Digital Commons Network^™

Virtual Compton Scattering And Neutral Pion Electroproduction In The Resonance Region Up To The Deep Inelastic Region At Backward Angles, G. Laveissiere, N. Degrande, S. Jaminion, C. Jutier, L. Todor, G. E. Dodge, C. E. Hyde, K. Mccormick, P. E. Ulmer, L. B. Weinstein, Jefferson Lab Hall A Collaboration

Physics Faculty Publications

We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e, e′p)γ exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the W-dependence at fixed Q²=1 GeV² and for the Q² dependence at fixed W near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions. The observed Q² dependence is smooth. The measured ratio of H(e, e′p)γ to H(e, e′p)π⁰ cross sections emphasizes the different sensitivity of these two reactions to the various nucleon resonances. Finally, when compared …

Photodisintegration Of 4He Into P+T, Clas Collaboration, M. J. Amaryan, S. L. Careccia, G. E. Dodge, C. E. Hyde, S. E. Kuhn, M. Mayer, C. S. Nepali, M. R. Niroula, H. Seraydaryan, S. Tkachenko, L.B. Weinstein, J. Zhang

Physics Faculty Publications

The two-body photodisintegration of 4He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid ⁴He target. This is the first measurement of the photodisintegration of ⁴He above 0.4 GeV. The differential cross sections for the γ ⁴He →pt reaction were measured as a function of photon-beam energy and proton-scattering angle and are compared with the latest model calculations by J.-M. Laget. At …

Electroexcitation Of Nucleon Resonances From Clas Data On Single Pion Electroproduction, Clas Collaboration, K. P. Adhikari, S. L. Careccia, T. A. Forest, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, C. S. Nepali, M. R. Niroula, H. Seraydaryan

Physics Faculty Publications

We present results on the electroexcitation of the low mass resonances Δ(1232)P₃₃ , N(1440)P₁₁ , N(1520)D₁₃ , and N(1535)S₁₁ in a wide range of Q². The results were obtained in the comprehensive analysis of data from the Continuous Electron Beam Accelerator Facility (CEBAF) large acceptance spectrometer (CLAS) detector at the Thomas Jefferson National Accelerator Facility (JLab) on differential cross sections, longitudinally polarized beam asymmetries, and longitudinal target and beam-target asymmetries for π electroproduction off the proton. The data were analyzed using two conceptually different approaches—fixed-t dispersion relations and a unitary isobar model—allowing us to …

Precise Measurement Of The Neutron Magnetic Form Factor Gnm In The Few-Gev² Region, Clas Collaboration, J. Lachniet, H. Bagdasaryan, S. Bültmann, N. Kalantarians, G. E. Dodge, T. A. Forest, G. Gavalian, C. E. Hyde-Wright, A. Klien, S. E. Kuhn, M. R. Niroula, R. A. Niyazov, L. M. Qin, L. B. Weinstein, J. Zhang

Physics Faculty Publications

The neutron elastic magnetic form factor was extracted from quasielastic electron scattering on deuterium over the range Q² = 1.0–4.8  GeV² with the CLAS detector at Jefferson Lab. High precision was achieved with a ratio technique and a simultaneous in situ calibration of the neutron detection efficiency. Neutrons were detected with electromagnetic calorimeters and time-of-flight scintillators at two beam energies. The dipole parametrization gives a good description of the data

Measurement Of Direct Fₒ(980) Photoproduction On The Proton, K. P. Adhikari, H. Bagdasaryan, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, N. Kalantarians, A. Klein, A.V. Klimenko, S. E. Kuhn, J. Lanchiet, M. R. Niroula, J. Zhang

Physics Faculty Publications

We report on the results of the first measurement of exclusive f₀(980) meson photoproduction on protons for E_γ = 3.0–3.8  GeV and −t = 0.4–1.0  GeV² . Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the π⁺π⁻ channel by performing a partial wave analysis of the reaction γp→pπ⁺π⁻ . Clear evidence of the f₀(980) meson was found in the interference between P and S waves at M _π+π− ∼1  GeV. The S -wave differential …

Search For The Photoexcitation Of Exotic Mesons In The Π+Π+Π- System, Clas Collaboration, M. J. Amaryan, H. Bagdasaryan, S. Bektasoglu, S. Bültmann, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, N. Kalantarians, A. Klein, S. E. Kuhn, J. Lachniet, M. R. Niroula, L. M. Qin, S. Tkachenko, L. B. Weinstein, J. Zhang

