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Full-Text Articles in Physical Sciences and Mathematics
Vla Imaging Of H I-Bearing Ultra-Diffuse Galaxies From The Alfalfa Survey, Lexi Gault, Lukas Leisman, Elizabeth A.K. Adams, Pavel E. Mancera Piña, Kameron Reiter, Nicholas Smith, Michael Battipaglia, John M. Cannon, Filippo Fraternali, Martha P. Haynes, Elizabeth Mcallan, Hannah J. Pagel, Katherine L. Rhode, John J. Salzer, Quinton Singer
Vla Imaging Of H I-Bearing Ultra-Diffuse Galaxies From The Alfalfa Survey, Lexi Gault, Lukas Leisman, Elizabeth A.K. Adams, Pavel E. Mancera Piña, Kameron Reiter, Nicholas Smith, Michael Battipaglia, John M. Cannon, Filippo Fraternali, Martha P. Haynes, Elizabeth Mcallan, Hannah J. Pagel, Katherine L. Rhode, John J. Salzer, Quinton Singer
Physics and Astronomy Faculty Publications
Ultra-diffuse galaxies have generated significant interest due to their large optical extents and low optical surface brightnesses, which challenge galaxy formation models. Here we present resolved synthesis observations of 12 H i-bearing ultra-diffuse galaxies (HUDs) from the Karl G. Jansky Very Large Array (VLA), as well as deep optical imaging from the WIYN 3.5-meter telescope at Kitt Peak National Observatory. We present the data processing and images, including total intensity H i maps and H i velocity fields. The HUDs show ordered gas distributions and evidence of rotation, important prerequisites for the detailed kinematic models in Mancera Pi˜na et al. …
Binary Central Stars Of Planetary Nebulae Discovered Through Photometric Variability. Iv. The Central Stars Of Hatr 4 And Hf 2-2, Todd C. Hillwig, Howard E. Bond, David J. Frew, S C. Schaub, Eva Hl Bodman
Binary Central Stars Of Planetary Nebulae Discovered Through Photometric Variability. Iv. The Central Stars Of Hatr 4 And Hf 2-2, Todd C. Hillwig, Howard E. Bond, David J. Frew, S C. Schaub, Eva Hl Bodman
Physics and Astronomy Faculty Publications
We explore the photometrically variable central stars of the planetary nebulae HaTr 4 and Hf 2-2. Both have been classified as close binary star systems previously based on their light curves alone. Here, we present additional arguments and data confirming the identification of both as close binaries with an irradiated cool companion to the hot central star. We include updated light curves, orbital periods, and preliminary binary modeling for both systems. We also identify for the first time the central star of HaTr 4 as an eclipsing binary. Neither system has been well studied in the past, but we utilize …
Observation Of Transverse Spin-Dependent Azimuthal Correlations Of Charged Pion Pairs In P + P At Sqrt(S) = 200 Gev, Adam Gibson-Even, Shirvel Stanislaus, Donald Koetke, Star Collaboration
Observation Of Transverse Spin-Dependent Azimuthal Correlations Of Charged Pion Pairs In P + P At Sqrt(S) = 200 Gev, Adam Gibson-Even, Shirvel Stanislaus, Donald Koetke, Star Collaboration
Physics and Astronomy Faculty Publications
No abstract provided.
Measurement Of Interaction Between Antiprotons, Adam Gibson-Even, Shirvel Stanislaus, Donald Koetke, Star Collaboration
Measurement Of Interaction Between Antiprotons, Adam Gibson-Even, Shirvel Stanislaus, Donald Koetke, Star Collaboration
Physics and Astronomy Faculty Publications
No abstract provided.
