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Physics Faculty Publications

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2011

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Articles 31 - 60 of 71

Full-Text Articles in Physics

Theory Of Optical Emission Enhancement By Coupled Metal Nanoparticles: An Analytical Approach, Greg Sun, Jacob B. Khurgin Mar 2011

Theory Of Optical Emission Enhancement By Coupled Metal Nanoparticles: An Analytical Approach, Greg Sun, Jacob B. Khurgin

Physics Faculty Publications

We present an analytical “coupled mode” model explaining enhancement of emission by an emitter placed within complexes of metal nanoparticles and apply it for an important case of an emitter placed inside the gap of two coupled Au nanospheres. This approach has dual advantages of exposing the underling physics of the enhancement and revealing a straightforward path toward optimization.

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Coherent Photoproduction Of Π+ From 3he, R. Nasseripour, Gerard P. Gilfoyle, Et. Al. Mar 2011

Coherent Photoproduction Of Π+ From 3he, R. Nasseripour, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We have measured the differential cross section for the γ3He→ π+t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid 3He target. The differential cross sections for the γ3He→ π+t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, …

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Episodic Tremors And Slip In Cascadia In The Framework Of The Frenkel-Kontorova Model, Naum I. Gershenzon, Gust Bambakidis, Ernest Hauser, Abhijit Ghosh, Kenneth C. Creager Jan 2011

Episodic Tremors And Slip In Cascadia In The Framework Of The Frenkel-Kontorova Model, Naum I. Gershenzon, Gust Bambakidis, Ernest Hauser, Abhijit Ghosh, Kenneth C. Creager

Physics Faculty Publications

The seismic moment for regular earthquakes is proportional to the cube of rupture time. A second class of phenomena, collectively called slow earthquakes, has very different scaling. We propose a model, inspired from the phenomenology of dislocation dynamics in crystals, that is consistent with the scaling relations observed in the Cascadia episodic tremor and slip (ETS) events. Two fundamental features of ETS are periodicity and migration. In the northern Cascadia subduction zone, ETS events appear every 14.5 months or so. During these events, tremors migrate along-strike with a velocity of 10 km/day and simultaneously zip back and forth in the …

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Electric Field Tunable Magnetic Properties Of Lead-Free Na0.5bi0.5tio3/Cofe2o4 Multiferroic Composites, S Narendra Babu, Seong Gi Min, Leszek Malkinski Jan 2011

Electric Field Tunable Magnetic Properties Of Lead-Free Na0.5bi0.5tio3/Cofe2o4 Multiferroic Composites, S Narendra Babu, Seong Gi Min, Leszek Malkinski

Physics Faculty Publications

Lead-free multiferroic particulate composites of Na0.5Bi0.5TiO3 (NBT) and CoFe2O4 (CFO) have been synthesized by solid-state sintering method. A systematic study of structural, magnetic and magnetoelectric (ME) properties is undertaken. Structural and morphology studies carried out by x-ray diffraction and field emission scanning electron microscopy indicate formation of single phase for parent phases and presence of both phases in the composites. Magnetic properties are investigated using vibrating sample magnetometer and ferromagnetic resonance (FMR) measurements at room temperature. Strong ME coupling is demonstrated in NBT-CFO 70-30 mol% composite by an electrostatically tunable FMR field …

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Calorimetric Evidence Of Strong-Coupling Multiband Superconductivity In Fe(Te0.57se0.43) Single Crystal, J. Hu, T. J. Liu, B. Qian, A. Rotaru, L. Spinu, Z. Q. Mao Jan 2011

Calorimetric Evidence Of Strong-Coupling Multiband Superconductivity In Fe(Te0.57se0.43) Single Crystal, J. Hu, T. J. Liu, B. Qian, A. Rotaru, L. Spinu, Z. Q. Mao

Physics Faculty Publications

We have investigated the specific heat of optimally doped iron chalcogenide superconductor Fe(Te0.57Se0.43) with a high-quality single crystal sample. The electronic specific heat Ce of this sample has been successfully separated from the phonon contribution using the specific heat of a nonsuperconducting sample (Fe0.90Cu0.10)(Te0.57Se0.43) as a reference. The normal-state Sommerfeld coefficient γn of the superconducting sample is found to be ~26.6 mJ/mol K2, indicating intermediate electronic correlation. The temperature dependence of Ce in the superconducting state can be best fitted using a double-gap …

