NaI is one of the most effective scintillators on the market. Specifically, Thallium-doped Sodium Iodide (Tl:NaI) is the brightest among known scintillators. Because of this, many professional resources reference the light yields of their scintillators as a percentage of Tl:NaI's output (38,000-40,000ph/MeV). The biggest downside of using it is its hygroscopic nature. Thallium in a water-soluble crystal can be toxic and dangerous, making other scintillators a more realistic option in certain use-cases.
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