CsI (Cesium Iodide)
Keywords:
Scintillation Crystals
- Product Introduction
- Key advantages
- Application areas
- Product Features
-
- Commodity name: CsI (Cesium Iodide)
Cesium Iodide (CsI) scintillation crystals belong to the CsI scintillator category, with their emission spectrum located in the wavelength range between ultraviolet and visible light.
Product Introduction
Cesium Iodide (CsI) Scintillation Crystals belong to the CsI scintillator category, with their emission spectrum spanning the ultraviolet to visible light wavelength range.
CsI scintillation crystals are made of cesium iodide as the base material and can be classified into three types:Tl-activated (CsI(Tl))，Na-activated (CsI(Na))，Pure CsI (CsI).All three are colorless, transparent cubic crystals. They are characterized by their high density and high average atomic number, which contribute to excellent γ-ray and X-ray detection efficiency. Additionally, CsI crystals are cleavage-free, making them easy to machine into various detector shapes.
The emission peak of pure CsI scintillators lies between 310 and 420 nm, depending on the nature of the radiation interaction and the excitation source. Compared to doped CsI crystals—such as CsI(Tl) or CsI(Na)—pure CsI offers a moderate light output, yet still sufficient to meet the requirements of certain detection applications. Perhaps most notably, pure CsI scintillation crystals stand out for their exceptionally short decay time, making them highly suitable for fast timing applications. Additionally, undoped CsI scintillation crystals exhibit a unique combination of fast and slow luminescent components. Their emission spectrum consists of a rapid intrinsic glow peaking around 305 nm (with a decay time of approximately 10 ns) and a slower component peaking between 350 and 600 nm, with decay times ranging from 100 to 4,000 ns. This 10-nanosecond fast-emission component makes pure CsI an ideal choice for time-sensitive measurements.
Compared to CsI doped with Tl or Na, the drawback of undoped CsI is that its light output in pure crystals is lower than that of CsI(Tl) and CsI(Na). Therefore, when time resolution is more critical than light output, pure CsI is typically the preferred choice. Another limitation of pure CsI is that its emission spectrum may not align as well with photodetectors.
CsI scintillation crystals are widely used in high-energy physics, nuclear physics, space physics, luggage security screening, radiation detectors, medical SPECT applications, university and research institute experiments, container inspection, industrial level gauges, well logging, space exploration, and more.
Key Advantages
- High average atomic number ensures excellent detection efficiency for γ-rays and X-rays.
- No cleavage planes in the crystal structure, enabling easy machining and fabrication into various detector shapes.
- Excellent spectral match with photodiodes (PD) at 550 nm (long-wavelength emission).
- High light output (especially in doped variants like CsI(Tl)).
- High energy resolution (critical for distinguishing between different energy photons).Application Areas
- High energy physics, nuclear physics, space physics
- Luggage security checks, container inspections, industrial level gauges, Well logging
- Radiation detector
- Medical SPECT
- University and research institute experiments
- Space research and moreProduct Features
Material Properties
Parameters
CsI(Tl)
CsI(Na)
CsI (undoped)
Density
4.51 g/cm³
4.51 g/cm³
4.51 g/cm³
Mohs Hardness
2 Mohs
2 Mohs
2 Mohs
Decay Time
1 μs
0.63 μs
0.016 μs
Coefficient of Thermal Expansion (K⁻¹)
54 × 10⁻⁶
49 × 10⁻⁶
49 × 10⁻⁶
Cleavage Plane
None
None
None
Moisture Absorption
Mild
Is
Mild
Refractive Index
1.95
1.79
1.95
Emission Peak Wavelength
550 nm
420 nm
315 nm
Lower cutoff wavelength
320 nm
300 nm
260 nm
Melting Point
621°C
621°C
621°C
Light Output (photons/MeV/γ)
52~56 x 10³
38~44 x 10³
2 × 10³
Light yield (percentage of NaI(Tl)) (γ-ray)
45
85
4 to 6
Product Processing Indicators
Effective Aperture
>90%
Dimensions
Customized to Customer Specifications
Diameter Tolerance
+0/-0.05 mm
Length Tolerance
±0.2 mm
Chamfer
≤0.2×45°
Surface Quality
40-20 S-D
Flatness
≤λ/6@632.8 nm
Parallelism
<20"
Perpendicularity
≤15′
Chipped Edge
<0.1 mm
Coating
Customized to meet customer demands
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- Luminescent properties
- Radiation resistance
- Short decay time
- Fine energy resolution
- Non-hygroscopic -
- High-energy physics experiments
- Nuclear Medicine
- Environmental Monitoring
- Space Science
- Large Electron-Positron Collider
- Dark Matter Detection -
Material Properties Molecular formula Bi4Ge3O12 Crystal structure Cubic crystal system Lattice constant a = 1.0518 Å Production method Tiraf Method Density 7.12g/cm3 Mohs Hardness 5Mohs Radiation Length 1.1cm Transmittance range 350 nm ~ 5500 nm Relative Light Output (%) 10-14 Nal (Tl) Fluorescence spectrum peak 480–510 nm Recession time 300ns Energy resolution 20 (511 keV, %) Refractive index 2.098 @ 632.8 nm Melting point 1050°C Product Processing Metrics Directional <001> +/- 0.5° Effective Aperture >90% Dimensions Customized to customer specifications Diameter Tolerance +0 / -0.05 mm Length Tolerance ±0.2mm Protective Chamfer ≤0.2 × 45° Surface finish 10-5 S-D Flatness ≤λ/10 @ 632.8 nm Analyzing wavefront distortion ≤λ/8 @ 632.8 nm Parallelism <20" Verticality ≤15′ Chipped edge < 0.1 mm Coating Customized to customer specifications
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