Session E01: Poster Session

Single-Mode Microwave Impact on the Grain Boundaries and Ionic Conductivity of LAGP for Solid State Battery Applications.

LAGP is a glass-ceramic with potential to be utilized as a solid-state electrolyte in Li-Ion batteries, although its utilization has been slowed by low ionic conductivity. Research has shown that grain boundaries can have a significant impact on a solid-state electrolyte's ability to transport ions and may be modified by methods ranging from thermal sintering to spark plasma sintering, among others. In many ceramic systems, microwave processing has been demonstrated to lower the sintering time while also affecting grain growth, but little study has been done on the resulting impact on ionic transport. We initiate a study of the impact of single mode microwave processing on grain development in LAGP. The effect of microwave interaction with LAGP is discussed with respect to the grain structure and underlying transport mechanisms.   

Low-Temperature Plasma Synthesis of Cubic Boron Nitride

Low-temperature plasma synthesis of cubic boron nitride (cBN) coatings on diamond seeded silicon substrates was carried out in a microwave plasma chemical vapor deposition (MPCVD). Low-temperature plasmas (LTP) are severely non-equilibrium systems that use free electrons to create a novel physical and chemical environment at low gas temperatures. In MPCVD, hydrogen (H₂), argon (Ar), a mixture of diborane in H₂ (95% H₂, 5% B₂H₆), and nitrogen (N₂) were used as the feed gas. A direct current (DC) bias system was used to externally bias the sample negatively where the MPCVD chamber wall was grounded. The presence of sp³ bonded BN in the synthesized coatings was demonstrated by X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR). The cBN content in the coating increases with increasing Ar flow, reaching a maximum at the maximum Ar flow of 400 sccm used in this study. High-resolution XPS scans for B1s and N1s indicate that the deposited coating contains more than 70% cBN. The surface roughness of the BN coatings was also measured using Atomic Force Microscopy (AFM). This study found that energetic argon ions generated in microwave-induced plasma are beneficial for cBN formation in MPCVD.

    

Detection of Heavy metals in soil samples of Birmingham urban area using Laser Induced Breakdown Spectroscopy

Chronic Obstructive Pulmonary Disease (COPD) is one of the leading causes of death in the USA, which could be triggered by inhaling heavy metals (such as Pb and Mn) transported via dust. Heavy metal and other toxic chemical pollution from open quarries, steel mills, coal-fired power stations, and coke furnaces has been a concern in North Birmingham for a long time and continues to be a problem today. Laser-induced breakdown spectroscopy (LIBS) is a notable analytical method that offers low cost, minimum sample preparation, and real-time soil characterization available for investigations. An Nd:YAG laser operating at 1064 nm (20 Hz repetition rate, up to 100 mJ pulse energy per pulse) and an Echelle spectrometer with an ICCD detector were utilized in these experiments. The soil samples collected from three different sites in Birmingham are analyzed. The detection threshold for heavy metal content in soil samples was 95 ppm.   

RHOK-SAT: A 1U CubeSat to Characterize Novel Photovoltaics in LEO

RHOK-SAT is a 1U CubeSat collaboration between Rhodes College and the University of Oklahoma’s Photovoltaic Materials and Devices group. The satellite is planned for launch in late 2023 or early 2024. The project’s primary mission is to provide real-world engineering experience to students at Rhodes College, a liberal arts institution with no formal engineering program. Students developed teams to divide labor and learn different aspects of the project. The payload team focuses on the structural and electrical components of the satellite. RHOK-SAT’s secondary mission is to characterize the performance and degradation of novel perovskite photovoltaic cells in Low Earth Orbit. RHOK-SAT’s payload will consist of 36 experimental perovskite cells, one control CIGS cell, eight measurement microcontrollers, 12 multiplexers, seven temperature sensors, and one sun sensor. The sun sensor was developed and constructed in-house from a  quad-photodiode and a square aperture above the active diode areas. The sun sensor will determine the angle of incident sunlight on the payload face of the satellite. This presentation will overview the payload development and its next steps.   

Automated Gantry Test Bed for the Characterization and Development of Gamma-Radiation Detection Platforms

Uranium-238 or more colloquially known as depleted uranium (DU) and its subsequent

decay products can pose a public health hazard as well as environmental damage through

the emission of gamma radiation. DU and its hazardous decay products are most commonly

found at the surface in areas where munitions training and nuclear weapons development are

taking place. These sites are large in area, so the resulting creation of high volume low-level

waste created presents a time intensive, financially expensive and over-burdening of resources

to dispose of. Consequently, identifying DU with quality data and decreasing false positives in

the results assists regulators in the decision making process to reduce the volume of low-level

waste. An automated system to locate DU, is being developed and characterized, utilizing a

gantry system above a sandbox test bed through a mounted movable Germanium Gamma-ray

Imager (GeGI). A data acquisition program has been developed to fully automate the detec-

tor’s movement, position, and initiation of data collection using LabVIEW systems engineering

software. An automated simulated observational environment for the development and char-

acterization of autonomous robotic platforms to search for and identify radioactive material

has been developed and is discussed. User-inputted parameters can control the position and

data collection time per position through the use of a pulse generation technique to control

the GeGI’s own external data acquisition. All of which are controlled through the LabVIEW

program’s user interface. Further a graphical user interface (GUI) has been streamlined for the

use of the newly developed automated features of the gantry test bed in a laboratory-controlled

environment. All of the user interactions through the LabVIEW program, including the initi-

ation of data collection, can be limited to same computer system on which the GeGI itself is

operating from. Opening the door for future autonomous robotic systems development and

characterization beyond the in-laboratory sand box test bed. The developed system will be

used to characterize radiological detection technologies to be deployed on radiological surveying

systems   

Microrobot Fabrication and Characterization

Microtechnology is becoming increasingly relevant in our everyday lives. To account for this shift in technological advancements, we are developing a microrobot factory to manipulate objects at the nano and micro scale. An important part of this factory is a reliable transportation system that can carry a payload to other microrobots. This study explores a new method of tracking a payload-carrying micro robotic crawler, the SolarPede. The microrobot uses 8 electrothermal Micro Electro Mechanical System (MEMS) actuators connected to 4 assembled legs consisting of 600-micron spheres. Leg motion is controlled via a microcontroller producing small 15 V electric pulses that move the actuators via thermal expansion. The design of the actuators was specifically chosen to actuate in only one direction and an appropriate gait combination of these actuators allows the SolarPede to have omnidirectional movement. During this project, we implemented a randomization algorithm for the gait pattern of the microrobot that can be combined with a microscope camera tracking system and machine learning to automatically adjust its gait pattern to guide a payload to its destination. The implementation of these algorithms improved the amount and reliability of gait data compared to previously tested manual signal generation and visual tracking. In the future, machine learning algorithms will be experimentally tested for the SolarPede, leading to its controlled and precise movement in the micro-factory.   

Need for Advanced Radiation Detection Simulations for Nuclear Decomissioning Applications

The Institute for Clean Energy Technology (ICET) at Mississippi State University has a history of developing semi-autonomous radiological surveying systems for assisting government agencies clean sites contaminated with radioactive materials. Data from radiation detectors are synced with GPS-registered data as the robotic platforms systematically scan areas of concern for radiological materials. These data are used to construct heat maps of residual contamination after the radiation data is converted to residual activity concentration (Bq/g) in soil. Current governmental guidance on calculating minimum detectable concentration (MDC) of residual contamination relies on using exposure-rate data from point-kernel simulations (Microshield^®) of the detector-source geometry, detector response measurements within calibrated radiation fields, background radiation measurements, and known physical properties of the detector. These data are combined to calculate the theoretical lower limit of detectable residual contamination. Current simulation tools are off-the-shelf software packages that are geared for site personnel to operate without an extensive background in software development. These simulations are rooted in International Commission on Radiological Protection (ICRP) published methods. ICRP methods are geared toward the safety and protection of radiation workers and are not necessarily intended to be used for simulating detector-source geometries. Currently, the United States Nuclear Regulatory Commission technical reports site using these simulations, but more advanced Monte Carlo methods can be more appropriate. Due to the advanced nature of the surveying technology being developed at ICET, advanced Monte Carlo simulations are required to address deficiencies in simulation detector-source geometries. There is also a need to develop methods for conducting experiments in simulation to reduce the risk of exposing staff unnecessarily to ionizing radiation. This work describes the current state of simulation and characterization methods in the nuclear decommissioning industry, associated limitations, and most importantly, the need for a more robust simulation package.   

Approximate helical symmetry at null infinity

Compact binary systems emit gravitational radiation that has an approximate helical symmetry at future null infinity. The symmetry is broken due to the effect of radiation reaction, precession, and eccentricity. We use the post-Newtonian formalism to find the level of failure of this symmetry for such effects. The flux due to the helical vector field assesses the departure from symmetry. This flux is analytically predicted and compared using the NR waveforms of the SXS catalog. In the case of waveforms with low eccentricity, the flux is used to get an instantaneous definition of eccentricity.   

