Basic Charge Sensitive Amplifier with Protection Diodes

[Richard Hester]

Attached is a basic schematic of a charge sensitive amplifier with protection diodes. Some recommended component values are given for fast (plastic) and medium speed (ZnS and NaI) scintillators. The actual amplifier circuit has been left deliberately vague, as just about any fast, high impedance inverting amplifier will do the trick. The protection diodes are pretty important, as just the turn-on transient of the high voltage photomultiplier supply may be sufficient to permanantly nail the amplifier input. Beware.