁵ (dynamic range is simply the ratio of the highest to the lowest light level measured).

• dark current and count rate increase with pmt diameter.
• dark current and count rate increase with pmt temperature.
• dark current increases approximately linearly with gain.
• dark count rate is essentially independent of gain.

Further information is available in our photomultiplier brochure, request a copy via this form.