Physics majors celebrated Physics Week March 23-29. Activities included: (1) demonstrations of electronics projects, (2) physics research poster presentations, (3) physics fair on the mall, (4) liquid nitrogen sundaes, and (5) last, but not least, bubble soccer behind the tower. What a sight it was!
Anthony Kersting, UD senior physics major with a German concentration, has been awarded a Fulbright Teaching Assistantship for the academic year 2015-16. Anthony has completed research in observational astronomy where he investigated dwarf nova ASASSN-14cv. He is also a member of Lyric Theater and Collegium Cantorum. Anthony joins physics majors William Spearman (Research Fulbright to CERN in 2008) and Jamie Antonelli (Research Fulbright to France in 2005) as recent physics majors who have won this prestigious award.
Anthony Kersting Fulbright 2015
Texas APS Presentations
Three senior physics majors presented the results of their senior research projects at the Spring 2015 Meeting of the Texas Section of the American Physical Society. The meeting was held at Lee College, March 6-7, 2015.
Observations and Analysis of the New Dwarf Nova ASASSN-14cv
Anthony Kersting, Richard Olenick, and Arthur Sweeney
(University of Dallas)
On June 21, 2014 a new bright cataclysmic variable star, ASASSN-14cv, was detected in the constellation Draco by the All-Sky Automated Survey for Supernovae, ASAS-SN. The 13th magnitude CV matches to a blue 19th magnitude SDSS star, but no previous outburst data is to be found in CRTS data. During follow-up observations performed using the University of North Texas' Monroe Robotic Observatory, the CV was observed over the course of ten nights for a total of 495 images from its early plateau stage until quiescence. Ensemble photometry performed on the raw images was used to produce light curves for the CV which were then analyzed in order to determine an early superhump period of 0.0592 d. During quiescence the orbital period was measured to be 0.0609 d. Early outburst data is rare and few observers go on to perform careful analysis of such data, making these results of particular interest in studying CVs.
Discovery and Follow-up Observations of the Exoplanet Candidate GSC02087-011261
Laura Aumen, Richard Olenick, and Arthur Sweeney
(University of Dallas)
Wide angle survey measurements;by the University of Dallas Small Telescope Extrasolar
Transit Survey (STExTS) in the summer of 2012 found that the star GSC02087-01126 exhibits
characteristics of a possible transit. According to the UCAC4 catalogue, the star
has a (B-V)o magnitude of 0.265, corresponding to a temperature of 7402 K, which
is a reasonable for a star in possession of a planet. Using the box least squares (BLS) function, we determined a likely period for the orbit of 0.79380 days.
Calculation of the ephemeris led to taking follow up data targeted toward the specific dates of the transit in the summer of 2014 with additional follow-up;measurements in the spring of 2015 using the University of North Texas' Monroe Robotic Observatory. The observational data and calculated quantities will be presented.
Visualizing the Growth of High Energy Density Mixing Layers
(University of Dallas and Lawrence Livermore National Lab)
(Lawrence Livermore National Lab)
At Lawrence Livermore National Lab, we computationally modeled the mixing layer between two fluids as high energy density shock waves passed through the interface between the fluids. This modeling was done with the aim of designing a NIF target which could be imaged using X-rays on the order of 10 keV in order to measure the width of the target's mixing layer. We used an Arbitrary Lagrangian-Eulerian modeling method and tested several different target designs and shock wave drives. One design which showed great potential for a successful measurement was a bifurcated target. Special consideration was given the error introduced with a bifurcated target.
Six senior physics majors gave talks at the Texas Section of the American Physical Society Fall Meeting held at Texas A&M University October 17-19, 2014. The five students who are also members of the TX Section of the APS received APS travel awards to attend the conference and present the results of their summer research. The University of Dallas Experience Awards covered other travel expenses to make this event very successful for our students. A seventh senior attended the conference.
Aaron Mebane, Michael Klem, Samuel Henderson, Thaddeus Howard, Michael Kalan, Luke Pecha, and Michael Hoff at the Texas Fall 2014 APS Meeting. (It seems they are all pretending to be engineers with their left-hand rule.)
Their abstracts are listed below:
Charging and Interaction of Two-Particle System within a Glass Box Immersed in a Low-Vacuum Argon Plasma
(University of Dallas)
Due to Debye screening, the interaction between charged dust particles within a plasma may not be considered as a simple Coulomb force. In order to observe particle interaction, the top particle in a vertical, two-particle chain is pushed from its equilibrium position using a high-power Verdi laser, and as it returns to equilibrium will interact with the second particle. In order to isolate the particle interaction force, the electrostatic force and neutral drag force are subtracted from the net force acting on the particle by using a single particle undergoing damped oscillations in the box as a reference. The net electric field and drag force within the glass box are examined by forcing damped oscillations of a single particle, in the vertical direction by an applied DC bias between electrodes and in the horizontal direction by laser-pushing. It is found that in both the horizontal and vertical dimensions the electric field depends linearly on the particle's distance from its equilibrium position, and the linear coefficient to describe the field in turn has a linear dependence on plasma power. After isolating the particle-particle interaction force, what is expected to be an equal and opposite interaction force between the particles is instead found to be asymmetric, and possible causes for this are discussed.
