This is the schedule of posters for the Rice CUWiP 2017 Conference. The poster session will be held in Brockman 101.
Lourdes Torres, San Antonio College
We have designed and built five solar panels, in three different configurations. This is a free standing prototype designed as an alternative to roof mounted solar panels. There are three leaf pattern panels, the octagonal pattern panel, and the control square panel. We have also designed and built a base to hold two leaf panels and the octagonal panel to act as a prototype for a solar tree. The Solar Tree will eventually be designed to have fixed angled tilts for the three panels, but in order for us to design the optimal arrangement, we have built a system that is capable of tilting and rotating on a few different axes to point the panels in different directions and at variable angles. The other two panels are designed to attach onto two prebuilt stands at EcoCentro that can be freely tilted and rotated. This allows us to compare our leaf panel to the control panel as well as compare the output of a sun-tracking style base to our solar tree arrangements.
Optimal Architectures for Single Photon Metrology
Margarite LaBorde, Louisiana State University
Previously, it was shown that devices utilizing quantum metrology schemes can result in quantum advantages over classical devices of the same nature through the application of effects such as the Hong-Ou-Mandel effect or the use of NOON states to achieve higher sensitivity [Contemp. Phys. 49, 125 (2008)]. Furthermore, devices using BOSONSAMPLING have garnered interest due to the increased practicality of using passive linear optic networks over the aforementioned methods. One particular device inspired by these systems has shown to have superior sensitivity to analogous classical devices [Phys. Rev. Lett. 114, 170802 (2015)]. Here, we generalize the structure of this device, maximize the phase sensitivity for realistic conditions, and determine not only a more practical scheme but one with superior sensitivity and an analytic form to compute this sensitivity; previously, such a result was merely postulated.
Synthesis and Characterization of 2-D Materials
Sharah Pazos, Louisiana Tech University
Atomically thin Transition-metal Dichacogenides (TMD), Graphene, and Boron Nitride (BN) are two-dimensional materials where the charge carriers (electrons and holes) are confined to move in a plane. They exhibit distinctive optoelectronic properties compared to their bulk layered counterparts. When combined into heterostructures, these materials open more possibilities in terms of new properties and device functionality. In this work, WSe2 and Graphene were grown using Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD) techniques. The quality and morphology of each material was checked using Raman, Photoluminescence Spectroscopy, and Scanning Electron Microscopy. Graphene had been successfully grown homogeneously, characterized, and transferred from copper to silicon dioxide substrates; these films will be used in future studies to build 2-D devices. Different morphologies of WSe2 2-D islands were successfully grown on SiO2 substrates. Depending on the synthesis conditions, the material on each sample had single layer, double layer, and multi-layer areas. A variety of 2-D morphologies were also observed in the 2-D islands.
Enhanced Magnetic Refrigeration Capacity in Co doped Mn5-xCoxGe3
Amber Williams, Miami University
Mn5Ge3 exhibits a Curie temperature of 296 K and has been reported to have a magnetic entropy change comparable to that of pure Gd, which makes it a potential candidate for near room temperature magnetic refrigeration applications. In this study we have synthesized and characterized a series of Mn5−xCoxGe3 compounds where x=0, 0.05, 0.1, and 0.15. The goal is to determine the effect of Co substitution for Mn on the magnetic and magnetocaloric properties of the materials. X-ray diffraction measurements revealed that all samples exhibit the D8 hexagonal structure at room temperature. Magnetization measurements show that all compounds exhibit ferromagnetism, with a decrease of Curie temperature with increasing Co concentration. Although, the magnetic entropy changes stays nearly constant across all values of x, Co substitution significantly enhances the refrigeration capacity of the materials. The largest magnetocaloric effect is observed in the Mn4.95Co0.15Ge3 compound with a peak magnetic entropy change of 7.75 J/kg K and a peak refrigeration capacity of 380.32 J/kg for a magnetic field change of 5T. The results provide further understanding of potential magnetocaloric applications for this series of compounds.
Testing of a Diamond Brewster Angle Waveguide Window at DIII-D
Emily LeViness, University of Alabama
Gyrotrons are devices used to apply power to plasma physics experiments such as DIII-D through electron-cyclotron resonance heating. To avoid reflections, gyrotrons operate with output windows having thickness of nlambda/2, where lambda is the wavelength of the rf wave in the window mate- rial and n is an integer. This limits the gyrotron output frequency to discrete values. Transmission of rf through a window at the Brewster angle, 67.2° in diamond, is insensitive to wavelength for rf waves polarized with the electric field out of the window plane. Use of a Brewster angle window therefore allows operation of a gyrotron at a near-continuum of frequencies, an advantage despite the cost of such a large window. Tests of a Brewster angle window were performed for waveguide with 31.75 mm diameter, designed for a frequency of 110 GHz, but with wide bandwidth. The tests included measurement of the rf loss in the window at relatively high power and the effect of the window on mode structure of an incident HE1,1 beam. Low power tests were performed for a range of frequencies and polarizations.
