Physical Sciences and Mathematics Commons^™

The Optical Luminosity Function Of Gamma-Ray Bursts Deduced From Rotse-Iii Observations, X. H. Cui, X. F. Wu, J. J. Wei, F. Yuan, W. K. Zheng, E. W. Liang, C. W. Akerlof, M. C. B. Ashley, H A. Flewelling, E. Göǧüş, T. Güver, Ü. Kızıloǧlu, T. A. Mckay, S. B. Pandey, E. S. Rykoff, W. Rujopakarn, B. E. Schaefer, J. C. Wheeler, Sarah A. Yost

Physics Faculty Publications

We present the optical luminosity function (LF) of gamma-ray bursts (GRBs) estimated from a uniform sample of 58 GRBs from observations with the Robotic Optical Transient Search Experiment III (ROTSE-III). Our GRB sample is divided into two sub-samples: detected afterglows (18 GRBs) and those with upper limits (40 GRBs). We derive R-band fluxes for these two sub-samples 100 s after the onset of the burst. The optical LFs at 100 s are fitted by assuming that the co-moving GRB rate traces the star formation rate. While fitting the optical LFs using Monte Carlo simulations, we take into account the …

Use Of Grooved Microchannels To Improve The Performance Of Membrane-Less Fuel Cells, J. D'Alessandro, Petru S. Fodor

Physics Faculty Publications

In this work, the fluid dynamics within a membrane-less microchannel fuel cell is analyzed computationally. The membrane-less design is a result of the laminar nature of the fluid flow at small Reynolds numbers, restricting the fuel and oxidant to the vicinity of the corresponding electrodes, without the need of a proton exchange membrane (PEM). However, the performance of such cells is limited by the slow diffusive mass transport near the electrodes, with a large fraction of the reactants leaving the channel without coming in contact with the catalytic surfaces, and thus not being used. We mitigate this problem through the …

Sustainability Research Through The Lens Of Environmental Ethics, Daniel Clifford Fouke, Sukh Sidhu, Robert J. Brecha

Physics Faculty Publications

Two core courses in the curriculum of the University of Dayton’s Sustainability, Energy, and the Environment minor, Sustainability Research I and II, were developed out of the frustration one author, Daniel Fouke, experienced while teaching a traditional course on environmental ethics for the Department of Philosophy. The often-overwhelming nature of environmental problems tended to demoralize both the instructor and the students. Seeking a way to integrate ethical analysis of complex problems with the search for solutions, two courses were proposed that would be team-taught by a philosopher and a scientist or an engineer.

Development of the courses was initially funded …

Measurements Of Turbulent Mixing And Subsiding Shells In Trade Wind Cumuli, Jeannine Katzwinkel, Holger Siebert, Thijs Heus, Raymond A. Shaw

Physics Faculty Publications

High-resolution measurements of the turbulent, thermodynamic, and microphysical structure of the edges of trade wind cumuli have been performed with the Airborne Cloud Turbulence Observation System. Lateral entrainment of subsaturated air into the cloud region leads to an evaporative cooling effect. The negatively buoyant air partly enhances the compensating downdraft, forming a subsiding shell at cloud edge. Based on the presented observations, the subsiding shell is divided into a turbulent and humid inner shell adjacent to the cloud interior and a nonbuoyant, nonturbulent outer shell. In the trade wind region, continuous development of shallow cumuli over the day allows for …

Multiple Representations And Epistemic Games In Introductory Physics Exam Solutions, Adrienne L. Traxler, Jonathan V. Mahadeo, Daryl Mcpadden, Eric Brewe

Physics Faculty Publications

Previous analysis of common exam questions in introductory physics at Florida International University has revealed differences in the number and type of epistemic games played by students in their solutions. Separated by course format (lecture/lab, lecture/lab/recitation, or inquiry-based), student work also shows varying use of multiple representational tools. Here we examine representation use in more detail to establish a descriptive picture of representation use across multiple instructors and course formats. We then compare these profiles with the epistemic games played by students, asking whether the same epistemic game shows the same pattern of representational tools across course types. We find …

Near Real-Time Measurement Of Forces Applied By An Optical Trap To A Rigid Cylindrical Object, Joseph Glaser, David Hoeprich, Andrew Resnick

Physics Faculty Publications

An automated data acquisition and processing system is established to measure the force applied by an optical trap to an object of unknown composition in real time. Optical traps have been in use for the past 40 years to manipulate microscopic particles, but the magnitude of applied force is often unknown and requires extensive instrument characterization. Measuring or calculating the force applied by an optical trap to nonspherical particles presents additional difficulties which are also overcome with our system. Extensive experiments and measurements using well-characterized objects were performed to verify the system performance.