56Fe Inelastic Neutron Scattering Cross Sections Deduced from γ-Ray Production Cross Sections
Thaddeus Howard, S.F. Hicks, A.J. French, S.L. Henderson, Z.C. Santonil, L.C. Sidwell
(University of Dallas)
M.T. McEllistrem, E.E. Peters, T.J. Ross, and S.W. Yates
(University of Kentucky)
J.R. Vanhoy and B.K. Thompson
(U.S. Naval Academy)
Inelastic neutron scattering cross sections have been deduced from γ-ray production cross sections for 56Fe. Measurements were made at the University of Kentucky Accelerator Laboratory using the neutron production and detection facilities located there. A natural iron sample (91.72%} isotopic abundance of 56Fe) was bombarded with a nearly mono-energetic incident neutron beam with energies in a range from 1.5-4.7 MeV. Gamma-ray excitation functions were determined for each observed γ ray in this energy range; from these, branching ratios and γ-ray production cross sections were determined and neutron scattering cross sections deduced. Gamma-ray excitation functions were also measured for 27Al, 48Ti, and 51V to investigate using the deduced neutron scattering cross sections as standards to normalize absolutely the 56Fe cross sections. Cross sections determined in this work are compared to evaluated data from the National Nuclear Data Center.
A Comprehensive Evaluation of the Performance and Materials Chemistry of a Silicone-Based Replicating Compound
(University of Dallas, Irving, Texas)
(Sandia National Laboratories, Albuquerque, New Mexico)
The objective of this project was to characterize the performance and chemistry of a silicone-based replicating compound. Some silicone replicating compounds are useful for critical inspection of surface features. Common applications are for examining micro-cracks, surface pitting, scratching, and other surface defects. Materials characterization techniques were used: FTIR, XPS, ToF-SIMS, AFM, and Confocal Microscopy to evaluate the replicating compound. These techniques allowed for the characterization and verification of the resolution capabilities and surface contamination that may be a result of using the compound. The AFM and Confocal Microscopy results showed the compound does accurately replicate the surface features to the claimed resolution. XPS and ToF-SIMS showed there is a silicone contaminant layer left behind when a cured replica is peeled off a surface. Attempts to clean off the contamination could not completely remove all silicone. The methods and results for the compounds will be presented.
Sensitivity of Inferred Electron Temperature from X-ray Emission of NIF Cryogenic DT Implosions
The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory seeks to achieve thermonuclear ignition through inertial confinement fusion. The accurate assessment of the performance of each implosion experiment is a crucial step. Here we report on work to derive a reliable electron temperature for the cryogenic deuterium-tritium implosions completed on the NIF using the x-ray signal from the Ross filter diagnostic. These x-rays are dominated by bremsstrahlung emission. By fitting the x-ray signal measured through each of the individual Ross filters, the source bremsstrahlung spectrum can be backed out, and an electron temperature of the implosion hot spot inferred. Currently, each filter is weighted equally in thisanalysis. We present work quantifying the error bars with such a technique, and results investigating the contribution of each filter to the overall accuracy of the temperature inference. Using this research, we also compare the inferred electron temperature against other measured implosion quantities to develop a more complete understanding of the hot-spot physics.
Correlation Between Optical Properties and Charge Carrier Mobility in Regioregular
Poly (3-hexylthiophene) Thin Films
The ability to efficiently and accurately determine the charge carrier mobility (CCM) in poly (3-hexylthiophene-2,5-diyl) (P3HT) thin films is important for measurements of quality in P3HT based electronic devices. P3HT is an important semiconducting organic polymer that is one of the leading candidates for use in organic thin-film and, flexible electronics. CCM is routinely determined using methods such as field effect mobility measurements; however, this requires the devices fabrication to be completed in addition to a process of probing the device for current vs voltage readings. Because of these requirements a non-contact optical method was investigated to efficiently predict the CCM of P3HT thin films. Ellipsometric methods were used to examine the anisotropic nature of P3HT with a goal of determining the overall order of the polymer chains in the film and thereby predicting CCM. Results indicate that P3HT chains easily adopt a preferred order in the film, that charge transport is two dimensional, and that annealing temperature does not affect the anisotropic nature of P3HT but does increase the size of the crystallites. These findings will be discussed in detail.
