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Articles 1 - 30 of 42
Full-Text Articles in Physical Sciences and Mathematics
Measurement Of The Neutron F2 Structure Function Via Spectator Tagging With Clas, N. Baillie, S. Tkachenko, J. Zhang, P. Bosted, S. Bültmann, M. E. Christy, H. Fenker, K. A. Griffioen, C. E. Keppel, S. E. Kuhn, K. P. Adhikari, D. Adikaram, M. J. Amaryan, H. Baghdasaryan, G. Dodge, N. Guler, C. E. Hyde, A. Klein, A. Klimenko, L. B. Weinstein
Measurement Of The Neutron F2 Structure Function Via Spectator Tagging With Clas, N. Baillie, S. Tkachenko, J. Zhang, P. Bosted, S. Bültmann, M. E. Christy, H. Fenker, K. A. Griffioen, C. E. Keppel, S. E. Kuhn, K. P. Adhikari, D. Adikaram, M. J. Amaryan, H. Baghdasaryan, G. Dodge, N. Guler, C. E. Hyde, A. Klein, A. Klimenko, L. B. Weinstein
Physics Faculty Publications
We report on the first measurement of the F2 structure function of the neutron from the semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ≲ 100MeV/c and their angles to ≳ 100° relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The Fn2 data collected cover the nucleon-resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65 < Q2 < 4.52 GeV2, with uncertainties from nuclear corrections estimated to be less …
Global Variations Of Hdo And Hdo/H2o Ratios In The Upper Troposphere And Lower Stratosphere Derived From Ace-Fts Satellite Measurements, William J. Randel, Elisabeth Moyer, Mijeong Park, Eric Jensen, Peter Bernath
Global Variations Of Hdo And Hdo/H2o Ratios In The Upper Troposphere And Lower Stratosphere Derived From Ace-Fts Satellite Measurements, William J. Randel, Elisabeth Moyer, Mijeong Park, Eric Jensen, Peter Bernath
Chemistry & Biochemistry Faculty Publications
High-quality satellite observations of water and deuterated water in the upper troposphere and lower stratosphere (UTLS) from the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) are used to map global climatological behavior. Spatial and temporal variability in these data suggest that convection plays a significant role in setting water vapor isotopic composition in these regions. In many instances, enhancements in HDO/H2O (i.e., δD) are closely tied to patterns of climatological deep convection and uncorrelated with water vapor, although convection appears to have different isotopic effects in different locations. The ACE-FTS data reveal seasonal variations in the tropics …
Properties Of Cu(In,Ga) Se2 Thin Films And Solar Cells Deposited By Hybrid Process, S. Marsillac, H. Khatri, K. Aryal, R. W. Collins
Properties Of Cu(In,Ga) Se2 Thin Films And Solar Cells Deposited By Hybrid Process, S. Marsillac, H. Khatri, K. Aryal, R. W. Collins
Electrical & Computer Engineering Faculty Publications
Cu(In,Ga)Se-2 solar cells were fabricated using a hybrid cosputtering/evaporation process, and efficiencies as high as 12.4% were achieved. The films were characterized by energy-dispersive X-ray spectroscopy, glancing incidence X-ray diffraction, scanning electron microscopy, auger electron spectroscopy, and transmittance and reflectance spectroscopy, and their properties were compared to the ones of films deposited by coevaporation. Even though the films were relatively similar, the ones deposited by the hybrid process tend to have smaller grains with a slightly preferred orientation along the (112) axis and a rougher surface. Both types of films have uniform composition through the depth. Characterization of these films …
Microfluidic Impedance Spectroscopy As A Tool For Quantitative Biology And Biotechnology, Ahmet C. Sabuncu, Jie Zhuang, Juergen F. Kolb, Ali Beskok
Microfluidic Impedance Spectroscopy As A Tool For Quantitative Biology And Biotechnology, Ahmet C. Sabuncu, Jie Zhuang, Juergen F. Kolb, Ali Beskok
Mechanical & Aerospace Engineering Faculty Publications