Measuring the Position Angle and Separation of WDS 13550-4235 & WDS 14082+3645

Measurements were made for the binary star systems WDS 13550-4235 and WDS 14082+3645 to find the position angle and separation of each star system's primary and secondary components. Images were obtained from the Las Cumbres Observatory Global Telescope Network using the 0.4-meter telescopes. The measured separation of WDS 13550-4235 is 13.573″ +/ -0.103″, and the position angle is 6.9° +/- 0.4°. The measured separation of WDS 14082+3645 is 9.7″ +/- 0.3″, and the position angle is 70.95° +/- 1.04°. These measurements were compared to Stelle Doppie and are consistent with past measurements.

In addition, images were collected of the tertiary component of the triple star system WDS 14082+3645 for speckle interferometry analysis at Mount Wilson Observatory using the 60-inch telescope. The measured separation is 1.588″, and the position angle is 209.35°.   

The New Structure for Black Holes and their Nature

A black hole is an object in the Universe where gravity is so extreme which escaping from that is impossible. Most black holes have been discovered by using the effects of their gravitational fields, and scientists have so far been unable to provide a structure for black holes due to the inability of particles escaping from black holes.

In this paper, we are going to explain a logical structure for black holes that is consistent with the observations about them.

Knowing that the density of a black hole is high, we can conclude that in a black hole there is a compact set of protons and neutrons that it creates such a high density and taking into account that a black hole has a surrounding area and this area can be oceans of protons and neutrons. One can also imagine the black hole as an extremely large atom whose nucleus is made of protons and neutrons and an ocean of protons and neutrons and electrons revolving around it.   

Gravitational Phase Transition in the Early Universe

The universe is a dynamic system. Recently there has been much interest in examining gravity as an emergent phenomena. Cosmologies where the gravitational constant is allowed to vary with the scale factor are considered. The gravitational parameter is modeled as a sigmoid-type function relating to qubits on a holographic screen that describes the information content of the three-dimensional universe encoded on a two-dimensional boundary surface. Kaniadakis and Tsallis deformed fractal statistics are employed in order to describe the interaction between the qubits on the holographic screen. When the qubits are in a highly symmetric state at the beginning of time, the gravitational parameter is repulsive; when the qubits on the holographic screen become more disorganized, the gravitational parameter undergoes a type of phase transition and becomes attractive. The scale factor as a function of time will be examined as well as the quantum properties of the early universe.   

Characterizing and Developing a Shape Model for a Potentially Hazardous Asteroid.

This study entails the development of a 3-D shape model for potentially hazardous asteroid (PHA), 68950 2002QF15 (QF15), using the combination of ephemeris points, optical and near-infrared lightcurves and radar observations. Apollo class asteroid, QF15 was discovered on August 27th, 2002, by the LINEAR project at the Lincoln Laboratory experimental test site in Socorro, New Mexico. In 2019, the near-Earth asteroid (NEA) made its nearest approach to Earth at approximately 0.08825 astronomical units (AU). The Arecibo Observatory (AO) monitored the near-Earth flyby with the 305-meter (m) telescope using an S-band radar system (2830 MHz). The AO carried out 7 radar observations of QF15, spanning from May 20th, 2019 – June 5th, 2019. In addition, 15 optical lightcurve profiles, for QF15, were obtained by the Center of Solar System Studies-Palmer Divide Station (CS3-PDS), spanning several days between June 1st, 2019 - June 24th, 2019. Furthermore, many 24+ hour thermal infrared observations, for QF15, in the 3.4 and 4.6 microns (μm) infrared bands, produced by the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) from 2016 to 2019, were utilized during the QF15 shape model construction. The combination of multiple data sources is useful for refining the characteristics and developing a shape model for an asteroid. The continuous wave spectra and delay-Doppler profiles, produced from radar observations, provide information about the asteroid's approximate shape, and surface features. Additionally, the rotational period for an asteroid is estimated by analyzing the time intervals between peaks and cusps in the lightcurves. Moreover, evaluating the variations between the maxima and minima peaks in the lightcurve data is used for approximating the size of an asteroid.   

Photoionization of the oxygen diatomic molecule

The configuration-average distorted wave method is applied to the calculations of the photoionization of O₂. The total cross section includes the outer 3dπ² shell with an ionization potential of 14.5 eV and the next outer 2pπ⁴ shell with an ionization potential of 19.2 eV. The theoretical cros sections are compared to the experimental resutls of JA Fennelly and DG Torr.   

An investigation into low temperature dielectronic recombination rate coefficients

In both astrophysical and laboratory plasmas, understanding the charge state balance of an element is key in interpreting the spectral emission. One of the dominant recombination mechanisms in both types of plasmas is dielectronic recombination (DR). For astrophysical photoionized plasmas, low electron temperature DR rate coefficients are critically important in the ionization balance and are known to have large uncertainties in their calculated values. In this work, we seek to address this problem of accurate low temperature DR. Current theoretical methods are known to have large uncertainties in the low temperature regime due to uncertainties in calculating low-n doubly excited states. This can be seen from differences with storage ring measurements. Large configuration-interaction atomic structure calculations and the R-matrix approaches are both candidates for producing a more accurate atomic structure. We explore the use of large CI AUTOSTRUCTURE calculations to improve the low temperature DR rate coefficients, comparing with existing storage ring measurements. This work is in collaboration with new measurements being performed at the heavy ion storage ring CRYRING@ESR at the FAIR facility in Darmstadt, Germany   

Periodic Nanohole Arrays with Enhanced Lasing and Spontaneous Emissions for Low-Cost Plasmonic Devices

Periodic arrays of air nanoholes in thin metal films that support surface plasmon resonances can provide an alternative approach for boosting the light−matter interactions at the nanoscale. Nanohole arrays have garnered great interest in recent years for their use in biosensing, light emission enhancement, and spectroscopy. Here, we employ a simple technique to fabricate nanohole arrays and examine their photonic applications including enhanced lasing and spontaneous emission of novel nanomaterials. In contrast to the complicated and most commonly used electron-beam lithography technique, hexagonal arrays of nanoholes are fabricated by using a simple combination of shadowing nanosphere lithography technique and electron-beam deposition. Through spectral and temporal characterizations, it was shown that these arrays offer an enhancement in the lasing emission of an organic dye liquid gain medium with a quality factor above 150 as well as an accelerated decay rate for CdSe quantum dots. The simple fabrication of nanohole arrays together with their excellent optical responses can therefore offer a great potential in the industrialization of plasmonic devices for use in various realms of emerging technologies such as gas sensing, biomedical imaging, and ultrafast on-chip coherent light sources.   

Antialpha particle impact ionization of He

Antialpha particle ionization cross sections are calculated for the He atom. A time-dependent 3D lattice method is used to obtain cross sections for the ground state of the He atom. Comparisons are made with previous antiproton ionization cross sections for the He atom.   

Enhanced Infrared Photosensitivity in DPP based Polymer Sensitized MoS2 Phototransistor

Two-dimensional semiconductors particularly Transition Metal Dichalcogenides (TMDCs) hold promising potential in future optoelectronic applications due to their high photoresponsivity and tunable band structure for broadband photodetection. Infrared (IR) photodetectors play a key role in various applications, including image sensing, communications, environmental monitoring, remote control, day and night-time surveillance, and chemical/biological sensing. Photo response of 2D TMDCs materials in the IR spectral region is one of the challenging tasks due to their band edge absorption. Here, we report the high photo-response behavior of a few-layered MoS₂ Field-effect Transistor (FET), sensitizing the surface of MoS₂ with IR absorbing DPPTT polymer. The proposed photodetector sensitized with DPPTT polymer shows an enhanced photocurrent response under the IR spectral range from 800 nm – 1050 nm with a high photocurrent responsivity of R = 10³ A/W where the pristine MoS₂ phototransistor fails to produce any responsivity. The photocurrent of the pristine MoS₂ phototransistor and the DPPTT polymer sensitized MoS₂ phototransistors are measured under white light illumination using a halogen lamp source. Under the white light, the R value of hybrid DPPTT coated MoS₂ phototransistor is higher, R = 398 A/W compared to its pristine MoS₂, R = 155 A/W at V_bg = 20V. The large photo response in the hybrid phototransistor device is due to the increase of IR absorption on DPPTT polymer and subsequent charge transfer to the MoS₂ layers. Photo-to-Dark Current Ratio (PDCR) in our hybrid MoS₂/Polymer Phototransistor is 70 at 800 nm and decreased to 10 at 1050 nm and Detectivity (D) in the range of 10¹¹ to 10⁹. Our study revealed that 2D semiconductor with IR absorbing polymer may pave the way to design the high sensitivity IR photodetector for promising optoelectronic applications.

    

An Optical Microscopy Apparatus for the Advanced Undergraduate Physics Laboratory

Optical Microscopy is a part of fundamental discoveries in physics, chemistry, and biology; is an important tool is many fields of engineering; and was the subject of Nobel Prizes in 2008 and 2014.  An Optical Microscopy Apparatus for undergraduate student use will be presented.  This apparatus is very versatile and can be used to conduct a semester-long laboratory course in Optical Microscopy for majors in physics, chemistry, biology, and engineering.  It can be used to perform numerous experiments, including Introduction to Optical Imaging, Aberrations and Illumination, Kohler Illumination, Conjugate Planes, Darkfield Imaging, Abbe Theory of Image Formation, Contrast Methods, Spectra and Filter, and Fluorescence Microscopy.

