CsI(Tl) or Thallium-activated Cesium Iodide crystals are among the brightest scintillator materials. Its emission peak sits at 550nm within the broad emission spectrum of 350-700nm, which matches well with photodiode readouts. And because photodiodes can be used, the sizes of the scintillator detectors can be reduced, with the additional advantage that one might need to use high-voltage supplies. Furthermore, photodiodes are less affected by magnetic fields. CsI(Tl) has a high light output of 54 photons/Kev, leading to a photoelectron yield to gamma radiations that amounts to 45% of the value of Na(I), making them one of the brightest scintillators ever known. CsI(Tl) is also well suited for detecting heavy charged particles utilizing particle pulse analysis technique as the ratio of its multiple decay time component is variant to the ionization capacity.  CsI(Tl) has a naturally larger photoabsorption cross-section compared to many other scintillator materials. This property in combination with its high radiation hardness and good stopping power made it great for applications like gamma spectroscopy and imaging.

Physically, CsI(Tl) is robust and has excellent mechanical properties because it has no cleavage plane, contributing to its reliable strength 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. However, it is worth noting that CsI(Tl) is a slow scintillator, which limits its potential when fast speed is critical.

Afterglow is defined as the fraction of scintillation light that persists for a specific time after the excitation source has stopped. In most applications, afterglow is undesirable because it can interfere with the detector’s performance. For example, in X-ray scanning, afterglow can retard the decay of illumination, leading to image blurring and reduced clarity. Low afterglow CsI(Tl) inherit high light yield from normal CsI(Tl) while restraining the afterglow phenomenon with high effectiveness, enhancing the image quality.

Shanghai North Optics offers custom Low Afterglow CsI(Tl) scintillators; the products highlight a low afterglow of 0.05~0.39% @20ms; we could tailor the value of afterglow upon your request. The products are available as CsI(Tl) blanks, polished crystals, encapsulated scintillators, CsI(Tl) arrays, CsI(Tl) array +PD assemblies, and 2-dimensional arrays upon customer's request. Our CsI(Tl) scintillation crystals and CsI(Tl) arrays feature excellent radiation hardness, high light output, and reliable robustness. Our CsI(Tl) crystals could be applied 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. 

Figure 1. shows a pair of comparison curves of the afterglow of normal CsI(Tl) and our low afterglow CsI(Tl)

Figure 2. shows a sample image obtained using our low afterglow CsI(Tl)