Event Details

A talk in 2 parts: the first part provides a high-level overview of U.S. activities in the field of nuclear energy; the second part focuses on inorganic scintillation detectors used for gamma-ray counting and energy spectroscopy.

This talk will be of interest not only to staff and students in Engineering and Nuclear, but also to colleagues and students in Chemistry and Physics with an interest in inorganic nanoscale materials for nuclear applications, as well as those interested in energy policy and US activities in the field of nuclear energy.

ABSTRACT: This talk will consist of two parts. The first part will provide a high-level overview of U.S. activities in the field of nuclear energy, while the second part of the talk will focus on inorganic scintillation detectors used for gamma-ray counting and energy spectroscopy. Inorganic scintillators are widely used for various radiation detection applications, including nuclear nonproliferation and safeguards, medicine, space exploration, and fundamental physics. Typically, they have a good energy resolution, stable performance, somewhat low cost, and relatively high gamma detection efficiency. However, many inorganic scintillators have high refractive indices and therefore suffer from significant light losses due to the light phenomenon called the total internal reflection (TIR). This research project investigates using optimized, two-dimensional, periodic nanostructures called photonic crystals (PHCs) to aid in recovering some of the TIR-driven light loss. PHCs can create, via constructive interference of electromagnetic light waves, an improved optical coupling between a scintillator and photosensor for the trapped light, thereby improving the overall light extraction, collection, and consequently the light output (LO). Improving the LO of an inorganic scintillator leads to enhanced energy and time resolution, which in turn allows for an extended range of radiation detection applications for inorganic scintillators. LYSO scintillator was chosen for the initial PHC-coating efforts because it has higher light yield and energy resolution than BGO while being hygroscopic, which substantially simplifies the PHC-manufacturing process. A PHC-coating method was developed for the LYSO scintillation material with Si3N4 through the e-beam lithography and ion etching. The radiation measurements show a LO improvement of up to 28% and up to 13% in energy resolution for the best performing PHC coating for 10 x 10 x 3 mm3 LYSO scintillators.

SPEAKER - Dr. Marek Flaska is Associate Professor of the Ken and Mary Alice Lindquist Department of Nuclear Engineering at the Pennsylvania State University. Dr. Flaska earned his Ph.D. in Applied Physics from Delft University of Technology in 2006, and he has expertise in computational and experimental radiation transport focused on fundamental and applied radiation detection. His current research projects encompass nuclear nonproliferation, safeguards, forensics, novel radiation sensing systems and sensor materials development, and fundamental and health physics applications. In the past, Dr. Flaska served as the Associate Department Head and Director of Graduate Studies for his current department, and he has many years of experience collaborating on large multi-institutional projects, such as DOE’s NNSA Consortia (CVT and MTV) and DOD’s DTRA Alliance (IIRM-URA).