CsI(Tl) has a light output of 54 photons/keV and is one of the brightest scintillators known. It has most of its emission in the long wavelength part of the spectrum (>500nm), it is well-suited for photodiode readout.
CsI(Tl) has very good stopping power, is slightly hygroscopic and with good plastic mechanical properties. Combined with a relatively good radiation hardness properties, CsI(Tl) is also well suited for High Energy Physics. It is used in Phoswiches for whole body counting and X-ray astronomy as the "guard crystal" with typically a thin NaI(Tl) as the primary detector. It also has no cleavage plane and is quite rugged – which makes it well-suited for well-logging, space research or other applications where severe shock conditions are encountered.
|Melting point [K]||894|
|Thermal expansion coefficient [C-1]||54 x 10-6|
|Wavelength of emission max. [nm]||550|
|Lower wavelength cutoff [nm]||320|
|Refractive index @ emission max||1.79|
|Primary decay time [ns]||1000|
|Light yield [photons/keVγ]||54|
|Photoelectron yield [% of NaI(Tl)] (for γ-rays)||45|