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Thermally Activated Transitions In A System Of Two Single Domain Ferromagnetic Particles, Dorin Cimpoesu, Alexandru Stancu, Ivo Kilk, Ching-Ray Chang, Leonard Spinu Jan 2011

Thermally Activated Transitions In A System Of Two Single Domain Ferromagnetic Particles, Dorin Cimpoesu, Alexandru Stancu, Ivo Kilk, Ching-Ray Chang, Leonard Spinu

Physics Faculty Publications

Numerical simulations based on the stochastic Langevin equation are applied here to a system of two uniaxial single domain ferromagnetic particles with antiferromagnetic dipolar coupling. The hysteresis loops of a strongly coupled systems exhibit fully demagnetized, intermediate metastable configurations which separate the two fully saturated states. At small magnetostatic couplings, on the other hand, and at sufficiently weak damping, the intermediate metastable configuration becomes only partially demagnetized. This state cannot be associated with any single local minimum of the free energy function.

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Establishing Building Recommissioning Priorities And Potential Energy Savings From Utility Energy Data, Kevin P. Hallinan, Philip Brodrick, Jessica Northridge, J. Kelly Kissock, Robert J. Brecha Jan 2011

Establishing Building Recommissioning Priorities And Potential Energy Savings From Utility Energy Data, Kevin P. Hallinan, Philip Brodrick, Jessica Northridge, J. Kelly Kissock, Robert J. Brecha

Physics Faculty Publications

An energy reduction program for commercial buildings is implemented for a SW Ohio natural gas utility. The aim of this study is to demonstrate that historical utility data for individual building customers, along with knowledge of pertinent building information (square footage, year built, number of floors, height of floors, wall construction type, and use type) available in county auditor databases, could be used to identify the best candidate buildings for recommissioning in terms of energy savings and simple payback. A study is completed for all natural gas customers of a utility in Montgomery and Clinton counties in Ohio. A total …

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Accuracy Of The Thin-Lens Approximation In Strong Lensing By Smoothly Truncated Dark Matter Haloes, S. Frittelli, Thomas Kling Jan 2011

Accuracy Of The Thin-Lens Approximation In Strong Lensing By Smoothly Truncated Dark Matter Haloes, S. Frittelli, Thomas Kling

Physics Faculty Publications

The accuracy of mass estimates by gravitational lensing using the thin-lens approximation applied to Navarro–Frenk–White mass models with a soft truncation mechanism recently proposed by Baltz, Marshall and Oguri is studied. The gravitational lens scenario considered is the case of the inference of lens mass from the observation of Einstein rings (strong lensing). It is found that the mass error incurred by the simplifying assumption of thin lenses is below 0.5 per cent. As a byproduct, the optimal tidal radius of the soft truncation mechanism is found to be at most 10 times the virial radius of the mass model.

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Demonstrating The Principles Of Aperture Synthesis With The Very Small Radio Telescope, Jonathan M. Marr, Karel Durkota, Francis P. Wilkin, Adam Pere, Alan E.E. Rogers, Vincent L. Fish, Gabriel Holodak, Martina B. Arndt Jan 2011

Demonstrating The Principles Of Aperture Synthesis With The Very Small Radio Telescope, Jonathan M. Marr, Karel Durkota, Francis P. Wilkin, Adam Pere, Alan E.E. Rogers, Vincent L. Fish, Gabriel Holodak, Martina B. Arndt

Physics Faculty Publications

We have developed a set of college-level, table-top labs for teaching the basics of radio interferometry and aperture synthesis. These labs are performed with the Very Small Radio Telescope (VSRT), an interferometer using satellite TV electronics as detectors and compact fluorescent light bulbs as microwave signal sources. The hands-on experience provided by the VSRT in these labs allows students to gain a conceptual understanding of radio interferometry and aperture synthesis without the rigorous mathematical background traditionally required.