Physics Faculty Publications

A search for exotic mesons in the π⁺π⁺π⁻ system photoproduced by the charge exchange reaction γp→π⁺π⁺π⁻(n) was carried out by the CLAS Collaboration at Jefferson Lab. A tagged-photon beam with energies in the 4.8 to 5.4 GeV range, produced through bremsstrahlung from a 5.744 GeV electron beam, was incident on a liquid-hydrogen target. A partial wave analysis was performed on a sample of 83 000 events, the highest such statistics to date in this reaction at these energies. The main objective of this study was to look for the …

Conformal Kernel For The Next-To-Leading-Order Bfkl Equation In 𝒩 = 4 Super Yang-Mills Theory, Ian Balitsky, Giovanni A. Chirilli

Physics Faculty Publications

Using the requirement of Möbius invariance of 𝒩 = 4 super Yang-Mills amplitudes in the Regge limit, we restore the explicit form of the conformal next-to-leading-order Balitsky-Fadin-Kuraev-Lipatov (BFKL) kernel out of the eigenvalues known from the forward next-to-leading-order BFKL result.

Design Optimization Of Superconducting Parallel-Bar Cavities, Subashini De Silva, Jean R. Delayen

Physics Faculty Publications

The parallel-bar structure is a new superconducting geometry whose features and properties may have significant advantages over conventional superconducting deflecting and crabbing cavities for a number of applications. Jefferson Lab is in need for a 499 MHz, 11 GeV rf separator as part of its 12 GeV upgrade program. We report on design optimization studies performed todate for this and other applications.

Options For An 11 Gev Rf Beam Separator For The Jefferson Lab Cebaf Upgrade, Jean R. Delayen, M. Spata, H. Wang

Physics Faculty Publications

The CEBAF accelerator at Jefferson Lab has had, since first demonstration in 1996, the ability to deliver a 5-pass electron beam to experimental halls (A, B, and C) simultaneously. This capability is provided by a set of three, room temperature 499 MHz rf separators in the 5th pass beamline. The separator cavity is a two-rod, two-cell TEM mode type resonator, which has high shunt impedance. The 12 GeV baseline design does not preserve the capability of separating the 5th pass, 11 GeV beam for the 3 existing halls. Several options for restoring this capability, including extension of the present room …

A New Tem-Type Deflecting And Crabbing Rf Structure, Jean R. Delayen, H. Wang

Physics Faculty Publications

A new type of rf structure for the deflection and crabbing of particle bunches is introduced. It is comprised of a number of parallel TEM-resonant lines operating in opposite phase from each other. One of its main advantages is its compactness compared to conventional crabbing cavities operating in the TM110 mode, thus allowing low frequency designs. The properties and characteristics of this type of structure are presented.

Imaging-Based Parametric Resonance In An Optical Dipole-Atom Trap, S. Balik, A. L. Win, M. D. Havey

Physics Faculty Publications

We report sensitive detection of parametric resonances in a high-density sample of ultracold ⁸⁷Rb atoms confined to a far-off-resonance optical dipole trap. Fluorescence imaging of the expanded ultracold atom cloud after a period of parametric excitation shows significant modification of the atomic spatial distribution and has high sensitivity compared with traditional measurements of parametrically driven trap loss. Using this approach, a significant shift of the parametric resonance frequency is observed and attributed to the anharmonic shape of the dipole trap potential. 2009 The American Physical Society.

Energy And System Size Dependence Of Φ Meson Production In Cu + Cu And Au + Au Collisions, B. I. Abelev, M. M. Aggarwal, Z. Ahammed, B. D. Anderson, D. Arkhipkin, G. S. Averichev, Y. Bai, J. Balewski, O. Barannikova, L. S. Barnby, S. Bültmann

Physics Faculty Publications

We study the beam-energy and system-size dependence of ϕ meson production (using the hadronic decay mode ϕ → K ⁺ K ⁻ ) by comparing the new results from Cu + Cu collisions and previously reported Au + Au collisions at √^sNN = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented in this Letter are from mid-rapidity ( | y | < 0.5 ) for 0.4 < PT < 5 GeV /c . At a given beam energy, the transverse momentum distributions for ϕ mesons are observed to be similar in yield and shape for Cu + Cu and Au + …

