Doctoral Dissertations

Date of Award

8-2021

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Nuclear Engineering

Major Professor

Howard L. Hall

Committee Members

Lawrence Heilbronn, Laurence Miller, James Bogard

Abstract

The focus of this work was to examine the thermoluminescence (TL), phototransferred thermoluminescence (PTTL), and optically stimulated luminescence (OSL) properties of the protective glasses utilized in modern smartphones and establish the ability to, after a radiation exposure, correlate the absorbed dose measured in a smartphone to that received by an individual carrying it. The primary reason for investigating the protective glasses is that their removal doesn’t completely incapacitate the phone, which is not true of methods utilizing other smartphone components, such as the display glass or surface-mount resistors (SMRs), and in the case of OSL, could potentially be used in an in-situ measurement technique. A significant background signal (BGS) contribution that could not be removed was observed during the TL and PTTL analyses, attributed to the use of UV light curing by the manufacturers, that greatly impacted the dose reconstruction process due to significant overlap with the radiation-induced signal (RIS). These results motivated the investigation of the protective glasses by means of OSL, where it was observed that the samples were not encumbered by any such BGS, making it the more encouraging luminescence technique to employ. The only drawback to utilizing an OSL technique is that the signal is susceptible to deterioration or complete erasure from light exposure; however, a recent study has shown that over 75% of smartphone users equip their devices with some form of protection. Therefore, for the devices outfitted with opaque cases or otherwise stored in the dark, utilizing an OSL technique on the protective glasses was shown to be a viable emergency dosimetry method. Previously, the majority of research focused on assessing the dose to the phone component itself, while, in reality, the dose to the individual is the most crucial to performing triage. Therefore, numerous irradiations were performed on an anthropomorphic phantom, equipped with smartphones, to calculate the conversion factors from the phone components (SMRs v and protective back glasses in this study) to the individual carrying them. The resultant factors were observed to be heavily influenced by the phone’s location and exposure geometry due to shielding from the body and exposure angle.

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