A Novel Cost Effective Method for Growing High Performance Radiation Sensors

Certain lanthanide halides have significantly higher light output than NaI:Tl, the comparison standard for scintillators, plus other important properties, including fast decay times and excellent proportionality. Unfortunately, lanthanide halides grown by traditional melt processes have high production costs and limited availability. Crystals are usually limited to about 5x5 cm2, right cylinder, and current techniques produce non-uniform dopant distribution (causing light output variation within the crystal, degrading energy resolution) and tend to produce an asymmetric crystal structure (which tends to induce cracking). Even if these problems could be overcome for current fabrication methods, the resulting material costs would be extraordinarily high. We therefore propose a rapid, alternate method to fabricate very thick, large area rare earth halide films, in volume, at an order of magnitude reduced cost. This technique will allow formation of unconventional compositions that may further enhance scintillation properties (impossible using existing techniques). The Phase I research goal is to demonstrate the feasibility of our novel growth technique. Specimens produced while varying fabrication parameters will be thoroughly evaluated to quantify their optical and scintillation properties, and comparative performance evaluations versus commercial lanthanide halide will be conducted. Technologies to protect these highly hygroscopic materials from atmospheric moisture will be investigated.