Yup.
It is critical to calibrate against a known source, and set HV accordingly. Arbitrarily choosing an HV based on 'gut instinct' might work with newly brand new, but after being in the hole at 350°F (and higher!) For hours on end tends to weaken seals and other physical aberrations.
This particular 14" Princeton tube was designed for neutron, but slowly lost its HE3 eventually rendering HV approaching arcing / cascade levels. My fun solution was to dip into paraffin, using the wax as neutron moderator. Still far from perfect, was good enough to provide an interesting feedback. Especially when someone transferring source from truck pig to ground pig.
I saved all the broken scintillation salt crystals, their photomultipliers, and dewar flasks from broken tool 'events'. Biggest was maybe 10"long x 1.5"dia, circumference cracked almost dead center. Patched back together with 3M optical compound ($150/gram!) and long piece of cold shrink. Repair didn't last, ends ground themselves apart. Had read on our internet how to pour new crystals, didn't have oven hit enough.
Ion Chamber... akin to what's found in smoke / particulate detectors?
~SD
