scintillation detector

[ant17]

hi guys i have been trying to build a scintillation counter from a xp5312/sn Phillips photomultiplier and some bc406 plastic scintillator i built it using this circuit diagram https://www.sphere.bc.ca/test/phototubes/+prutchi-paint-can-scintillator.pdf but found the ouput to high the output to be to high voltage its being driven by a ccfl inverter with a full bridge on the output to make it dc but this fellow wanted just to connect it to a cdv 700 geiger counter but i want to be able to measure and process the signal through a analog to digital converter to in to a op amp amplifier but at 1200vdc most ics would could anyone give me a idea on how to achive this thanks

 

[chuckey]

Build your 1200V PSU, in series with its earth connection connect a 1M ohm resistor to actual earth so all the 1200V current flows through this resistor, connect the 1200V + to the centre of your co-ax the outer of the co-ax to earth and to the tube. Now the "live" for you op-amp is the non earthy end of the 1 M. This point should be less then 10 V negative of earth, but feed your op-amp via a good coupling capacitor (1mF, 250V) and a 10 K resistor. The input to the op-amp should have a pair of diodes connected a-> 10K, c ->Vcc+ and c -> -Vcc (or 0V) and a-> 10K. This will limit the voltage into the OP-amp if the tube flashes over.
Frank

 

[ant17]

ok thanks for that