Charge preamplifier 2006 series

low-noise

• Low noise design: <350 ion pairs at Cs = 0 pF • High charge rate capacity for high count rate applications; up to 2 x 10-7 coulombs/second • FET input, diode protected • Fast risetime: <20 ns at Cs = 0 pF • High voltage operation up to ±2000 V dc The Mirion Model 2006 preamplfier is designed for use with proportional counter detectors. The preamp converts the ionization charge from the detector into a step voltage pulse whose amplitude is proportional to the total charge collected in each event. The pulse decays with a time constant of 50 ms for presentation to a main amplifier. For typical use with a positive HV bias to the anode of the detector, the preamplifier generates positive polarity energy pulses which are shaped in the amplifier as necessary for counting or low energy x-ray analysis. This preamplifier contains a diode-protected FET input stage optimized for low noise operation. The first stage acts as an operational integrator which produces an output potential proportional to the accumulated charge. This integrator configuration is followed by a pole/zero adjustment to return the unipolar pulse to a reference or baseline level without overshoot, and a differentiator to provide the 50 ms tail pulse. The second active stage operates as a buffer for driving various cable lengths without pulse degradation. Conversion gains of nominally 47 mV/M-ion-pairs or 235 mV/M-ion-pairs may be selected by a jumper plug inside the unit. The higher scale factor is especially useful for best signal-to-noise ratio in experiments involving low energy sources.