Physics Commons^™

Reed Research Reactor Neutron Beam Characterization And Analysis, Vee Bartko, Jerry Newhouse

Student Research Symposium

Using neutron activation analysis of 99% pure gold foils, the authors characterize the neutron dose and shape of the neutron beam at the Reed Research Reactor (RRR). The experimental procedure followed extensive modeling in Monte Carlo N-Particle (MCNP) and Tool for Particle Simulation (TOPAS) simulations, in which the beam was projected to be roughly collimated. The shape, defined in terms of neutron flux, was measured by placing the foils directly on top of the neutron beam cap at powers of 1, 5, and 10 kilowatts. The flux was then converted to neutron dose via the Nuclear Regulatory Commission's neutron fluence …

Development Of A Two-Photon Laser Scanning Microscope, Jess Hollenbaugh

Student Research Symposium

The objective of this project was to convert a Sarastro 2000 confocal laser scanning microscope into a system capable of imaging using two-photon excitation (TPE) fluorescence for the use of the PSU biology department. TPE microscopy operates on the ability of fluorophores to accept two photons each with half the energy of a desired transition in a single quantum event via a virtual energy state and then emit a higher energy photon upon relaxation. This is preferable to single-photon excitation (SPE) due to the lower energy photons causing less damage to delicate biological samples. The adaptation process included physically altering …

Going Down An Incline With Chatgpt, Corey R. Sissons

Student Research Symposium

In our Large Language Model (LLM) research, examining ChatGPT 4, we devised a physics problem involving an object descending an inclined plane. Through variations in terminology such as "rolling," "sliding," "solid sphere," "hollow sphere," "wooden ramp," "no-slip ramp," and more, we sought to evaluate LLM responses for different scenarios. Our analysis aimed to discern whether the LLM’s answers exhibited expertise in the field of physics. This experiment sheds light on LLM’s ability to give accurate and precise physics answers as well as variation in responses to nuanced changes in problem formulation. This provides valuable insights into its proficiency and potential …

Development Of A Fast-Neutron Source Localization System, Abdulsalam F. Al Mutairi

Student Research Symposium

Power generation by nuclear fusion is a continuing ambition that has been the focus of nuclear fusion research for nearly a hundred years. However, small-scale fusion reactors have further propulsion and neutron imaging applications that don’t require greater than breakeven efficiencies that a fusion energy source needs. Inertial Electrostatic Confinement (IEC) fusion devices have the potential for miniaturization, making them a strong candidate for such applications. Yet the contributions of different interactions within an IEC fusion device are still not fully understood. Imaging an IEC device and investigating each interaction's Neutron Production Rate (NPR) can enhance design efficiency. Neutron imaging …

Using Digital Holographic Microscopy To Characterize Vibrio's Chemotaxis, Jacqueline Acres, Eric Valentino

Student Research Symposium

Vibrio alginolyticus is a marine bacterium that displays distinctive chemotactic behavior. Chemotaxis is the ability to move in response to a concentration gradient, either in the direction of nutrients or away from repellants. Vibrio's single, polar flagellum allows it to form a tight cloud in the presence of a chemoattractant. In this work, we experimentally characterize cloud sizes after both normal culture conditions and simulated microgravity using digital holographic microscopy or DHM. DHM allows visualization of volumetric samples by recording x,y,z and t information in holograms. Plane-by-plane reconstruction retrieves the z-plane information which can then by stitched together into hyperstacks …

Surface Plasmon Characterization In Ag Nanotriangles For Evaluation Of Fano Resonance Conditions, Nabila Islam

Student Research Symposium

Surface plasmon polariton (SPP) is a collective oscillation of electrons and light at the metal -dielectric interface excited by the incident radiation on metal surface through the momentum matching conditions. The properties of SPPs and the resonance conditions are highly dependent on the confining materials and geometry of the confining nanostructure. The sensitivity of the surface plasmon resonance to the property of the confining materials made Surface plasmon resonance (SPR) sensors a central tool for biosensing. However, the frequency resolution of SPR sensors is typically limited by the broad resonance of the SPR mode. The resolution can be enhanced through …

Effects Of Wavelength Variation On Localized Photoemission In Triangular Gold Antennas, Christopher M. Scheffler, Robert Campbell Word, Rolf Könenkamp

