NuclearPhoenixx
commented
10 months ago I've identified what I believe to be a fairly decent deal for a Nal(Ti) crystal, which is 25mmx25mm. I'd want to be able to identify isotopes with a fair amount of certainty, but I cannot find any information about how the crystal size affects the reading accuracy, apart from the obvious limitation of isotope size that I can easily sample.
There is a comment on this in the hardware readme: https://github.com/OpenGammaProject/Open-Gamma-Detector/tree/main/hardware#scintillator-cyrstals
In general, try to avoid giant crystal faces with just a single SiPM coupled to it. The optical losses will be quite substantial and you'll probably get worse energy resolution. You can use a 25x25mm crystal no problem, but I'd recommend you get yourself the 2x2 SiPM array board: https://github.com/OpenGammaProject/MicroFC-SiPM-Array-Board
That way you can pretty easily get down to ~8% if you assemble everything correctly.
Would it be simply the case that I may just need to sample my isotope for longer due to the decreased area of the crystal? Additionally, would discoloration and spots on the crystal affect the results of my gamma spectroscopy much?
Sampling longer always helps, but only to a certain degree. You can't go lower than the intrinsic energy resolution of your entire assembled system, so there is a hardware limit. Discoloration can, depending on the extent, significantly reduce the amount of light that reaches the SiPM and therefore also the resolution. However, if there's just a hint of yellow, it'll probably work fine to be honest. You really have to try it if you're unsure. Hope that helps.
GhostDog98
I've identified what I believe to be a fairly decent deal for a Nal(Ti) crystal, which is 25mmx25mm. I'd want to be able to identify isotopes with a fair amount of certainty, but I cannot find any information about how the crystal size affects the reading accuracy, apart from the obvious limitation of isotope size that I can easily sample.
Would it be simply the case that I may just need to sample my isotope for longer due to the decreased area of the crystal? Additionally, would discoloration and spots on the crystal affect the results of my gamma spectroscopy much?
Cheers for your advice, Ghostoverflow