Engineering Commons^™

Development Of Metal Halide Perovskites For Radiation Detection, Ryan Tan

Doctoral Dissertations

Metal halide perovskite (MHP) semiconductors have attracted significant interest in recent years within photovoltaic and radiation detection communities due to their inexpensive solution growths, high effective atomic number for gamma and X-ray sensing, suitable bandgap, large resistivity, and moderate mobility-lifetime products. The MHP stoichiometry can also be tuned as needed to achieve desired physical and electronic properties. Moreover, the hybrid or organometallic halide perovskite (OMHP) variants contain a large atomic fraction of hydrogen for fast neutron sensing. These qualities make MHPs an attractive low-cost option for meeting detector needs within nuclear security and imaging applications. This work presents the development …

Development Of Codoped Cesium Iodide Scintillators For Medical Imaging Applications, Everett M. Cavanaugh

Masters Theses

Cesium iodide has a rich history of use as a scintillating material. CsI finds use in a variety of fields, but it is primarily used in radiography, tomography, and geological exploration. Of the three common variants of CsI, thallium doped CsI is by far the most widely used among these applications. It possesses favorable physical characteristics like a high density and high effective Z and exhibits high light output at room temperature. Despite how great CsI scintillators may be on paper, they have an Achilles heel: afterglow. CsI:Tl has significant afterglow which leads to imaging artifacts that can be difficult …

Radiation Effects On Lithium Indium Diselenide Semiconductors As Neutron Imaging Detectors, Robert M. Golduber

Masters Theses

The studies presented in this work aim to improve upon the knowledge base of lithium indium diselenide (LISe) semiconductors to understand how the material behaves in high radiation environments and refine the process of turning it into a neutron detector. LISe has great potential as neutron imaging detector because of the high neutron absorption efficiency of its enriched ⁶Li component and its ability to discriminate between gamma-rays and neutrons. Its ability to remain functional after being irradiated with large amounts of neutron fluence has been tested and the change in its electro-optical properties with relation to fluence has been …

Fabrication Of Specialized Scintillators For Nuclear Security Applications, Cordell James Delzer

Doctoral Dissertations

Radiation detectors are important for a variety of fields including medical imaging, oil drilling, and nuclear security. Within nuclear security, they can serve a multitude of purposes whether that be imaging, localization, isotopic identification, or even just activity measurement. Even without directly seeing a nuclear material it is often able to notice their existence without a detector. Scintillators make up an important part of these detectors due to their large intrinsic efficiency, low cost, large volume, and relatively low upkeep. Due to the importance of the large number of purposes these scintillators may be used for, it can often be …

Distributed Sensor Network Data Fusion For Nuclear Security Applications, Ian Robert Stewart

Doctoral Dissertations

Detecting, locating, and interdicting radiological materials out of regulatory control or that pose a threat to the general public remains a high national security priority. Conventional methods employed a radiation detection system to detect radiological materials and alert the appropriate authorities for interdiction procedures. More recently, the concept of operations has focused to deploying multiple radiation detection systems to detect and track radiological materials, providing more detail to aid end-users during the interdiction process. The research proposed in this document utilizes data from a distributed sensor network to detect and track radiation anomalies through a network. The primary original contributions …

An Exploration Of The Optical Detection Of Ionizing Radiation Utilizing Modern Optics Technology, Sean D. Fournier, Adam Hecht, Cassiano De Oliveira, Jeffrey B. Martin, Richard K. Harrison, Charles Potter

Nuclear Engineering ETDs

Modern ultraviolet (UV) cameras, when combined with UV-transmitting lenses/filter arrangements, can be used to detect radiation dose in air. Ionizing radiation excites nitrogen molecules in ambient air, the resulting decay includes weak emission of ultraviolet photons. Previous work has proven this phenomenon is detectable using highly-sensitive electronically cooled cameras traditionally used in astronomy for low-background imaging. While the ability to detect the presence of radiation (i.e. qualitative measurement) has been demonstrated at Sandia National Laboratories, there are several challenges in correlating images to known dose-fields (quantitative measurement). These challenges include: a low signal to background ratio, interferences due to electronic …

Proactive Strategies In Personal Dose Monitoring, Prevention And Mitigation, Manish Kumar Sharma

Doctoral Dissertations

"At certain threshold, nuclear radiation (like x-rays and gamma-rays) may adversely impact the health of living tissues. The exposure to these radiations in nuclear facilities is measured by devices called dosimeters. The devices are generally worn on the torso and are monitored by health physics division to report the radiation dose received by the personnel. However, this approach is not proactive--since the dosimeters reflect the dose that has already been absorbed in the body of the wearer.

This work presents a scheme to proactively avoid large dose acquisition at radiation-prone facilities. The work was divided into three major segments: (i) …