Gamma Scintillation Probes

What type do I need? Should I get  1X1 or a 2X2 scintillation probe? What connectors are available? SE International can help you find just the right probe for your application.

Typically, crystals are grown to order once we find the right one for your needs. Below are the specifications for the most common detectors that we offer in this variety.

NaI(Tl), or Sodium Iodide, crystal is recommended for nuclide identification in room temperature application. It provides the best energy resolution for gamma rays in this environment and is relatively inexpensive. Sodium Iodide probes are available in a wide variety of sizes.

The CsI (Tl), or Cesium Iodide, crystal used in Radiation Alert® Probes has a higher atomic number, is more rugged, and less hygroscopic than a typical Nal detector. The improved gamma ray absorption allows a thinner crystal to be used, effectively reducing the background count rate.

1 Inches X 1 Inches (Typically 1.0″ dia x 1.0″ thick (25.4 x 25.4mm)
2 inches X 2 Inches (Typically 2.0″ dia x 2.0″ thick (50.8 x 50.8mm)
Smaller and larger custom sizes available.
Nal(Tl) Standard. Optional Extra: BGO, Cs(Tl) or (Na), TSO. Contact for more info.

Scintillation Probes

CsI (Tl) Probes

CsI (Tl) crystal (Cesium Iodide Thallium)

Gamma Sensitivity

>180,000 CPM/mR/hr (137 Cs)

Energy Sensitivity

Gamma 8 keV to 3 MeV.
Typical Absorption 70% at 600 keV, 50% at 840 keV




Nal(Tl) Crystal (Sodium Iodide Thallium)

Gamma Sensitivity

Typically 90,000 cpm/µSv/h (Cs137)

Energy Sensitivity

60 KeV ~ 2 MeV
2% at 8KeV, 17% at 14.4KeV, and 94% at 60KeV



Operating Voltage

500V – 1200V


C-Connector standard with user specified option for SHV or MHV

Probe Construction

Anodized aluminum housing.


1X1: Approx. 13.6oz (386g) without cable
2X2: Approx. 41.6oz (1180g) without cable


1X1: 8.5 X 1.8 in (21.6 x 4.6 cm)
2X2: 9.5 x 2.25 in (24.1 x 5.7 cm)


One Year Limited