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Thermodynamics Of The Solar Corona And Evolution Of The Solar Magnetic Field As Inferred From The Total Solar Eclipse Observations Of 2010 July 11, Shadia Rifai Habbal, Miloslav Druckmüller, Huw Morgan, Adalbert Ding, Judd Johnson, Hana Druckmüllerová, Adrian Daw, Martina B. Arndt, Martin Dietzel, Jon Saken Jan 2011

Thermodynamics Of The Solar Corona And Evolution Of The Solar Magnetic Field As Inferred From The Total Solar Eclipse Observations Of 2010 July 11, Shadia Rifai Habbal, Miloslav Druckmüller, Huw Morgan, Adalbert Ding, Judd Johnson, Hana Druckmüllerová, Adrian Daw, Martina B. Arndt, Martin Dietzel, Jon Saken

Physics Faculty Publications

We report on the first multi-wavelength coronal observations, taken simultaneously in white light, Hα 656.3 nm, Fe IX 435.9 nm, Fe X 637.4 nm, Fe XI 789.2 nm, Fe XIII 1074.7 nm, Fe XIV 530.3 nm, and Ni XV 670.2 nm, during the total solar eclipse of 2010 July 11 from the atoll of Tatakoto in French Polynesia. The data enabled temperature differentiations as low as 0.2 × 106 K. The first-ever images of the corona in Fe IX and Ni XV showed that there was very little plasma below 5 × 105 K and above 2.5 × …

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Wave-Function Functionals For The Density, Marlina Slamet Jan 2011

Wave-Function Functionals For The Density, Marlina Slamet

Physics Faculty Publications

We extend the idea of the constrained-search variational method for the construction of wave-function functionals ψ[χ] of functions χ. The search is constrained to those functions χ such that ψ[χ] reproduces the density ρ(r) while simultaneously leading to an upper bound to the energy. The functionals are thereby normalized and automatically satisfy the electron-nucleus coalescence condition. The functionals ψ[χ] are also constructed to satisfy the electron-electron coalescence condition. The method is applied to the ground state of the helium atom to construct functionals ψ[χ] that reproduce the density as given by the Kinoshita correlated wave function. The expectation …

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Numerically Determined Transport Laws For Fingering ("Thermohaline") Convection In Astrophysics, Adrienne L. Traxler, Pascale Garaud, Stephan Stellmach Jan 2011

Numerically Determined Transport Laws For Fingering ("Thermohaline") Convection In Astrophysics, Adrienne L. Traxler, Pascale Garaud, Stephan Stellmach

Physics Faculty Publications

We present the first three-dimensional simulations of fingering convection performed in a parameter regime close to the one relevant for astrophysics, and reveal the existence of simple asymptotic scaling laws for turbulent heat and compositional transport. These laws can straightforwardly be extrapolated to the true astrophysical regime. Our investigation also indicates that thermocompositional "staircases," a key consequence of fingering convection in the ocean, cannot form spontaneously in the fingering regime in stellar interiors. Our proposed empirically-determined transport laws thus provide simple prescriptions for mixing by fingering convection in a variety of astrophysical situations, and should, from here on, be used …

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Targeting Residential Energy Reduction For City Utilities Using Historical Electrical Utility Data And Readily Available Building Data, Kevin P. Hallinan, J. Kelly Kissock, Robert J. Brecha, Austin Mitchell Jan 2011

Targeting Residential Energy Reduction For City Utilities Using Historical Electrical Utility Data And Readily Available Building Data, Kevin P. Hallinan, J. Kelly Kissock, Robert J. Brecha, Austin Mitchell

Physics Faculty Publications

Energy use data for the eight-year period 2003–2010 was analyzed for over 1200 single family residences in Village of Yellow Springs, Ohio. Electricity, natural gas, residential building, and weather databases are merged to permit determination of the energy intensity of each home in the village. The energy use intensity for each home is disaggregated into weather independent and weather dependent electric and natural gas use. This use is compared to typical baseline, cooling, and heating energy use for the region. From this comparison, priority homes are identified for energy reduction investment. Collective potential low cost energy reduction is estimated for …

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Design Of Low-Frequency Superconducting Spoke Cavities For High-Velocity Applications, Jean R. Delayen, C. S. Hopper, R. G. Olave Jan 2011

Design Of Low-Frequency Superconducting Spoke Cavities For High-Velocity Applications, Jean R. Delayen, C. S. Hopper, R. G. Olave

Physics Faculty Publications

Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β~0.15 to β~0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of 325 and 352 MHz spoke cavities optimized for β=0.8 and β=1.

