Keywords

Ce:GAGG, Garnet, Scintillation, Monte-Carlo, Simulation

Abstract

Cerium-doped Gadolinium Aluminum Gallium Garnet (Ce:GAGG) is a rugged scintillator material renowned for its high light output, fast luminescence decay, good stopping power, and energy resolution, making it an ideal candidate for gamma radiation detection. Its optically isotropic crystalline structure enables the fabrication of transparent optical ceramics, effectively addressing certain limitations associated with single-crystal growth. However, the production of highly transparent ceramics often involves costly processing methods with low overall yield. Reactive sintering offers a more economical alternative, but as with other processing techniques, the elimination of scattering centers—such as porosity and secondary phases—remains a significant challenge. These defects hinder the production of optically superior materials and impede wider adoption. Despite efforts to address these issues, the precise impact of microstructural defects on scintillation performance remains insufficiently understood. This thesis investigates the relationship between ceramic microstructure, optical quality, and scintillation performance in Ce:GAGG ceramics synthesized via reactive sintering. A series of GAGG samples with cerium doping between 0.1 and 10 at% was prepared using solid- state powder processing under varied conditions to achieve reduced levels of optical scattering. Radioluminescence characterizations indicate that while increased cerium concentration reduces luminescence intensity, it accelerates decay kinetics. Using absorption spectra measured by spectrophotometry alongside GEANT4 Monte-Carlo simulations, the reduction in optical transport efficiency due to cerium's self-absorption is estimated to be less than 10%. Scattering centers within the ceramics were successfully minimized by compositional balancing of cationic site ratios, resulting in materials with Fresnel limited optical transmission (80% transmission). Although bulk optical scattering is identified as the dominant factor affecting performance, near-opaque materials experience optical transport efficiency loss of no more than 46%. The findings of this thesis highlight the potential for substantial cost savings in the fabrication of scintillator ceramics for radiography with trade-offs such as optical quality and transport performance.

Completion Date

2025

Semester

Spring

Committee Chair

Gaume, Romain

College

College of Optics and Photonics

Department

CREOL, The College of Optics and Photonics

Identifier

DP0029272

Document Type

Dissertation/Thesis

Campus Location

Orlando (Main) Campus

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