A microfluidic device that is able to perform dielectric spectroscopy is developed. The device consists of a measurement chamber that is 250 μm thick and 750 μm radius. Around 1000 cells fit inside the chamber assuming average quantities for cell radius and volume fraction. This number is about 1000 folds lower than the capacity of conventional fixtures. A T-cell leukemia cell line Jurkat is tested using the microfluidic device. Measurements of deionized water and salt solutions are utilized to determine parasitic effects and geometric capacitance of the device. Physical models, including Maxwell-Wagner mixture and double shell models, are used to …
Anomalous Centrality Evolution Of Two-Particle Angular Correlations From Au-Au Collisions At √ˢᴺᴺ = 62 And 200 Gev, G. Agakishiev, M. M. Aggarwal, S. Bueltmann, I. Koralt, D. Plyku, Star Collaboration
Anomalous Centrality Evolution Of Two-Particle Angular Correlations From Au-Au Collisions At √ˢᴺᴺ = 62 And 200 Gev, G. Agakishiev, M. M. Aggarwal, S. Bueltmann, I. Koralt, D. Plyku, Star Collaboration
Physics Faculty Publications
We present two-dimensional (2D) two-particle angular correlations measured with the STAR detector on relative pseudorapidity η and ϕ for charged particles from Au-Au collisions at √ˢᴺᴺ = 62 and 200 GeV with transverse momentum pt ≥ 0.15 GeV/c, │η│ ≤ 1, and 2 π in azimuth. Observed correlations include a same-side (relative azimuth <π/2) 2D peak, a closely related away-side azimuth dipole, and an azimuth quadrupole conventionally associated with elliptic flow. The same-side 2D peak and away-side dipole are explained by semihard parton scattering and fragmentation (minijets) in proton-proton and peripheral nucleus-nucleus collisions. Those structures follow N-N binary-collision scaling in Au-Au collisions until midcentrality, where a transition to a qualitatively different centrality trend occurs within one 10% centrality bin. Above the transition point the number of same-side and away-side correlated pairs increases rapidly relative to binary-collision scaling, the η width of the same-side 2D peak also increases rapidly (η elongation), and the ϕ width actually decreases significantly. Those centrality trends are in marked contrast with conventional expectations for jet quenching in a dense medium. The observed centrality trends are compared to perturbative QCD predictions computed in HIJING, which serve as a theoretical baseline, and to the expected trends for semihard parton scattering and fragmentation in a thermalized opaque medium predicted by theoretical calculations and phenomenological models. We are unable to reconcile a semihard parton scattering and fragmentation origin for the observed correlation structure and centrality trends with heavy-ion collision scenarios that invoke rapid parton thermalization. If the collision system turns out to be effectively opaque to few-GeV partons the present observations would be inconsistent with the minijet picture discussed here.
Inclusive Charged Hadron Elliptic Flow In Au + Au Collisions At √ˢᴺᴺ = 7.7-39 Gev, L. Adamczyk, G. Agakishiev, S. Bültmann, I Koralt, D. Plyku, Star Collaboration
Inclusive Charged Hadron Elliptic Flow In Au + Au Collisions At √ˢᴺᴺ = 7.7-39 Gev, L. Adamczyk, G. Agakishiev, S. Bültmann, I Koralt, D. Plyku, Star Collaboration
Physics Faculty Publications
A systematic study is presented for centrality, transverse momentum pT, and pseudorapidity (η) dependence of the inclusive charged hadron elliptic flow v2 at midrapidity (|η| < 1.0) in Au + Au collisions at √ˢᴺᴺ = 7.7, 11.5, 19.6, 27, and 39 GeV. The results obtained with different methods, including correlations with the event plane reconstructed in a region separated by a large pseudorapidity gap and four-particle cumulants (v2{4}), are presented to investigate nonflow correlations and v2 fluctuations. We observe that the difference between v2{2} and v2{4} is smaller at the lower collision energies. Values of v2, scaled by the initial coordinate space eccentricity, v2/ϵ, as a function of pT are larger in more central collisions, suggesting stronger collective flow develops in more central collisions, similar to the results …
