The Mirion Model 2005 unit is a charge sensitive preamplifier which collects the charge output from scintillation/photomultiplier detectors for presentation to a pulse shaping main amplifier. For the typical application with input from the decoupled anode signal from a photomultiplier tube base, the preamplifier generates a positive polarity energy pulse output.
Functionally the unit operates as an integrator utilizing an operational type configuration by which the potential difference across the feedback capacitor is directly proportional to the charge accumulated from the detector input. The integrator is followed by a pole/zero cancellation circuit for optimum overload performance, and a differentiator to provide the 50 ms tail pulse. In addition, a buffer stage allows the Model 2005 preamplifier to drive a long cable length without pulse degradation.
Charge conversion gains of nominally 4.5 or 22.7 millivolts per picocoulomb may be selected by a jumper plug on the printed circuit board inside the unit. Power for the unit is usually supplied from the associated main amplifier through the 3 m (10 ft) power cable provided with the preamp.