Abstract
Scintillators are high-density luminescent materials that convert X-rays to visible light. Thallium doped cesium iodide (CsI:Tl) scintillation materials are widely used as converters for X-rays into visible light, with very high conversion efficiency of 64.000 optical photons/MeV. CsI:Tl crystals are commercially available, but, the possibility of developing these crystals into different geometric shapes, meeting the need for coupling the photosensor and reducing cost, makes this material very attractive for scientific research. The objective of this work was to study the feasibility of using radiation sensors, scintillators type, developed for use in imaging systems for X-rays. In this paper, the CsI:Tl scintillator crystal with nominal concentration of the 10-3 M was grown by the vertical Bridgman technique. The imaging performance of CsI:Tl scintillator was studied as a function of the design type and thickness, since it interferes with the light scattering and, hence, the detection efficiency plus final image resolution. The result of the diffraction X-ray analysis in the grown crystals was consistent with the pattern of a face-centered cubic (fcc) crystal structure. Slices 25 × 2 × 3 mm3 (length, thickness, height) of the crystal and mini crystals of 1 × 2 × 3 mm3 (length, thickness, height) were used for comparison in the imaging systems for X-rays. With these crystals scintillators, images of undesirable elements, such as metals in food packaging, were obtained. One-dimensional array of photodiodes and the photosensor CCD (Coupled Charge Device) component were used. In order to determine the ideal thickness of the slices of the scintillator crystal CsI:Tl, Monte Carlo method was used.
Highlights
X-rays were first discovered by Wilhelm Roentgen in Germany, in 1895 [1]
In order to determine the ideal thickness of the slices of the scintillator crystal cesium iodide (CsI):thallium doping element (Tl), Monte Carlo method was used
The experiments demonstrated that the crystal of cesium iodide doped with thallium grown in our laboratory showed good results, when used in imaging equipment with X-rays
Summary
X-rays were first discovered by Wilhelm Roentgen in Germany, in 1895 [1]. The constant and increasing number of applications of X-rays in many fields of human activity has stimulated the research in scintillation materials. There has been a rise in this field, over the last 10 years, induced by new demanding applications of medical, industrial and scientific imaging together with the development and exploitation of powerful X-ray sources, such as synchrotron radiation. Intense research and development [2] [3] have continued, looking for new scintillation materials or the optimization of the current ones, taking advantage of new technological methods for their preparation. Understanding the underlying physical mechanisms of energy transfer and storage and the role of particular material defects is of crucial importance for bringing the materials performance close to their intrinsic limits. Further progress in the achievement of the ideal detector design is related to the rapid development in the field of photodetectors, which are an indispensable part of scintillation detectors [4]
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