Di-Electron Spectrum At Mid-Rapidity In P+P Collisions At √S=200 Gev, L. Adamczyk, S. Bueltmann, I. Koralt, D. Plyku, Y. Zoulkarneeva, Star Collaboration
Di-Electron Spectrum At Mid-Rapidity In P+P Collisions At √S=200 Gev, L. Adamczyk, S. Bueltmann, I. Koralt, D. Plyku, Y. Zoulkarneeva, Star Collaboration
Physics Faculty Publications
We report on the mid-rapidity mass spectrum of di-electrons and cross sections of pseudoscalar and vector mesons via e+e- decays, from √s = 200 GeV p + p collisions, measured by the large-acceptance experiment STAR at the Relativistic Heavy Ion Collider. The ratio of the di-electron continuum to the combinatorial background is larger than 10% over the entire mass range. Simulations of di-electrons from light-meson decays and heavy-flavor decays (charmonium and open charm correlation) are found to describe the data. The extracted ω → e+e- invariant yields are consistent with previous measurements. The mid-rapidity …
Multipacting Analysis Of High-Velocity Superconducting Spoke Resonators, C. S. Hopper, J. R. Delayen
Multipacting Analysis Of High-Velocity Superconducting Spoke Resonators, C. S. Hopper, J. R. Delayen
Physics Faculty Publications
Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.
Superconducting Spoke Cavities For Electron And High-Velocity Proton Linacs, J. R. Delayen
Superconducting Spoke Cavities For Electron And High-Velocity Proton Linacs, J. R. Delayen
Physics Faculty Publications
Spoke resonantors are currently under development for many proton machines but these structures are also considered for high beta electron linacs as well. These structures compare well to traditional elliptical cavities.
Measurement Of Exclusive Πº Electroproduction Structure Functions And Their Relationship To Transverse Generalized Parton Distributions, Clas Collaboration, K. P. Adhikari, M. J. Amaryan, R. P. Bennett, S. Koirala, S. E. Kuhn, M. Mayer, L. B. Weinstein, I. Bedlinsky, V. Kubarovsky
Measurement Of Exclusive Πº Electroproduction Structure Functions And Their Relationship To Transverse Generalized Parton Distributions, Clas Collaboration, K. P. Adhikari, M. J. Amaryan, R. P. Bennett, S. Koirala, S. E. Kuhn, M. Mayer, L. B. Weinstein, I. Bedlinsky, V. Kubarovsky
Physics Faculty Publications
Exclusive π0 electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q2, xB , t , and ϕπ , in the Q2 range from 1.0 to 4.6 GeV2 , −t up to 2 GeV2 , and xB from 0.1 to 0.58. Structure functions σT+ϵσL , σTT , and σLT were extracted as functions of t for each of 17 combinations of Q2 and xB . …
Measurement Of The Generalized Form Factors Near Threshold Via ˠ*P→Nπ+ At High Q², Clas Collaboration, K. Park, R. W. Gothe, K. P. Adhikari, D. Adikaram, R. P. Bennett, C. E. Hyde, A. Klein, S. E. Kuhn, H. Seraydaryan
Measurement Of The Generalized Form Factors Near Threshold Via ˠ*P→Nπ+ At High Q², Clas Collaboration, K. Park, R. W. Gothe, K. P. Adhikari, D. Adikaram, R. P. Bennett, C. E. Hyde, A. Klein, S. E. Kuhn, H. Seraydaryan
Physics Faculty Publications
We report on the first measurement of the F2 structure function of the neutron from the semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ≲ 100 MeV/c and their angles to ≳ 100° relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The Fn2 data collected cover the nucleon-resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65 < Q2 2, with uncertainties from nuclear corrections estimated to be less …
Photon Impact Factor And 𝑘T Factorization In The Next-To-Leading Order, Ian Balitsky
Photon Impact Factor And 𝑘T Factorization In The Next-To-Leading Order, Ian Balitsky
Physics Faculty Publications
The photon impact factor for the BFKL pomeron is calculated in the next-to-leading order (NLO) approximation using the operator expansion in Wilson lines. The result is represented as a NLO kT-factorization formula for the structure functions of small-x deep inelastic scattering.