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Higher Order Mode Properties Of Superconducting Two-Spoke Cavities, C. S. Hopper, Jean R. Delayen, R. G. Olave Jan 2011

Higher Order Mode Properties Of Superconducting Two-Spoke Cavities, C. S. Hopper, Jean R. Delayen, R. G. Olave

Physics Faculty Publications

Multi-Spoke cavities lack the cylindrical symmetry that many other cavity types have, which leads to a more complex Higher Order Mode (HOM) spectrum. In addition, spoke cavities offer a large velocity acceptance which means we must perform a detailed analysis of the particle velocity dependence for each mode's R/Q. We present here a study of the HOM properties of two-spoke cavities designed for high-velocity applications. Frequencies, R/Q and field profiles of HOMs have been calculated and are reported.

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Scaling Properties At Freeze-Out In Relativistic Heavy-Ion Collisions, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, S. Bueltmann, I. Koralt, D. Plyku, Star Collaboration Jan 2011

Scaling Properties At Freeze-Out In Relativistic Heavy-Ion Collisions, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, S. Bueltmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

Identified charged pion, kaon, and proton spectra are used to explore the system size dependence of bulk freeze-out properties in Cu+Cu collisions at √sNN=200 and 62.4 GeV. The data are studied with hydrodynamically motivated blast-wave and statistical model frameworks in order to characterize the freeze-out properties of the system. The dependence of freeze-out parameters on beam energy and collision centrality is discussed. Using the existing results from Au + Au and pp collisions, the dependence of freeze-out parameters on the system size is also explored. This multidimensional systematic study furthers our understanding of the QCD phase diagram revealing the importance …

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Design Of Superconducting Parallel Bar Cavities For Deflecting/Crabbing Applications, Jean R. Delayen, Subashini De Silva Jan 2011

Design Of Superconducting Parallel Bar Cavities For Deflecting/Crabbing Applications, Jean R. Delayen, Subashini De Silva

Physics Faculty Publications

The superconducting parallel-bar cavity is a deflecting/ crabbing cavity with attractive properties, compared to other conventional designs, that is currently being considered for a number of applications. The new parallel-bar design with curved loading elements and circular or elliptical outer conductors have improved properties compared to the designs with rectangular outer conductors. We present the designs proposed as the deflecting cavities for the Jefferson Lab 12 GeV upgrade and for Project-X and crabbing cavities for the proposed LHC luminosity upgrade and electron-ion collider at Jefferson Lab.

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Fundamental And Hom Coupler Design Of The Superconducting Parallel-Bar Cavities, Subashini De Silva, Jean R. Delayen Jan 2011

Fundamental And Hom Coupler Design Of The Superconducting Parallel-Bar Cavities, Subashini De Silva, Jean R. Delayen

Physics Faculty Publications

The superconducting parallel-bar cavity [1] is currently being considered as a deflecting system for the Jefferson Lab 12 GeV upgrade and as a crabbing cavity for a possible LHC luminosity upgrade. Currently the designs are optimized to achieve lower surface fields within the dimensional constraints for the above applications. A detailed analysis of the fundamental input power coupler design for the parallel-bar cavity is performed considering beam loading and the effects of microphonics. For higher beam loading the damping of the HOMs is vital to reduce beam instabilities generated due to the wake fields. An analysis of threshold impedances for …

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Multipacting Analysis Of The Superconducting Parallel-Bar Cavity, Subashini De Silva, Jean R. Delayen Jan 2011

Multipacting Analysis Of The Superconducting Parallel-Bar Cavity, Subashini De Silva, Jean R. Delayen

Physics Faculty Publications

The superconducting parallel-bar cavity [1] is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. Multipacting can be a limiting factor to the performance of in any superconducting structure. In the parallel-bar cavity the main contribution to the deflection is due to the transverse deflecting voltage, between the parallel bars, making the design potentially prone to multipacting. This paper presents the results of analytical calculations and numerical simulations of multipacting in the parallel-bar cavity with resonant voltage, impact energies and corresponding particle trajectories.

