Dear colleagues,
Regarding backscatter and lead fluorescence, I forgot to mention my measurement setup. I use 10 cm thick lead shielding, with the measurement chamber lined with approximately 1 mm of copper and 1 mm of pewter (essentially an Sn–Sb–Bi alloy). The chamber is cylindrical and quite compact, with approximately 2 cm between the plastic sample container and the chamber walls. Increasing this distance could help reduce backscattering, but this is not possible with my current equipment.
My Scintillix spectrometer uses a 63 × 63 mm NaI(Tl) scintillator coupled to a PMT operated at 850 V and fitted with a passive resistor divider.
I plan to post more details on my blog, but you know how it is - finding the time…