Rf Modeling Using Parallel Codes Ace3p For The 400-Mhz Parallel-Bar/Ridged-Waveguide Compact Crab Cavity For The Lhc Hilumi Upgrade, Zenghai Li, Lixin Ge, Jean R. Delayen, Subashini U. De Silva
Rf Modeling Using Parallel Codes Ace3p For The 400-Mhz Parallel-Bar/Ridged-Waveguide Compact Crab Cavity For The Lhc Hilumi Upgrade, Zenghai Li, Lixin Ge, Jean R. Delayen, Subashini U. De Silva
Physics Faculty Publications
Schemes utilizing crab cavities to achieve head-on beam-beam collisions were proposed for the LHC HiLumi upgrade. These crabbing schemes require that the crab cavities be compact in order to fit into the tight spacing available in the existing LHC beamlines at the location where the crab cavities will be installed. Under the support of US LARP program, Old Dominion University and SLAC have joint efforts to develop a 400-MHz compact superconducting crab cavity to meet the HiLumi upgrade requirements. In this paper, we will present the RF modeling and analysis of a parallel-bar/ridged-waveguide shaped 400-MHz compact cavity design that can …
High Power Test Of Rf Separator For 12 Gev Upgrade Of Cebaf At Jefferson Lab, S. Ahmed, M. Wissmann, J. Mammosser, M. Spata, C. Hovater, Geoffrey A. Krafft, Jean R. Delayen
High Power Test Of Rf Separator For 12 Gev Upgrade Of Cebaf At Jefferson Lab, S. Ahmed, M. Wissmann, J. Mammosser, M. Spata, C. Hovater, Geoffrey A. Krafft, Jean R. Delayen
Physics Faculty Publications
CEBAF at JLab is in the process of an energy upgrade from 6 GeV to 12 GeV. The existing setup of the RF separator cavities in the 5th pass will not be adequate enough to extract the highest energy (11 GeV) beam to any two existing halls (A, B or C) while simultaneously delivering to the new hall D in the case of the proposed 12 GeV upgrade of the machine. To restore this capability, several options including the extension of existing normal conducting (NC) and a potential 499 MHz TEM-type superconducting (SC) cavity design have been investigated using computer …
Meic Design Progress, S. Ahmed, Y. Zhang, Y.S. Derbenev, D. Douglas, R. Ent, A. Hutton, A. Kimber, G.A. Krafft, R. Li, F. Lin, V. S. Morozov, P. Nadel-Turonski, E. W. Nissen, R. Rimmer, F.C. Pilat, T. Satogata, C. Tennant, Balsa Terzić, H. Wang, S. Wang, B. C. Yunn, D. P. Barber, Y. Filatov, C. Hyde, A. M. Kondratenko, S. L. Manikonda, P. N. Ostroumov, M. K. Sullivan
Meic Design Progress, S. Ahmed, Y. Zhang, Y.S. Derbenev, D. Douglas, R. Ent, A. Hutton, A. Kimber, G.A. Krafft, R. Li, F. Lin, V. S. Morozov, P. Nadel-Turonski, E. W. Nissen, R. Rimmer, F.C. Pilat, T. Satogata, C. Tennant, Balsa Terzić, H. Wang, S. Wang, B. C. Yunn, D. P. Barber, Y. Filatov, C. Hyde, A. M. Kondratenko, S. L. Manikonda, P. N. Ostroumov, M. K. Sullivan
Physics Faculty Publications
This paper will report the recent progress in the conceptual design of MEIC, a high luminosity medium energy polarized ring-ring electron-ion collider at Jefferson lab. The topics and achievements that will be covered are design of the ion large booster and the ERL-circulator-ring-based electron cooling facility, optimization of chromatic corrections and dynamic aperture studies, schemes and tracking simulations of lepton and ion polarization in the figure-8 collider ring, and the beam-beam and electron cooling simulations. A proposal of a test facility for the MEIC electron cooler will also be discussed.