    

Optical, electrical, and EPR studies of Polycrystalline Al:Cr:ZnSe Gain Elements

Middle infrared (Mid-IR) lasers are at the forefront of new technological developments in optics. Transition metal-doped chalcogenides (TM:II-VI) are promising gain media for mid-IR lasers. Cr:ZnSe, a key representative of (TM:II-VI) materials, is considered a material of choice for optically pumped mid-IR lasers. In addition to effective mid-IR lasing under optical excitation, Cr:ZnSe, being a wide band semiconductor, holds potential for direct electrical excitation. We report on optimizing the doping technique for providing n-type conductivity to polycrystalline ZnSe via Al diffusion. These crystals were doped with an alloy of 0.5% Al in Zn at 1050°C for 1-5 days. These parameters yielded samples with resistivities ranging from 3.5 to 1.5x10³ W*cm. Conductive Al:ZnSe crystals were co-doped through diffusion from Cr thin film deposited on crystal facets. Optical characterization of these samples demonstrated that the level of Cr²⁺ was much smaller than the expected value of 1.3x10¹⁹ cm^-3 measured in non-conductive ZnSe samples. It was suggested that a decrease of the Cr²⁺ ions could result from the formation of Cr⁺ ions by capturing an electron from the conductive band. EPR measurements supported this assumption. The maximum Cr⁺ concentration was measured to be 10¹⁸ cm^-3.   

Dual Photonics Probing of Structural Abnormalities in Cells/Tissues and DNA Molecular Mass Spatial Densities in the Human Brain with the Progression of Alzheimer's disease

Alzheimer’s disease (AD) is the most common form of dementia, characterized pathologically by amyloid plaques and neurofibrillary tangles. One of the earliest overt signs of AD is a loss of cognitive function.  It has been reported that AD affects the nanoscale structure of the brain cells which begins long before the cognitive symptoms appear. However, these alterations are undetectable in the initial stages with currently used bulk diagnostic techniques such as MRI and OCT. Thus, the elucidation of a neuroimaging method that can uniquely characterize these structural disorders at the nanoscale is imperative for clinical diagnosis. Recently developed finer-focused partial wave spectroscopy (PWS) is a sensitive technique for probing nanoscale structural alterations in cells /tissues in terms of the average structural disorder strength. Results of PWS technique measurements of brain tissues from the human subjects show a significant increase in the disorder strength with the progression of AD relative to their controls. To enhance our study, the IPR approach was utilized to further analyze the spatial structure of changes in the molecular mass density of nuclear DNA components using confocal imaging. In addition, IPR studies conducted on DNA nuclei indicate that spatial structural disorder is significantly increased in DNA nuclei.

 

 

    

STRUCTURE AND DIFFUSION OF LYSOZYME IN IONIC SOLUTION

Lysozyme is an antimicrobial enzyme that is fundamental to the innate immune response. Like all proteins, lysozyme's function is dependent upon folding into its native state. By introducing the protein into solutions with varying ion concentrations, we can visualize the effect these conditions have on the stability of the protein. Using GROMACS molecular dynamics simulator. We study how different concentrations of sodium chloride influence proper folding of lysozyme. Once this state of equilibrium was reached, various structural properties of the protein were measured including the radius of gyration, mean square displacement and the radial distribution function. Our goal is to find what conditions increase the stability and what is the dynamics of ions on the enzyme.

    

Giving Vitamins to the Most 'Basic' Bacterium

This project revolves around the JCVI-syn3A and uses it as a platform to contribute to the understanding of the fundamental rules of life and how living things respond to changing environments and situations. The JCVI-syn3A is a minimal bacterial cell, i.e, it only contains genome essential for survival. The motivation behind the creation of the minimal cell is to create a simple cell that can be complexified to understand more complex cells and systems.

We explored the JCVI-syn3A and used methods such as the Chemical Master Equation and Gillespie algorithm (a Monte Carlo Method for numerically generating trajectories of molecular populations) to simulate trajectories for processes such as the assembly of the ECF (energy-coupling factor) transporter. Due to the reduction in genome of the JCVI-syn3A, ECF transporters play an important part in the transportation of cofactors since the JCVI-syn3A cannot metabolize its cofactors and needs to transport cofactors from the external medium. Our aim was to simulate trajectories of the assembly of the ECF transporter under different conditions using Lattice Microbes (an implementation of the Gillespie algorithm using GPUs). From a biophysical standpoint, if we understand the assembly of such transporters, we can analyze the physical underpinnings of both their structure and the transportation they aide in. Future work may focus on determining the assembly models for all membrane protein complexes in the JCVI-syn3A and use these models for other complex cells.

 

    

Molecular dynamic simulation of the conformation state of human micelle-bound alpha-synuclein protein in various concentrations of potassium

The misfolding of the protein alpha-synuclein (aS) has been implicated in the biochemical cascades of several neurodegenerative diseases, such as Parkinson's disease and Alzheimer's. The aS protein can naturally exist in a compacted or an extended conformation, but it is the extended shape that is most frequently associated with aggregation and the development of deleterious fibrils known as Lewy bodies, a common presentation in neurodegenerative diseases. Previous research has indicated that the presence of four potassium ions can effect an unwinding conformation in aS but has yet to determine whether the same extending effects are seen as potassium concentrations increase. The aim of this work was to investigate the modulating effects of various potassium ion concentrations on the conformation of aS in aqueous solutions. The aS protein was studied using molecular dynamics simulations run in the software GROMACS. Once the energy of the system was minimized and the system reached an equilibrium with respect to temperature and pressure, molecular dynamic (MD) simulations were run for fifteen nanoseconds with 0.002 fs steps. To expedite calculations, these simulations were performed in dodecahedral environments instead of the cube environments used in previous research as dodecahedrons have only seventy percent the volume of a cube. The radius of gyration was then measured to quantify any changes to the conformation of aS in the presence of zero, eight, sixteen, and thirty-two potassium ions. The goal of this research was to shed light on whether increasing potassium concentrations continue to effect an extended conformation in aS or if higher potassium ion levels reverse this effect, therapeutically returning the protein to a more compacted state.   

Tracking passive particles in baths of E.coli

With the aim to understand the dynamics of passive colloids surrounded by active particles. Here, we study the Brownian movement of varying sizes of latex particles in a bath of E. coli bacteria in comparison to water. Vials were mixed with latex particles, luria broth, and E. Coli. 

Using a single-particle tracking method, we calculated the mean square displacement based on observations of the trajectories of individual particles. Our results for the mixture of latex particles in a bath of E. coli indicate super diffusion in short times and normal diffusion in long times.  Determination of diffusion coefficients from the correlation of positions of the particles is discussed.   

Highly ordered plasmonic Au nano prism on conductive and transparent Indium Tin Oxide through nanosphere lithography

The generation of localized surface plasmon (LSP), collective oscillation of conduction band electrons, at the surface of plasmonic nanostructures (PNs) by resonant light excitation has garnered broad scientific interest as it represents a promising way to manipulate light-matter interactions at the nanoscale, leading to various light harvesting applications.¹ The non-radiative decay of the LSP can result in the generation of hot carriers (holes and electrons) whose energy deviates from the equilibrium Fermi-Dirac distribution.² Hot carriers have been widely explored in several applications such as photodetection, quantum transport, photocatalysis, and solar energy harvesting.^3,4 It is therefore critical to develop and optimize strategies for the fabrication of highly ordered PN arrays on different types of surfaces. In this work, we used nanosphere lithography as a simple and high throughput technique to fabricate highly ordered Au nano prisms (AuNPs) on conductive indium tin oxide (ITO) film and insulating glass substrate. The fabricated nanostructures were characterized systematically using atomic force microscope (AFM) techniques. UV-vis extinction plot of the AuNPs on thin film exhibit LSPR peaks with maximum absorbance at 612 nm. The achieved result has experimental promises in understanding plasmon-driven chemical and physical processes, such as photocatalysis and hot carrier generation.   

Enhanced Dielectric Constant and Breakdown Voltage in Polymer nanocomposite with 2D Fillers for of High Energy-density Storage Devices

The increasing use of electronic devices in the present era has demanded lightweight and portable high-capacity energy storage devices. Dielectrics are such types of materials that are used to store electrostatic energy by polarizing the materials under an applied electric field. However, dielectrics with high breakdown voltage and large polarization (dielectric constant) are crucial constituents to having high-energy storage devices. Here we have demonstrated the functional capacitors using polymers with 2D nanofillers such as h-BN, Mica, and MoS₂ and observed enhanced dielectric constant and breakdown voltage for the application of high-energy storage thin film capacitor devices.

