NaI (Tl) Sodium Iodide Scintillation

NaI(Tl) Sodium Iodide Scintillation Detectors

High-quality Sodium Iodide crystal scintillators are available with a large variety of form factors and sizes. These detectors offer the best performance and resolution for your nuclear spectroscopy applications. Custom crystal & detector assemblies. 

The longtime work horse for BNC’s SAM III generation and SAM 940, sodium iodide (NaI) crystals are the most widely used scintillation material for gamma-ray spectroscopy. Their high light output and the excellent match to the sensitivity of photomultiplier tubes, provide good, economical energy resolution. The energy resolution at 662 keV is about 6% at fullwidth, half-maximum amplitude (FWHM). 

Size does matter.  NaI crystals can be grown to large dimension and at relatively low cost. When increasing the diameter of the scintillator, the solid angle under which the detector "sees" the source also increases. This increases the detection efficiency.

Gamma spectroscopy is all about good statistics. Fast response with high sensitivity tells the operator that this is the right time and place to make a measurement. A 2x2 inch sodium iodide (NaI) detector will allow the user to identify the presence of Cs137 at < 1 urem/hr/sec. The 3x3 inch NaI detector can identify Cs137 at 500 nrem/hr/sec.     

This is why BNC’s SAM III generation and SAM 940 are designed to easily hold large detectors and operate them with one hand.

Specifications 

Properties of Sodium Iodide Scintillators

Density (g/cm3) 3.67
Melting point (K) 924
Thermal expansion coefficient (C-1) 47.7 x 10-6
Cleavage plane <100>
Hardness (Mho) 2
Hygroscopic Yes
Wavelength of emission max. (nm) 415
Refractive index @ emission max 1.85
Primary decay time (ns) 250
Light yield (photons/keV) 38
Temperature coefficient of light yield 0.3%C-1

Frequently Asked Questions (FAQ) 

Do you have a device that detects alpha, beta, gamma and x-ray radiation? 

Do you have a device that detects alpha, beta, gamma and x-ray radiation? 

The Model 907 measures alpha, beta, and gamma radiation. The device is a health and safety instrument that is optimized to detect low levels of radiation.

Does temperature affect the response of a scintillation detector?

Does temperature affect the response of a scintillation detector?

The light output (number of photons per MeV gamma) of most scintillators is a function of temperature. This is caused by the fact that in scintillation crystals, radiative transitions, responsible for the production of scintillation light, compete with nonradiative transitions (no light production). In most scintillation crystals, the light output is quenched (decreased) at higher temperatures. An example to the contrary is the fast component of BaF2 which the emission intensity is essentially temperature independent.

The scintillation process usually involves three stages, production, transport and quenching centers. Competition between these three stages and all three behaving differently with temperature creates a complex temperature dependence for scintillation light output.

Below is a chart with the temperature dependence of common scintillation crystals.


Temperature dependence of the scintillation yield of NaI(Tl), CsI(Tl), BGO and CeBr3

For most applications, the combination of the temperature dependent light output of the scintillator together with the temperature dependent amplification of the light detector should be considered.

The doped scintillators NaI(Tl), CsI(Tl) and CsI(Na) show a distinct maximum in intensity whereas many undoped scintillators such as BGO show an increase in intensity with decreasing temperature. The temperature dependence of the Ce doped scintillators LBC, CeBr3 and YAP:Ce is significantly less than that of other scintillators.

What Types of Radiation Are There?

What Types of Radiation Are There?

Alpha radiation, beta radiation, gamma radiation, and x radiation. Neutron radiation is also encountered in nuclear power plants and high-altitude flight and emitted from some industrial radioactive sources.

What wavelength is the light emission of a scintillator material?

What wavelength is the light emission of a scintillator material?

Each scintillation material has a characteristic emission spectrum, with wavelength and intensity. The shape of this emission spectrum is sometimes dependent on the type of excitation (photons/particles).


Emission spectra of NaI(Tl), CsI(Tl) and CeBr3, scaled on maximum emission intensity.
Also a typical quantum efficiency curve of a bialkali photocathode and a Silicon Photomultiplier (SiPm) are shown above

This emission spectrum is of importance when choosing the optimum readout device (PMT / photodiode/SiPm) and the required window material. The graph above shows the emission spectrum of some common scintillation materials

Downloadable Resources 

Downloadable resources such as datasheets, firmware, software, drivers and products manuals. Alternatively, you can browse resources directly by visiting our downloads page.

Product Datasheets
• Product Firmware
• Product Software and Drivers
• Product Manuals

Media

Media 
Video URL 
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SiPM vs PMT Webinar with a look at MCAs
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Planning your Custom Scintillator ? An overview !
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CeBr3 and LaBr3 Tradeoffs, with a comparison to NaI Backgrounds
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Low vs High-Resolution Detectors Webinar
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Compton Suppressors: Practice and Theory Webinar
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NaI (Tl) Sodium Iodide Scintillation Detector | Applications
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NaI (Tl) Sodium Iodide Scintillation Detector | How It's Made
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NaI (Tl) Sodium Iodide Scintillation Detector | Properties
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NaI (Tl) Sodium Iodide Scintillation Detector | History