PMT raw signal

[hev455]

Hi there,

Currently I am looking into pulse shapes of different scintillating material and in order to do that I need to look at the raw signal from the PMT. So I recently got a voltage divider saving me the trouble of building one. I already tested it on a regular NaI(TI) detector at 650V and got some great pulses straight out of the voltage divider with pulse heights around 100mV. However when I hook it up the voltage divider with my old EMI PMTs there is no signal. I could see the baseline rises as the HV gets turned on and fall back on the oscilloscope, and its in the correct polarity HV input. The EMI PMT does work with a pre-amp at the same HV 650V but the pulse is shaped after that point. I dont see anything that is out of place so any advice?

[Sesselmann]

Welcome to the forum, but please observe the forum rules, new members should introduce themselves before posting and should preferably post under their real names.

Regarding your PMT, it is quite possible that the two PMT's have very different gain, so the old EMI might require a lot higher voltage. Check the label on the PMT it might have some information on the gain.

Steven