Excitons in scintillator materials: Optical properties and electron-energy loss spectra of NaI, LaBr 3 , BaI 2 , and SrI
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Xiao Zhang Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
Qi Li Physical Sciences Division IBM TJ Watson Research Center, NY 10598, USA; and Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
Paul Erhart Department of Applied Physics, Chalmers University of Technology, Gothenburg SE-412 96, Sweden
Daniel Åbergb) Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (Received 1 July 2016; accepted 5 October 2016)
Materials for scintillator radiation detectors need to fulfill a diverse set of requirements such as radiation hardness and highly specific response to incoming radiation, rendering them a target of current materials design efforts. Even though they are amenable to cutting-edge theoretical spectroscopy techniques, surprisingly many fundamental properties of scintillator materials are still unknown or not well explored. In this work, we use first-principles approaches to thoroughly study the optical properties of four scintillator materials: NaI, LaBr3, BaI2, and SrI2. By solving the Bethe–Salpeter equation for the optical polarization function we study the influence of excitonic effects on dielectric and electron-energy loss functions. This work sheds light into fundamental optical properties of these four scintillator materials and lays the ground-work for future work that is geared toward accurate modeling and computational materials design of advanced radiation detectors with unprecedented energy resolution. Prof. Dr. rer. nat. André Schleife received his Ph.D. in physics at Friedrich-Schiller-University in Jena, Germany on realstructure effects on electronic and optical properties. He then moved to the US to pursue research on non-adiabatic electronion dynamics as Directorate Postdoctoral Researcher at Lawrence Livermore National Lab. There, he developed a massively parallel implementation of Ehrenfest dynamics and extensively learned high-performance computing.
André Schleife
Developing and using predictive computational techniques to understand the quantum-mechanical electron–electron interaction in materials is his main focus for more than nine years. He studied excited-state properties, quasiparticle band structures, spin–orbit coupling, densities of states, band alignments, and optical-absorption spectra in strained, doped, and non-equilibrium crystals, alloys, point defects, inclusions, surfaces, nitrides, and scintillators. He is recipient of the NSF CAREER award and as Blue Waters Assistant Professor currently builds a group in computational materials science, centered around excited quantum-mechanical states, non-adiabatic electron–electron and electron–ion dynamics, and covering multiple length and time scales to transfer first-principles insight to real-world applications.
I. INTRODUCTION
Scintillator radiation detectors have many important applications in the context of high-energy physics, medicine, as well as homeland secu
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