Semi-Inclusive Charged-Current Neutrino-Nucleus Reactions, O. Moreno, T. W. Donnelly, J. W. Van Orden, W. P. Ford

Physics Faculty Publications

The general, universal formalism for semi-inclusive charged-current (anti) neutrino-nucleus reactions is given for studies of any hadronic system, namely, either nuclei or the nucleon itself. The detailed developments are presented with the former in mind and are further specialized to cases where the final-state charged lepton and an ejected nucleon are presumed to be detected. General kinematics for such processes are summarized, and then explicit expressions are developed for the leptonic and hadronic tensors involved and for the corresponding responses according to the usual charge, longitudinal and transverse projections, keeping finite the masses of all particles involved. In the case …

The Impact Of The Initial Surface Reconstruction On Heteroepitaxial Film Growth And Defect Formation, Jessica E. Bickel, Joanna Mirecki Millunchick

Physics Faculty Publications

While it is well known that growth conditions such as temperature greatly affect defect incorporation in thin films, less is known about the direct effects of the surface reconstruction. In this work, we examine the effect of the initial surface reconstruction on defect incorporation in GaSb/GaAs(001) lattice mismatched films. The stress built up in GaSb films grown on As-terminated and Sb-terminated GaAs was monitored during film growth and shows that the total relaxation is similar in both films along the [110], but lower on the Sb-terminated surface along the . These differences can be understood by examining the ability for …

Rare Earth Dopant (Nd, Gd, Dy, And Er) Hybridization In Lithium Tetraborate, Tony D. Kelly, James C. Petrosky, John W. Mcclory, Volodymyr T. Adamiv, Yaroslav V. Burak, Bohdan V. Padlyak, Ihor M. Teslyuk, Ning Lu, Lu Wang, Wai-Ning Mei, Peter A. Dowben

Physics Faculty Publications

The four dopants (Nd, Gd, Dy, and Er) substitutionally occupy the Li+ sites in lithium tetraborate (Li2B4O7: RE) glasses as determined by analysis of the extended X-ray absorption fine structure. The dopants are coordinated by 6-8 oxygen at a distance of 2.3 to 2.5 Å, depending on the rare earth. The inverse relationship between the RE-O coordination distance and rare earth (RE) atomic number is consistent with the expected lanthanide atomic radial contraction with increased atomic number. Through analysis of the X-ray absorption near edge structure, the rare earth dopants adopt the RE3+ valence state. There are indications of strong …

Detection And Antibiotic Treatment Of Mycoplasma Arginini Contamination In A Mouse Epithelial Cell Line Restore Normal Cell Physiology, Brianna Boslett, Subhra Nag, Andrew Resnick

Physics Faculty Publications

Mycoplasma contamination of cultured cell lines is difficult to detect by routine observation. Infected cells can display normal morphology and the slow growth rate of mycoplasma can delay detection for extended periods of time, compromising experimental results. Positive identification of mycoplasma typically requires cells to be either fixed and stained for DNA or processed with PCR. We present a method to detect mycoplasma using live-cell optical microscopy typically used for routine observation of cell cultures. Images of untreated mycoplasma-infected epithelial cells alongside images of infected cells treated with Plasmocin, a commercially available antibiotic targeted to mycoplasma, are shown. We found …

The Creation Of 360° Domain Walls In Ferromagnetic Nanorings By Circular Applied Magnetic Fields, Jessica E. Bickel, Spencer A. Smith, Katherine E. Aidala

Physics Faculty Publications

Switching behavior in ferromagnetic nanostructures is often determined by the formation and annihilation of domain walls (DWs). In contrast to the more familiar 180° DWs found in most nanostructures, 360° DWs are the proposed transition state of nanorings. This paper examines the formation of 360° DWs created by the application of a circular magnetic field using micromagnetic simulations. 360° DWs form from pairs of canting moments that are oppositely aligned, which each grow to form rotated domains bounded by two 180° DWs and the 180° DWs combine to form 360° DWs. The resulting 360° DWs occur in pairs of opposite …

Schwinger’S Variational Principle In Einstein-Cartan Gravity, Nikodem Poplawski

Physics Faculty Publications

By applying Schwinger’s variational principle to the Einstein-Cartan action for the gravitational field, we derive quantum commutation relations between the metric and torsion tensors.

