Info on some PMTs?

[brehwens]

Hi Neil!

I could test the R374HA using a VD I had for a ET Enterprises 9124B tube, which was wired the same, and I was pleased to see that it worked. I did not have any good NaI crystal to test it with, all I had was a thin (XRF-style) crystal with a thin end window but with a crack. I figured it would at least tell me if the PMT was a dud. I was surprised to see that despite the crack, the crystal actually performed quite well. Add to this, I don't really know how good the PMT actually is so there might be room for improvement with a better PMT/optimization.

I already have an XRF probe, so this crystal is on its way to Steven now, it will be interesting to see what it can do.

I incuded Am241 and Eu152 spectra for comparison. Note that the X-axis is not calibrated, I could not bother. My XRF probe appears to have better resolution, but then again it is not cracked. The end window of my XRF crystal is aluminum, but I am not sure what the end window of the cracked crystal is, it doesn't look precisely like aluminum, maybe it is beryllium. I also suspect the cracked crystal is thinner than the 6mm of my XRF crystal; look at how quickly the response disappears at the higher energies in the Eu152 spectrum.

The two larger 2" PMTs were dead, I tested them with the same crystal.