Determination of Decay Characteristics of 54Fe Excited Levels through Inelastic Neutron Scattering
Robert L. Pecha, S.F. Hicks, A.J. French, S.L. Henderson, Z.C. Santonil, L.C. Sidwell
(University of Dallas)
M.T. McEllistrem, E.E. Peters, T.J. Ross, and S.W. Yates
(University of Kentucky)
J.R. Vanhoy and B.K. Thompson
(U.S. Naval Academy)
Due to the importance of neutrons for the successful and safe operation of fission reactors, it is necessary to obtain accurate and expansive knowledge about how they interact with the surrounding materials. Iron is commonly used to build reactor components, and how neutrons interact with Fe can affect the efficiency and rate of reaction within a reactor. This research studies the gamma ray emission and neutron scattering probabilities from two common iron isotopes, 54Fe and 56Fe, when bombarded with a monoenergetic neutron beam in the 1.5 MeV-4.7 MeV range. This talk will focus on the gamma ray emissions from an enriched 54Fe sample that has been excited by inelastic scattering of neutrons. From these emissions, a nuclear excitation level scheme was built, and new information about the excitation of 54Fe nuclei was obtained. A basic overview of the experimental equipment used, measurements taken, results, and final level scheme will be discussed and compared to previous measurements.
UD Affiliate Physics Professor Presents at the Texas Section of the American Physical Society Meeting, Oct. 17-19, 2014
Interactive Cosmological Modeling with Easy Java Simulations: Constraints from a New Growth of Structure Module of CosmoEJS
Jacob Moldenhauer and William Zimmerman
(University of Dallas)
Several cosmological observations suggest the universe's expansion is accelerating. Some possible explanations include a cosmological constant, or other form of repulsive dark energy, i.e. negative pressure and negative equation of state, a modification to general relativity at cosmological scales of distances, or an apparent effect of inhomogeneities in the universe. CosmoEJS is an interactive simulation package that allows educators and researchers to investigate cosmological models by simultaneously fitting several observations numerically. Previously, this package only used expansion history data sets, like supernovae, gamma ray bursts, baryon acoustic oscillations, the Hubble parameter, and the cosmic microwave background radiation; but data sets which measure the growth of galaxy structure formation, or clustering, have been shown to be more constraining for particular sets of models. We present a new module that enables constraints from growth data sets for various cosmological models. When combined with expansion history observations, these constraints from the growth of structure can drastically reduce the number of competitive cosmological models. CosmoEJS is available from Compadre Open Source Physics website, i.e. http://www.compadre.org/osp/items/detail.cfm?ID=12406.
Congratulations to Physics Senior Michael Kalan for co-authoring a research paper in the Journal of Vacuum Science and Technology.
Zach Santonil, Jack Bredemann, Matt Melendez, Elizabeth Sizemore, Nick Hedlesky, Aaron Stolle, and Stan Tinsley graduated on May 18, 2014. We wish our graduates well as they move forward in life.
Samuel Henderson - ACS Nuclear Chemistry Summer School at Brookhaven National Laboratory
Thaddeus Howard - NEUP Neutron Scattering Research at U. of KY
Michael Klem - Fusion Research at Lawrence Livermore National Laboratory
Luke Pecha - NEUP Neutron Scattering Research at U. of KY
Luke Simmons - Hydrodynamic Modeling at Lawrence Livermore National Laboratory
3-D Printer Presents Opportunities for Student Projects
Students at Stipes Elementary observe Ne spectral lines.
University of Dallas outreach to Stipes Elementary provided many 5th graders with an opportunity to investigate energy and energy production. Students observed electromagnetic induction, electric generators, hydroelectric and nuclear power generation (the latter two through Youtube!).
Ten physics majors and students concentrating in physics were induced into the physics honor society Sigma Pi Sigma on May 9, 2014. First row: Luke Pecha, Michael Hoff, Olivia LaFond, Jack Bredemann, and Laura Aumen. Second row: Dr. Hicks, Thaddeus Howard, Anthony Kersting, Samuel Henderson, and Dr. Olenick. Not shown are Laura Downes and Adam Collard.
Observations and Modeling of Two New W UMa Stars
by Nick Hedlesky
W Ursae Majoris (W UMa) binary stars are important in the investigation of the evolution of close contacting binary stars. We present the discovery of two new W UMa binary stars in the boundary between the Lyra and Hercules regions: USNO-‐B1.011159-‐0266370 and 1154-‐0266276. Using time sequenced differential photometry and PHOEBE we determined the characteristics and classifications of systems and created a preliminary models, which will be presented.