Design and Construction of a Low Cost Optical Trap for Use in Undergraduate Advanced Labs
Emily Churchman, Texas Lutheran University
Optical traps, sometimes called optical tweezers, can be used to explore fundamental optical phenomenon. The cost of a ready-made instrument can be upwards of $30,000. We present an instrument constructed using a simple design integrating off-the-shelf components, keeping the cost of the functional instrument under $5,000.The instrument will be used in upper level advanced physics labs and for undergraduate research projects.
Assembling, Cleaning, and Testing of a Unique Open-ended Cylindrical Penning Trap
Kassie Marble, Tarleton State University
A new experimental beamline containing a prototype unique open-ended cylindrical Penning trap has recently been constructed at Texas A&M’s Cyclotron Institute. The new beamline and trap will enable precision experiments that enhance our understanding of the limits on the non-SM processes in the weak interaction through the measurement of the β − ν correlation parameter for T = 2, 0+ → 0+ super allowed β-delayed proton emitters. The prototype TAMUTRAP consists of an open-ended cylindrical Penning trap of diameter of 90 mm with gold-plated electrodes of oxygen free high conductivity copper to prevent oxidation. The traps electric quadrupole field is provided by a SHIP TRAPS RF electronic circuit to the four segmented electrodes at the center of the trap while the traps 7 Tesla magnetic field is provided by an Agilent 210 mm ASR magnet.
Fabrication and Calibration Analysis of the Scintillating Attenuation Spectrometer
Hannah Hasson, University of Texas System
Scintillation detectors are essential diagnostics in gamma spectrometry, however their slow response times often limit their ability to measure such spectra in high flux or short pulse environments. We propose a new spectrometer design called the Scintillating Attenuation Spectrometer (SAS), which utilizes high-yield LYSO scintillators and images with a CCD camera rather than photomultiplier tubes. The scintillator is cut into pixels and partitioned with reflective foils such that the incoming gamma beam travels down the axis of the crystal matrix. The reach of the scintillation in the matrix is then inverted into a spectrum with resolution corresponding to the amount of pixels encompassing the signal. We describe here the rationale and procedure of the detectors fabrication, as well as calibration comparisons of GEANT4 simulations with data collected from known sources. We also present preliminary spectral data collected with the SAS for the Texas Petawatt Laser Experiment.
Modeling a New Type of Gamma-Ray Detector for Nuclear Physics
Kelly Yao, Rice University
This study simulates the response of a new type of gamma-ray detector called scintillation attenuation spectrometer (SAS) using GEANT4, the CERN Monte Carlo code for radiation and high-energy physics. The scintillator consists of a lead collimator and a large 2D matrix of fully-coated LYSO crystal pixels (1.5mm x 1.5mm x 1cm) with 100% reflectivity at the pixel boundaries. Monoenergetic gamma-rays are injected from the side each time, and the energy deposition at each pixel is acquired, representing local scintillation optical photon output (approximately 30000 blue photons per MeV of energy absorbed). The 2D light pattern is then recorded using a CCD camera. Each image represents the detector response at that particular gamma-ray energy. Using a large collection of scintillation light patterns of gamma-rays spanning a broad range of energies (e.g. 0.1 to 50 MeV), we can construct the detector response matrix. This matrix can then be used to deconvolve the observed optical images from real experiments into gamma-ray spectra. This new approach to gamma-ray spectroscopy solves the difficulties of conventional detectors based on filter stack attenuation, Compton scattering or single-photon counting methods. It is ideal for short-pulse ultra-intense gamma-ray sources. We will compare our simulation results with experimental data from calibration radioisotope sources.
Photon Detection Efficiency in Photo-multiplier Tubes
Eliza Gazda, Embry Riddle Aeronautical University
The photon detection efficiency of two sets of R10560-100-20 superbialkali photomultiplier tubes from Hamamatsu were measured between 200 nm and 750 nm to quantify a possible degradation of the photocathode sensitivity after four years of operation in the cameras of the VERITAS Cherenkov telescopes. A sample of 20 photomultiplier tubes, which was removed from the telescopes was compared with a sample of 20 spare photomultiplier tubes, which had been kept in storage. It is found that the average photocathode sensitivity marginally increased below 300 nm and dropped by 10% to 30% above 500 nm. The average photocathode sensitivity folded with the Cherenkov spectrum emitted by particles in air showers, however, reveals a consistent detection yield of 18.9±0.2% and 19.1±0.2% for the sample removed from the telescope and the spare sample, respectively.
