Based on the discussions I decided to change my approach from using an organic scintillator and go with a crystal scintillator. It will add a bunch to the size and weight of the overall unit, but will definitely improve sensitivity and may allow me to do pulse energy measurements. Presuming I can learn enough about the mechanisms to understand how to build the detector.
I will do the crystal unboxing and put photos (or maybe video) up in the near future.
Unfortunately recent events have shown me how virtually every instrument or networking device in my lab is in poor condition. A lack of time over the last 10 years has encouraged my unhealthy habit of doing "quick fix" patches and not ever getting back to "doing it right". After all if it works, why fix it? Well, I am fed up with spending more time patching than on projects and am undertaking a remodel/refurbishment of the lab.
If anyone is interested in how I do that, just let me know in the discussion and I will consider posting it as a project here. It may be useful for someone wanting to build their own lab. At the very least they could learn what not to do (ha, ha).