Blazhko Effect in a Newly Discovered and a Known RR Lyrae Star
by Matthew Melendez
Studies of RR Lyrae stars provide insight into the pulsation processes of variable stars. Several RR Lyrae stars were observed in a wide angle search for extrasolar planets in the boundary between Hercules and Lyra. We present observations of a newly observed RR Lyrae star, USNO1138-0264690, as well as a new perspective on a known RR Lyrae Star, LW Her. Variations in the period and amplitude of RR Lyrae stars, known as the Blazhko effect, were observed found in these stars. The data, analysis, and preliminary dynamical systems modeling of the Blazhko effect in these stars will be presented.
Both projects were completed in collaboration with Dr R. P. Olenick, Mr. Arthur Sweeney, Thaddeus Howard, and Anthony Kersting.
UD physics major Zach Santonil and chemistry major Aaron French completed gamma-ray measurements at the University of Kentucky over winter break (Jan. 4-17, 2014). Shown below are the two students with the UK accelerator engineer, Gene Baber, changing the rf ion source on the model CN 7 MV Van de Graaff accelerator.
Jacob Moldenhauer (University of Dallas), Larry Engelhardt (Francis Marion University)
We present essential interactive simulations that enable testing of a general spectrum of cosmological models. These Easy Java Simulation based programs utilize genuine data sets obtained from various observational surveys and quantitative comparison routines to produce results. The software collection provides a means of combining plotting features and parameter manipulation in a single package. Versions of the programs have been designed for educators and researchers alike. These programs can be found at Compadre Open Source Physics website, i.e. http://www.compadre.org/osp/items/detail.cfm?ID=12406.
Texas APS Presentations Fall 2013
Three UD physics majors - Jack Bredemann, Elizabeth Sizemore, and Sam Henderson - presented their summer research results at the Fall meeting of the Texas Section of the American Physical Society. The abstracts from their talks are given below
Elizabeth Sizemore, Department of Physics, University of Dallas
Claire Sexton, Carey Davies, Anne Almeda, and Stephen Slaughter, Department of Biology, University of Dallas
Inertial measurement units (IMUs) are used to acquire acceleration, rotation, and magnetic field data in three dimensions. When attached to individual body segments these devices can wirelessly stream this data to computer workstations for analysis. The patterns seen can then be used to evaluate relative movements. In this study, rotation at the knee was analyzed by devices worn on the leg and thigh. Gait was studied over dissimilar surfaces, including flat, railroad ballast, and stairs. Image density, neural network, and fractal analysis techniques were employed to evaluate acquired data. Imaging software contributed to the quantification of rotation data in the X and Z axes. Error propagation neural networks create heuristic problem solvers that excel at analyzing non-linear relationships and capturing associations within a set. Fractal analysis gives us terms to express the degree of self similarity, which was applied to the different surface data. Determinations from these techniques will be presented.
Using RPC Data to Assist CSC Data when Dealing with Pt Assignment
John Bredemann, Department of Physics, University of Dallas
Ivan Furic and Matthew Carver, Department of Physics, University of Florida
The Compact Muon Solenoid's (CMS) two main detectors used in the endcaps, the CSC and RPC, are positioned closely together . This means that, while the RPC's main function is one of time synchronization and the CSC's is one of precise position measurement, the former may be able to be used as a supplement to the latter's data when assigning the momentum value (Pt) to a muon passing through the two detectors. Using the RPC's positions variable (Phi), a comparison was made between it and the CSC's Phi reading in order to determine whether there was sufficient correlation between them to use the RPC's data where the CSC has gaps. Preliminary results on this analysis will be presented.
 Wotschack, Joerg (CERN), ATLAS Muon Chamber Construction Parameters for CSC, MDT, and RPC chambers, ATL-MUON-PUB-2008-006, (2009)
Samuel Henderson, Leslie Sidwell, and Sally Hicks, Department of Physics, University of Dallas
Jeffrey Vanhoy, Evaristo Garza, and Joshua Steves, Department of Physics, United States Naval Academy
Marcus McEllistrem, Ben Crider, and Tim Ross, Department of Physics and Astronomy, University of Kentucky
Erin Peters, Francisco Prados-Estevez and Steven W. Yates, Department of Chemistry, University of Kentucky
Accurate and precise neutron scattering data from 54Fe and other structural materials in the fast neutron energy region are essential for the optimization of current and future fission reactors. Neutron scattering and absorption by Fe affects the ideal operating parameters for the nuclear fission process and also affects the overall efficiency of the nuclear reactor. While neutron elastic cross sections for 54Fe at incident neutron energies between 3 and 4 MeV have been previously measured, the previous experiments tended towards larger error in the elastic, and there is a significant dearth of experimental data for the inelastic states. Neutron elastic and inelastic differential scattering crosssections of 54Fe have been measured at the University of Kentucky Accelerator Laboratory at the fast neutron energies of En=3 MeV and 4 MeV. Results from our measurements and comparisons to evaluated cross sections from the National Nuclear Data Center will be presented.