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Precise Measurements Of Beam Spin Asymmetries In Semi-Inclusive Π0 Production, M. Aghasyan, H. Avakian, P. Rossi, E. De Sanctis, D. Hasch, M. Mirazita, D. Adikaram, M. J. Amaryan, M. Anghinolfi, H. Baghdasaryan, R. P. Bennett, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein Jan 2011

Precise Measurements Of Beam Spin Asymmetries In Semi-Inclusive Π0 Production, M. Aghasyan, H. Avakian, P. Rossi, E. De Sanctis, D. Hasch, M. Mirazita, D. Adikaram, M. J. Amaryan, M. Anghinolfi, H. Baghdasaryan, R. P. Bennett, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein

Physics Faculty Publications

We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial sin phi(h) amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle φh of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations. (C) 2011 Elsevier B.V.

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Experimental Results In Dis, Sidis And Des From Jefferson Lab, Sebastian E. Kuhn Jan 2011

Experimental Results In Dis, Sidis And Des From Jefferson Lab, Sebastian E. Kuhn

Physics Faculty Publications

Jefferson Lab’s electron accelerator in its present incarnation, with a maximum beam energy slightly above 6 GeV, has already enabled a large number of experiments expanding our knowledge of nucleon and nuclear structure (especially in Deep Inelastic Scattering—DIS—at moderately high x, and in the resonance region). Several pioneering experiments have yielded first results on Deeply Virtual Compton Scattering (DVCS) and other Deep Exclusive Processes (DES), and the exploration of the rich landscape of transverse momentum‐dependent (TMD) structure functions using Semi‐Inclusive electron scattering (SIDIS) has begun. With the upgrade of CEBAF to 12 GeV now underway, a significantly larger kinematic …

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Mellin Representation Of The Graviton Bulk-To-Bulk Propagator In Ads Space, Ian Balitsky Jan 2011

Mellin Representation Of The Graviton Bulk-To-Bulk Propagator In Ads Space, Ian Balitsky

Physics Faculty Publications

A Mellin-type representation of the graviton bulk-to-bulk propagator from E. D’Hoker, D. Z. Freedman, S. D. Mathur, A. Matusis, and L. Rastelli [Nucl. Phys. B562, 330 (1999)] in terms of the integral over the product of bulk-to-boundary propagators is derived.

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Evolution Of Conformal Color Dipoles And High Energy Amplitudes In 𝒩 = 4 Sym, Ian Balitsky Jan 2011

Evolution Of Conformal Color Dipoles And High Energy Amplitudes In 𝒩 = 4 Sym, Ian Balitsky

Physics Faculty Publications

The high-energy behavior of the 𝒩 = 4 SYM amplitudes in the Regge limit can be calculated order by order in perturbation theory using the high-energy operator expansion in Wilson lines. At large Nc, a typical four-point amplitude is determined by a single BFKL pomeron. The conformal structure of the four-point amplitude is fixed in terms of two functions: pomeron intercept and the coefficient function in front of the pomeron (the product of two residues). The pomeron intercept is universal while the coefficient function depends on the correlator in question. The intercept is known in the first two …

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Beam Dynamics Studies Of Parallel-Bar Deflecting Cavities, S. Ahmed, G. A. Krafft, K. Deitrick, Subashini U. De Silva, Jean R. Delayen, M. Spata, M. Tiefenback, A. Hofler, K. Beard Jan 2011

Beam Dynamics Studies Of Parallel-Bar Deflecting Cavities, S. Ahmed, G. A. Krafft, K. Deitrick, Subashini U. De Silva, Jean R. Delayen, M. Spata, M. Tiefenback, A. Hofler, K. Beard

Physics Faculty Publications

We have performed three-dimensional simulations of beam dynamics for parallel-bar transverse electromagnetic mode (TEM) type RF separators: normal- and superconducting. The compact size of these cavities as compared to 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 eight 2-cell normal conducting cavities or a one- or two-cell superconducting structure are enough to produce the required vertical displacement at the Lambertson magnet. Both the normal and superconducting structures show very small emittance dilution due to the …

