Most radiation detector sensors, except Geiger Muller tubes, require a
preamplifier to boost their weak signals to a level a Multi-Channel-Analyzer can deal with and display the familiar histograms we use for energy (MCA) or time?studies (MCS or Multi-Channel-Scaler mode). This stage also acts as a buffer to convert the high impedance pulses from the sensor to drive a low impedance stage, perhaps a coaxial cable or some conventional electronic stage (bipolar transistor or IC).
After the preamplifier, which is most often located in the sensor package, is a
shaping amplifier.
That stage shapes the raw pulses of the sensor into something that the following stages can recognize. With solid state sensors, this is often a triangular wave shape, and the shaping amplifier may be located within the sensor package as well.
The various terms in the topic title are all the same item, just different names. FET input stages have been around for a very long time. If you've used an Eberline bench instrument, chances are it has a FET input. So do base mounted preamps for NaI(Tl) detectors, such as all the Canberra 12 and 14 plug on bases for Bicron scintillators etc.
Rather than use some sort of homebrew setup, these first two stages can be purchased cheaply as LSI (Large Scale Integration) modules from several different manufacturers. From the same source, there are prewired PCB's to hold the modules and provide rudimentary functions such as power line bypass capacitors,
input/ output terminals or connecters and any filtering needed on the power lines.?
Cremat is one mfg. that has very reasonable prices, suitable for the amateur experimenter's Home Lab, or Physics Class demonstrations.
Using this approach, a customized package for various different sensors can be assembled at low cost.
Pics are of the C.C. Preamp and Shaping Amp boxes Dr. Pruitchi used in his article on introductory Alpha Spec.
Geo