Congratulations to our 2013 graduates - Jeff Schniederjan, Matt Heuser, Laura Downes, Jessie Girgis, Leslie Sidwell, James Meier, Adam Collard, and Brett Combs.
Five UD senior physics majors presented talks on their research at the Spring Meeting of the Texas Section of the American Physical Society Meeting at Tarleton State University, April 4-6, 2013. A sixth senior presented her research results at the South Central Undergraduate Women in Physics 2013 Conference held at UT, Austin January 18–20, 2013. A seventh presented her research at the Southwest Theoretical Chemistry Conference at TX A&M on October 26-28, 2012, and the eight senior presented her research at the North Texas Life Science Research Symposium, November 3, 2012, University of North Texas Health Science Center, Ft. Worth, TX. Nice job seniors!
Adam Collard, University of Dallas, Yancen Li and Joel Therrien, University of Massachusetts, Lowell
Abstract: Single atom thickness carbon nitride sheets have been predicted as good high speed semiconductors. However, it is diﬃcult to synthesize large continuous single layer sheets. Although large amorphous multilayer sheets can be produced easily, single layer sheets require a precise deposition method and solution. We synthesized the carbon nitride at the University of Massachusetts Lowell in the Center for High-rate Nanomanufacturing. Synthesis starts by depositing solutions on silicon wafers using various deposition methods. Wafers are then baked in an ultrahigh purity argon environment where ammonia is removed thereby transforming the chemical deposit of Dicyandiamide into carbon nitride. After baking samples they are tested with Raman Spectroscopy and Atomic Force Microscopy. Single atom thickness samples are then patterned using negative photoresist lithography and coated with aluminum. Excess aluminum is removed and the samples are probed to test band gap and resistivity. Diﬃculties were encountered in ﬁnding a good solvent, proper concentration, and deposition method that worked. The synthesis techniques, solution types, baking speciﬁcations, characterization techniques, and results will be presented.
Matt Heuser, Richard Olenick, Arthur Sweeney, James Meier, Jeff Scheiderjan, University of Dallas STEXTS Team
Abstract: Crucial in the data pipeline for transit searches are dependable algorithms which hunt for transits in accumulated light curves. We used C++ versions of EEBLS (Edge Enhanced Box Least Squares) and QATS (Quasi Automated Transit Search) algorithms to search for possible transits in the STExT group database of light curves of approximately 2500 stars. The outputs of these two programs were compared and a list of potential binary candidates was determined. We will compare the algorithms and discuss possible candidates for transits.
James John Meier, Richard Olenick, Arthur Sweeney, Jeffrey Schniederjan, Matthew Heuser, University of Dallas, STEXTS TEAM
Abstract: We report the results of time-resolved CCD photometry of two new binaries and V1097 in the constellation Hercules. Our observations were carried out using a six-inch, wide angle lens astrograph with a set focal length of 200 mm, three-degree ﬁeld of view and f/1.5 stopped down to an f/2.8 in Pitkin, Colorado in the R band for 35 nights during the early summer of 2012. We exposed each image for one minute and took 300 images per night, obtaining 10,500 images in total. Using Peranso software, Lomb-Scargle period analysis was carried out for the binaries. We will present the O-C calculations for the two new binaries, GSC 2087- 0364, GSC 2083-1870 as well as for V1097 Her.
Modeling of Three New Binaries in Hercules
Jeffrey Schniederjan, Richard Olenick, Arthur Sweeney, James Meier and Matthew Heuser, University of Dallas, STEXTS TEAM
Abstract: We report the results of modeling of three new binaries in Hercules discovered through time-resolved photometry by the Small Telescope Exoplanet Transit Search (STExTS) project. Observations were made with a 200 mm astrograph f/1.5 stopped down to an f/2.8 in the R band over a period of seven weeks in summer 2012 in Pitkin, CO. A total of 10,500 calibrated images and PHOEBE were used to model the light curves of the newly discovered binaries GSC 2087-1870, GSC 2083-1875, and GSC 2087-0364. The binaries' parameter and classiﬁcations will be presented.