 

    

Pressure Evolution of the Hubbard U in Rare-Earth Metals via the Linear Response Approach

Calculating the properties of rare-earth metals using ab-initio methods is an important component in understanding these strongly correlated materials. Traditional density functional theory (DFT) calculations are insufficient in describing their properties and phase transitions due to electronic correlation effect. On the other hand, the DFT+U approach is a more robust method for obtaining experimentally-consistent electronic and magnetic structures. One critical question, however, is how to determine the Hubbard value from first principles. Here, we employ the linear response approach to calculate the effective U for various rare-earth metals. We study how the U value evolves as a function of unit cell size and structure type. The pressure evolution of the Hubbard U is calculated using both experimental unit cell and DFT relaxed crystal structures. The resulting U values provide important input information for DFT+U calculations to understand the behavior of rare-earth materials and their applications in extreme pressure environments.   

Plasma Enhanced Chemical Vapor Deposition of few layer MoS2

Due to its remarkable electronic and optical properties, few layer molybdenum disulfide (MoS2) has received intense interest for its use in a variety of devices. However, achieving highly uniform, large area MoS2 is still a challenge. Here, we use Plasma Enhanced Chemical Vapor Deposition (PE-CVD) to grow centimeter-scale, few-layer MoS2 on thermally oxidized silicon with an argon carrier gas over a wide temperature range using MoO3 and S solid phase precursors. These results were compared to standard LPCVD using Raman spectroscopy, X-Ray diffraction, and scanning electron microscopy with energy dispersive X-Ray spectroscopy. Our results show that the presence of an argon plasma results in a larger nucleation density, smaller grain size, and ultimately a more uniform thin film sample, in line with recent works focusing on graphene. Further, the plasma promotes larger growth regions at lower temperatures as compared to LPCVD.   

51V NMR studies on single crystal of A15 superconductor V3Si

The Martensitic transformation (MT) in A15 binary-alloy superconductor V₃Si is a second-order, displacive structural transition from cubic to tetragonal symmetry, at temperature T_m a few K above the superconducting transition temperature T_c = 17 K. Though studied extensively, the MT has not yet been conclusively linked with a transition to superconductivity, while V₃Si continues to be of current interest. Previous NMR studies on the MT in V₃Si have been on powder samples, and with little emphasis on temperature dependence during transformation. Here we study a high-quality single crystal, where quadrupolar splitting and Knight shift of NMR spectra for ⁵¹V allowed us to distinguish between transverse chains of V as a function of temperature. This capability has led to evidence of coexistence of transformed and untransformed phases over a few K below and above T_m [Gapud et al., Physica C, vol. 602, 1354137, 2022], as well as new details regarding the evolution of the Knight Shift and of the longitudinal relaxation time T1 across this transition, as will be reported and discussed.   

The Exploration of Thulium Halides and Oxyhalides as Strongly Fluctuating Quantum Magnets

Quantum spin liquids (QSL) are an exotic state of matter in which the ground state is composed of highly entangled spins. This research explores the possibility of finding QSLs composed of the rare earth metal Thulium in a Halide structure. Three Rare Earth Halides TmX₃ (X = Cl, Br, I) are studied to determine their magnetic properties and crystalline structure. The Oxy-Halide TmOCl was also synthesized to control for the material structure’s effect on the properties of Thulium. Measurements of the magnetic susceptibility down to 1.8K of each Halide reveal the possible beginning of a magnetic phase transition for all three compounds and especially so for TmBr₃ and TmI₃. A linear fit was performed on the inverse susceptibility data for each compound to determine the Curie-Weiss Temperature which revealed that all four compounds were antiferromagnetic. Based on these results and an analysis of each compound’s molecular structure, additional heat capacity measurements were taken on TmI₃, which revealed possible anisotropic behavior below 1.5K. Additional heat capacity and X-ray diffraction measurements will need to be performed in order to determine the magnetic properties and molecular structure of every compound.   

Green Function Approach for Calculating Surface Electronic Structure of Iron Selenide on Strontium Titanate

Electronic band structure has proven to be a useful way of observing the electronic properties of materials. Due to the cumbersome nature through which electronic band plots are generated, there is value in developing computational methods to calculate them in more complicated systems, like multilayered structures. We examine the crystalline superconductor Iron Selenide (FeSe), which exhibits a distinct shift in its surface band structure when isolated versus monolayer FeSe grown on bulk Strontium Titanate (STO) expressed through a change in superconducting temperature from the order of 10K to 70K. This case is simplified by exploiting the periodic nature of the molecular structure in crystalline materials, allowing for unit cells to be defined in different layers. For this, we turn to the use of DFT calculations to provide the basis for our model Hamiltonians, which describe the interactions between layers. Using these calculations, we modify previously written methods for calculating surface electronic structure for homogeneous materials to fit our inhomogeneous case and investigate changes to the Fermi surface in FeSe.   

Synthesis Of Novel Double Perovskites With 4d/5d- and 3d-elements

Past research into double perovskites, with the general formula A₂BB’O₆, led to discovery of compounds that have a wide range of unique magnetic, thermal, and electrical properties. In this research project, two different transition metals occupy the B and B’ sites, with 3d transition metal occupying the B site and a 4d (or 5d) transition metal occupying the B’ site. The two sites differ as 3d transition metals tends to be more localized than the 4d (or 5d) transition metals. Additionally, 3d elements experience higher electron correlation, compared to their 4d and 5d counterparts, while the 4d and 5d transition metals tends to experience higher spin-orbit coupling interaction. Previous research into double perovskite compounds with the 3d and 4d/5d transition metals occupying the B and B’ site respectively, have shown the potential of these materials to host multiferroic properties, causing great interest for possible applications in sensors and memory devices. Synthesis of novel double perovskite materials that could host these properties will be discussed, as well as the various methods used in characterization, such as atomic composition and crystal structure. Some of these techniques include single crystal X-ray diffraction (SXRD) and Energy Dispersive X-ray Spectroscopy (EDS). 

    

Ensemble Tree Machine Learning Prediction of Superhard Compositions

Superhard materials with a hardness > 40 GPa have various important applications. Here, we use machine learning (ML) simulations to find the elastic properties of chemical compounds. Following the work by Chen et al. [in npj Computational Materials 7, 114 (2021)], we use approximately 10,400 target compounds and 60 features, which are based on the properties of elements, orbital occupations, stoichiometric traits, and ionic bonding levels, to train ML models. Once the models are generated, they are utilized to predict the shear modulus, bulk modulus, and hardness of B-C-N compounds. We compare different ensemble models including random forests and gradient boosting trees. We also consider weighted samples in the training and compare the ML predictions to first-principles calculations. The results indicate that ML models can efficiently predict the mechanical properties with a reasonably good accuracy.   

Low-Pressure Chemical Vapor Deposition of Ni and NiMo Sulfides on Ni Foam for Electrocatalysis

Due in part to its large surface area to volume ratio and easy accessibility, nickel foam has been extensively researched as a support electrode for a variety of electrochemical processes. Further, a variety of Ni alloys have shown excellent performance in oxygen and hydrogen evolution reactions, and therefore, are currently being evaluated for use in wide ranging applications from energy storage to water splitting. In this work, we use low pressure chemical vapor deposition to grow an outer layer of Ni sulfides and NiMo sulfides on Ni foam by varying the amount of precursor material, growth temperatures, as well as the growth geometry. The resulting sulfide films are then evaluated by X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy to determine the structure and morphology of the resulting electrode surfaces. The electrochemical properties of the structures are evaluated utilizing cyclic voltammetry.

    

The Hunt for Red Structural Color

Structural color is an optical phenomenon where light reflecting from nanostructures produces color primarily via scattering, interference, and diffraction rather than pigmentation. Structural colors are some of the most brilliant colors in nature, and the blue of the Morpho butterfly is one of the most vivid examples. This project involves computer simulations of nanostructures using the finite-difference time-domain (FDTD) method and modifying the geometry to observe the effects on the spectra and angular distribution of the reflected light. While blue is the most common structural color, we aim to determine why red structural color is so rare in nature and whether nanostructures that generate red structural color can be designed and optimized computationally. Here we present our progress towards understanding structural color and exploring the parameter space of Morpho-inspired nanostructures with a view to simulating structural color that is tunable across the visible spectrum.   

Search for Novel Magnetic Textures in Chiral Magnet CoMoTeO6

Chiral magnetic oxides often host abnormal magnetic topologies, such as skyrmion [1]. If a crystal structure is non-centrosymmetric, the Dzyaloshinskii–Moriya interaction between local spins may be of similar strength to the spin-exchange interaction. If a chiral non-centrosymmetric material is also an insulator with ferroelectric properties, it could possibly be magnetoelectric multiferroic. In magnetoelectric multiferroic materials, isolated metastable skrymions can possibly be manipulated by an electric field. With this hypothesis, polycrystalline samples of chiral insulating oxides of the MTeMoO₆ (M = Co, Mn, Fe, Cu, Ni) family are being synthesized and tested for ideal magnetoelectric properties. I will present the synthesis method, and electrical and magnetic characterization of one candidate CoTeMoO₆. Our initial observations indicate the presence of non-collinear magnetic structure with strong magnetodielectric coupling in this material.

[1] Lim, Z.S., Jani, H., Venkatesan, T. and Ariando, A., 2022. Skyrmionics in correlated oxides. MRS Bulletin, pp.1-10.   

