Heightened airport security has increased the need for greater inspection of luggage and cargo. Still the most popular method is X-ray detection with the use of silicon line detectors over passing objects on a conveyor. Silicon photodiodes themselves cannot detect X-rays as they pass right through as with most objects. Instead a scintillation material, such as thallium doped caesium iodide single crystals (Tl-doped CsI) is applied to the silicon photodiode. Incident X-rays are converted to visible light (565nm), which can in turn be detected by silicon.
A typical example of this technology is the PDB-C216 by Advanced Photonix, Inc. (API), which is a 16 element Si-PIN array utilising the CsI (Tl) scintillator. As these arrays have no borders they can be strung together to create very long arrays, suiting any conveyor width. In addition to such standard products offered by API, they also have a variety of custom-made components, including of X-ray detectors for applications in medical technology.