L. Sidwell, B. Combs, S.F. Hicks, University of Dallas, J.R. Vanhoy, United States Naval Academy, E.E. Peters, B.C. Crider, A. Kumar, M.T. McEllistrem, F.M. Prados-Estevez, S.W. Yates, University of Kentucky
Abstact: Elastic and inelastic neutron scattering differential cross sections from 23Na, useful in certain ﬁssion reactor applications, were measured using the neutron
scattering and detection facilities at the University of Kentucky (UK) in June of
2012. A pulsed proton beam was accelerated using the 7-MV Van de Graaf accelerator, and
neutrons were produced using the 3H(p,n)3He source reaction, which occurred when the proton beam was incident on a tritium
cell at the end of the beam line. The neutrons were scattered off a 23Na sample and detected by a C6D6 liquid scintillation detector using pulse shape discrimination and time-of-ﬂight
methods. Angular distributions of scattered neutrons were measured for incident neutron
energies of 3.20 and 3.40 MeV. These incident neutron energies were chosen because
they are of interest for reactor applications and because few previous measurements
exist in this region. As the result of data analysis performed at the University of
Dallas, the elastic and inelastic neutron scattering differential cross sections on
23Na were determined for the 3.20 and 3.40 MeV incident neutron energy measurements.
Results from this analysis and comparisons to evaluated nuclear data predictions for
these cross sections will be presented.
1This work was supported by the Department of Energy, through the NEUP Program, and by the Cowan Physics Fund at the University of Dallas.
UD senior physics major Brett Combs presented the results of her summer 2012 research at the South Central Undergraduate Women in Physics 2013 Conference held at UT, Austin January 18–20, 2013. Brett studied neutron scattering from Na-23 as her senior thesis research.
Two UD physics majors give talks over their summer research during the Fall 2012 semester.
Here are their abstracts:
Dispersion-Corrected Rung-3.5 Density Functionals
Abstract: Density functional theory (DFT) is a method used to approximate molecular electronic structure. Weak dispersion (van der Waals) interactions are important in many chemical processes, and not well approximated by standard DFT approximations. These chemical processes can be treated by adding an empirical dispersion correction to standard DFT methods. We tested an empirical dispersion correction for some standard DFT methods, and for new 'Rung 3.5' DFT approximations. We used benchmark calculations on noble gas dimers to fit an adjustable parameter in the dispersion correction, as well as parameters in the 'Rung 3.5' functionals. We then tested the parameterized methods for standard sets of accurately known gas-phase small molecule interaction energies (hydrogen bonds, charge-transfer, and so on). We conclude that dispersion corrected 'Rung 3.5' functionals are as accurate as standard dispersion-corrected DFT for weak interactions.
Presented at the Southwest Theoretical Chemistry Conference at TX A&M on October 26-28, 2012
Poison Pill: Using a Blocked Mutant to Study Microtubule Dynamics
Abstract: Microtubules are dynamic cytoskeletal polymers that have critical roles in intracellular organization and chromosome segregation. Microtubules display 'dynamic instability', switching apparently randomly between phases of growing and shrinking. Despite years of study, the molecular details underlying catastrophe-the switch from growing to shrinking-remain largely unknown. One cause of this persistent lack of understanding is the inability to use site-directed αβ-tubulin as a way to modulate and understand dynamic instability. The Rice lab has developed an αβ-tubulin mutant which blocks at the growing microtubule end and will open up a field of observation inaccessible to wild-type tubulin concentration changes alone. By using DICT microscopy and flow chambers promoting microtubule growth, I observed that microtubules had shorter average lifetimes and unaffected growth velocities in the presence of blocked mutant compared to the wild-type controls. Through my experiments, we have identified a regime of microtubule dynamics that we could not access by simply changing the concentration of αβ-tubulin. Further investigation includes developing a computational model of this experiment.
Presented at the North Texas Life Science Research Symposium, November 3, 2012, University
of North Texas Health Science Center, Ft. Worth, TX.
S. F. Hicks1, L. J. Kersting1, P. J. McDonough1, C. J. Lueck1, A. J. Sigillito1, J. R. Vanhoy4, E. E. Peters3, B. C. Crider2, A. Kumar2, M. T. McEllistrem2, A. Chakraborty2, F. M. Prados-Estevz2, S. W. Yates2,3
(1)Department of Physics, University of Dallas, Irving TX 75062, United States
(2)Department of Physics and Astronomy, University of Kentucky, Lexington KY 40506, United States
(3)Department of Chemistry, University of Kentucky, Lexington KY 40506, United States
(4)Department of Physics, United States Naval Academy, Annapolis MD 21402, United States
Abstract: Nuclear data important for the design and development of the next generation of light-water reactors and future fast reactors include elastic and inelastic neutron scattering cross sections on important structural materials, such as Fe, and on coolant materials, such as Na. These reaction probabilities are needed since neutron reactions impact fuel performance during irradiations and the overall efficiency of reactors. While neutron scattering cross sections from these materials are available for certain incident neutron energies, the fast neutron region, particularly above 2 MeV, has large gaps for which no measurements exist, or the existing uncertainties are large. Measurements have been made at the University of Kentucky Accelerator Laboratory to measure neutron scattering cross sections on both natFe and 23Na in the region where these gaps occur and to reduce the uncertainties on scattering from the ground state and first excited state of these nuclei. Results from measurements on natFe at incident neutron energies between 2 and 4 MeV will be presented and comparisons will be made to model calculations available from data evaluators.