The Look-Locker Method In Magnetic Resonance Imaging: A Brief, Personal History, David C. Look

Physics Faculty Publications

The “Look-Locker” method of measuring nuclear spin-lattice relaxation times in a single sweep was invented by David C. Look and Donald R. Locker in 1970 and in the last twenty years has become widely used in magnetic resonance imaging. This article is a brief history of the invention from the remembrances of David Look.

Model Of Deep Nonvolcanic Tremor Part I: Ambient And Triggered Tremor, Naum I. Gershenzon, Gust Bambakidis

Physics Faculty Publications

There is evidence of triggering of tremor by seismic waves emanating from distant large earthquakes. The frequency content of triggered and ambient tremor are largely identical, suggesting that tremor does not depend directly on the nature of the source. We show here that the model of plate dynamics developed earlier by us is an appropriate tool for describing the onset of tremor. In the framework of this model, tremor is an internal response of a fault to failure triggered by external disturbances. The model predicts generation of radiation in a frequency range defined by the fault parameters. Other specific features …

Influence Of Small Scale Heterogeneity On Co2 Trapping Processes In Deep Saline Aquifers, Naum I. Gershenzon, Mohamadreza Soltanian, Robert W. Ritzi, David F. Dominic

Physics Faculty Publications

The physical mechanism of CO₂ trapping in porous media by capillary trapping (pore scale) incorporates a number of related processes, i.e. residual trapping, trapping due to hysteresis of the relative permeability, and trapping due to hysteresis of the capillary pressure. Additionally CO₂ may be trapped in heterogeneous media due to difference in capillary pressure entry points for different materials (facies scale). The amount of CO₂ trapped by these processes depends upon a complex system of non-linear and hysteretic relationships including how relative permeability and capillary pressure vary with brine and CO₂ saturation, and upon the spatial …

Energy Dependence Of Moments Of Net-Proton Multiplicity Distributions At Rhic, L. Adamczyk, J. K. Adkins, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

We report the beam energy (√ˢᴺᴺ = 7.7-200 GeV) and collision centrality dependence of the mean (M), standard deviation (σ), skewness (S), and kurtosis (κ) of the net-proton multiplicity distributions in Au + Au collisions. The measurements are carried out by the STAR experiment at midrapidity (|y| < 0.5) and within the transverse momentum range 0.4 < p_T < 0.8 GeV/c in the first phase of the Beam Energy Scan program at the Relativistic Heavy Ion Collider. These measurements are important for understanding the quantum chromodynamic phase diagram. The products of the moments, Sσ and Kσ², are sensitive to the correlation length of the hot and dense medium created in the collisions and are related to the ratios of baryon number susceptibilities of corresponding orders. The products of moments are found to have values significantly below the Skellam expectation and close to expectations based on independent …

Beam Energy Dependence Of Moments Of The Net-Charge Multiplicity Distributions In Au + Au Collisions At Rhic, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, D. Plyku, Star Collaboration

Physics Faculty Publications

We report the first measurements of the moments-mean (M), variance (σ²), skewness (S), and kurtosis (κ)-of the net-charge multiplicity distributions at midrapidity in Au + Au collisions at seven energies, ranging from √ˢᶰᶰ = 7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net charge, and are sensitive to the location of the QCD critical point. We compare the products of the moments, σ²/M, Sσ, and κσ², with the expectations from Poisson and negative binomial distributions (NBDs). The Sσ …

Data Analysis Techniques, Differential Cross Sections, And Spin Density Matrix Elements For The Reaction ᵞp → Φp, K.P. Adhikari, D. Adikaram, M.J. Amaryan, A. Klein, S. Koirala, Clas Collaboration

Physics Faculty Publications

High-statistics measurements of differential cross sections and spin density matrix elements for the reaction ᵞp → ϕp have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (√s) from 1.97 to 2.84 GeV, with an extensive coverage in the ϕ production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the ϕ natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged-(ϕ → K⁺ K^-) and neutral( ϕ → (K^O_SK …

