The 1" eljen button is roughly twice as good (efficient) as the best I've made (or anyone else I know of, having tested some other attempts made and sold at HEAS). It's giving me about 980 cpm per 1m neuts/second right at the fusor shell - well, about 1" from it. At the same time, a long 3He tube is in pulse pileup with the tube about 14" away horizontally, and an old 18" GE B10 tube roughly 3' away is giving me about the same cpm as the hornyak. I've eliminated EMI issues on them all, but still trust the hornyak better, and due to proximity, it gets me a little more info on just where the fusion is occuring. The issue with using ZnS:Ag is that it's much more sensitive to charged particles than gammas, but the downside is the very high index of refraction of it (~2.45?), which tends to trap the light inside the phosphor (total internal reflection). There's nothing plastic or epoxy you can embed it in that lets the light out very well - those all tend toward indexes around 1.45 or thereabouts. You really do NOT need the super sensitivity of a 3He tube, and I had to in fact stop using mine for live data collection due to that pulse pileup issue (on audio though, you can hear the taller/wider pulses fine, it's just that counters only count one for that). Moving it further away to cut down the pulse rate means it will now detect motion of that other big moderator in the room - me. So I just hook it to the audio system, along with the 10B tube, for tuning things up. The ear is a pretty good pattern detector, and I don't have to look away from other controls or gauges to hear the results.
You could probably do about as well with a recoil gas detector. He has a "giant" resonance around 1 MeV, so big that in "Fast Neutron Physics" many experimenters were cleaning high energy neutrons out of their beams with a couple helium baloons. About a megavolt of energy in recoil is pretty easy to detect inside what is otherwise a geiger tube, or so I'd think, and it'd be a lot cheaper to make if you were actually making things, rather than just repackaging them. I have a book from 1945 showing that and a regular hydrogen recoil tube...so the pooh poohing I got on fusor.net when I mentioned that - even statements that it wouldn't work, rather than useful info on what moderator (probably thin carbon) would tend to work best to get 2.45 MeV neutrons down to around 1 MeV was pure bullshit - and part of the reason this board is here. I suppose I should have scanned in pages from books and papers they haven't read that show it DOES work from the 40's through the 60's and told them to eat dust, but I decided to simply stop posting over there - you can take them to school, but they just eat the books, mostly.
As John joked while here - we get hit by murphy's law more often because we actually DO things, not just sit in armchairs and make bad theory. In case no one else has noticed, fusors exhibit emergent behavior, and an armchair theorist thinking about individual particles knows about as much as someone thinking that because they study one ant, they understand an ant hill/colony. Good luck with that.