Technical Note: A Trace Gas Climatology Derived From The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (Ace-Fts) Data Set, A. Jones, K. A. Walker, J. J. Jin, J. R. Taylor, C. D. Boone, P. F. Bernath, S. Brohede, G. L. Manney, S. Mcleod, R. Hughes, W. H. Daffer
Technical Note: A Trace Gas Climatology Derived From The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (Ace-Fts) Data Set, A. Jones, K. A. Walker, J. J. Jin, J. R. Taylor, C. D. Boone, P. F. Bernath, S. Brohede, G. L. Manney, S. Mcleod, R. Hughes, W. H. Daffer
Chemistry & Biochemistry Faculty Publications
The Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) aboard the Canadian satellite SCISAT (launched in August 2003) was designed to investigate the composition of the upper troposphere, stratosphere, and mesosphere. ACE-FTS utilizes solar occultation to measure temperature and pressure as well as vertical profiles of over thirty chemical species including O3, H2O, CH4, N2O, CO, NO, NO2, N2O5, HNO3, HCl, ClONO2, CCl3F, CCl2F2, and HF. Global coverage for each species is obtained approximately over a three month …
Compositional Features Of Japanese Humic Substances Society Standard Soil Humic And Fulvic Acids By Fourier Transform Ion Cyclotron Resonance Mass Spectrometry And X-Ray Diffraction Profile Analysis, Kosuke Ikeya, Rachel L. Sleighter, Patrick G. Hatcher, Akira Watanabe
Compositional Features Of Japanese Humic Substances Society Standard Soil Humic And Fulvic Acids By Fourier Transform Ion Cyclotron Resonance Mass Spectrometry And X-Ray Diffraction Profile Analysis, Kosuke Ikeya, Rachel L. Sleighter, Patrick G. Hatcher, Akira Watanabe
Chemistry & Biochemistry Faculty Publications
The composition of humic acids (HAs) and Fulvic Acids (FAs) from Inogashira (Umbric Andosol) and Dando (Dystric Cambisol) soils authorized as standard samples by the Japanese Humic Substances Society was characterized using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and X-ray diffraction (XRD) 11 band profile analysis. In FTICR-MS, the number of peaks that molecular formulas were assigned to was 2549-2913 for the FAs and 1943-2457 for the HAs. Molecular formulas with H/C and O/C ratios similar to condensed hydrocarbons were dominant in both the HAs, while those with H/C and O/C ratios similar to lignin were more abundant …
First Remote Sensing Observations Of Trifluoromethane (Hfc-23) In The Upper Troposphere And Lower Stratosphere, Jeremy J. Harrison, Christopher D. Boone, Alexander T. Brown, Nicholas D. C. Allen, Geoffrey C. Toon, Peter F. Bernath
First Remote Sensing Observations Of Trifluoromethane (Hfc-23) In The Upper Troposphere And Lower Stratosphere, Jeremy J. Harrison, Christopher D. Boone, Alexander T. Brown, Nicholas D. C. Allen, Geoffrey C. Toon, Peter F. Bernath
Chemistry & Biochemistry Faculty Publications
This work reports the first remote sensing measurements of atmospheric HFC-23 (CHF3) using solar occultation measurements made by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) and the Jet Propulsion Laboratory Mark IV (MkIV) balloon interferometer. A total of 8809 ACE occultations measured between 2004 and 2010 have been processed, along with 24 MkIV occultations measured between 1989 and 2007. ACE data (yearly averages over the 10-25 km altitude range) in the tropics/subtropics (40°S-40°N) reveal a trend of 4.0 ± 1.6% per year in the growth of HFC-23 for 2004-2009 (or 3.9 ± 1.2% per year for 2004-2010), …
Characteristics And Fabrication Of A 499 Mhz Superconducting Deflecting Cavity For The Jefferson Lab 12 Gev Upgrade, Hyekyoung Park, Subashini U. De Silva, Jean R. Delayen
Characteristics And Fabrication Of A 499 Mhz Superconducting Deflecting Cavity For The Jefferson Lab 12 Gev Upgrade, Hyekyoung Park, Subashini U. De Silva, Jean R. Delayen
Physics Faculty Publications
A 499 MHz parallel bar superconducting deflecting cavity has been designed and optimized [1,2] for a possible implementation at the Jefferson Lab. Previously the mechanical analysis [3], mainly stress, was performed. Since then pressure sensitivity was studied further and the cavity parts were fabricated. The prototype cavity is not completed due to the renovation at Jefferson Lab which resulted in the temporary shutdown of the electron beam welding facility. This paper will present the analysis results and facts encountered during fabrication. The unique geometry of the cavity and its required mechanical strength present interesting manufacturing challenges.