Spin-orbit coupling effects on the band strucutre of prismatic core/shell nanowires

Core/shell nanowires (CSNWs) exhibit strong radial confinement of electrons within the shell, often leading to a description as a two-dimensional electron gas. We study three-dimensional electron gases within the shell of CSNWs with realistic, polygonal cross-sections. This cross-sectional geometry is determined by the underlying crystal structure, and is unique for specific growth directions. For zinc-blende nanowires grown along the [111] direction, the cross-section may be hexagonal or triangular, whereas for the [001] direction they may be square. Sharp corners in the cross-sections introduce an extra level of confinement, beyond the radial confinement, due to discrete rotational symmetry. The confinement forces the probability density of low energy states to be restricted to the corners of the polygon. For lower symmetry cross-sections, this results in large gaps in the conduction band structure between states confined in the corners and those which have peak probability in the sides of the cross-section. Our study focuses on conduction electrons within thin shells of CSNWs, the energies and eigenstates of which are determined using an exact diagonalization scheme. We present the probability densities and band structures for conduction electrons in the shell of circular, hexagonal, square, and triangular CSNWs. The model includes effective forms of spin-orbit coupling and the inclusion of external magnetic fields.   

Machine Learning Prediction of the Entropy Forming Ability for Synthesizability in High Entropy Borides

High-entropy materials have a plethora of useful properties that make them a topic of interest in many areas of research. A major descriptor in synthesizing these materials is the entropy-forming ability (EFA). This describes how likely a high-entropy material is to be synthesized in a single-phase form. It is time-consuming to calculate the EFA, so we used machine learning models to predict the EFA of high-entropy carbides (HEC) and borides (HEB). The HEC compounds already have literature, so they were used to confirm what we already knew and to ensure the validity of our models. We found that HEB and HEC compounds containing Chromium have the same positive correlation between the EFA and the mean ionic character, while those without Chromium have the same negative correlation. Random forest and XGBoost models were successfully built to predict the EFA values of the HEC and HEB compounds.   

Synthesis and Characterization of Complex Chalcogenide Glasses

Chalcogenide glasses are important in today’s society due to their numerous useful properties such as Near- and Mid-IR transparency, large refractive indices, and large optical nonlinearity. Multicomponent or complex chalcogenide glasses are known to possess a phase change memory effect under elevated temperatures, pressures, electric shock, or photo exposure. Novel complex chalcogenide glasses (Ge-Ga-P-Sb-Se-Te) were prepared with varying P content (1-9%) to study structural, electrical, and optical properties. The amorphous nature of the samples was verified with the X-Ray Powder Diffraction Method. The crystallization behavior was studied using Differential Scanning Calorimetry. As shown by optical spectroscopy, the prepared glasses are transparent within the 1-23 µm range, making them especially suitable for telecommunication.

    

Yttria as a secondary phase in LAGP for Solid State Battery Applications

Solid state batteries represent significant improvements in energy density, operating temperature, and safety over liquid batteries, but low ionic conductivity limits their commercial applicability. Ionic conductivity results from the interplay of several factors, including grain boundary interfaces, grain size, porosity, and crystal structure. Secondary phases may also play an important role. For example, yttria helps stabilize the crystal structure of ceramics such as zirconia at high temperatures, and it has also been demonstrated to improve ionic transport in solid-state electrolytes such as LAGP when introduced via glass melt synthesis. To explore the role of yttria in LAGP via more energy-efficient methods, we introduce yttria extrinsically to powder LAGP. Ball milling and hand mixing were used to disperse the yttria, and the material was consolidated by thermal sintering as well as microwave processing. Samples are analyzed with respect to the effect of yttria on grain growth, ionic conductivity, and microwave absorbance, and the results are discussed with respect to the underlying physical properties.   

Neutron Capture Cross Section Measurements of 112,113Cd using DANCE

Neutron capture cross section information on Cadmium nuclei is needed for a variety of applications such as the use of Cadmium in Non-Destructive Assay (NDA) techniques and the s- and r-processes in astrophysics. Although cross section information is needed, there is little direct measurement data, especially in the resonance region. To address this, a series of experiments were performed on different isotopes of Cadmium. In these experiments, the highly-enriched Cadmium target was illuminated by an intense neutron beam with energies ranging from a few eV to hundreds of keV. The measurements took place at the Los Alamos Neutron Science Center (LANSCE) using the Detector for Advanced Neutron Capture Experiments (DANCE). Even with a highly enriched target, impurities in the form of other Cadmium isotopes which are not the focus of a particular experiment can be observed. This poster will demonstrate efforts to separately isolate neutron capture yields for ¹¹²Cd and ¹¹³Cd, which is a critical step to extracting final neutron capture cross sections on these nuclei

    

Quantification of plasma using optical emission spectroscopy for hypersonic actuator research

The new era of flight has led to the development of more sophisticated technology to meet the needs of newer aircraft. One of these needs is a more advanced flow control system. The use of plasma as an actuator provides several advantages over the conventional mechanical counterparts, such as faster response times and lower likelihood of failure. Research was done by the High Speed Aeroacoustics Group of the National Center for Physical Acoustics using optical emission spectroscopy to quantify plasma parameters. Once these parameters are known, design and development of plasma flow control systems can be tested in a trisonic wind tunnel.   

The Deterministic Environmental Radiation Intensity Survey-Simulator (DERISS)

Environmental radiological surveys are preformed to assist sites contaminated with radioactive materials characterize and remediate residual radioactive materials hazardous to onsite individuals and the local ecosystem. Surveys are difficult to replicate, time-consuming, involve use of radiological material in the environment, and may expose the surveyor to hazardous ionizing radiation. There is a need to rapidly, reliably, and safely generate radiological survey data for the development and testing of enhanced background segregating algorithms used during post-survey data analysis and optimization of surveying parameters (survey velocity, detector spacing, sampling rate, etc.). This poster describes the Deterministic Environmental Radiation Intensity Survey-Simulator (DERISS). DERISS is a point-kernel based model developed to preform radiation exposure rate calculations within a simulated survey area. DERISS generated data sets will be used to assist in optimization of Institute for Clean Energy Technology (ICET) robotic survey system parameters, evaluation of post-survey analysis methods, and development of visualization tools. DERISS preforms these calculations by populating point-sources and point-detectors into a simulated survey area. The exposure rate is calculated at each point-detector's position using the aggregated exposure rate generated from each point-source with the detector-source distance known. Exposure rate intensity is proportional to the inverse square of these detector-source distances and is scaled by the source's activity, photon energies, properties of the detector, and attenuation effects. DERISS uses user-defined configuration files that describe survey parameters (survey-platform speed, path spacing, measurement frequency, etc.), environmental conditions, sources of radioisotopes, and radiation detectors to create simulated data sets mimicking data sets produced by ICET semi-autonomous radiological survey systems. Described in this paper is a technical description of DERISS functionality, generated results, and future efforts.   

GPU Accelerated Nuclear Cross Section Calculation in the Glauber Model

Information on the nuclear radii and other parameters of nucleon distributions has been obtained from nucleus-nucleus collisions at energies of about 1 GeV. The experimental data on nucleus-nucleus cross-section is usually analyzed using the Glauber theory. It is possible to obtain values for relevant cross-sections without any simplifications (optical or rigid target approximations) using Monte Carlo (MC) integration techniques. To increase accuracy of numerical MC integration and decrease computational time, calculations are usually done using Message Passing Interface (MPI) together with a programming language of choice on a CPU computational cluster. In contrast to MPI, executing the calculation on a single modern consumer GPU using the CUDA C++nets a factor of roughly 1000x speedup in execution over a single CPU thread. This means a single consumer GPU (we use an RTX 2070, far from the highest performance available) can outperform even a modestly sized CPU cluster and deliver higher accuracy MC results in less time. We discuss the developed CUDA MC routine, demonstrate key differences between GPU-based and MPI-based algorithms for MC integration, present nuclear cross-section calculations and extract parameters of nuclear densities for various stable and unstable isotopes.

    

Searching for New Higgs Couplings in Muon Colliders. Would We Find Them?

               Muon Colliders are a great avenue to explore physics Beyond the Standard Model (BSM). Leptons are useful for collider experiments due to their cleaner signatures relative to hadrons, however muons have an even greater advantage over electrons and positrons since their larger means they emit much less synchrotron radiation, allowing them to be accelerated at a much higher rate. One BSM channel potentially explored by muon colliders is that of Long-Lived Particle (LLP) couplings to the Higgs. These theoretical particles would produce displaced decay products that might be picked up by the inner tracker of the collider. It was found that Beam-Induced Background (BIB) reduction techniques for common Higgs production avenues are slightly less effective at preserving the potential LLP signal. However, for reasonable cuts, a large portion of the signal is left intact, allowing for additional analysis in further out layers of the detector, as well as offline discrimination.