Nlo Evolution Of Color Dipoles In N=4sym, Ian Balitsky, Giovanni A. Chrilli

Physics Faculty Publications

High-energy behavior of amplitudes in a gauge theory can be reformulated in terms of the evolution of Wilson-line operators. In the leading logarithmic approximation it is given by the conformally invariant BK equation for the evolution of color dipoles. In QCD, the next-to-leading order BK equation has both conformal and non-conformal parts, the latter providing the running of the coupling constant. To separate the conformally invariant effects from the running-coupling effects, we calculate the NLO evolution of the color dipoles in the conformal N = 4 SYM theory. We define the "composite dipole operators" with the rapidity cutoff preserving conformal …

New Compact Tem-Type Deflecting And Crabbing Rf Structure, J. R. Delayen, H. Wang

Physics Faculty Publications

A new type of rf structure for the deflection and crabbing of particle beams is presented. The structure is comprised of a number of parallel TEM resonant lines operating in opposing phase from each other. One of its advantages is its compactness compared to conventional crabbing cavities operating in the TM₁₁₀ mode, thus allowing low frequency designs. This geometry would also be effective for the deflection of beams propagating at velocities substantially less than that of light.

Comment On "On The Theory Of Nuclear Resonant Forward Scattering Of Synchrotron Radiation", Gilbert R. Hoy, Jos Odeurs

Physics Faculty Publications

Recently, in a paper by Kohn and Smirnov, a formula previously derived by Kagan et al. was developed to explain the forward scattering of gamma radiation by a nuclear-resonant sample excited by pulsed synchrotron radiation. Their derivation followed, directly, a procedure developed by Heitler, Harris, and Hoy. Previously, a completely different formula was developed by Hoy et al. to explain the same process. As a result, Kohn and Smirnov discuss the correctness and validity of the two models. In this Comment a detailed numerical comparison of the two theories has also been made. It is shown that their comparison is …

Electroproduction Of P Π⁺Π⁻ Off Protons At 0.2 < Q² < 0.6 Gev² And 1.3 < W < 1.57 Gev With The Clas Detector, M. J. Amaryan, H. Baghdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde, W. Kim, A. Klein, F. J. Klein, A. Klimenko, S. E. Kuhn, S. Tkachenko, L. B. Weinstein, Et Al., Clas Collaboration

Physics Faculty Publications

This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process ep → e'pπ⁺π^-. The data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the as yet unexplored kinematic region of photon virtuality 0.2 < Q² < 0.6 GeV² and invariant mass of the final hadron system W from 1.3 to 1.57 GeV. For the first time, nine independent one-fold differential cross sections were determined in each bin of W and Q² covered by the measurements. A phenomenological analysis of the data allowed …

Measurement Of The Differential Cross Section For The Reaction Γn →Π⁻P From Deuterium, M. J. Amaryan, H. Badasaryan, S. L. Careccia, G. E. Dodge, C. E. Hyde, S. E. Kuhn, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Zhang, Et Al., The Clas Collaboration

Physics Faculty Publications

We report a measurement of the differential cross section for the γn →π⁻p process from the CLAS detector at Jefferson Laboratory in Hall B for photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles (𝜃 _c.m.) between 50° and 115°. We confirm a previous indication of a broad enhancement around a c.m. energy (√ s) of 2.1 GeV at 𝜃_c.m. = 90° in the scaled differential cross section s^{7 dσ}_dt and a rapid falloff in a center-of-mass energy region of about 400 MeV following the enhancement. Our data show an angular dependence of …

Everyone Is A Curator: Human-Assisted Preservation For Ore Aggregations, Frank Mccown, Michael L. Nelson, Herbert Van De Sompel

Computer Science Faculty Publications

The Open Archives Initiative (OAI) has recently created the Object Reuse and Exchange (ORE) project that defines Resource Maps (ReMs) for describing aggregations of web resources. These aggregations are susceptible to many of the same preservation challenges that face other web resources. In this paper, we investigate how the aggregations of web resources can be preserved outside of the typical repository environment and instead rely on the thousands of interactive users in the web community and the Web Infrastructure (the collection of web archives, search engines, and personal archiving services) to facilitate preservation. Inspired by Web 2.0 services such as …

Correlation Of Music Charts And Search Engine Rankings, Martin Klein, Olena Hunsicker, Michael Nelson

Computer Science Faculty Publications

We investigate the question whether expert rankings of real-world entities correlate with search engine (SE) rankings of corresponding web resources. We compare Billboards "Hot 100 Airplay" music charts with SE rankings of associated web resources. Out of nine comparisons we found two strong, two moderate, two weak and one negative correlation. The remaining two comparisons were inconclusive.