Precision Measurement Of The Longitudinal Double-Spin Asymmetry For Inclusive Jet Production In Polarized Proton Collisions At S√=200 Gev, Adam Gibson-Even, Shirvel Stanislaus, Donald Koetke, Star Collaboration
Precision Measurement Of The Longitudinal Double-Spin Asymmetry For Inclusive Jet Production In Polarized Proton Collisions At S√=200 Gev, Adam Gibson-Even, Shirvel Stanislaus, Donald Koetke, Star Collaboration
Physics and Astronomy Faculty Publications
We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, ALL, in polarized pp collisions at center-of-mass energy s√=200 GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC pp data. The measured asymmetries provide evidence at the 3σ level for positive gluon polarization in the Bjorken-x region x>0.05.
Binary Central Stars Of Planetary Nebulae Discovered Through Photometric Variability. Iii. The Central Star Of Abell 65, Todd Hillwig, David J. Frew, Melissa Louie, Orsola De Marco, Sam Schaub
Binary Central Stars Of Planetary Nebulae Discovered Through Photometric Variability. Iii. The Central Star Of Abell 65, Todd Hillwig, David J. Frew, Melissa Louie, Orsola De Marco, Sam Schaub
Physics and Astronomy Faculty Publications
A growing number of close binary stars are being discovered among central stars of planetary nebulae. Recent and ongoing surveys are finding new systems and contributing to our knowledge of the evolution of close binary systems. The push to find more systems was largely based on early discoveries which suggested that 10%–15% of all central stars are close binaries. One goal of this series of papers is confirmation and classification of these systems as close binaries and determination of binary system parameters. Here we provide time-resolved multi-wavelength photometry of the central star of Abell 65 as well as further analysis …
Lambda Lambda Correlation Function In Au + Au Collisions At Sqrt(S_Nn) = 200 Gev, Adam Gibson-Even, Shirvel Stanislaus, Donald Koetke, Star Collaboration
Lambda Lambda Correlation Function In Au + Au Collisions At Sqrt(S_Nn) = 200 Gev, Adam Gibson-Even, Shirvel Stanislaus, Donald Koetke, Star Collaboration
Physics and Astronomy Faculty Publications
No abstract provided.
A Long-Term Variability Study Of Dying Low And Intermediate Mass Stars, Allyse Appel, Justin Reed
A Long-Term Variability Study Of Dying Low And Intermediate Mass Stars, Allyse Appel, Justin Reed
Symposium on Undergraduate Research and Creative Expression (SOURCE)
We are studying the long-term light variation of dying stars (similar to the sun). These stars pulsate, causing them to vary in light. Our purpose is to better understand the internal structure of these objects though light curve and period analysis. These dying stars are in the proto-planetary nebula (PPN) phase, which lasts only a few thousand years between the red giant phase and the planetary nebula phase. First discovered with the Infrared Astronomical Satellite Survey in 1983, PPN emit strongly in the region, but the central stars of PPN can be studied in visible light. This summer we have …
Binary Stars In Planetary Nebulae, Hannah Rotter
Binary Stars In Planetary Nebulae, Hannah Rotter
Symposium on Undergraduate Research and Creative Expression (SOURCE)
When a star like the sun dies, it swells into a red giant and then expels its outer layers to form a planetary nebula. Eventually the outer layers leave the leftover core and it becomes a white dwarf. The cause of the many exotic shapes in the planetary nebulae is unknown; however, it is thought that binary stars may play a role in the shaping process. In this project we are studying the central stars of planetary nebulae to see if they vary in brightness, and to see if that variability is due to the central star having a binary …
A Study Of Two Newly-Discovered Eclipsing Binary Systems, Austin Bain
A Study Of Two Newly-Discovered Eclipsing Binary Systems, Austin Bain
Symposium on Undergraduate Research and Creative Expression (SOURCE)
I have observed three newly-discovered variable stars using the 16-inch telescope and CCD at the Valparaiso University Observatory. Of these three variables, two have been verified as binary star systems, where one of the stars passes in front of the other. The third is found to be a pulsating variable, which varies due to a change in its size and temperature. One of the goals of this project has been to further refine the periods of these three variables. From my new data and some previous observations at the Valparaiso University Observatory, I have been able to determine that the …
Neutral Pion Background Analysis At Star, Adam Clark
Neutral Pion Background Analysis At Star, Adam Clark
Symposium on Undergraduate Research and Creative Expression (SOURCE)
The STAR detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory takes measurements of polarized proton collisions which can then be used to extract cross sections and spin asymmetries. The Endcap Electromagnetic Calorimeter (EEMC) in STAR allows measurements of electromagnetic particles in the forward direction, 1 < η < 2. The EEMC will be used to determine the neutral pion (π0) cross section and the double longitudinal spin asymmetry (ALL) which gives us information about the gluon contribution to the proton’s spin. The π0 cross section is an important supporting measurement to verify our signal reconstruction and the background characterization for the π0 asymmetry. In order to measure the π0 cross section and asymmetry, the backgrounds must be well understood (such as those from photon conversions and reconstruction errors where one photon reconstructs as two clusters). Efforts toward the π0 cross section and asymmetry measurements and, specifically, those to understand π0 backgrounds are discussed.