    

Machine Learning Implementation for Tau Neutrino Appearance in the DUNE Far Detector

The Deep Underground Neutrino Experiment (DUNE) is an upcoming long-baseline neutrino oscillation experiment representing the next milestone of steady growth in neutrino physics. With many features surpassing current long-baseline experiments, DUNE would be the first experiment capable of generating a large sample of visible ντ for study of the νμ →ντ oscillation channel. In this project, the DUNE far detector (FD) monte carlo simulation sample is used to study selection efficiency and purity for ντ event classification. Results show that the current classification routine for ντ event selection in the DUNE analysis framework performs poorly and must be improved if a reliable distinction between ντ signal (S) and background (B) is to be achieved. Using a set of weak classifiers derived from reconstructed event statistics, an adaptive boosted decision tree (BDT) is implemented into the FD classification procedure. BDT classification on neutrino events for the tau flavor results in a tenfold increase in selection purity and a threefold increase in signal significance (S/√B) for a 3.5-year simulation sample. A separate χ2 analysis on the BDT output suggests near-discovery-level ντ signal significance in 3.5 years of data-taking across 99% of possible oscillation parameters.   

Measurement of the Ξc+ Lifetime Using Belle II Simulations

We present a measurement of the lifetime of the Ξ_c⁺, a rapidly decaying charmed baryon, using Belle II simulation. Studies are underway using five different decay modes (Ξ_c⁺ —> Ξ^- π⁺

π⁺ , Ξ_c⁺ —> p⁺ K^- π⁺, Ξ_c⁺ —> ∑⁺ K^- π⁺ , Ξ_c⁺ —> ∑⁺ π^- π⁺, Ξ_c⁺ —> Ξ⁰ π⁺ π⁺ π^-) with 500 fb^-1 of Monte Carlo, comparable to the size of the data collected by the Belle II experiment, with the goal of combining all modes for a combined fit to determine the Ξ_c⁺ lifetime. With a single, all charged, final state, the lifetime extracted from simulation (464 ± 15 fs) is consistent with the simulated lifetime within 1.5σ. With the addition of more decay modes, the uncertainty will be reduced and potentially become competitive with other experiments.

Paul Gebeline  3:13 PM   

Analysis B± → Ks0 π± π0 with Belle II Data

Belle II is a particle physics experiment based at the KEK laboratory in Tsukuba Japan. It is

the successor to the Belle experiment, which ran from 1999 to 2010, and aims to collect 50 times

more data than its predecessor. One of the main goals of the Belle experiments is to explore CP

violation, which is a necessary condition to explain our matter-dominated universe. A particular

area of interest is in the study of charmless B-meson decays, which are sensitive to the CKM

angle and provide an excellent laboratory to search for physics beyond the Standard Model. I

will present an ongoing analysis of one such decay, B^± → K_s⁰ π^± π⁰ , using simulated samples

from the Belle and Belle II experiments.

    

Dark Matter and Baryogenesis from Gravitational Waves

Gravitational wave detectors will be expressed to probe models of assymetric dark matter. Such theories can simultaneously explain dark matter and the matter-antimatter asymmetry of the Universe. I will present the results of our calculation for a model extending the Standard Model symmetry by a non-Abelian gauge group. Under this new symmetry, the leptons form doublets with new fermionic partners, one of which is a dark matter candidate. The model exhibits a strong first order phase transition at a high scale, which leads to the production of gravitational waves through sound waves and bubble collisions. The resulting signatures are within the reach of near-future gravitational wave experiments, like the Einstein Telescope, Cosmic Explorer, DECIGO, and Big Bang Observer.   

Monitoring and Control Systems for Test Beam Activities for CMS Outer Tracker Upgrade

In preparation for the high luminosity upgrade of the LHC, CMS has been developing new silicon detector modules for the CMS outer tacker. While beam tests of detector prototypes had been completed in the past, CMS had not had the opportunity to perform beam tests in the presence of a magnetic field until August of 2022. To facilitate these tests, systems to monitor the temperature and relative humidity inside the module housing, and systems to monitor and remote control the HV/LV supplies were created. These monitoring and control systems allowed for offline analysis and correlating of the data.   

A reinterpretation of an LHC search for displaced vertices and muons in RPV SUSY models

This reinterpretation analysis aims to test the limitations of R-parity violating (RPV) SUSY models. A previous ATLAS search looked for long-lived massive particles with a displaced vertex and muon with a large impact parameter. This reinterpretation of that search looks to exclude regions of unprobed RPV SUSY parameter space. After generating simulated particle collision event samples, signal events were selected based on whether or not they passed the event selection criteria. The selected events were then used to calculate a normalized number of events that fall into the analysis signal regions. Using these event yields and comparing to the published 95% CL upper limits, new RPV SUSY model limits are achieved. By repeating this process with a large array of samples, an exclusion contour can be traced out onto a two dimensional space of the mass of the stop quark and lifetime of the neutralino, which provides new limits on RPV SUSY models in regions previously unexcluded.    

Process Quality Control for HGCAL at Florida State University

The HL-LHC project aims to increase the instantaneous luminosity of the LHC by a factor of 5, in order to extend the potential of the LHC for new discoveries. More proton-proton collisions will increase the number of additional interactions per bunch crossing, referred to as pile-up (PU), and will expose the detectors to a greatly increased amount of radiation damage. For CMS, this means the existing endcap calorimeters will need to be replaced, which has prompted the proposal of a new high-granularity sampling calorimeter, called HGCAL. The active elements of HGCAL are 8-inch hexagonal silicon sensors; the final calorimeter will contain ~ 30,000 such sensors. For proper performance of HGCAL, it is important that the characteristics of the sensors be well-understood, and consistent throughout production. Process Quality Control (PQC) takes advantage of the fact that the hexagonal sensors are cut from circular wafers, by implementing test structures on the unused material. These test structures can be used to measure properties of the material (i.e. oxide type, surface generation velocity, etc.) and are therefore very sensitive to differences between batches of sensors. Hence we will present the experimental setup for testing PQC at FSU, as well as preliminary results.   

An instrument for predicting performance in introductory physics courses

Physics education research (PER) is an important sub-field of physics, with a focus on the teaching and learning of physics both at schools and universities. One important branch of PER has been the development of research-based assessments for measuring educational outcomes. While many instructors develop questions to assess student learning, research-based assessments undergo rigorous design, testing, and validation processes to facilitate objective comparisons between students and methods of instruction. Here we describe the development and refinement of a diagnostic physics exam designed to predict students' performance across all introductory physics courses. Using data collected at Auburn University, we calculated difficulty and discrimination coefficients for all test questions, as well as the overall correlation between diagnostic exam performance and final exam grade. By removing questions with poor predictive power of final exam performance, we were able to reduce the assessment to a more limited set of 17 questions. We found strong correlations (R-squared between 0.27 and 0.31) between scores on this assessment and final exam performance across all introductory courses, regardless of math level or physics content. The resulting instrument is currently being used to identify students likely to struggle in physics so that instructors are able to intervene early in the semester.   

A LEGO Model of the Kibble Watt Balance for Physics Education and Outreach

In 2019, the International System of Units unit of mass, the kilogram, was redefined based on the fixed value of the fundamental Planck’s constant, therefore eliminating the need for the International Prototype of Kilogram, the platinum-iridium cylinder that was forged in 1879. The apparatus that allows to realize the kilogram based on the Planck’s constant has been constructed at the National Institute of Standards and Technology (NIST). It is based on the idea of Bryan Kibble to balance the weight of the object by the electromagnetic force generated by the current-carrying coil immersed in a magnetic field, therefore the name, Kibble Watt balance. The apparatus is housed in a dedicated room under clean-room conditions and can measure a kilogram within a few parts in 10⁸. In 2015, a simple LEGO model of the Kibble Balance was constructed by NIST scientists [L. S. Chao et all, American Journal of Physics 83, 913 (2015); doi: 10.1119/1.4929898] and has been replicated several times. Since 2015, the design has been changed because of the efficiency and availability of the components.

            Our chapter of the Society of Physics Students decided to construct a LEGO Watt Balance model based on the new design for our 2022 Research Project which has been funded by the SPS National research grant. We really enjoyed working on this project, and believe this is a very good undergraduate project, even for a small physics department. We also plan to use the model for recruitment and outreach. In this presentation, we will share the obstacles we had to overcome and the lessons we have learned while making this inexpensive table-top model capable of measuring gram-level masses with 1% uncertainty.

    

Bringing Gravitational Waves into the Classroom: Science Outreach at the LIGO Livingston Science Education Center

The Laser Interferometer Gravitational-wave Observatory (LIGO) detector in Livingston, Louisiana has a dedicated facility for Science Education and Outreach, consisting of a fully equipped auditorium, a classroom, and an exhibit hall with around 50 interactive science exhibits. The center focuses on bringing LIGO science and cutting-edge astrophysics research into classrooms, and use it to engage K-12 students while teaching basic physics concepts. It also trains undergraduate STEM students from the Southern University in Baton Rouge, an HBCU, to be docents for school visits and public outreach events at LIGO, putting under-represented minorities in STEM at the forefront in giving science exposure to the next generation. I served as a LIGO outreach fellow here in Spring '22 and participated in various virtual as well as in-person tours and outreach events. This poster will present my experiences there, information about how big experiments/collaborations such as LIGO can engage local communities, and a new web-based tool I developed to teach the physics of oscillations and waves using LIGO gravitational-wave data.   