Dielectron Mass Spectra From Au Plus Au Collisions At √ˢᴺᴺ = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, D. Plyku, Star Collaboration

Physics Faculty Publications

We report the STAR measurements of dielectron (e⁺e^-) production at midrapidity ( |y_ee| < 1) in Au + Au collisions at √ˢᴺᴺ = 200 GeV. The measurements are evaluated in different invariant mass regions with a focus on 0.30-0.76 (ρ-like), 0.76-0.80 (ω-like), and 0.98-1.05 (ɸ-like) GeV/c². The spectrum in the ω-like and ɸ-like regions can be well described by the hadronic cocktail simulation. In the ρ-like region, however, the vacuum ρ spectral function cannot describe the shape of the dielectron excess. In this range, an enhancement of 1.77 ±0.11(stat) ± 0.24(syst) ± 0.33(cocktail) is determined with respect to the hadronic cocktail simulation that excludes the ρ meson. The excess yield in the ρ-like region increases with the number of collision participants faster than the ω …

Measurement Of "Pretzelosity" Asymmetry Of Charged Pion Production In Semi-Inclusive Deep Inelastic Scattering On A Polarized ³He Target, Y. Zhang, X. Qian, K. Allada, C. Dutta, M. Canan, Jefferson Lab Hall A Collaboration

Physics Faculty Publications

An experiment to measure single-spin asymmetries of semi-inclusive production of charged pions in deep-inelastic scattering on a transversely polarized ³He target was performed at Jefferson Laboratory in the kinematic region of 0.16 < x < 0.35 and 1.4 < Q² < 2.7 GeV². Pretzelosity asymmetries on ³He, which are expressed as the convolution of the h^┴_1T transverse-momentum-dependent distribution functions and the Collins fragmentation functions in the leading order, were measured for the first time. Under the effective polarization approximation, we extracted the corresponding neutron asymmetries from the measured ³He asymmetries and cross-section ratios between the proton and ³He. Our results show that …

Question 1: Trash To Fuel; Question 2: Planes From Cans, Larry Weinstein

Physics Faculty Publications

The article presents questions concerning trash used as fuel and building airplanes from recycled soda cans.

Superconducting Accelerating Cavity Pressure Sensitivity Analysis And Stiffening, J. Rodnizki, Yakir Ben Aliz, Asher Grin, Zvi Horvitz, Amichay Perry, Leonid Weissman, Kirk Davis, Jean Roger Delayen

Physics Faculty Publications

The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light ions superconducting RF linac. Phase-I of SARAF delivers up to 2 mA CW proton beams in an energy range of 1.5 - 4.0 MeV. The maximum beam power that we have reached is 5.7 kW. Today, the main limiting factor to reach higher ion energy and beam power is related to the HWR sensitivity to the liquid helium coolant pressure fluctuations. The HWR sensitivity to helium pressure is about 60 Hz/mbar. The cavities had been designed, a decade ago, to be soft in …

Beam-Energy Dependence Of Charge Separation Along The Magnetic Field In Au + Au Collisions At Rhic, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev, A. Banerjee, D. R. Beavis, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, H. Bichsel, M. Zyzak, Et Al., Star Collaboration

Physics Faculty Publications

Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with …

Dielectron Azimuthal Anisotrophy At Mid-Rapidity In Au+Au Collisions At √ˢᶰᶰ = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, S. Bültmann, I Koralt, Star Collaboration

Physics Faculty Publications

We report on the first measurement of the azimuthal anisotropy v₂ of dielectrons (e⁺e^- pairs) at mid-rapidity from √ˢᶰᶰ = 200 GeV Au + Au collisions with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), presented as a function of transverse momentum p_T for different invariant-mass regions. In the mass region M_ee < 1.1 GeV/c² the dielectron v₂measurements are found to be consistent with expectations from π⁰, η, ω, and Φ decay contributions. In the mass region 1.1 < M_ee < 2.9 GeV/c², the measured dielectron v₂is consistent, within experimental …

Simultaneous Optimization Of The Cavity Heat Load And Trip Rates In Linacs Using A Genetic Algorithm, Balša Terzić, Alicia S. Hofler, Cody J. Reeves, Sabbir A. Khan, Geoffrey A. Krafft, Jay Benesch, Arne Freyberger, Desh Ranjan

Physics Faculty Publications

In this paper, a genetic algorithm-based optimization is used to simultaneously minimize two competing objectives guiding the operation of the Jefferson Lab's Continuous Electron Beam Accelerator Facility linacs: cavity heat load and radio frequency cavity trip rates. The results represent a significant improvement to the standard linac energy management tool and thereby could lead to a more efficient Continuous Electron Beam Accelerator Facility configuration. This study also serves as a proof of principle of how a genetic algorithm can be used for optimizing other linac-based machines.