Development Of Superconducting 500 Mhz Multi-Spoke Cavity For Electron Linacs, Dmitry Gorelov, Charles H. Boulware, Terry Grimm, Jean R. Delayen, C. S. Hopper, R. G. Olgave, Subashini U. De Silva
Development Of Superconducting 500 Mhz Multi-Spoke Cavity For Electron Linacs, Dmitry Gorelov, Charles H. Boulware, Terry Grimm, Jean R. Delayen, C. S. Hopper, R. G. Olgave, Subashini U. De Silva
Physics Faculty Publications
Multi-spoke cavities are well-known options for acceleration of heavy and light ions. A recently developed multi-spoke cavity for β=1 presents an attractive opportunity to use this cavity type for electron accelerators. One of the main attractive features of this cavity type is its compactness for relatively low frequency. A simplified design at 500 MHz allowed building of a multi-spoke cavity and cryomodule in a 2-year time frame with confidence and development of effective manufacturing techniques. It also constitutes an important step in proving the usefulness of this kind of cavity design for new applications in the electron machines. Niowave is …
Design Of Electron And Ion Crabbing Cavities For An Electron-Ion Collider, A. Castilla, Jean R. Delayen, Geoffrey A. Krafft
Design Of Electron And Ion Crabbing Cavities For An Electron-Ion Collider, A. Castilla, Jean R. Delayen, Geoffrey A. Krafft
Physics Faculty Publications
Beyond the 12 GeV upgrade at the Jefferson Lab a Medium Energy Electron-Ion Collider (MEIC) is being considered. In order to achieve the desired high luminosities at the Interaction Points (IP), the use of crabbing cavities is under study. In this work, we will present up to date designs of superconducting cavities, considered for crabbing both ion and electron bunches. A discussion of properties such as peak surface fields and Higher Order Modes (HOMs) separation will be presented.
Evidence For The Onset Of Color Transparency In Ρ0 Electroproduction Off Nuclei, L. El Fassi, L. Zana, H. Hafidi, M. Holtrop, B. Mustapha, W. K. Brooks, H. Hakobyan, Z. Zheng, K. P. Adhikari, D. Adikaram, M. J. Amaryan, H. Baghdasaryan, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein
Evidence For The Onset Of Color Transparency In Ρ0 Electroproduction Off Nuclei, L. El Fassi, L. Zana, H. Hafidi, M. Holtrop, B. Mustapha, W. K. Brooks, H. Hakobyan, Z. Zheng, K. P. Adhikari, D. Adikaram, M. J. Amaryan, H. Baghdasaryan, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein
Physics Faculty Publications
We have measured the nuclear transparency of the incoherent diffractive A( e , e ′ ρ0 ) process in 12C and 56Fe targets relative to 2H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced ρ0 ʼs on a nucleus relative to deuterium, which is sensitive to ρA interaction, was studied as function of the coherence length (lc), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared (Q2). While the transparency for both 12C and 56Fe …
Directed And Elliptic Flow Of Charged Particles In Cu + Cu Collisions At √ˢᶰᶰ =22.4 Gev, G. Agakishiev, M. M. Aggarwal, S. Bueltmann, I. Koralt, X. Zhu, Star Collaboration
Directed And Elliptic Flow Of Charged Particles In Cu + Cu Collisions At √ˢᶰᶰ =22.4 Gev, G. Agakishiev, M. M. Aggarwal, S. Bueltmann, I. Koralt, X. Zhu, Star Collaboration
Physics Faculty Publications
This paper reports results for directed flow v1 and elliptic flow v2 of charged particles in Cu + Cu collisions at √ˢᶰᶰ = 22.4 GeV at the Relativistic Heavy Ion Collider. The measurements are for the 0-60% most central collisions, using charged particles observed in the STAR detector. Our measurements extend to 22.4-GeV Cu + Cu collisions the prior observation that v1 is independent of the system size at 62.4 and 200 GeV and also extend the scaling of v1 with η/ybeam to this system. The measured v2pT in Cu + Cu …