Object Reuse And Exchange, Michael L. Nelson, Carl Lagoze, Herbert Van De Sompel, Pete Johnston, Robert Sanderson, Simeon Warner, Jürgen Sieck (Ed.), Michael A. Herzog (Ed.)

Computer Science Faculty Publications

The Open Archives Object Reuse and Exchange (OAI-ORE) project defines standards for the description and exchange of aggregations of Web resources. The OAI-ORE abstract data model is conformant with the Architecture of the World Wide Web and leverages concepts from the Semantic Web, including RDF descriptions and Linked Data. In this paper we provide a brief review of a motivating example and its serialization in Atom.

Multicast Encryption Infrastructure For Security In Sensor Networks, Richard R. Brooks, Brijesh Pillai, Matthew Pirretti, Michele C. Weigle

Computer Science Faculty Publications

Designing secure sensor networks is difficult. We propose an approach that uses multicast communications and requires fewer encryptions than pairwise communications. The network is partitioned into multicast regions; each region is managed by a sensor node chosen to act as a keyserver. The keyservers solicit nodes in their neighborhood to join the local multicast tree. The keyserver generates a binary tree of keys to maintain communication within the multicast region using a shared key. Our approach supports a distributed key agreement protocol that identifies the compromised keys and supports membership changes with minimum system overhead. We evaluate the overhead of …

Evaluating Multicore Algorithms On The Unified Memory Model, John E. Savage, Mohammad Zubair

Computer Science Faculty Publications

One of the challenges to achieving good performance on multicore architectures is the effective utilization of the underlying memory hierarchy. While this is an issue for single-core architectures, it is a critical problem for multicore chips. In this paper, we formulate the unified multicore model (UMM) to help understand the fundamental limits on cache performance on these architectures. The UMM seamlessly handles different types of multiple-core processors with varying degrees of cache sharing at different levels. We demonstrate that our model can be used to study a variety of multicore architectures on a variety of applications. In particular, we use …

Patterns Of Spiny Lobster (Panulirus Argus) Postlarval Recruitment In The Carribbean: A Crtr Project, Mark J. Butler Iv, Angela M. Mojica, Eloy Sosa-Cordero, Marines Millet, Paul Sanchez-Navarro, Miguel A. Maldonado, Juan Posada, Bladimir Rodriguez, Carlos M. Rivas, Adrian Oviedo, Marcio Arrone, Martha Prada, Nick Bach, Nilda Jimenez, Maria Del Carmen Garcia-Rivas, Kirah Forman, Donald C. Behringer Jr., Thomas Matthews, Claire Paris, Robert Cowen

Biological Sciences Faculty Publications

As part of the Coral Reef Targeted Research (CRTR) Program, a partnership between the Global Environment Facility and the World Bank, our research team examined the recruitment patterns of Caribbean spiny lobster (Panulirus argus) postlarvae among regions in the Caribbean, with a particular focus on Mesoamerica. Our goal was to collect comparable information on postlarval supply among regions and to provide data to test predictions of connectivity generated from a coupled biophysical oceanographic model of lobster larval dispersal. Here we present the results of the postlarval recruitment monitoring program. We monitored the catch of postlarvae on Witham-style collectors …

Genetic Variation At Hair Length Candidate Genes In Elephants And The Extinct Woolly Mammoth, Alfred L. Roca, Yasuko Ishida, Nikolaidis Sergios, Sergios-Orestis Kolokotronis, Stephen Fratpietro, Kristin Stewardson, Shannon Hensley, Michele Tisdale, Gennady Boeskorov, Alex D. Greenwood

