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Theses

Étude et optimisation de matériaux scintillateurs pour l'imagerie médicale

Abstract : This work is dedicated to the comprehension of the scintillation mechanisms in LYSO:Ce single crystals and in Gd2O2S:Pr and LuGdO3:Eu dense ceramics, and to the optimization of their scintillation properties. For medical imaging applications, a high stopping power of X and  rays, a high light yield, fast response time and a low afterglow are amongst the main requirements. Threw the comprehension of the involved mechanisms we have evidenced that point defects (anionic vacancies for LYSO:Ce and Gd2O2S:Pr, and interstitial oxygen for LuGdO3:Eu) are responsible for decreasing the scintillation performances of the studied compounds. Two routes were deepened for optimizing these scintillators: co-doping and annealing. Co-doping LYSO:Ce single crystals with Ca2+ or Mg2+ leads to a significantly improved light yield and afterglow, while also stabilizing part of the doping ions as Ce4+ with an efficient charge compensating mechanism. Air annealing also leads to improved scintillation. The afterglow of LuGdO3:Eu can be significantly reduced when co-doping with Ce3+,Pr3+ or Tb3+. Finally, annealing Gd2O2S:Pr ceramics in a sulfur-rich atmosphere was evidenced as the most promising way to reduce the afterglow without degrading the light yield.
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https://pastel.archives-ouvertes.fr/pastel-00647841
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Submitted on : Friday, December 2, 2011 - 5:44:50 PM
Last modification on : Wednesday, October 14, 2020 - 4:06:51 AM
Long-term archiving on: : Saturday, March 3, 2012 - 2:35:52 AM

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  • HAL Id : pastel-00647841, version 1

Citation

Samuel Blahuta. Étude et optimisation de matériaux scintillateurs pour l'imagerie médicale. Chimie inorganique. Université Pierre et Marie Curie - Paris VI, 2011. Français. ⟨pastel-00647841⟩

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