Ρ0 Photoproduction In Auau Collisions At √ Snn = 62.4 Gev Measured With The Star Detector, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, C. D. Anson, D. Arkhipkin, S. Bueltmann, I. Koralt, D. Plyku
Ρ0 Photoproduction In Auau Collisions At √ Snn = 62.4 Gev Measured With The Star Detector, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, C. D. Anson, D. Arkhipkin, S. Bueltmann, I. Koralt, D. Plyku
Physics Faculty Publications
Vector mesons may be photoproduced in relativistic heavy-ion collisions when a virtual photon emitted by one nucleus scatters from the other nucleus, emerging as a vector meson. The STAR Collaboration has previously presented measurements of coherent ρ0 photoproduction at center of mass energies of 130 GeV and 200 GeV in AuAu collisions. Here, we present a measurement of the cross section at 62.4 GeV; we find that the cross section for coherent ρ0 photoproduction with nuclear breakup is 10.5 ± 1.5 ± 1.6mb at 62.4 GeV. The cross-section ratio between 200 GeV and 62.4 GeV is 4.4 ± 0.6, …
Observation Of A Narrow Structure In 1H(Ykso)X Via Interference With Φ-Meson Production, M. J. Amaryan, G. Gavalian, C. Nepali, M. V. Polyakov, W. J. Briscoe, G. E. Dodge, C. E. Hyde, F. Klein, V. Kuznetsov, I. Strakovsky, J. Zhang
Observation Of A Narrow Structure In 1H(Ykso)X Via Interference With Φ-Meson Production, M. J. Amaryan, G. Gavalian, C. Nepali, M. V. Polyakov, W. J. Briscoe, G. E. Dodge, C. E. Hyde, F. Klein, V. Kuznetsov, I. Strakovsky, J. Zhang
Physics Faculty Publications
We report observation of a narrow peak structure at ~1.54 GeV with a Gaussian width σ = 6 MeV in the missing mass of KS in the reaction γ+p → pKSKL. The observed structure may be due to the interference between a strange (or antistrange) baryon resonance in the pKL system and the φ(KSKL) photoproduction leading to the same final state. The statistical significance of the observed excess of events estimated as the log-likelihood ratio of the resonant signal + background hypothesis and the φ-production-based background-only hypothesis …
Comparison Of Forward And Backward Pp Pair Knockout In 3He(E,E'Pp)N, H. Baghdasaryan, L. B. Weinstein, J. M. Laget, K. P. Adhikari, M. Aghasyan, M. J. Amaryan, M. Anghinolfi, J. Ball, M. Battaglieri, A. S. Biselli, G. Dodge, C. E. Hyde, S. E. Kuhn, H. Seraydaryan
Comparison Of Forward And Backward Pp Pair Knockout In 3He(E,E'Pp)N, H. Baghdasaryan, L. B. Weinstein, J. M. Laget, K. P. Adhikari, M. Aghasyan, M. J. Amaryan, M. Anghinolfi, J. Ball, M. Battaglieri, A. S. Biselli, G. Dodge, C. E. Hyde, S. E. Kuhn, H. Seraydaryan
Physics Faculty Publications
Measuring nucleon-nucleon short range correlations (SRCs) has been a goal of the nuclear physics community for many years. They are an important part of the nuclear wave function, accounting for almost all of the high-momentum strength. They are closely related to the EMC effect. While their overall probability has been measured, measuring their momentum distributions is more difficult. In order to determine the best configuration for studying SRC momentum distributions, we measured the 3He(e,e'pp)n reaction, looking at events with high-momentum protons (pp > 0.35 GeV/c) and a low-momentum neutron (p …
Energy And System Size Dependence Of Two- And Four-Particle Ν2 Measurements In Heavy-Ion Collisions At √ˢᴺᴺ = 62.4 And 200 Gev And Their Implications On Flow Fluctuations And Nonflow, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, M. Bueltmann, Star Collaboration