Student Research Symposium

Exposing metal-dielectric structures to light can result in surface plasmon excitation and propagation along the transition interface, creating a surface plasmon polariton (SPP) response. Photoemission electron microscopy (PEEM) has been used to image nanometer scale plasmonic responses in micron-sized plasmonic devices. With PEEM, optical responses can be characterized in detail, aiding in the development of new types of plasmonic structures and their applications. In thin, triangular gold platelets SPPs can be excited and concentrated within specific regions of the material. In this regard, the platelets act as receiver antennas by converting the incident light into localized excitations in specific regions …

Diagnostic Platform For Current Health Status Monitoring, Albert S. Benight, Megan M. Koslen, Matthew W. Eskew

Student Research Symposium

Our approach is based on physical measurements of blood plasma and exploits the plethora of information contained in the human plasma proteome, as a reporter of human health status. The assay involves collection and analysis ofthermograms of plasma from human blood measured by differential scanning calorimetry (DSC).

Plasma thermograms arise from the temperature-induced denaturation profile of proteins within blood plasma measured by DSC. This insightful measurement thereby provides a snapshot of the current state of the human plasma proteome which directly informs on overall systemic health. Such measurements have been shown to be highly accurate and sensitive indicators of health …

Opportunities In Physics Education: Low-Cost Position Tracking For Use In Kinematics Labs, Paul R. Destefano, Cora Siebert, Roberto Perez-Franco, Thomas Allen, Gabriel Mukobi, Ralf Widenhorn

Student Research Symposium

Traditional introductory physics kinematics laboratories utilized a few different instruments for locating objects in motion, all of which have shortcomings. Some provide only timing data, which heavily restricts trajectories and data collection. Some instruments provide more measurements but restrict object shapes, orientations, and textures. Still others require extensive pre-processing. None of these traditional instruments provide two- or three-dimensional position data. New, low-cost, local positioning technology, based on radio frequency wireless communications, is available that enables novel redesigns of physics laboratories. This technology provides two- and three-dimensional position measurements, continuously, at data rates of 10 Hz or faster, from any object …

Find, Build, And Export Information For 3d Printing Of Your Favorite Molecules And Crystal Structures At Two Dedicated Websites, Paul R. Destefano, Peter Moeck

Student Research Symposium

As 3D printers require instructions, the Nano-Crystallography Group at Portland State University is creating two websites (http://nanocrystallography.org/3dconvert/ and http://nanocrystallography.research.pdx.edu/3d-print-files/convert/) where such instructions are created, interactively, for the atomic arrangements of virtually all known molecules and crystals.

We will prepare a "pipeline" into which crystallographic information enters from two curated open access crystallographic databases, is manipulated to create the desired 3D models, and then is exported in either STL format (the standard for monochrome 3D printing) or VRML/X3D (the ISO successor to STL). The two aforementioned databases are the North-American mirror of the Crystallography Open Database (http://nanocrystallography.org) …

Finite Element Method Analysis Of Resonant Cavity For Whispering Gallery Acoustic Sensing Microscopy, Thanh N.D. Le, Ha Tran, Andres H. La Rosa

Student Research Symposium

Whispering Gallery Acoustic Sensing (WGAS) has been studied by Department of Physics at Portland State University as a mean of controlling sample to probe distance in tuning-folk-based scanning probe microscopy (TF-SPM). WGAS uses the microscope frame as a resonance acoustic cavity. The setup shows high potential because of high-quality factor nature of acoustic cavity as well as using mechanical motions of the TF itself instead of electrical signals. However, the analytic solution of the eigenfrequencies of the current microscope frame is very complex due to the asymmetric geometry. The purpose of this study is to use finite element method to …

Quasi-Optical Measurement For Low Loss Material Characterization In Submillimeter Wave Range, Ha Khiem Tran, Thanh Ngoc Dan Le, Branimir Pejcinovic

Student Research Symposium

An accurate knowledge of dielectric constant of materials is required in many sub-millimeter wave applications. Free-space measurement of materials has always been one of the first choices due to their non-destructive nature and relatively simple sample preparation. However, free-space measurement systems at sub-millimeter frequency range suffer from two main problems: high loss because of divergent beam pattern and diffraction when the beam waist of the radiated beam is relatively large compared to the size of the sample under tests. In order to mitigate these issues, we set up a quasi-optical system using off-axis parabolic mirrors, which enhance the dynamic range …