Biological Sciences Faculty Publications

Background: Like humans, the living elephants are unusual among mammals in being sparsely covered with hair. Relative to extant elephants, the extinct woolly mammoth, Mammuthus primigenius, had a dense hair cover and extremely long hair, which likely were adaptations to its subarctic habitat. The fibroblast growth factor 5 (FGF5) gene affects hair length in a diverse set of mammalian species. Mutations in FGF5 lead to recessive long hair phenotypes in mice, dogs, and cats; and the gene has been implicated in hair length variation in rabbits. Thus, FGF5 represents a leading candidate gene for the phenotypic differences in hair length …

A New Generation Of Goals For Technology Education, John M. Ritz

STEMPS Faculty Publications

[Introduction, First paragraph]

To develop meaningful instructional programs for technology education, goals need to be in place to direct the outcomes of curriculum development and teaching. Goals are program terminal outcomes that focus curriculum writers or teachers who structure content for learners. Goals provide direction so content can be delivered for long-term impact to students who study the subject. They go beyond everyday teaching objectives; they are directed at long-term learning and programmatic outcomes.

Discovery Of The Depths, Petros J. Katsioloudis

STEMPS Faculty Publications

Throughout history the oceans have directly or indirectly influenced humans. The importance of knowing how to protect this valuable resource and insure it for future generations is vital. Underwater Vehicles are tools essential for this process, and therefore research and development to perfect these devices is needed. However, the main goal of these devices--to transmit images from places where humans cannot go--remains the same, and their importance to future discoveries remains vital. This article discusses the different types of underwater vehicles and describes an activity wherein students will fabricate an underwater remotely operated vehicle.

Probing The Urea Dependence Of Residual Structure In Denatured Human Α-Lactalbumin, Victoria A. Higman, Heike I. Rösner, Raffaella Ugolini, Lesley H. Greene, Christina Redfield, Lorna J. Smith

Chemistry & Biochemistry Faculty Publications

Backbone ¹⁵N relaxation parameters and ¹⁵N–¹H^N residual dipolar couplings (RDCs) have been measured for a variant of human α-lactalbumin (α-LA) in 4, 6, 8 and 10 M urea. In the α-LA variant, the eight cysteine residues in the protein have been replaced by alanines (all-Ala α-LA). This protein is a partially folded molten globule at pH 2 and has been shown previously to unfold in a stepwise non-cooperative manner on the addition of urea. ¹⁵N R₂ values in some regions of all-Ala α-LA show significant exchange broadening which is reduced as the urea …

Electrospray And Photoionization Mass Spectrometry For The Characterization Of Organic Matter In Natural Waters: A Qualitative Assessment, William C. Hockaday, Jeremiah M. Pucell, Alan G. Marshall, Jeffery A. Baldock, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

Fourier-transform ion cyclotron resonance mass spectrometry (MS) has demonstrated potential to revolutionize the fields of limnology and chemical oceanography by identifying the individual molecular components of organic matter in natural waters. The use of MS for this purpose is made possible by the electrospray technique which successfully ionizes polar, nonvolatile organic molecules. Another recently developed ion source, atmospheric pressure photoionization (APPI), extends MS capabilities to less polar molecules. This article presents early results on the application of APPI MS to natural organic matter. We compare APPI MS and electrospray MS data for dissolved organic matter from Lake Drummond (Virginia, USA). …

Enhancing The Collection Process For The Delphi Technique, Petros Katsioloudis, John Brocato (Ed.)

STEMPS Faculty Publications

The purpose of this manuscript is to describe a process that enhances the data collection process for a Delphi technique. The approach consists of online platforms to expedite the process and reinforce the validity of the Delphi technique. The context of the study was the identification of quality indicators for visual-based learning material development for Technology Education programs for grades 7-12.

The Ghosts Of Our Mothers: From Oral Tradition To Written Words—A History And Critique Of Jewish Women Writers Of Iranian Heritage, Farideh Goldin

English Faculty Publications

Throughout the 2,000 years of Iranian Jewish history, women usually were either illiterate or silenced. Iranian Jewish women in exile have been making up for their foremothers by creating prose literature at a fast pace in the last two decades. Through their poetry, novels and memoirs, they validate the claim that with financial security, access to education, and freedom of speech—rarely accessible to Iranian women until the twentieth century—they can shine. This article explores the history and background of Jewish women writers of Iranian heritage.