Virtuality Distributions In Application To Ɣɣ* → Π​0 Transition Form Factor At Handbag Level, Anatoly V. Radyushkin

Physics Faculty Publications

We outline basics of a new approach to transverse momentum dependence in hard processes. As an illustration, we consider hard exclusive transition process ɣ*ɣ -> π⁰ at the handbag level. Our starting point is coordinate representation for matrix elements of operators (in the simplest case, bilocal O(0, z)) describing a hadron with momentum p. Treated as functions of (pz) and z², they are parametrized through virtuality distribution amplitudes (VDA) Φ(x, σ), with x being Fourier-conjugate to (pz) and σ Laplace-conjugate to z². For intervals with z⁺ = 0, we introduce the transverse momentum distribution …

Beam-Energy Dependence Of The Directed Flow Of Protons, Antiprotons, And Pions In Au+Au Collisions, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, I. Koralt, Star Collaboration

Physics Faculty Publications

Rapidity-odd directed flow (v1) measurements for charged pions, protons, and antiprotons near midrapidity (y= 0) are reported in √ˢᴺᴺ = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeVAu+Au collisions as recorded by the STAR detector at the Relativistic Heavy Ion Collider. At intermediate impact parameters, the proton and net-proton slope parameter d v₁/ d y│_y=0 shows a minimum between 11.5 and 19.6 GeV. In addition, the net-proton d v₁/ d y│_y=0 changes sign twice between 7.7 and 39 GeV. The proton and net-proton results qualitatively resemble predictions …

Measurement Of Double-Polarization Asymmetries In The Quasielastic ³→He (→E, E' D) Process, M. Mihovilovic, G. Jin, M. Canan, S. Golge, R. Schiavilla, Jefferson Lab Hall A. Collaboration

Physics Faculty Publications

We present a precise measurement of double-polarization asymmetries in the ³→He (→e, e' d) reaction. This particular process is a uniquely sensitive probe of hadron dynamics in ³He and the structure of the underlying electromagnetic currents. The measurements have been performed in and around quasielastic kinematics at Q² = 0.25(GeV/c)² for missing momenta up to 270 MeV/c. The asymmetries are in fair agreement with the state-of-the-art calculations in terms of their functional dependencies on p_m and ω, but are systematically offset. Beyond the region of the quasielastic peak, the discrepancies become even more pronounced. Thus, our …

Measurement Of Charge Multiplicity Asymmetry Correlations In High-Energy Nucleus-Nucleus Collisions At √ˢᶰᶰ = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, S. Bültmann, Star Collaboration

Physics Faculty Publications

A study is reported of the same-and opposite-sign charge-dependent azimuthal correlations with respect to the event plane in Au+ Au collisions at √ˢᶰᶰ = 200 GeV. The charge multiplicity asymmetries between the up/down and left/right hemispheres relative to the event plane are utilized. The contributions from statistical fluctuations and detector effects were subtracted from the (co-) variance of the observed charge multiplicity asymmetries. In the mid-to most-central collisions, the same- (opposite-) sign pairs are preferentially emitted in back-to-back (aligned on the same-side) directions. The charge separation across the event plane, measured by the difference, Δ, between the like-and unlike-sign up/down-left/right …

Measurement Of Longitudinal Spin Asymmetries For Weak Boson Production In Polarized Proton-Proton Collisions At Rhic, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, S. Bültmann, Star Collaboration

Physics Faculty Publications

We report measurements of single- and double-spin asymmetries for W± and Z/ɣ* boson production in longitudinally polarized p + p collisions at √s = 510 GeV by the STAR experiment at RHIC. The asymmetries for W± were measured as a function of the decay lepton pseudorapidity, which provides a theoretically clean probe of the proton's polarized quark distributions at the scale of the W mass. The results are compared to theoretical predictions, constrained by polarized deep inelastic scattering measurements, and show a preference for a sizable, positive up antiquark polarization in the range 0.05 < x < 0.2.