Listening To Lasers: Photoacoustic Gas Sensing, Michael Hopkins

Student Research Symposium

Herein lies the makings of a sensor for gaseous materials due to the technique known as photo-acoustic spectroscopy. Whereby a gas filled metallic tube of known resonance has an impingement to its open aspect a beam of photons of known colour and at a specified rate such that the rate of incoming light corpuscles matches the natural standing wave frequency for the column of gas within said tube, to wit resonance. Through foresight of the molecular orbital theory and historic datums on the subject of infrared spectroscopy one naturally comes to the employment of absorbance transfiguring energy to kinetic motions …

Design, Construction, And Utilization Of Physical Vapor Deposition Systems For Medical Sensor Fabrication, Nicholas Sayre, Erik J. Sánchez, Joe Kowalski

Student Research Symposium

The development of a novel blood glucose sensor is realized through construction of a homemade plasma coating system and utilization of semiconductor manufacturing processes in a small scale cleanroom environment. Photolithography, plasma sputtering, chemical etching and thin film measurement technologies are used in the medical sensor fabrication process. General process flow will be discussed, and system design and the plasma sputtering process will be presented as it is achieved by the system currently under development.

Bicrystallography In Two Dimensions: A Graphical Procedure And Comparison Of Its Results To Experiments, Andrew M. Maas, Peter Moeck

Student Research Symposium

Three dimensional (3D) bicrystallography describes ideal structures of grain boundaries comprehensively at the atomic level as a function of the five macroscopic and two of the four microscopic parameters [1,2]. Free energy minimization of these structures leads to the real structure of these topologically distinct regions within crystals. These minimizations may either reduce the symmetries of ideal bicrystals or leave them intact. Since the symmetries of physical properties need to be compatible (by the Shubnikov-Curie and Curie-Minnigerode-Neumann principles [3]) with the symmetries of the atomic arrangements from which they arise, bicrystallography allows for predictions about which phenomena can occur in …

Predicting The Optical Response Of A Generalized Multilayer Thin Film, A.J. Lawrence, Erik J. Sánchez

Student Research Symposium

The contrast mechanism in Kerr imaging is the apparent angle through which the plane of polarization is rotated upon reflection from a magnetic surface, and this can be calculated for a well characterized surface given the polarization state of the incident light. As in traditional optical microscopy, the spatial resolution is limited by diffraction to roughly half the wavelength of the illumination light. The diffraction limit can be circumvented through the use of near-field scanning optical microscopy, in which the illumination source is an evanescent field at the tip of a tapered optical fiber. The complication in merging these two …

Zinc Oxide Random Laser Threshold Enhancement Via Addition Of Passive Scatterers, Zachariah M. Peterson, Rolf Könenkamp, Robert Campbell Word

Student Research Symposium

Zinc oxide (ZnO) is a wide bandgap n-type semiconductor with a variety of optical and electrical applications and many methods of fabrication. Strong optical scattering and photoluminescence from ZnO nanoparticles and films makes the material an ideal candidate for a random laser. Previous studies have shown both incoherent and coherent random lasing from ZnO films and particles agglomerations. When used as a passive scatterer in a laser dye gain medium, the addition of ZnO has been shown to improve the threshold for lasing. By combining active scattering ZnO with a passive scatterer, MgO, we show here that the lasing threshold …

Differential Effects Of Membrane Order On Membrane Permeability, Miranda J. Bradley, Marshall J. Colville, Miles J. Crumley, Drake C. Mitchell

Student Research Symposium

Phospholipid membranes segregate into lateral domains of liquid ordered (lo) and liquid disordered (ld) phases when cholesterol and mixed species of lipids with saturated and unsaturated acyl chains are present. To examine membrane permeability and rate of vesicle rupture by Triton in pure lo, pure ld, and mixed lo/ld phases, LUVs were prepared based on the ternary phase diagram of POPC, sphingomyelin, and cholesterol. These LUVs were loaded with 2mM carboxyfluorescein (CF) and formed by extrusion at 65oC. Using a stopped-flow fluorometer, changes in CF fluorescence were measured when LUVs were exposed to sudden osmotic gradients, pH gradients, or 0.1% …