An Event-By-Event Comparison Of Clustering Algorithms For Photon Detection In The Star Endcap Calorimeter, William J. Pochron
An Event-By-Event Comparison Of Clustering Algorithms For Photon Detection In The Star Endcap Calorimeter, William J. Pochron
Symposium on Undergraduate Research and Creative Expression (SOURCE)
The STAR detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory uses polarized proton collisions to determine the origin of the proton spin, using measurements such as neutral pion asymmetries. The Endcap Electromagnetic Calorimeter (EEMC) in the STAR detector is especially useful for detecting photons from π° decays at forward angles. This latter measurement is obtained from the Shower Maximum Detector (SMD) in the EEMC where narrow crossed scintillator strips measure the energy deposited in them and can be used to identify the location of the photon shower. The electromagnetic shower most often deposits energy in a …
Dispersion Of Radon-222 Gas In Air, Erin Beckmeyer
Dispersion Of Radon-222 Gas In Air, Erin Beckmeyer
Symposium on Undergraduate Research and Creative Expression (SOURCE)
Radon-222 is a heavy radioactive gas with a half-life of 3.8 days, often found in basements and other enclosed, underground spaces. It is produced by decaying deposits of uranium-238, and presents a significant health risk to those who encounter it in their homes and places of work. The only gas in the uranium decay chain, radon atoms work their way through layers of soil, usually to dissipate harmlessly into the atmosphere. In buildings, however, the gas accumulates and causes dangerous environmental radiation. Much work has been done to measure the transmission of the gas through water and solid materials, but …
Generating A ‘Clean’ Pi0 Spectrum In Star, William J. Pochron
Generating A ‘Clean’ Pi0 Spectrum In Star, William J. Pochron
Symposium on Undergraduate Research and Creative Expression (SOURCE)
The STAR detector at Brookhaven National Laboratory’s Relativistic Heavy Ion Collider uses polarized proton collisions to investigate the origin of the proton spin, using measurements such as neutral pion (π0) asymmetries. STAR’s Endcap Electromagnetic Calorimeter (EEMC) is especially useful for detecting photons from π0 decays at forward-angle scattering from ≈15 to ≈40 degrees above the beam direction. We identify π0’s by constructing invariant mass spectra from these photons. Large background contributions are present in these spectra and distort the true value of the π0 invariant mass. By applying constraints (cuts) on parameters such as the opening angle of the photons …
Stability Of The Gains Of The Star Endcap Calorimeter From 2006 To 2011, Kayla Kutz
Stability Of The Gains Of The Star Endcap Calorimeter From 2006 To 2011, Kayla Kutz
Symposium on Undergraduate Research and Creative Expression (SOURCE)
The Solenoid Tracker at RHIC (STAR) experiment, based at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC), uses polarized-proton collisions to investigate sea quark and gluon contributions to the fundamental proton property called “spin.” The STAR detector's Endcap Electromagnetic Calorimeter (EEMC) measures the energy of particles produced by those collisions using a lead-scintillator sampling calorimeter, consisting of several layers that include pre-shower, shower maximum, tower, and post-shower detectors. In these detectors, the energy gains, which convert a measured pulse into an energy deposition, have been determined using data taken from the years 2006, 2009, and 2011. Changes in the gains …
Testing The Klein-Nishina Model For Compton Scattering Of 0.662 Mev Photons With A Focus On Lower Scattering Angles, Joel Rogers
Testing The Klein-Nishina Model For Compton Scattering Of 0.662 Mev Photons With A Focus On Lower Scattering Angles, Joel Rogers
Symposium on Undergraduate Research and Creative Expression (SOURCE)
The Thomson and Klein-Nishina equations for obtaining the differential cross section by Compton scattering of photons from free electrons in aluminum will be tested using 0.662 MeV photons from a Cesium-137 source. A NaI detector will be used to count the number of photons scattering from the target as a function of the scattering angle. A previous experiment carried out by VU student Josh Vredevoogd showed good agreement with the Klein-Nishina theory for angles greater than 45 but discrepancies with angles less than 45 degrees. This experiment will concentrate on testing the Klein-Nishina theory at angles less than 45 degrees.
