How can I amplify a weak PMT signal without creating too much error?

[physguy09]

I was trying to use the Ortec Aspec-927 MCA with Maestro-32, and realized the PMT signal is too weak for it to detect. I passed the signal through a 16-channel amplifier, yet it is still not detecting anything. I passed the output from the PMT into an oscilloscope, and the PMT is working just fine, did the same thing from the amplifier output, and the amplifier did amplify the signal. Is it inadvisable to feed the output from the amplifier into the same amplfier (different channel) to try amplifying once more without creating too much error for the signal output? Please help! I would very much appreciate it.

NOTE: I am trying to use the PMT to detect muons, but running it by itself to make sure the apparatus as a whole will work, rather than trying to identify the missing components later.

 

[Bob S]

Make sure you are using the correct PMT output signal; anode for a negative signal, dynode for a positive signal. Be sure to use the proper (same) termination for the 'scope and the MCA. Muons are a minimum ionizing particle, and provide a signal ~ 2 MeV per gram/cm² (similar to a radioactive source), and a very weak signal in a Cerenkov radiator.

[added note] The anode signal should be dc-coupled to the transmission line and termination; the electrons need to flow to ground. The dynode signal has to be ac coupled to the transmission line; if the RC time constant is too fast, the MCA may not be able to integrate the area..

Bob S