Exploring the Metal Retention Fractions of Dwarf Galaxies
Melissa Morris, University of Texas at Austin
Using a novel technique that combines star formation and chemical evolution histories from resolved stellar populations, nebular abundances, and gas masses, McQuinn et al. 2015 measured that only 5% of the oxygen produced by stellar nucleosynthesis was retained in the gas and stars in the very low-mass (stellar mass = 6×105 Msun) galaxy Leo P. In contrast to expectations, metal production and metal loss for spirals in the mass range 109−1011Msun show that these galaxies retain 20-25% of their metals, independent of mass (Peeples et al. 2014). This suggests there is only a factor of 5 difference in the ability of galaxies to retain metals, despite a factor of 106 difference in mass. In this prototype study, we explore using the same technique from McQuinn et al. on a small sample of dwarfs with HST archival data, with particular attention to understanding the uncertainties in the approach. Our results will provide a measurement in the intervening mass range between Leo P and more massive spirals. This will allow us to test theoretical predictions of metal loss as a function of galaxy mass.
The Frequency of Starbursts in Dwarf Galaxies
Anna McGilvray, University of Texas System
Starbursts are periods of intense star formation that can dramatically impact the evolution of a galaxy, particularly in the shallow potential well of dwarf galaxies. Starbursts in dwarf galaxies have been measured to last hundreds of Myr based on star formation histories derived from resolved stellar populations. Often, these temporally extended events do not have direct evidence of an external trigger mechanism; this suggests that it is possible starbursts in dwarfs may be internally driven. Using archival HST data, we probe for (post-)starburst signatures using SFHs of a wider sample of dwarfs. These results will help constrain the fraction of dwarf galaxies in the local volume that experience a starburst event and the likelihood of whether starbursts can be internally triggered.
The Environmental Dependence of the Galaxy Stellar Mass Function in the ECO Survey
Hannah Richstein, Texas Christian University
We study the environmental dependence of the galaxy stellar mass function in the ECO survey and compare it with models that associate galaxies with dark matter halos. Specifically, we quantify the environment of each galaxy in the ECO survey using an Nth nearest neighbor distance metric, and we measure how the galaxy stellar mass distribution varies from low density to high density environments. As expected, we find that massive galaxies preferentially populate high density regions, while low mass galaxies preferentially populate lower density environments. We investigate whether this trend can be explained simply by the stellar-to-halo mass relation combined with the environmental dependence of the halo mass function. In other words, we test the hypothesis that the stellar mass of a galaxy depends solely on the mass of its dark matter halo and does not exhibit a residual dependence on the halos larger environment. To test this hypothesis, we first construct mock ECO catalogs by populating dark matter halos in an N-body simulation with galaxies using a model that preserves the overall clustering strength of the galaxy population. We then assign stellar masses to the mock galaxies using physically motivated models that connect stellar mass to halo mass and are constrained to match the global ECO stellar mass function. Finally, we impose the radial and angular selection functions of the ECO survey and repeat our environmental analysis on the mock catalogs. We find that the environmental dependence of stellar mass in the mock catalogs is in agreement with that observed in the ECO survey. Our results are thus consistent with the simple hypothesis that galaxy stellar mass only depends on halo mass. The RESOLVE/ECO surveys were supported by NSF award AST-0955368.
Comparing Methods for Solving Nonlinear Wave Equations
Andrea Vancil, Birmingham Southern College
Einsteins theory of general relativity has increased our understanding of astrophysical events. Computational physicists can model these astrophysical events to allow for interpretation of experimental results, such as the recent gravitational wave observation made by the LIGO laboratory. The purpose of this project is to investigate techniques for solving a scalar partial differential equation with general relativity-type nonlinearity. A particular focus is to compare the results of common numerical methods applied to this equation. Methods compared include CFLN, Iterated Crank-Nicolson, Velocity Verlet, and 3rd and 4th-order Runge Kutta approximation methods, as well as an original method similar to the Velocity Verlet.
Stratospheric Organisms and Radiation Analyzer Payload
Fre’Etta Brooks, University of Houston
The SORA payload will sample for the existence of microorganisms and bacterial spores in the upper atmosphere. The payload will also analyze different aspects of the surrounding environment such as radiation exposure, temperature, pressure and humidity. The payload has three main scientific objectives. First, design and build a novel system that will isolate surrounding air and sample for cells. Second, onboard sensors will analyze exposure to solar and cosmic radiation that microorganisms may encounter. Finally, monitor the environmental conditions such as temperature, pressure, and humidity. Furthermore, the design will employ additive manufacturing and hobby electronics in its construction to provide an accessible basis for future missions and explore the bounds of the technology available.
