Crystal scintillator play an important role in many fundamental researches and applications such as nuclear and high energy physics experiments, medical imaging, radiation monitoring, well logging, nuclear non-proliferation and homeland security. High performance scintillator is highly demand for the development of these applications. The requirements for an idea scintillation crystal are high light output, good energy resolution, high effective atomic number and density, non- hygroscopic, possible of large size crystal growth, good linearity and low cost.
Scintillation crystals can be device into two group depending on their composition; oxide-based and halide-based scintillators. Oxide-based scintillators usually have the advantage of high density, high mechanical strength and non- hygroscopic but they have poor light output, energy resolution and elevated melting point. In contrast, commercially available halide crystals are high light output, good energy resolution and low melting point, but they usually possess lower effective atomic number, density strength and hygroscopic that requires special equipment to handle.
The purpose of this research is to develop new efficient scintillators by replacing alkali ion in alkali halide compounds with heavy Tl ion. By this way, we enhance the effective atomic number of halide crystal which is one of the drawbacks of halide scintillator for X- and γ-rays detection. Materials with high effective atomic number is desire for high energy physics experiments and capable to develop a compact detector for many other applications. In this work, we study crystal growth, luminescence and scintillation properties of intrinsic Tl2HfCl6 and Tl2ZrCl6 scintillation crystal. The effective atomic number of Tl2HfCl6 and Tl2ZrCl6 are 72 and 69 respectively which are compatible with that of oxide-based scintillators. The crystals were grown from the melt by using in-house developed Bridgman furnace. Both materials have cubic structure, which is desirable for a large size crystal growth. Pulse shape discrimination capability of THC and TZC crystal were also investigated for α-particles and γ-rays by using several methods. These scintillators can be considered for many applications in the field of radiation detection due to its novel scintillation performance and pulse shape discrimination capability.
Thesis Advisor: Prof. Hongjoo Kim