Stability Of The Gains Of The Star Endcap Calorimeter From 2006 To 2011,
2013
Valparaiso University
Stability Of The Gains Of The Star Endcap Calorimeter From 2006 To 2011, Kayla Kutz
Symposium on Research and Creative Expression (SORCE)
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 …
A Study Of Light Variability In Dying Stars,
2013
Valparaiso University
A Study Of Light Variability In Dying Stars, Hannah Rotter, Aaron Seider, Austin Bain
Symposium on Research and Creative Expression (SORCE)
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, …
An Event-By-Event Comparison Of Clustering Algorithms For Photon Detection In The Star Endcap Calorimeter,
2013
Valparaiso University
An Event-By-Event Comparison Of Clustering Algorithms For Photon Detection In The Star Endcap Calorimeter, William J. Pochron
Symposium on Research and Creative Expression (SORCE)
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,
2013
Valparaiso University
Dispersion Of Radon-222 Gas In Air, Erin Beckmeyer
Symposium on Research and Creative Expression (SORCE)
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 …
A Study Of Two Newly-Discovered Eclipsing Binary Systems,
2013
Valparaiso University
A Study Of Two Newly-Discovered Eclipsing Binary Systems, Austin Bain
Symposium on Research and Creative Expression (SORCE)
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 …
Testing The Klein-Nishina Model For Compton Scattering Of 0.662 Mev Photons With A Focus On Lower Scattering Angles,
2013
Valparaiso University
Testing The Klein-Nishina Model For Compton Scattering Of 0.662 Mev Photons With A Focus On Lower Scattering Angles, Joel Rogers
Symposium on Research and Creative Expression (SORCE)
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.
Generating A ‘Clean’ Pi0 Spectrum In Star,
2013
Valparaiso University
Generating A ‘Clean’ Pi0 Spectrum In Star, William J. Pochron
Symposium on Research and Creative Expression (SORCE)
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 …
Classification And Analysis Of Emission-Line Galaxies Using Mean Field Independent Component Analysis,
2013
University of Cambridge, UK
Classification And Analysis Of Emission-Line Galaxies Using Mean Field Independent Component Analysis, James T. Allen, Paul C. Hewett, Chris T. Richardson, Gary J. Ferland, Jack A. Baldwin
Physics and Astronomy Faculty Publications
We present an analysis of the optical spectra of narrow emission-line galaxies, based on mean field independent component analysis (MFICA), a blind source separation technique. Samples of galaxies were drawn from the Sloan Digital Sky Survey (SDSS) and used to generate compact sets of ‘continuum’ and ‘emission-line’ component spectra. These components can be linearly combined to reconstruct the observed spectra of a wider sample of galaxies. Only 10 components – five continuum and five emission line – are required to produce accurate reconstructions of essentially all narrow emission-line galaxies to a very high degree of accuracy; the median absolute deviations …
Strongly Localized Magnetization Modes In Permalloy Antidot Lattices,
2013
Northwestern University
Strongly Localized Magnetization Modes In Permalloy Antidot Lattices, J. Sklenar, V. S. Bhat, Lance E. De Long, O. Heinonen, J. B. Ketterson
Physics and Astronomy Faculty Publications
Antidot lattices (ADLs) patterned into soft magnetic thin films exhibit rich ferromagnetic resonance (FMR) spectra corresponding to many different magnetization modes. One of the predicted modes is highly localized at the edges of the antidots; this mode is difficult to detect experimentally. Here we present FMR data for a permalloy thin film patterned into a square array of square antidots. Comparison of these data with micromagnetic simulations permits identification of several edge modes. Our simulations also reveal the effect of the antidot shape on the mode dispersion.
Astronomy / Galactic Structure - Rensselaer Polytechnic Institute,
2013
Rensselaer Polytechnic Institute
Astronomy / Galactic Structure - Rensselaer Polytechnic Institute, Kathryn M. Dunn
Data Curation Profiles Directory
The researcher participates in large-scale astronomical survey projects, which are collaborative efforts of many institutions and individuals. Management of the raw and processed/calibrated data is handled by those projects, but data for specific research questions is handled by the researcher. The researcher would like to have a better way to share the data behind the figures in their published papers with other researchers. The effort involved in retrieving and documenting the data so it’s usable by others is a barrier to sharing the data. It would be easier to share data from publications if it could be deposited to a …
Suppression Of Dielectronic Recombination Due To Finite Density Effects,
2013
Western Michigan University
Suppression Of Dielectronic Recombination Due To Finite Density Effects, D. Nikolić, T. W. Gorczyca, K. T. Korista, Gary J. Ferland, N. R. Badnell
Physics and Astronomy Faculty Publications
We have developed a general model for determining density-dependent effective dielectronic recombination (DR) rate coefficients in order to explore finite-density effects on the ionization balance of plasmas. Our model consists of multiplying by a suppression factor those highly-accurate total zero-density DR rate coefficients which have been produced from state-of-the-art theoretical calculations and which have been benchmarked by experiment. The suppression factor is based upon earlier detailed collision-radiative calculations which were made for a wide range of ions at various densities and temperatures, but used a simplified treatment of DR. A general suppression formula is then developed as a function of …
Erratum: 'Improved He I Emissivities In The Case B Approximation',
2013
University of Georgia
Erratum: 'Improved He I Emissivities In The Case B Approximation', R. L. Porter, Gary J. Ferland, P. J. Storey, M. J. Detisch
Physics and Astronomy Faculty Publications
No abstract provided.