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Conceptual Design Of A Polarized Medium Energy Electron-Ion Collider At Jlab, S. Ahmed, A. Bogacz, Ya. Derbenev, A. Hutton, Geoffrey Krafft, R. Li, V. Morozov, F. Pilat, R. Rimmer, Y. Roblin, T. Satogata, M. Spata, B. Terzić, M. Tiefenback, H. Wang, B. Yunn, Y. Zhang, P. Chetsov, Jean R. Delayen, Subashini Desilva, Hisham Sayed, V. Dudnikov, R. Johnson, F. Marhauser, M. Sullivan, S. Manikonda, P. N. Ostroumov, S. Abeyratne, B. Erdelyi, Y. Kim, A. Kondratenko Jan 2011

Conceptual Design Of A Polarized Medium Energy Electron-Ion Collider At Jlab, S. Ahmed, A. Bogacz, Ya. Derbenev, A. Hutton, Geoffrey Krafft, R. Li, V. Morozov, F. Pilat, R. Rimmer, Y. Roblin, T. Satogata, M. Spata, B. Terzić, M. Tiefenback, H. Wang, B. Yunn, Y. Zhang, P. Chetsov, Jean R. Delayen, Subashini Desilva, Hisham Sayed, V. Dudnikov, R. Johnson, F. Marhauser, M. Sullivan, S. Manikonda, P. N. Ostroumov, S. Abeyratne, B. Erdelyi, Y. Kim, A. Kondratenko

Physics Faculty Publications

A medium energy electron-ion collider is envisioned as the primary future of the JLab nuclear science program beyond the 12 GeV upgraded CEBAF. The present conceptual design selects a ring-ring collider option, covers a CM energy range up to 65 GeV for collisions of polarized electrons with polarized light ions or unpolarized light to heavy ions, and reaches a luminosity at above 1034 cm-2s-1 per detector over multiple interaction points. This paper presents a brief description of the current conceptual design of the accelerator.

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Coherent Photoproduction Of Π+ From 3He, K. P. Adhikari, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, F. Sabatié, L. B. Weinstein, Et Al., The Clas Collaboration Jan 2011

Coherent Photoproduction Of Π+ From 3He, K. P. Adhikari, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, F. Sabatié, L. B. Weinstein, Et Al., The Clas Collaboration

Physics Faculty Publications

We have measured the differential cross section for the 𝛾 3He → π+t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid 3He target. The differential cross sections for the 𝛾 3He → π+t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at …

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High-Energy Amplitudes In The Next-To-Leading Order, Ian Balitsky Jan 2011

High-Energy Amplitudes In The Next-To-Leading Order, Ian Balitsky

Physics Faculty Publications

High-energy scattering in the saturation region is described by the evolution of color dipoles. In the leading order this evolution is governed by the non-linear BK equation. To see if this equation is relevant for existing or future accelerators (like EIC or LHeC) one needs to know how big are the next-to-leading order (NLO) corrections. I review the calculation of the NLO corrections to high-energy amplitudes in QCD.

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Design Of Superconducting Parallel-Bar Deflecting/Crabbing Cavities With Improved Properties, Jean R. Delayen, Subashini De Silva Jan 2011

Design Of Superconducting Parallel-Bar Deflecting/Crabbing Cavities With Improved Properties, Jean R. Delayen, Subashini De Silva

Physics Faculty Publications

The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. All designs to-date have been based on straight loading elements and rectangular outer conductors. We present new designs of parallel-bar cavities using curved loading elements and circular or elliptical outer conductors, with significantly improved properties such as reduced surface fields and wider higher-order mode separation.

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Design Of Superconducting Spoke Cavities For High-Velocity Applications, Jean R. Delayen, Subashini De Silva, C. S. Hopper Jan 2011

Design Of Superconducting Spoke Cavities For High-Velocity Applications, Jean R. Delayen, Subashini De Silva, C. S. Hopper

Physics Faculty Publications

Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β0 ~ 0.15 to β0 ~ 0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β0 = 0.8 and β0 = 1.

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Design Of Superconducting Parallel Bar Deflecting/Crabbing Cavities, Jean R. Delayen, Subashini De Silva Jan 2011

Design Of Superconducting Parallel Bar Deflecting/Crabbing Cavities, Jean R. Delayen, Subashini De Silva

Physics Faculty Publications

The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is being considered for a number of applications. We present an analysis of several designs of parallel-bar cavities and their electromagnetic properties.

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