High Resolution X-Ray Imaging with Thin SrI 2 -Scintillator Screens
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High Resolution X-Ray Imaging with Thin SrI2-Scintillator Screens Leonard Alaribe1 Alex Fauler1, Angelica Cecilia2, Tomy Dos Santos Rolo2, Michael Fiederle1,2 and Arnold Burger3 1 FMF-Freiburg Materials Research Center, Freiburg, Germany. 2 Institute for Synchrotron radiation and Photons (ISP)/Karlsruhe Institute for Technology (KIT), Karlsruhe, Germany. 3 FISK University, Nashville, USA. ABSTRACT Much has been reported on the excellent performance of the Eu2+ activated SrI2scintillator in spectroscopic applications, like the high light yield (97 660 ph/MeV) and good energy resolution (2.7% FWHM at 662 keV). The exploitation of these properties for other application fields is limited by the hygroscopic nature of the SrI2. Single crystal scintillating screens exhibit high spatial resolution, this combined with the high density, high effective atomic number, and the high light yield of the SrI2 could be used for high resolution X-ray imaging. Some of the questions we tried to answer in this work are the following: owing to the excellent performance of the SrI2-scintillator in spectroscopic applications, how would it perform in X-ray imaging applications. X-ray images are described based on their (spatial) resolution and contrast, how would they look like when recorded using the SrI2-scintillator detector. First a packaging technique was developed that protected the hygroscopic screens during the measurements. Our results show a high resolution of the images obtained with thin SrI2scintillator screens both in 2D radiography and 3D tomography measurements. With these results, we think that the SrI2-scinitillator is not only a candidate for spectroscopic applications, but also for high resolution X-ray imaging purposes. Keywords: scintillator, Bridgman crystal growth technique, X-ray imaging, image resolution INTRODUCTION The role of scintillators is very fast expanding today. Scintillators are used in homeland security, nuclear nonproliferation, national defence, high energy physics experiments, medical diagnostics and X-ray imaging applications (ie X-ray radiography and computed tomography). X-ray imaging is a technique in which X-rays from a source pass through an object and are detected by a high resolution detector based on a scintillator, diffraction limited optical system and a CCD camera. The light distribution on the scintillator is conveyed by the optical system to a CCD camera, the contrast arises from differential attenuation of x-rays in different materials. Thin single crystal scintillators with high densities, large atomic numbers, high conversion efficiency and good optical properties are very necessary in high-resolution X-ray imaging in order to solve the compromise between X-ray stopping power and spatial resolution [1]. Eu2+ activated SrI2 has excellent scintillator characteristics, but the possible areas of application are limited by its hygroscopic property.
In this work a packaging technique was developed that would protected thin SrI2-screens from humidity and also allow the recording of X-ray i
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