Alex, if you want to take this on and run with it - go for it. You'll find this community fairly frustrating sometimes when you want to do a useful detector project, since no one thing can be all things to everyone. I'd originally created this particular forum for things that were so miniature you wouldn't believe it possible (even being a techie) and in response to friend Joe Sousa's propensity to do things like that - so tiny you can't believe they'd fit into a mint tin. You started bigger than that, and then got bigger yet, with ideas for removable/replaceable sensors and such like. Those things have a need to exist, I grant you. But they're not altoids tech, they're just tech and we do have a metrology thread, hardware and software forums and so on. I'm trying really hard to keep this organized as a book editor would do for I think good reasons, so it's best to put things where they fit best, or so I think.
I started out with a standard counter vision, simply for personal safety around fusors and to count things we activate with the resulting neutrons, in a way that it's calibrated and the numbers are comparable across labs. Now, look at all the comments on that thread-set, which have thankfully died. One guy wanted to prospect for uranium -- utterly ignoring the vision statement. Another wanted super sensitivity and ability to discriminate alphas/betas/gammas and with energy readout...the next guy wants us to try some newfangled new detector scheme with no track record, because he's all talk and no action and wants to live vicariously though our doing all the work. So, frankly, I DON'T suggest you ask for suggestions much except at first, because these guys will get you so off track you'll wind up with something the doesn't satisfy your original vision, or any one elses. I had to just ignore all that and do the right thing instead for that project (which is about to be available for sale -- we do around here, not just talk).
As Henry Ford once said, "if I'd asked what my customers wanted, they'd have said a nicer horse carriage". Or something like that. If you want info on what detector works best for what sort of desired detection, we can all help with things like that. But stay true to your vision or look out! Use the board to learn how to do what YOU want to get done, and then go do it -- ignore us after that. Else the performance demands will get so out of line you'll never get anything at all done if my experience on this is any guide.
I strongly suspect that such a thing as you want ain't agoin' to fit in a mint tin, but that doesn't really matter for the board as a whole, just this subforum. Which as it says in the pink line above is for things *already finished* and intended to be a showcase thereof.