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size of the cristal

Posted: 17 Oct 2019, 19:30
by Peter-1
What influence does the size of the scintillator crystal have on the resolution? Does it make sense to switch from a 2" to a 3" crystal? I have both the 3" crystal as well as the PMT in addition but it is a great effort to rebuild the whole shield.

Re: size of the cristal

Posted: 18 Oct 2019, 05:31
by luuk
Hi Peter,
Size has non or very limited influence on the resolution, configuration is the main subject that causes a detector to be good or bad.
Best results will be achieved when the crystal is just a little smaller than the pmt so the coverage of the crystal is maximized.
Secondly the dimensions of the crystal, best result will be achieved when the crystal is symmetrical so 1x1 ,2x2,3x3, etc.
And of course a good crystal and good pmt but that is obvious!

Re: size of the cristal

Posted: 20 Oct 2019, 06:19
by Svilen
Hi Peter,
As Luuk said above, the resolution is not expected to be much different if at all. You may get a little bit more from the higher energies, a Compton continuum here a little bit lower, a photopeak there a bit higher, but I guess nothing that will be significant and worth redoing the shield. You showed some great spectra from even low activity samples, this detector seems to be very good. I don't think it will get any better with the 1" difference, assuming the assembly quality and the PMT are comparable.
Otherwise, not much helpful for your case, but just for information about the events in a very small theoretical crystal compared with a very big one, you can read here (it is an old source, but this conclusions are not outdated): ... 06-355.pdf