Tuning Electronic Structure Via Exipatial Strain In Sr2Iro4 Thin Films,
2013
University of Kentucky
Tuning Electronic Structure Via Exipatial Strain In Sr2Iro4 Thin Films, J. Nichols, Jsaminka Terzic, Emily Geraldine Bittle, Oleksandr B. Korneta, Lance E. De Long, Joseph Brill, Gang Cao, Sung S. Ambrose Seo
Physics and Astronomy Faculty Publications
We have synthesized epitaxial Sr2IrO4 thin-films on various substrates and studied their electronic structure as a function of lattice-strain. Under tensile (compressive) strain, increased (decreased) Ir-O-Ir bond-angle is expected to result in increased (decreased) electronic bandwidth. However, we have observed that the two optical absorption peaks near 0.5 eV and 1.0 eV are shifted to higher (lower) energies under tensile (compressive) strain, indicating that the electronic-correlation energy is also affected by in-plane lattice-strain. The effective tuning of electronic structure under lattice-modification provides an important insight into the physics driven by the coexisting strong spin-orbit coupling and electronic …
Using Photometry To Probe The Circumstellar Environment Of Δ Scorpii,
2013
Western University
Using Photometry To Probe The Circumstellar Environment Of Δ Scorpii, Carol E. Jones, Paul A. Wiegert, Christopher Tycner, Gregory W. Henry, Richard P. Cyr, Robbie J. Halonen, Matthew W. Muterspaugh
Information Systems and Engineering Management Research Publications
We acquired Johnson BV photometry of the binary Be disk system δ Scorpii during its 2009, 2010, 2011, and 2012 observing seasons and used it to probe the innermost regions of the disk. We found that several disk building events have occurred during this time, resulting in an overall brightening in the V band and reddening of the system. In addition to these long-term trends, we found cyclical variability in each observing season on timescales between 60 and 100 days. We were able to reproduce the changes in the magnitude and color of δ Sco using our theoretical models and …
Acceleration Of Low-Energy Ions At Parallel Shocks With A Focused Transport Model,
2013
Florida Institute of Technology
Acceleration Of Low-Energy Ions At Parallel Shocks With A Focused Transport Model, Pingbing Zuo, Ming Zhang, Hamid K. Rassoul
Aerospace, Physics, and Space Science Faculty Publications
We present a test particle simulation on the injection and acceleration of low-energy suprathermal particles by parallel shocks with a focused transport model. The focused transport equation contains all necessary physics of shock acceleration, but avoids the limitation of diffusive shock acceleration (DSA) that requires a small pitch angle anisotropy. This simulation verifies that the particles with speeds of a fraction of to a few times the shock speed can indeed be directly injected and accelerated into the DSA regime by parallel shocks. At higher energies starting from a few times the shock speed, the energy spectrum of accelerated particles …
Tracers Of Chromospheric Structure. I. Caii H&K Emission Distribution Of 13000 F, G And K Stars In Sdss Dr7 Spectroscopic Sample,
2013
Chinese Academy of Sciences
Tracers Of Chromospheric Structure. I. Caii H&K Emission Distribution Of 13000 F, G And K Stars In Sdss Dr7 Spectroscopic Sample, J. K. Zhao, T. D. Oswalt, G. Zhao, Q. H. Lu, L. Y. Zhang
Publications
We present chromospheric activity index SHK measurements for over 13,000 F, G and K disk stars with high signal-to-noise ratio (> 60) spectra in the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) spectroscopic sample. A parameter S is defined as the difference between SHK and a ‘zero’ emission line fitted by several of the most inactive stars. The SHK indices of subgiant stars tend to be much lower than dwarfs, which provide a way to distinguish dwarfs and giants with relatively low resolution spectra. Cooler stars are generally more active and display a larger scatter than hotter stars. …
A Redline Starburst: Co(2-1) Observations Of An Eddington-Limited Galaxy Reveal Star Formation At Its Most Extreme,
2013
McGill University
A Redline Starburst: Co(2-1) Observations Of An Eddington-Limited Galaxy Reveal Star Formation At Its Most Extreme, J. E. Geach, R. C. Hickox, A. M. Diamond-Stanic, M. Krips