Presented at the 22nd International conference on the Use of Small Accelerators for Teaching and Research, August 5-10, 2012, Ft. Worth, TX.
An observational campaign involving undergraduates was made of the open cluster Dolidze-Dzimseleshvili 9 with an f/1.5 152 mm astrograph for 37 nights in 2011. Lightcurves were obtained for approximately 1900 stars that were extracted and catalogued from the images. A software processing pipeline and SQL were created to provide methods for similar research at other universities. We report on the binaries, variable stars, and transit candidates found.
Presented at the European Week of Astronomy and Space Science, July 1-6, 2012, Pontificia Università Lateranense, Rome.
Jared Rovny, Andrew Bechter, Blaise Dufrain, Eric Bechter, and Gerard Nichel received their B.S. degrees in physics on a beautiful day - May 13, 2012. Jared also gave the valedictory address.
May 8, 2012
The “Elastic/Inelastic Measurement Project” is supported under the Nuclear Energy University Programs (NEUP) of the Department of Energy (DOE). The work is part of a total grant of over $880k for a collaborative research effort between the University of Kentucky (Profs. Marcus T. McEllistrem and Steven W. Yates, the University of Dallas (Prof. Sally F. Hicks), the United States Naval Academy (Prof. Jeffrey R. Vanhoy), and Idaho National Laboratory (Dr. Tony S. Hill) . The proposed neutron scattering cross sections are important for the advanced nuclear fuels program of the DOE, which sponsors research and development of innovative next-generation light water nuclear reactors and future fast reactors. This award provides financial support for UD students to participate in the research, both for experiments at the University of KY and for data analysis at UD.
Eric Bechter, Richard Olenick, Arthur Sweeney, Blaise, DuFrain, and Andrew Bechter
The Small Telescope Extrasolar Transit Searches (STExTS) project is a small aperture, wide-angle search for planetary transits and variable stars. Observations of the open cluster Dolidze-Dzimseleshvili 9 were made with an f/2.8 152 mm astrograph for 37 nights in 2011. Lightcurves were obtained for approximately 1900 stars that were extracted and catalogued from the images. We report on preliminary results and characteristics of new binary stars discovered.
Small Telescope Exoplanet Transit Search (STExTS) Transit Candidates in the Open Cluster
Blaise DuFrain, Richard Olenick, Arthur Sweeney, Andrew Bechter, Eric Bechter
The STExTs project searched for transit candidates in the open cluster Dolidze-Dzimselshvili 9 in Hercules for 37 nights using a f/2.8 152 mm astrograph. Approximately 11,000 images were obtained, processed, and analyzed for signatures of transits. We will present preliminary candidates and orbital periods.
(University of Dallas)
In digital astronomical image processing, distortion limits the quality of photometric data. Often, this precludes accurate and precise analysis of stars or planetary features imaged close to one another. This is a problem in particular for period analysis of binary stars and searching for planetary transits, due to the merging of nearby stars into the area of interest. I proposed a method which utilizes a pair of filters and pixel math to increase resolution, thereby improving astronomical image features and enabling more precise analysis thereof. Comparison of processed and unprocessed data was done by comparing signal to noise ratio and brightness profiles of each. All calculations were performed and results analyzed using Astronomical Image Processing for Windows (AIP4WIN) by Richard Berry. In many cases, previously unusable star profiles were resolved sufficiently to take photometric data from them, while those with low signal to noise ratios improved by a factor of two to three. These results suggest that the proposed method could be used to enable photometric analysis of previously un-usable data.
Andrew Bechter, Richard Olenick, Arthur Sweeney, Blaise Dufrain, Eric Bechter, University of Dallas
In 2011 the STExTs project surveyed the open cluster Dolidze-Dzimselshvili 9 in Hercules for 37 nights using a f/2.8 152 mm astrograph during which time approximately 11,000 images were obtained. We will discuss the star extraction algorithm, systematic error removal algorithm, and analyses used in processing the lightcurves for approximately 1900 stars. We will present our findings on new variable star candidates as well as new characteristics of existing variable stars.