A Study Of Light Variability In Dying Stars, Hannah Rotter, Aaron Seider, Austin Bain
A Study Of Light Variability In Dying Stars, Hannah Rotter, Aaron Seider, Austin Bain
Symposium on Undergraduate Research and Creative Expression (SOURCE)
In this research project, we observed and analyzed the light variability in a class of dying stars that are in the stage between Red Giant and White Dwarf in the evolution of stars like the Sun. Our observations were carried out during the summer and fall of 2012 at the Valparaiso Observatory. Thirty-two of these objects were observed in total. We analyzed a subset of 18 of these and found that they all varied in visual brightness by 10-70 percent. Periods for the variability were found for 8 out of 18 objects, and they range from 27 to 125 days, …
Neutron Electric Dipole Moment: Research And Development, Benjamin Barber
Neutron Electric Dipole Moment: Research And Development, Benjamin Barber
Symposium on Undergraduate Research and Creative Expression (SOURCE)
The neutron's electric dipole moment (nEDM) serves as an important test of the Standard Model of particle physics and it's various alternatives. Various models of fundamental physics allow for different magnitudes for the nEDM, and recent experiments have begun to exclude some models. Valparaiso University is part of a collaboration of institutions working on an improved experiment to measure the nEDM, to be conducted at Oak Ridge National Laboratory in the next few years. The experiment will be performed at 0.4 Kelvin, and will involve the use of magnetic fields and very large electric fields. Research at Los Alamos National …
Finding Variable Stars In Planetary Nebulae Using The Isis Image Subtraction Software, Jake Long, Kevin Nault
Finding Variable Stars In Planetary Nebulae Using The Isis Image Subtraction Software, Jake Long, Kevin Nault
Symposium on Undergraduate Research and Creative Expression (SOURCE)
Planetary nebulae are a brief and often spectacular stage in the life of stars like the sun during which the star expels its outer layers into space. In order to explain the great variety of observed shapes among planetary nebulae, we are examining the theory that binary central stars of planetary nebulae are a significant factor in their shaping. We determine if the central star of planetary nebulae is binary by looking for photometric periodic variability, a common feature of close binary systems. Using existing data we evaluate the variability using a computer program called ISIS. We have seen the …
The Reaction Of Methane With Platinum Oxide Nanoclusters: A Computational Study, Dane Stewart
The Reaction Of Methane With Platinum Oxide Nanoclusters: A Computational Study, Dane Stewart
Symposium on Undergraduate Research and Creative Expression (SOURCE)
Previous studies have shown that small clusters of transition metals like Pt, when reacted with oxygen, have useful catalytic properties compared to thin-film or bulk catalysts. These clusters have the potential for use in developing cheaper methods for converting propane to propene, which is a high-value compound used in making plastics. Understanding the structure and formation of these clusters is essential to gauging how reactive each catalyst is. Computational studies of Pt4O2 are being done using Gaussian 03 to understand their formation, and determine the stability of different spin states. The effectiveness of these clusters is then being tested using …
Performance Studies Of The Forward Gem Tracker, Malorie Stowe
Performance Studies Of The Forward Gem Tracker, Malorie Stowe
Symposium on Undergraduate Research and Creative Expression (SOURCE)
