Barrett, The Honors College Thesis/Creative Project Collection

Advances in photoinjector technology have given rise to applications such as XFELs, UED, and UEM. Brighter electron beams from the source increase pulse energies and photon lasing energies for XFELs, as well as an increase in coherence lengths at femtosecond timescales on the Ultrafast Electron technologies. Deeper investigations of the photoemission process have placed stringent requirements on electron sources for next generation electron accelerator technology, and certain novel photocathode sources have been identified as candidates to satisfy these required specifications. At Arizona State University, a cryogenically cooled 200 kV DC electron gun and accompanying photocathode diagnostics beamline was developed and conditioned specifically to implement these novel photocathodes and provide diagnostics for their performance.

In this project, we aim to fabricate PIN structure-like diodes for radiation detectors using Boron Nitride (BN). This fabrication is done by performing lithography and metal deposition processes on a Cubic Boron Nitride (cBN) of around 200 nm in thickness layer on top of a boron doped diamond substrate. The main goal is to create the most efficient and affordable alpha particle—and ideally neutron—detector in a radiation setting. Thus, making more accessible radiation detectors that can be more easily produced and disposed of, as well as minimizing the size of conventional detectors.

Most asteroids originated in larger parent bodies that underwent accretion and heating during the first few million years of the solar system. We investigated the parent body of S-type asteroid 25143 Itokawa by developing a computational model which can approximate the thermal evolution of an early solar system body. We compared known constraints on Itokawa’s thermal history to simulations of its parent body and constrained its time of formation to between 1.6 and 2.5 million years after the beginning of the solar system, though certain details could allow for even earlier or later formation. These results stress the importance of precise data required of the material properties of asteroids and meteorites to place better constraints on the histories of their parent bodies. Additional mathematical and computational details are discussed, and the full code and data is made available online.

This thesis focuses on how domain formation and local disorder mediate non-equilibrium order in the context of condensed matter physics. More specifically, the data supports c-axis CDW ordering in the context of the rare-earth Tritellurides. Experimental studies were performed on Pd:ErTe3 by ultra-fast pump-probe and x-ray free electron laser (XFEL). Ginzburg Landau models were used to simulate domain formation. Universal scaling analysis on the data reveals that topological defects govern the relaxation of domain walls in Pd:ErTe3. This thesis presents information on progress towards using light to control material domains.

Growing interest in using volatile organic compounds (VOCs) as markers of biological function and health has highlighted the need for a standardized method to analyze gas metabolites released by biological organisms. Non-destructive VOC collection techniques have emerged, allowing researchers to study diseases over time without compromising the sample. However, continuous sampling is often not performed, and previous systems have not undergone rigorous testing. To overcome current limitations, we developed a gas flow-based device and tested it for consistent headspace sweeping, cell viability and morphology, and detection accuracy. The results showed that the device offers a high degree of reproducibility, and our modeling shows that laminar flow conditions are maintained at experimental gas flow rates, ensuring consistent headspace sweeping. Furthermore, our modular design allowed us to adjust the temperature and input gas, allowing us to maintain a favorable environment for cell culture. Isotopic labeling and heavy VOC production confirmed that the system achieves sufficient sensitivity and reproducibility to monitor metabolic changes across time. This comprehensive evaluation demonstrates that our flow-based device has great potential in further research and subsequent clinical applications.

Hepatocellular Carcinoma (HCC) is one of the main types of liver cancer accounting for 75% of cases and is the second deadliest cancer worldwide. Chronic Hepatitis B (HBV) and Hepatitis C (HCV) remain one of the most important global risk factors and account for 80% of all HCC cases. HCC also exhibits sex-differences with significantly higher incidence and worse prognosis in males. The mechanistic basis of these sex-differences is poorly understood. To identify genes and pathways that are sex-differentially expressed in viral-mediated HCC, we performed differential expression analysis on tumor vs. tumor adjacent samples that were stratified based on sex, viral etiology, and both. The differentially expressed genes were then used in a pathway enrichment analysis to identify potential pathways of interest. We found differentially expressed genes in both sexes and both etiologies. 65 genes were unique to females and 184 genes unique to males. 381 genes are unique to HBV and 195 genes are unique to HCV. We also found pathways that were significantly enriched by the differentially expressed genes. Ten pathways unique to the female tumor tumor-adjacent comparison and a majority of those pathways were a part of the cell cycle. Four enriched pathways unique to male tumor tumor-adjacent and three of them were a part of the immune system. There were no pathways unique to either etiology, but seven pathways shared by both etiologies. Two were a part of the cell cycle and one involved lipid metabolism. These differentially expressed genes and significant pathways are potential targets for individualized therapeutics and diagnostics for HCC.

Startups in the paper manufacturing industry are few and far between. Agrix paper takes a step towards innovating the traditional mass-scale paper making process and introduces non-wood fiber sourcing into the papermaking space. Using a hemp fiber base, Agrix Paper hopes to develop a new paper manufacturing process that derives high-quality paper sourced from hemp and agriculture waste. Agrix Paper will reinvent the papermaking process for a more green and sustainable future.

Studying the so-called ”hidden” phases of quantum materials—phases that do not exist under equilibrium conditions, but can be accessed with light—reveals new insights into the broader field of structural phase transitions. Using terahertz irradiation as well as hard x-ray probes made available by x-ray free electron lasers (XFELs) provides unique capabilities to study phonon dispersion in these materials. Here, we study the cubic peak of the quantum paraelectric strontium titanate (SrTiO3, STO) below the 110 K cubic-to-tetragonal tran- sition. Our results reveal a temperature and field strength dependence of the transverse acoustic mode in agreement with previous work on the avoided crossing occurring at finite wavevector, as well as evidence of anharmonic coupling between transverse optical phonons and a fully symmetric A1g phonon. These results elucidate previous optical studies on STO and hold promise for future studies on the hidden metastable phases of quantum materials.

The self-assembly of strongly-coupled nanocrystal superlattices, as a convenient bottom-up synthesis technique featuring a wide parameter space, is at the forefront of next-generation material design. To realize the full potential of such tunable, functional materials, a more complete understanding of the self-assembly process and the artificial crystals it produces is required. In this work, we discuss the results of a hard coherent X-ray scattering experiment at the Linac Coherent Light Source, observing superlattices long after their initial nucleation. The resulting scattering intensity correlation functions have dispersion suggestive of a disordered crystalline structure and indicate the occurrence of rapid, strain-relieving events therein. We also present real space reconstructions of individual superlattices obtained via coherent diffractive imaging. Through this analysis we thus obtain high-resolution structural and dynamical information of self-assembled superlattices in their native liquid environment.

In nuclear physics, there is a discrepancy between theory and experiment concerning the number of existing nucleon resonances. Current models predict far more states than have been observed. In particular, few searches have found excited nucleon resonances with energies above 2.2 GeV in the K Lambda channel. To investigate high-mass nucleon resonances, efficiency-corrected yields of the reaction ep --> e K+ Lambda(1520) --> e K+ K- p in the center-of-mass energy range 2.1-4.5 GeV are constructed utilizing Jefferson Lab's CLAS12 detector. This paper presents the results of an analysis searching for high-mass nucleon resonances in the K Lambda channel between 2.1-4.5 GeV.