Updated scintillator and wide range energy linearity

A project log for Pomelo: Gamma Spectroscopy Module

A complete low-power gamma ray spectrometer that can be used by itself or integrated into other projects

mihaicuciucmihai.cuciuc 06/17/2024 at 16:150 Comments

Pomelo sales rep showing off the latest prototype sporting a 10mm x 10mm x 20mm CsI(Tl) crystal

I designed the device dimensions with a 2cc (10mm x 10mm x 20mm) CsI(Tl) scintillator in mind, but only had 3cc ones to test with. It’s why the detector element extended beyond the device’s edge, but now that the 2cc crystals arrived, I can share the final design and some preliminary performance plots.

The scintillator is not yet potted in silicone, which does decrease light output a little (and thus worsens resolution). I took spectra with several lab sources and computed the resolutions for every gamma line and checked the detector linearity.

Spectra for Am-241, Na-22, Cs-137, Mn-54, Co-60, and Th-232 on the same plot in logarithmic scale. Energy resolutions for each energy shown in the last column

Detector linearity plot. There is a small quadratic term that is typical of SiPMs