Video Analysis of Group Interactions in an Active-Learning Classroom

One of the most important pieces of any active learning methodology is interaction between students in the classroom. This research was conducted by recording students’ group interactions within an introductory Physics course via Zoom, and analyzing certain conversations and body language. Two groups were recorded each class period over the course of the semester, excluding days when exams were given. The groups were placed into categories by the analyzers, either 1) non-constructive, interactive 2) constructive, interactive 3) constructive, non-interactive and 4) non-constructive, non-interactive, and the analyst measured throughout the semester the progress of each group, and identified what the “ideal group interaction” would consist of. Through these efforts, the researchers will be able to continue to pursue a different approach to the traditional idea of lecture learning within these introductory classes, and determine certain factors within student led groups that make one group more successful than the other.

    

Experimental Study of Kramers' Rate in a Magnetically Driven Duffing Oscillator

A Duffing oscillator is a damped, periodically driven, and bistable system which does not perfectly obey Hooke’s Law and can therefore be described as nonlinear. This nonlinearity produces interesting dynamics, such as stochastic resonance, a phenomenon by which a system experiences a gain in signal-to-noise ratio (SNR) due to the addition of low amplitude noise. In thisthe experimental setup, inspired by the system proposed in Donoso, Ladera, Eur. J. Phys. 33 (2012), a magnet on a spring oscillates in the magnetic field of a small coil while a larger coil at the base of the setup drives the system with an oscillating magnetic field. The bistable nature of the system’s potential energy allows noise-induced phase transitions between potential wells corresponding to a Kramers’ rate for the system. In this presentation, we show progress on an experimental study of this rate of transition (Kramers’ rate) and compare obtained experimental results with the theoretical value of the system’s Kramers’ rate. In addition, we present new experimental data showing stochastic resonance behavior of the SNR dependence on the value of the amplitude of an external force.

    

Fast-timing measurements using LaBr3(Ce) detectors in the neutron-rich N = 20 region

Variations in the proton and neutron numbers inside the nucleus lead to changes in the nuclear shell structure. Nuclear transition rates are sensitive indicators of those changes, so-called “nuclear shell evolution”, which depend in part on knowledge of the level lifetimes. Radioactive nuclei were implanted into a CeBr₃ scintillator coupled to a Position-Sensitive Photomultiplier Tube (PSPMT) as part of a β decay experiment in the neutron-rich N = 20 region conducted at the National Superconducting Cyclotron Laboratory (NSCL). This allowed for correlating the decays to the implanted ions using spatial and temporal techniques. 15 LaBr₃(Ce) detectors, providing fast timing measurement and γ radiation detection, were used to generate time-difference spectra for β-delayed γ radiation following a decay event to measure half-lives. In the neutron-rich N = 20 region, corrections for the energy-dependent time-walk effects and validation results will be provided.

    

The Georgia PEAcH: A Portable Electrostatic Accelerator

In collaboration with the University of North Georgia, we

are constructing a portable electrostatic ion accelerator 

at Georgia College.  It will use a model  2JA066280 R.F. ion 

source from National Electrostatics Corporation to produce 

ions from gaseous elements and a model AU-100N1 100 kV 

power supply to produce the accelerating voltage.  The linear 

accelerator  is less than 2 meters in length. The beam 

energy will be roughly determined by the acceleration voltage.

The accelerator will be tested

 through measurements of the 17 MeV γ-ray

produced from the ⁷Li(p,γ)⁸Be reaction. 

Low energy proton-induced fusion reactions are envisioned 

for both pure and applied physics research.   

Compton Polarimetry in the Electron-Ion Collider

Electron polarimetry is to be an essential part of the next-generation nuclear facility, the Electron-Ion Collider (EIC). The EIC will facilitate the detailed study of the internal structure of the proton by creating high-energy interactions between a stream of electrons and a stream of deshielded protons. To interpret these interactions, the polarization of the electron beam must be known. Accordingly, a Compton polarimeter will be stationed within the EIC to measure and monitor the polarization of the electron beam by colliding photons with the electron beam to produce Compton scattering. The physical quantities measured in the scattering will correlate to the electron beam's degree of polarization, rendering the polarization calculable. A fast- pulse laser system will be used in this process, since the EIC necessitates that polarization measurements be significantly more accurate than 1%. To determine properties of the laser to be used, an autocorrelator was designed and assembled for pulse measurement. The autocorrelator splits the original pulse into two identical beams which are then superimposed with variable temporal difference. Though the pulse duration is not directly observed, measurable signals are produced from the interactions, allowing it to be calculated. Since the sensitivity of the polarimeter largely depends on the properties of the electron and photon beams, simulation studies were also performed. Three simulations of Compton interactions were produced: the first assumed infinitely focused beams, while the second assumed a realistic electron beam size and a large laser beam size, and the third assumed a realistic electron beam size and a realistic laser beam size. The impact on the sensitivity of the system was analyzed via these simulations, the results of which proved the proposed laser system adequate.   

Designing Satelite Flight Software

When developing a CubeSat, many focus on its mechanical and electrical engineering components. This presentation details the intricacies of high-level flight software, discussing our challenges, solutions, and structure and execution of code. Our software uses FreeRTOS, a real-time operating system that functions based on tasks and priorities. The challenge lies in managing the pipeline of task execution. Priority, order, and duration must follow a deterministic path so no unexpected behaviors may occur. Memory is a scarce resource. We use statically allocated memory to reduce the possibility of memory fragmentation. Our hardware limits communication to a bitrate of 9600 bits per second. Therefore, we achieve cohesive communication through a custom-designed protocol employing checksums and identifiers that ensure robust and resilient data transfer. Our last challenge lies in internal communication with subsystems and sensors. Such subsystems include the array of AMUs (Aerospace Measurement Units) and its various supporting systems: electrical power system, transceiver, antennas, magnetorquer, and solar panels. Together with smaller sensors, the challenge lies in managing and balancing a cohesive system that maintains its health, performs the experiment, and transfers the data.

    

Rapid Electrical Characterization for Superconducting Thin Films Using Gifford-McMahon Cryocoolers

Epitaxially-grown superconducting thin films have many applications in high-speed cryogenic electronics and quantum computing devices. In this project, we design and build a user-friendly and efficient low-temperature measurement system to improve the optimization process for our thin film superconducting epitaxy. Using Gifford-McMahon cryocoolers in inverted geometry, we built three closed-loop He4 cryostats for DC transport, AC transport, and capacitance measurements. We demonstrated an average cool-down time of 2.5hrs from room temperature (300 K) to the base temperature (6-8 K). We evaluated the operation of our cryostats by measuring the superconductivity of niobium on silicon thin films grown by MBE. Our results showed accurate resistance measurements, observation of clear superconducting transition, and cooling times below three hours from room temperature to a stable base temperature below 8K. The final setup will allow our team to rapidly cool superconducting films after each growth cycle to evaluate their superconducting properties, including transition temperature and normal and residual resistivities.   

Examining the Linearity of Silicon Detectors in the Nab Experiment

When neutrons are outside of a nucleus, they undergo β decay; they decay into a proton, an electron, and an antineutrino. The Nab experiment seeks to precisely determine the electron-neutrino correlation parameter through unpolarized neutron β decay. The Nab experimental methods are highly sensitive to the energies of electrons produced during β decay, which are measured with silicon detectors. It is commonly expected that silicon detectors are linear. However, we must test this assumption to a high level of precision. To accomplish this, we conducted linearity studies with a precision pulser in three stages to (1) characterize pulser output, (2) investigate methods for splitting the pulse, and (3) search for nonlinearity in the detection system. We created Python programs to organize and analyze the data. We found maximum residuals of 0.068% in the detection system, which exceeds the Nab precision goal of 0.01%, indicating that further study is required.

    

Ultrasonic Parametric Imaging of the Brain

Advances in transcranial ultrasound are generating increased interest in understanding the ultrasonic properties of brain in a more detailed way. The goal of this study was to create two-dimensional maps of the brain for three ultrasonic parameters: speed of sound (SOS), frequency slope of attenuation (FSA) and the integrated backscatter coefficient (IBC). Ultrasonic measurements were performed on 1-cm thick slices of fresh bovine brain in a tank of physiologic saline at room temperature. 14 slices were prepared from the coronal anatomic plane of 5 brains and 14 slices were prepared from the sagittal plane of 4 brains. A mechanical scanning system was used to move a 5 MHz transducer in a rectangular grid pattern to perform measurements in steps equal to a half beam diameter (0.97 mm). Averaged over all 28 slices, the measured values (reported as mean ± standard deviation) were: SOS = (1522 ± 3) m/s, FSA = (0.43 ± 4.75) × 10-2dB/cm/MHz, IBC = (2.400 ± 3.688) × 10-3cm-1str-1. Measurements at individual sites were used to create parametric images of SOS, FSA and IBC for each tissue slice.   

