CsI(Tl) - Cesium Iodide (Tl) Scintillator Crystal

Cesium Iodide, activated with Thallium - CsI(Tl) - is one of the brightest available scintillators, with a broad emission peaking at 550nm. CsI(Tl) has good stopping power, physically rugged and and well suited to a broad range of applications.

Cesium Iodide - CsI(Tl) - scintillator crystals are:

Relatively bright - emitting 54,000 photons/MeV (45% of NaI(Tl))
Good absorbers with good stopping powers - density 4.51 g/cm³ and an Effective Z of 54
Broadly emitting with a 550nm peak, well matched to use with photodiode
Robust with good mechanically characteristics

Cesium Iodide - CsI(Tl) - scintillator crystals have the following issues which should be noted. They:

Have a light emission which a is good part is above 500nm, a region where photomultipliers are less sensitive
Are relatively slow with a decay time of c.1us
Are slightly hygroscopic

Cesium Iodide - CsI(Tl) - scintillator crystals are useful in diverse applications such as:

Geological logging
Specialist applications in high energy, nuclear, space and medical physics

CsI(Tl) Scintillation Crystals - Optical Properties

Property	Units	Value
Wavelength (Max. Emission)	nm	550
Lower Wavelength Cut-off	nm	320
Decay Times	ns	900
Light Yield	photons/keV	54
Photoelectron Yield	% of NaI(Tl)	45
Radiation Length	cm	1.86
Optical Transmission	µm	TBA
Transmittance	%	TBA
Refractive Index		1.80 (@550nm)
Reflection Loss/Surface	%	TBA
Neutron Capture Cross-section	barns	1.47

CsI(Tl) Scintillation Crystals - Mechanical Properties

Property	Units	Value
Chemical Formula		CsI(Tl)
Density	g/cm³	4.51
Atomic Number (Effective)		54
Melting Point	ºK	621
Thermal Expansion Coeff.	C⁻¹	54.0 x 10⁻⁶
Cleavage Plane		None
Hardness	Mho	2
Hygroscopic		Slightly
Solubility	g/100gH₂0	N/A

Sizes

Property	Value
Diameters	80mm max
Lengths	400mm max.

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