CsI (Tl), or Thallium Doped Cesium Iodide, is one of the most commonly used alkali halide scintillation crystals with its advantages of high light yield, superior γ-ray stopping power attributed to its high density, and its compatibility with Photodiodes or SiPMs. CsI(Tl) Scintillation crystals are excellent for applications like medical imaging, well logging, high-energy physics, radiation detection, and so on. 

CsI(TI) offers premium brightness and is one of the brightest scintillation materials with a light yield of 54 photons keV emitted, which amounts to 45% of that Na(I).

The broad emission spectrum of CsI (Tl) spans between 350nm to 700nm, with most of its emission exceeding 500nm and an emission peak at the 550nm wavelenth, which matches well with photodiode readouts. Therefore the integration of CsI(Tl) facilitates the simplification and miniaturizing of scintillation detectors and can eliminate the need for high-voltage power supplies. Photodiode-based scintillators also avoid issues with magnetic fields, which can affect traditional PMTs.

Also, with a large atomic number, CsI(Tl) shows higher photo-fraction than Na(I) and provides a large photoabsorption cross-section, making it efficient for detecting gamma radiations or x-rays.

CsI(Tl) is a rather slow scintillator material with an average decay time of 1 μs when interacting with gamma rays. For CsI(Tl), suitable electronics with shaping times in the range of 4-6 µs are recommended. For CsI(Tl), the slow decay time limits its potential in fast-speed scintillator systems, CsI(Tl) is often chosen for applications where energy resolution is more critical than high-speed detection. The decay time of CsI(Tl) consists of multiple components, encompassing the fastest component of around 0.6μs and the slowest component of around 3.5μs. And since the ratio of the fast and slow components changes depending on the ionizing power when the CsI(Tl) crystal is excited by ionizing particles and heavy charged particles, CsI(Tl) can be utilized for pulse shape discrimination of alpha particles, detecting heavy ions.

The other virtues of CsI(Tl) crystals include good radiation hardness which provides high damage resistance against exposures to high doses of radiation over time, making CsI(Tl) a reliable option for performing high-energy experiments. In addition, CsI(Tl) exhibits robust and excellent physical properties (it is not very hygroscopic), making it reliable and versatile under various conditions. CsI(Tl) can be utilized in medical applications such as jaw and head scanning, security X-radiation inspection, well-logging, space research, etc. 

Shanghai North Optics offers a series of scintillator products based on CsI(Tl), including CsI(Tl) blanks, polished crystals, encapsulated scintillators, and CsI(Tl) arrays, CsI(Tl) array +PD assemblies, and 2-dimensional of custom specifications. Engaging the eco-conscious Bridgman growth technique, North Optics is capable of manufacturing a whole class of variations of CsI crystals, including undoped CsI crystals, CsI(Tl)/thallium doped CsI, CsI(Na)/Sodium doped CsI, low- afterglow CsI(Tl) and related products. And with leading-edge manufacturing techniques, we are able to fabricate CsI(Tl) with a maximum size of 400mm x 400mm x 100mm. North Optics provides autonomous custom choices for the dimensions, shapes, compositions, reflectors, packages, coupled detectors, or integrated electronics for the scintillation crystals. We are confident in our capability of presenting custom-shaped CsI(Tl) Scintillators tailored to meet different requirements, including well-shaped CsI(Tl) scintillators, CsI(Tl) scintillators with single or multiple windows, in addition to diverse combinations of reflectors. These custom shapes and designs are crafted to accommodate unique application needs.

This page specializes in our CsI(Tl) crystals, with high light output, excellent gamma radiation-stopping power, and radiation hardness.  The good match with photodiode readout makes our CsI(Tl) crystals achieve the optimal results in diverse fields, including nuclear radiation detection, high energy physics, security X-radiation scanning machines, Industrial inspection, and medical equipment of Computerized Tomographic (CT) Scanning. This page is about our standard CsI(Tl) crystal materials, while Low Afterglow CsI(Tl) Scintillator Crystals are also available. You could click on the bold text to learn more.

You can move on to the tab Resources to see a comparison chart of properties of CsI, CsI(Na), and CsI(Tl).