Speed Dependent Amplitude Error for a Photomultiplier Preamp

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Richard Hester
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Speed Dependent Amplitude Error for a Photomultiplier Preamp

Post by Richard Hester »

Attached is a PDF file discussing amplitude error for a fast photomultiplier preamplifier. The amplifier circuit was designed explicitly to measure peak output current for a ZnS scintllator-PMT combination, to aid in design of dedicated preamps for this scintillator type. Preliminary testing showed >20% amplitude error for a 200 nsec exponential input pulse, similar to what would be expected from a ZnS or NaI scintillator. I was surprised, as 200nsec is not a particularly short pulse width. I'll be doing some more research to see if the amplitude error is consistent with amplitude, and also how much one can reduce the error by speeding up the preamplifier circuit. This will be included in a later report.
All in all, this shows why charge sensitive amplifiers are such valuable tools in the physicist's arsenal. It is easier to get an accurate signal based on total charge than for peak current.
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Fas_Aint.pdf
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