Presented at the Joint Spring 2012 Meeting of the Texas Sections of the APS and AAPT and Zone 13 of the SPS
Jared Rovny, Kyle Mezier, Irina Voloshina, Richard Olenick, and Vladimir Metlov (University of Dallas)
J2138+26 is a new WZ Sge-type dwarf nova, discovered by Dae-Am Yi et al. on May 7, 2010 (CBET 2273). The object is suggested to be similar to GW Lib, another WZ Sge star outbursting in 2007, in terms of a low inclination angle and apparent brightness. J2138+26 is a binary star system with a variable light output caused by precession of the accretion disk around the white dwarf in the cataclysmic variable system. J2138 enters certain periods of outburst when it is significantly brighter, and its regular light variations (from precession), called superhumps, have a changing period. Additional photometric observation of this system provides information about the changing amplitude and period of its superhumps and outbursts, which in turn helps to determine the system's history and physical activity, as well as providing insight into cataclysmic variable systems and their behavior in general. The research in July 2010, done by the named authors and using a 0.6-m telescope from the Sternberg Astronomical Institute's branch of the Crimean Observatory in Crimea, was focused on such photometric observation. Data and analysis of the superhump periods will be presented. The analysis of data taken by Dr. Voloshina and ourselves will be presented with a focus on the changing amplitude and period of J2138, and the physical significance of these results discussed.
The Beauty of the (n,n'γ) Reaction for Investigating Collective Excitations Across the Te Isotopic Chain
Invited talk on nuclear structure delivered by Dr. Sally Hicks at the nuclear physics seminar at the University of Notre Dame on 2/20/2012. UD students who worked on the study of the Te nuclei were acknowledged for their work. These include: J. C. Boehringer, Matthew Burns, Meghan M. Walbran, Beth Sklaney, Gary Alexander, Corey Collard, Steve Etzkorn, William Faulkner,Patrick Roddy, Chris Davoren, Chris Aubin, Jeff Ellis, and Peter Burkett.
Advanced Elastic/Inelastic Neutron Data Development Project
Research talk delivered at the AEINDDP NEUP meeting in Irving TX by Dr. Sally Hicks. (10/7/2011) UD physics majors who have made the research possible and acknowledged during the presentation:L. J. Kersting, C.J. Luke, P. J. McDonough, A. J. Sigillito, J. Schniederjan, L. Downes, J. Girgis
Measurement of the Absolute Elastic and Inelastic Differential Neutron Cross Sections
23Na between 2 and 4 MeV
A Kumar , M.T. McEllistrem , B.P. Crider , E.E. Peters, F.M.Prados-Est´evez, A Chakraborty, J.R. Vanhoy, L.J. Kersting , C. J. Lueck , P.J. McDonough , A Sigillito , S.F. Hicks , S.W. Yates, Talk delivered by Ajay Kumar at the Fourteenth International Symposium on Capture Gamma-Ray Spectroscopy and Related Topics, University of Guelph, Canada August 28 - September 2, 2011. University of Dallas students who participated in the research are highlighted with bold letters. Their name also appears in the conference proceedings, written by Dr. Sally Hicks and Dr. Jeff Vanhoy. Dr. Hicks also served as a session chair at this conference.
Nine physics majors graduate in 2011. From left to right the graduates are Luke Kersting, Kyle Meziere, Anthony Sigillito, Christen Racciato, Andrew Miller, Paul Stauduhar, Natalie Weisse, Zofia Kaminski, and Mary Catalano. Congratulations to all!
Sophomore physics major Jeff Schniederjan reports that , "We got to see one of the two telescopes on Castel Gandolfo. We also got to see the offices where anyone who works in the Vatican Observatory spends most of their time. Our tour was courtesy of Fr. Brown. Besides working in the Observatory he is also the librarian there. So he showed us some more familiar modern day textbooks and some really old ones too. The first book is Copernicus' De Revolutionibus Orbium Coelestium 2nd edition from about 1550. Then Galileo's book that got him in trouble with the church. Also equally as notable is Newtons Principia Mathematica printed in 1713. We all had a great time getting to tour the castle and visiting with Fr. Brown."
Senior physics major Anthony Sigillito was awarded the Outstanding Student Presentation Award at the Texas Section of the American Physical Society Fall-2010 meeting in San Antonio, TX. His oral presentation "The Design and Fabrication of Bismuth Hall Effect Biosensors" stood out among the 100+ presentations of students who participated in the competition. Anthony received a $200 prize for his accomplishment. (Award announced 1/3/2011.)
The Meziere Family Observatory was built by senior physics major Kyle Meziere and his father. The 10-foot diameter dome was donated to the UD Physics Department for student and faculty use. Mr. Meziere and his family (shown in the above figure along with Mr. Arthur Sweeney on the right) hauled the observatory from San Diego to its temporary location at the home of adjunct physics professor Mr. Arthur Sweeney over the Thanksgiving holidays. The department hopes to move the observatory to a dark site outside of the Dallas-Ft. Worth area as soon as an appropriate site is determined. The physics faculty deeply appreciate this generous donation and will do their best to make sure many UD students are able to use the facility for observations and research. See Meziere Observatory in Astronomy Corner for more details.