The spin of the proton is thought to be produced by several constituents including quarks, antiquarks, and gluons. It has been the goal of STAR (Solenoidal Tracker at RHIC) to measure the contribution of gluons and various sea quarks to the proton spin. The Forward GEM Tracker (FGT) is a detector in STAR, which is located at the RHIC (Relativistic Heavy Ion Collider) collider at Brookhaven National Laboratory. The FGT serves to track the position of forward-going charged particles, and it will be instrumental in observing the decay leptons from W bosons created by the interaction of the quark of …
Neutral Pion Background Analysis At Star, Adam Clark
Neutral Pion Background Analysis At Star, Adam Clark
Symposium on Undergraduate Research and Creative Expression (SOURCE)
The STAR detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory takes measurements of cross section and spin observables of polarized proton collisions. The Endcap Electromagnetic Calorimeter (EEMC) allows measurements of electromagnetic particles in the forward direction, 1 < η < 2. The EEMC detector will be used to measure the neutral pion (π0) double longitudinal spin asymmetry which gives us information about the gluon contribution to the proton's spin. The π0 cross section is an important measurement to verify our signal reconstruction and the background characterization. In order to measure the π0 cross section and asymmetry, the backgrounds must be identified (such as those from photon conversions and …
Studying The Variability Of Dying Stars, Austin Bain, Hannah Rotter, Aaron Seider
Studying The Variability Of Dying Stars, Austin Bain, Hannah Rotter, Aaron Seider
Symposium on Undergraduate Research and Creative Expression (SOURCE)
In this project, we are observing and analyzing the light variability in a class of dying stars. This involves observing then on clear nights, primarily at the Valparaiso University Observatory but also including a few nights at the SARA Telescope at Kitt Peak National Observatory in Arizona. Thus far this summer we have observed for 25 nights and we observed 31 stars. Some of them we observed on every clear night and others we observed once or twice a week. We are analyzing a subset of 18 of these. We find that they have varied in light by 12 to …
The Reduction And Reporting Of Data On Proto-Planetary Nebulae From Two Observatories, Wesley Cheek
The Reduction And Reporting Of Data On Proto-Planetary Nebulae From Two Observatories, Wesley Cheek
Symposium on Undergraduate Research and Creative Expression (SOURCE)
I am documenting the light variability in a sample of proto-planetary nebulae (PPNs) observed from two observatories. PPNs are stars in the stage of evolution between the AGB and planetary nebula phases. I analyzed the digital images of the data taken on 34 nights from the SARA-South observatory located in Cerro Tololo, Chile along with data taken from the SARA-North Observatory located in Tucson, Arizona. This was done to obtain quantitative measurements of the brightness variations over time. Once I had this information for each object, I plotted light curves, which can be used to document the amplitudes and possible …
Measurements Of The Angular Cross-Sections Of The Decay Products Of Proton Capture By Lithium-6, Benjamin Barber
Measurements Of The Angular Cross-Sections Of The Decay Products Of Proton Capture By Lithium-6, Benjamin Barber
Symposium on Undergraduate Research and Creative Expression (SOURCE)
We have studied the nuclear reaction Li-6 + p => He-3 + He-4 using protons from the 200-keV linear accelerator located in the Manning Nuclear Physics Laboratory in the Neils Science Center. We have measured the angular distribution and energy of the resulting He-3 and He-4 nuclei. Measurements were made using a Si surface barrier detector. The incident proton energy was 125 keV, and the angular measurements were made between 150 and 120 degrees downstream of the beam. Results and highlights are presented.