Determining the Relationship Between Observed Algal Activity and Ultrasonic Attenuation Measurements

A Single Frequency Acoustic Attenuation Surrogate (SFAAS) was developed by NCPA to measure suspended sediment concentrations using 20 MHz acoustic signals. Previous work hypothesized that biological factors, such as population variation or algal movements, could also be determining factors in increasing acoustic signal attenuation when there is an absence of suspended sediment transport. A change in attenuation may occur during the day in dense colonies because increasing light intensity leads to high photosynthetic rates, which can produce O₂ bubbles within colonies that increase buoyancy and cause algae to rise in the water column. Respiration at night consumes O₂ bubbles, resulting in sinking algal colonies.

Semi-controlled underwater acoustic experiments in still water with large algae populations were initiated in conjunction with USDA-ARS-NSL. Ancillary measurements were also monitored including light intensity, dissolved oxygen, and water temperature in an environment without sediment transport. Cyanobacteria was the dominant algal group in the limnocorral, and vertical movement of cyanobacteria is modulated by changes in cell density, gas vesicles inside of cells, and gas bubbles between cells in dense colonies.   

Quantifying Sea-Turtle Impacts on Turtle-Excluder-Devices in Shrimp Trawls in the Gulf of Mexico

Several species of sea turtles native to the Gulf of Mexico and the Atlantic Ocean are listed as endangered under the Endangered Species Act. The capture of sea turtles as bycatch during shrimp trawling has been cited as a significant contributor to sea turtle population declines. The impact of shrimp trawling on sea turtle populations has been difficult to ascertain, primarily because it is difficult to estimate turtle relative abundance and turtle bycatch with any degree of accuracy. Turtle Excluder Devices (TEDs) have been required by law in the Gulf of Mexico shrimping industry since the late 1980’s to reduce the number of bycaptured turtles taken during shrimp trawling activities. Personnel with the National Oceanic and Atmospheric Administration (NOAA) are responsible for continued verification of the efficiency of the TEDs. To do this, they developed an underwater camera system to monitor wild-caught turtles in the Gulf of Mexico and observe their escape times. The goal of the current project is to record sound underwater these verification operations and use the sound of turtles impacting the TEDs to quantify the number of turtles encountered. In conjunction with NOAA personnel, a 10-day excursion on a shrimp trawling vessel was made in May 2022. A camera and a hydrophone were deployed inside two trawling nets close to the TED to record the audio and video during trawling operations. Researchers aboard the vessel monitored the video feed on screens to record the time of impact and species for turtle encounters in each of the two nets deployed. During the ten day trip, the researchers on the vessel observed 51 turtles that went through the nets, impacted the TEDs, and escaped. In addition, several rays and sharks also went through. Analysis of this acoustic data and preliminary results will be presented.

    

Infrasound from tornadoes

Tornadoes are known to radiate infrasound. The physical mechanism underlying the infrasonic radiation generated by tornadoes is not well understood. In this work, we use Lighthill's acoustic analogy and the theory of vortex sound to predict the pressure signals emitted from numerically simulated tornadoes which are produced in an LES model by researchers from the Penn State Department of Meteorology. The interesting patterns of the acoustic pressure in a low-frequency band strongly imply a rotating quadrupole source inside the tornado. A column of Kirchhoff vortices is the best potential candidate as a tornado-like source based on the analytical work. By applying acoustic propagation models in a stratified atmosphere, we want to find evidence of the predicted infrasonic signals in the signals detected in data collected during field experiments.   

Effect of Transducer Distance on Ultrasonic Backscatter Measurements of Cancellous Bone

Ultrasonic backscatter measurements may be used to detect changes in bone caused by osteoporosis and other diseases. Backscatter measurements are commonly performed at peripheral skeletal sites such as the heel bone (calcaneus). The transducer is usually placed in direct contact with the body which locates the interrogated region of bone tissue in the acoustic near-field of the transducer. The goal of the study was to determine how the distance between the transducer and bone affects backscatter measurements of bone. A rigid, open cell polymer foam specimen was used to simulate cancellous bone tissue. Ultrasonic measurements were performed in a water tank using a planar 2.25 MHz single element transducer. Backscatter measurements were performed by propagating ultrasonic pulses into the specimen and receiving the returned, backscattered signal. Signals were acquired for five transducer-specimen distances: 15.125 mm, 30.250 mm, 45.375 mm, 60.500 mm, and 75.625 mm corresponding to N/4, N/2, 3N/4, N and 5N/4 where N is the near field distance. Seven backscatter parameters were measured: apparent integrated backscatter (AIB), frequency slope of apparent backscatter (FSAB), frequency intercept of apparent backscatter (FIAB), normalized mean of the backscatter difference (nMBD), normalized slope of the backscatter difference (nSBD), normalized intercept of the backscatter difference (nIBD), and backscatter amplitude decay constant (BADC). FSAB was most sensitive to changes in the transducer-specimen distance, decreasing by approximately 400% as the distance was increased. In contrast, BADC changed by approximately 3%. The results indicate that transducer-specimen distance may have a strong effect on backscatter measurements of cancellous bone, depending on the backscatter parameter measured.   

Computational Characterization of Aluminum Nitride Clusters for Materials Science and Interstellar Chemistry

Aluminum Nitride clusters are essential species for material science and are an understudied Al-containing species in the interstellar medium (ISM). In materials science, the importance of these compounds stems from their physical properties such as high thermal conductivity allowing them to be alternative semiconducting materials. State-of-the-art QFF methodologies based on explicitly-correlated coupled cluster theory are used to generate accurate spectroscopic data to assist in the potential observation of aluminum nitride clusters in the ISM and provide more accurate energetics calculations than previously conducted to assist in finding semiconducting alternatives. The Al-N stretch of the H₂AlN molecular at 454.4 cm^–1 exhibit an anharmonic transition intensity of 81 km/mol. Additionally, Al-N has a net dipole moment of 2.266 D. This large dipole moment and bright vibrational transition make this a suitable candidate for interstellar observation of a new Al-containing species.   

F12+DFT Quartic Force Fields for Cost-Effective Theoretical Spectroscopy

CCSD(T)-F12 and DFT calculations are combined to compute accurate spectroscopic data for a set of benchmark molecules within 1.82% error of a high-level benchmarking method for vibrational frequencies. This is done by combining 3^rd order and 4^th order DFT force constants with 2^nd order CCSD(T)-F12 force constants in order to produce a “cheap + expensive” method. This approach can be applied to larger molecules where CCSD(T)-F12 single-point energies would take an infeasible amount time to calculate. Benchmark comparisons are made with the F12cCR approach with a triple zeta level basis set. This methodology is also used to calculate accurate spectroscopic data for several electronically excited states using time-dependent density functional theory combined with equation of motion coupled cluster techniques.

    

Fluoro Hydrogen Peroxide and Other Substituted Peroxides as Sinks for the Elusive Fluorine and Sulfur Atoms

Fluorine’s hostile nucleosynthetic environment makes it one of the least common elements and, consequently, understudied both on the earth and in the interstellar medium (ISM). However, the presence of fluorine-containing species in both the ISM and in the earth’s atmosphere necessitates the existence of a pathway out of this environment to form fluorine-containing molecules. To that end, the presence of fluorine and hydroperoxyl radical (HO₂) in either of these environments may lead to the formation of fluorinated molecules like fluoro hydrogen peroxide (HOOF) on dust grains of protoplanetary disks in the planet-forming regions of ρ Oph and in the earth’s atmosphere as a sink for other fluorine pollutants that have yet to be detected. This theoretical study utilizes explicitly correlated coupled cluster theory computed with core correlation and corrections from scalar relativity to provide the first anharmonic fundamental vibrational frequencies and rotational constants of HOOF, and other similarly substituted hydrogen peroxide species, for use as reference benchmarking of further computational or experimental study, as well as potential astrophysical and atmospheric observation. The ν₆ bending frequency for HOOF at 454.4 cm^–1 exhibits an anharmonic transition intensity of 78 km/mol, while the ν₄ frequency at 738.2 cm^–1 is 66 km/mol. Additionally, HOOF has a large net dipole moment of 2.12 D compared to the previously detected HF and HOOH molecules, 1.82 and 1.85 D, respectively, resulting from the electronegativity of the fluorine. Consequently, HOOF is a likely candidate for possible detection via vibrational and rotational spectroscopy to further the understanding of fluorine’s small, but important, role in astrochemical and atmospheric environments.   

Using Magnetic Particle Trapping and Transport to Investigate Magnetism at the Micro-Scale

We study the guided transport of fluid-borne micro-scale spherical particles about grids of permalloy disks, driven by varying, weak (<100 Oe) magnetic fields. These microspheres, made of iron oxide encased in polystyrene, are designed for bioseparation of cells, proteins, DNA, and RNA, whereas they can be specifically bound to these targets allowing for field gradients to separate the particles from a mixture. We investigate phenomena that arise during transport of individual particles, for example variation in particle motion with external fields and transition from orderly phased-locked motion to less predictable phase-slipping behavior. We use results from these experiments to guide development of computer models for understanding magnetic characteristics of both the microparticles (i.e. susceptibility) as well as the permalloy disks (i.e. magnetization landscapes). Furthermore, we discuss recent updates to o?ur lab's transport apparatus, including methods for minimizing unwanted surface adhesion and increased magnetic field stability.