Scintillator/PMT assembly, manufactured by REXON
Schematic of the base
factory spectrum
Hamamatsu 1307
Raw scintillator spectra for runs 50, 51, and the subtracted spectrum (green). Lots of structure in the spectra, probably artifacts due to threshold behavior of the PMT or the amplifier.
Detailed analysis of this spectrum in coincidence with a 3He counter by Fred is here
We lowered the HV to 1000V. Raw spectra look more reasonable now.
Our interpretation is that the peak at zero is PMT dark current (electronic noise), and
the broad peak at ~200 is due to cosmic rays.
The signal from the neutron source is below channel 150.