Calibrating The Star Endcap Electromagnetic Calorimeter Using Pi-O’S, Benjamin Barber
Calibrating The Star Endcap Electromagnetic Calorimeter Using Pi-O’S, Benjamin Barber
Symposium on Undergraduate Research and Creative Expression (SOURCE)
The default energy calibration of the STAR EEMC (Endcap ElectroMagnetic Calorimeter) uses the energy deposition of minimally ionizing particles (MIPs). An alternate method is to use pi-0's. We are reporting a preliminary proof-of-principle calibration method using pi-0's. This method reconstructs the invariant mass of photon pairs, assumed to be resulting from pi-0 decays, using standard two-body kinematics. When many photon pairs are analyzed, a peak is expected in the resulting invariant mass distribution near the pi-0 mass. Using the measured mass of this peak, and the known mass of the pi-0, a minimization routine adjusts the detector gains to optimize …
The Study Of Variability In Oxygen-Rich Proto-Planetary Nebulae, Kristie Shaw
The Study Of Variability In Oxygen-Rich Proto-Planetary Nebulae, Kristie Shaw
Symposium on Undergraduate Research and Creative Expression (SOURCE)
In this project, I am studying and analyzing the light and color variations for two proto-planetary nebulae (PPNe). PPNe is a stage in a star’s life where the star is in the process of losing its outer layers and exposing its core. I observed at the Valparaiso University Observatory, using the 0.4 meter telescope and an electronic camera to take digital images. I reduced these data using an image processing program to get the numerical data results. I plotted these results as a light curve showing the variation in brightness of the star versus time. By observing in three different …
The Effect Of Strong Electrostatic And Magnetostatic Fields On The Activity Of Radioactive Nuclides, Sam Schaub
The Effect Of Strong Electrostatic And Magnetostatic Fields On The Activity Of Radioactive Nuclides, Sam Schaub
Symposium on Undergraduate Research and Creative Expression (SOURCE)
This experiment seeks to measure the effect of strong electrostatic and magnetostatic fields on the decay constant of short-lived radioactive isotopes. Though it is assumed in modern radioactivity theory that such fields should not have any measurable effect, conclusive evidence utilizing modern equipment is absent from published literature. Samples have been monitored that exhibit beta-minus, beta-plus, electron capture, and internal conversion modes of radioactive decay. Radioactive nuclides chosen for this study include I-128, Cs-134, and Cu-64. The half-lives in this collection of radioactive nuclides range from 25 minutes to 12.7 hours. Sodium Iodide detectors are used to monitor the samples …
An Observational Study Of Variable Stars, Joel Rogers, Wesley Cheek
An Observational Study Of Variable Stars, Joel Rogers, Wesley Cheek
Symposium on Undergraduate Research and Creative Expression (SOURCE)
This past summer, we carried out an observational study of light variability in approximately 20 stars. Our goal was to document their changes in brightness, determine a period of the variability, and investigate whether their brightness changes were correlated with changes in color (and thus temperature). These stars are part of a special class of stars that have evolved beyond the red giant phase but have not yet become white dwarfs. Little is known about their variability during this phase. We observed them on almost every clear night during the summer of 2010. We then compared the data for this …
Measurement Of Neutron Reflectivity From A Silicon Crystal: Preparation For An Nmdm Measurement, Benjamin Barber
Measurement Of Neutron Reflectivity From A Silicon Crystal: Preparation For An Nmdm Measurement, Benjamin Barber
Symposium on Undergraduate Research and Creative Expression (SOURCE)
Physicists from Argonne National Laboratories, Valparaiso University, the University of Hawaii, and the National Institute for Standards and Technology have designed an experiment to use the known neutron magnetic dipole moment (nMDM) to measure Schwinger scattering in silicon (Si), a process whereby the orientation of the magnetic dipole polarization is altered by interactions with the atomic electric fields in a Si crystal. This measurement is intended to be a precursor to a search for a neutron electric dipole moment (nEDM) employing a similar spin rotation via a different interaction. Both measurements depend on neutron Bragg reflections down a slotted Si …