Good man, Richard. I hope you will post your blisteringly fast design too. Agreed on the PMT amps sort of being optimized for the NaI (Tl activated) xtals. They will definitely work with the BC-720 because that uses the ZnS (Ag activated) scintillator to really flash the proton signal. The time on that is long enough for the little amp I desplay to follow. The proton recoil in normal polystrene (anathracene doped) scintillator is very fast, indeed.
I also sorta' figured that discretes were going to be the amp of choice still for all the reasons you and I have stated. If IC's beat them even by a bit, they would have been used extensively already by cost and labor reducing greed factors within the industry.
I have thought about the mini-circuits ERA series RF amps (90 cents each), but the decoupling capacitors might be the limiting factors. They are all direct coupled and running in the 200mhz rang eand above.
The real secret to any PMT preamp is to mount it, if possible in a shielded can attached to the pmt socket and send it out of a properly terminated 50 ohm cable to any instrument or further amplification. So many folks do not terminate these high speed lines and pay the price in noise and false triggering. I once saw some college types (probably undergrads) at an accelerator fiddling with nuclear measurement gear 40 feet from the detector woundering why they were getting high counts. First, no one scoped the input line and secondly, they had not terminated the long run at the amp input!! Tsk..tsk.
Richard Hull
Created on Thursday, June 14, 2001 2:12 PM EDT by Richard Hull