Directional Dependence for Dark Matter Annihilation in Extreme Astrophysical Environments
Olivia Grahm Valadie, Hendrix College
This research explores the directional dependence that extreme magnetic fields have on the annihilation of dark matter into electron-positron pairs. We take the neutralino of the Minimally Supersymmetric Standard Model (MSSM) as our dark matter candidate and assume magnetic field strengths on the order of the critical field (Bc ∼ 1013 G). This is characteristic of extreme astrophysical environments in which dark matter may accumulate. We will present the results for the annihilation cross section at varying incoming particle direction. In addition, we will present how these results differ with neutralino mass and energy, as well as with the magnetic field strength. Our goal is to demonstrate the ways that the direction of the magnetic field affects the states of the final electron and positron.
Reaction Coordinate Evaluation Through Bayesian Analysis
Brooklyn Tanner, University of Houston
Finding a good “reaction coordinate” is necessary to clarify the physical mechanism of a reaction. This is important for capturing the transition state and the free energy barrier. Previously, Gerhard Hummer designed a Bayesian-like formula to quantitatively evaluate the quality of any reaction coordinate, based on its potential to identify the transition path ensemble. Robert Best and collaborators applied this algorithm to assess typical examples of protein folding and decided Q, the fraction of native contacts formed in protein structures, is a reasonable reaction coordinate. However, except for the study in some special cases, a systematic evaluation of existing reaction coordinates in biomolecular transition is missing. We investigated the behaviors of Qdiff, the difference between Q of two end states, in several structurally transitioning protein examples. We find Qdiff captures the transition states of any structural transition reasonably well. In particular, our calculation indicates this Bayesian-like evaluation is valid not only in a two-state system, but also in cases where there is an intermediate state, but we also notice that different reaction coordinates provide better results for different proteins. Here we exam some reaction coordinates with different protein to understand why this is.
Effect of Simulated Microgravity and Cosmic Radiation on Elasticity of Rat Femur and Tibia Bones
Hayley Heacox, University of Central Arkansas
It is known that space conditions such as microgravity and cosmic radiation have detrimental effects on the skeletal system of humans, such as decreased bone mineral density. This research studies the changes in elasticity of rat femur and tibia bones when exposed to hind-limb suspension and x-ray irradiation, simulated microgravity and cosmic radiation. A technique known as three-point bending was employed to estimate the Youngs (elastic) modulus for the leg bones. A high elastic modulus indicates a large force is needed to alter the shape of the bone while a low elastic modulus is indicative of little force being required to change the shape. It is hypothesized that if microgravity and cosmic radiation lead to decreased bone mineral density, then these conditions will produce weakened bones and lower elastic moduli, as compared to bones not subject to these conditions. To investigate these elastic alterations, four treatment groups of male rats were established. One group received an x-ray radiation (IR) dose of 2.0 GY to simulate cosmic radiation; one group was hind-limb suspended (HLS) for two weeks to imitate microgravity; one group was both hind-limb suspended and irradiation (HLS-IR) to best simulate space-like conditions; the final group served as a control group (CON). Analysis of results suggest a less elastic nature of leg bones exposed to HLS or IR compared to leg bones that were not suspended or irradiated; this weakening was more apparent in the tibias. When the effects of HLS and IR are combined, a weakening of the bones was observed but not in as great of magnitude as hypothesized. The findings from this research will ultimately aid in quantifying the negative effects of spaceflight. From this quantification, a regimen to counteract such effects can be proposed.
The Effects of Stimulated Microgravity on Physical Components of Mice Hind Limb Bones
Kristan Jones, University of Central Arkansas
Simulated microgravity is often proposed to correlate with a decreased bone density and strength. This study was designed to simulate spaceflight through hind limb suspension system in mice. We subjected 2 month old mice to OVX and SHAM surgeries and evaluated the overall effects of the surgeries and the hind limb suspension on the bones using a three point bending method, bone dimensions and evaluating their food and water intake. Body weight and food and water intake were monitored throughout the research. In previous research, we found that the SHAM mice bones could withstand a significantly greater amount of pressure before breaking versus the OVX mice bones. We expect to see the same results as we break the OVX and SHAM mice bones that were involved in the HLU experiment. We are surprised to see that the body weight was unchanged from the time that the mice were suspended to the time that they were sacrificed. Our study demonstrates what effects antigravity and OVX has on physical parameters of the mice bones as we assess the strength of the bones.