Nondestructive method for quantifying thallium dopant concentrations in CsI:Tl crystals

We report a quantitative method for using X-ray fluorescence (XRF) to nondestructively measure the true content of Tl dopant in CsI:Tl scintillator crystals. The instrument is the handheld LeadTracer™, originally developed at RMD Instruments for measuring Pb concentration in electronic components. We describe both the measurement technique and specific findings on how changes in crystal size and growth parameters affect Tl concentration. This method is also applicable to numerous other activator ions important to scintillators, such as Ce3+ and Eu2+.