Dartmouth Scholarship
We report observations of the CO(2-1) emission of SDSSJ1506+54, a compact (r_e~135pc) starburst galaxy at z=0.6. SDSSJ1506+54 appears to be forming stars close to the limit allowed by stellar radiation pressure feedback models: the measured L_IR/L'_CO 1500 is one of the highest measured for any galaxy. With its compact optical morphology but extended low surface brightness envelope, post-starburst spectral features, high infrared luminosity (L_IR>10^12.5 L_Sun), low gas fraction (M_H2/M_stars~15%), and short gas depletion time (tens of Myr), we speculate that this is a feedback- limited central starburst episode at the conclusion of a major merger. Taken as such, SDSSJ1504+54 …
Tracers Of Chromospheric Structure. I. Ca Ii H&K Emission Distribution Of 13,000 F, G, And K Stars In Sdss Dr7 Spectroscopic Sample,
2013
Chinese Academy of Sciences, Beijing
Tracers Of Chromospheric Structure. I. Ca Ii H&K Emission Distribution Of 13,000 F, G, And K Stars In Sdss Dr7 Spectroscopic Sample, J. K. Zhao, T. D. Oswalt, G. Zhao, Q. H. Lu, A. L. Luo, L. Y. Zhang
Publications
We present chromospheric activity index SHK measurements for over 13,000 F, G, and K disk stars with high signal-to-noise ratio (>60) spectra in the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) spectroscopic sample. A parameter δS is defined as the difference between SHK and a “zero” emission line fitted by several of the most inactive stars. The SHK indices of subgiant stars tend to be much lower than dwarfs, which provide a way to distinguish dwarfs and giants with relatively low-resolution spectra. Cooler stars are generally more active and display a larger scatter than …
X-Ray Source Variability Study Of The M31 Central Field Using Chandra Hrc-1,
2013
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße
X-Ray Source Variability Study Of The M31 Central Field Using Chandra Hrc-1, F. Hofmann, W. Pietsch, M. Henze, F. Haberl, R. Sturm, M. Della Valle, Dieter H. Hartmann, D. Hatzidimitriou
Publications
Context. The central field of the Andromeda galaxy (M 31) has been monitored, using the Chandra HRC-I detector (about 0.1-10 keV energy range) from 2006 to 2012 with the main aim to detect X-rays from optical novae. We present a systematic analysis of all X-ray sources found in the 41 nova monitoring observations, along with 23 M 31 central field HRC-I observations available from the Chandra data archive starting in December 1999. Aims. Based on these observations, we studied the X-ray long-term variability of the source population and especially of X-ray binaries in M 31. Methods. We created a catalogue …
The Cluster And Field Galaxy Active Galactic Nucleus Fraction At Z = 1-1.5: Evidence For A Reversal Of The Local Anticorrelation Between Environment And Agn Fraction,
2013
The Ohio State University
The Cluster And Field Galaxy Active Galactic Nucleus Fraction At Z = 1-1.5: Evidence For A Reversal Of The Local Anticorrelation Between Environment And Agn Fraction, Paul Martini, E. D. Miller, M. Brodwin, S. A. Stanford, Anthony H. Gonzalez, M. Bautz, R. C. Hickox
Dartmouth Scholarship
The fraction of cluster galaxies that host luminous active galactic nuclei (AGNs) is an important probe of AGN fueling processes, the cold interstellar medium at the centers of galaxies, and how tightly black holes and galaxies co-evolve. We present a new measurement of the AGN fraction in a sample of 13 clusters of galaxies (M >= 1014 M ⊙) at 1 < z < 1.5 selected from the Spitzer/IRAC Shallow Cluster Survey, as well as the field fraction in the immediate vicinity of these clusters, and combine these data with measurements from the literature to quantify the relative evolution of cluster and field AGN from the present to z ~ 3. We estimate that the cluster AGN fraction at 1 < z < 1.5 is f_A = 3.0^{+2.4}_{-1.4}% for AGNs with a rest-frame, hard X-ray luminosity greater than L X, H >= 1044 erg s-1. This fraction is measured relative to all cluster galaxies more luminous than M^*_{3.6}(z) + 1, where M^*_{3.6}(z) is the absolute magnitude of the break in the galaxy luminosity …