Energy And System Size Dependence Of Two- And Four-Particle Ν2 Measurements In Heavy-Ion Collisions At √ˢᴺᴺ = 62.4 And 200 Gev And Their Implications On Flow Fluctuations And Nonflow, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, M. Bueltmann, Star Collaboration
Physics Faculty Publications
We present STAR measurements of azimuthal anisotropy by means of the two- and four-particle cumulants ν2 ν2{2} and ν2{4}) for Au + Au and Cu + Cu collisions at center-of-mass energies √ˢᴺᴺ = 62.4 and 200 GeV. The difference between ν2{2}2 and ν2{4}2 is related to ν2fluctuations (σν2) and nonflow (δ2). We present an upper limit to σν2/ν2. Following the assumption that eccentricity fluctuations σε dominate ν2 fluctuations σν2/ν2 ≈ σε/ε we …
Beam Dynamics Studies For Transverse Electromagnetic Mode Type Rf Deflectors, Shahid Ahmed, Geoffrey A. Krafft, Kirsten Deitrick, Subashini U. De Silva, Jean R. Delayen, Mike Spata, Michael Tiefenback, Alicia Hofler, Kevin Beard
Beam Dynamics Studies For Transverse Electromagnetic Mode Type Rf Deflectors, Shahid Ahmed, Geoffrey A. Krafft, Kirsten Deitrick, Subashini U. De Silva, Jean R. Delayen, Mike Spata, Michael Tiefenback, Alicia Hofler, Kevin Beard
Physics Faculty Publications
We have performed three-dimensional simulations of beam dynamics for transverse electromagnetic mode (TEM) type rf deflectors: normal and superconducting. The compact size of these cavities as compared to the conventional TM110 type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of six 2-cell normal conducting cavities or a single cell superconducting structure is enough to produce the required vertical displacement at the target point. Both the normal and superconducting structures show very small emittance dilution due to the …
Flow Over A Traveling Wavy Foil With A Passively Flapping Flat Plate, Nansheng Liu, Yan Peng, Youwen Liang, Xiyun Lu
Flow Over A Traveling Wavy Foil With A Passively Flapping Flat Plate, Nansheng Liu, Yan Peng, Youwen Liang, Xiyun Lu
Mathematics & Statistics Faculty Publications
Flow over a traveling wavy foil with a passively flapping flat plate has been investigated using a multiblock lattice Boltzmann equation and the immersed boundary method. The foil undergoes prescribed undulations in the lateral direction and the rigid flat plate has passive motion determined by the fluid structure interaction. This simplified model is used to study the effect of the fish caudal fin and its flexibility on the locomotion of swimming animals. The flexibility of the caudal fin is modeled by a torsion spring acting about the pivot at the conjuncture of the wavy foil and the flat plate. The …
Introduction To Special Section On Recent Advances In The Study Of Optical Variability In The Near-Surface And Upper Ocean, T. Dickey, M. L. Banner, P. Bhandari, T. Boyd, L. Carvalho, O. Wurl
Introduction To Special Section On Recent Advances In The Study Of Optical Variability In The Near-Surface And Upper Ocean, T. Dickey, M. L. Banner, P. Bhandari, T. Boyd, L. Carvalho, O. Wurl
OES Faculty Publications
Optical variability occurs in the near-surface and upper ocean on very short time and space scales (e.g., milliseconds and millimeters and less) as well as greater scales. This variability is caused by solar, meteorological, and other physical forcing as well as biological and chemical processes that affect optical properties and their distributions, which in turn control the propagation of light across the air-sea interface and within the upper ocean. Recent developments in several technologies and modeling capabilities have enabled the investigation of a variety of fundamental and applied problems related to upper ocean physics, chemistry, and light propagation and utilization …