Physical Sciences and Mathematics Commons^™

Progress On The Interaction Region Design And Detector Integration At Jlab's Meic, V. S. Morozov, P. Brindza, A. Camsonne, Ya S. Derbenev, R. Ent, D. Gaskell, F. Lin, P. Nadel-Turonski, M. Ungaro, Y. Zhang, C. E. Hyde, K. Park, M. Sullivan, Z. W. Zhao

Physics Faculty Publications

One of the unique features of JLab's Medium-energy Electron-Ion Collider (MEIC) is a full-acceptance detector with a dedicated, small-angle, high-resolution detection system, capable of covering a wide range of momenta (and charge-to-mass ratios) with respect to the original ion beam to enable access to new physics. We present an interaction region design developed with close integration of the detection and beam dynamical aspects. The dynamical aspect of the design rests on a symmetry-based concept for compensation of non-linear effects. The optics and geometry have been optimized to accommodate the detection requirements and to ensure the interaction region's modularity for ease …

Multipacting Optimization Of A 750 Mhz Rf Dipole, A. Castilla, J. R. Delayen

Physics Faculty Publications

Crab crossing schemes have been proposed to re-instate luminosity degradation due to crossing angles at the interaction points in next generation colliders to avoid the use of sharp bending magnets and their resulting large synchrotron radiation generation, highly undesirable in the detector region. The rf dipole has been considered for a different set of applications in several machines, both rings and linear colliders. We present in this paper a study of the effects on the multipacting levels and location depending on geometrical variations on the design for a crabbing/deflecting application in a high current (3/0.5 A), high repetition (750 MHz) …

Cryogenic Testing Of High-Velocity Spoke Cavities, C. S. Hopper, Hyekyoung Park, J. R. Delayen

Physics Faculty Publications

Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0 = 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.

Hom And Impedance Study Of Rf Separators For Lcls-Ii, S. U. De Silva, B.R.P. Gamage, R. G. Olave, J. R. Delayen, G. A. Krafft, T. Satogata

Physics Faculty Publications

The LCLS-II upgrade requires an rf spreader system to guide bunches into a switchyard delivering beam to two undulators and the primary beam dump. The beam pattern therefore needs a 3-way beam spreader. An rf deflecting cavity concept was proposed that includes both superconducting and normal conducting options. We characterize the higher order modes (HOM) of these rf separator cavities and evaluate beam dynamics effects due to potential HOM excitation. This study includes both short term wake and multi-bunch effects.

Neutral Pion Cross Section And Spin Asymmetries At Intermediate Pseudorapidity In Polarized Proton Collisions At √ S = 200 Gev, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, S. Bültmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

The differential cross section and spin asymmetries for neutral pions produced within the intermediate pseudorapidity range 0.8<η/c and is found to agree with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry A_LL is measured in the same pseudorapidity range and spans a range of Bjorken-x down to x≈0.01. The measured A_LL is consistent with model predictions for varying degrees of gluon polarization. The parity-violating asymmetry A_L is also measured and found to be consistent with zero. The transverse single-spin asymmetry AN is measured over a previously unexplored kinematic range in Feynman-x and P_T. Such measurements may aid our understanding of the onset and kinematic dependence of the large asymmetries observed …

Measurement Of The Structure Function Of The Nearly Free Neutron Using Spectator Tagging In Inelastic ²H(E,E'Pˢ) X Scattering With Clas, S. Tkachenko, S. E. Kuhn, J. Zhang, K. P. Adhikari, M. J. Amaryan, A. Klein, S. Koirala, M. Mayer, L. Zana, Clas Collaboration

Physics Faculty Publications

Background: Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x . As a consequence, the same data can lead to different conclusions, for example, about the behavior of the d quark distribution in the proton at large x .

Purpose: The Barely Off-shell Nucleon Structure experiment at Jefferson …

Neutron Spin Struccture With Polarized Deuterons And Spectator Proton Tagging At Eic, W. Cosyn, V. Guzey, D. W. Higinbotham, C. Hyde, S. Kuhn, P. Nadel-Turonski, K. Park, M. Sargsian, M. Strikman, C. Weiss

Physics Faculty Publications

The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x ≪ 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < pR < several 100MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.

Publisher’S Note: Data Analysis Techniques, Differential Cross Sections, And Spin Density Matrix Elements For The Reaction 𝛾p -> Φp (Phys. Rev. C. Vol 89, 055208, 2014), K. P. Adhikari, D. Adikaram, M. J. Amaryan, C. E. Hyde, A. Klein, S. Koirala, S. E. Kuhn, M. Mayer, I. Niculescu, J. Zhang, Et Al., The Clas Collaboration

Physics Faculty Publications

No abstract provided.

Nlo Bfkl And Anomalous Dimensions Of Light Ray Operators, Ian Balitsky

Physics Faculty Publications

The anomalous dimensions of light-ray operators of twist two are obtained by analytical continuation of the anomalous dimensions of corresponding local operators. I demonstrate that the asymptotics of these anomalous dimensions at the “BFKL point” j → 1 can be obtained by comparing the light-cone operator expansion with the high-energy expansion in Wilson lines

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 …

Characterization And Fabrication Of Spoke Cavities For High-Velocity Applications, C. S. Hopper, Hyekyoung Park, Jean R. Delayen

Physics Faculty Publications

A 500 MHz, velocity-of-light, two-spoke cavity has been designed and optimized for possible use in a compact light source [1]. Here we present the mechanical analysis and steps taken in fabrication of this cavity at Jefferson Lab.

Multipole And Field Uniformity Tailoring Of A 750 Mhz Rf Dipole, A. Castilla, Jean R. Delayen

Physics Faculty Publications

In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency …

Narrow-Band Emission In Thomson Sources Operating In The High-Field Regime, Balša Terzić, Kirsten Deitrick, Alicia S. Hofler, Geoffrey A. Krafft

Physics Faculty Publications

We present a novel and quite general analysis of the interaction of a high-field chirped laser pulse and a relativistic electron, in which exquisite control of the spectral brilliance of the up-shifted Thomson-scattered photon is shown to be possible. Normally, when Thomson scattering occurs at high field strengths, there is ponderomotive line broadening in the scattered radiation. This effect makes the bandwidth too large for some applications and reduces the spectral brilliance. We show that such broadening can be corrected and eliminated by suitable frequency modulation of the incident laser pulse. Furthermore, we suggest a practical realization of this compensation …

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 …

Observation Of D⁰ Meson Nuclear Modifications In Au + Au Collisions At √SNn = 200 Gev, 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

We report the first measurement of charmed-hadron (D⁰) production via the hadronic decay channel (D⁰→K⁻+π⁺) in Au+Au collisions at √s_NN=200  GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, N_bin, from p+p to central Au+Au collisions. The D⁰ meson yields in central Au+Au collisions are strongly suppressed compared to those in p+p scaled by N_bin, for transverse momenta p_T > 3  GeV/c, demonstrating significant energy loss of charm quarks in the hot …

Krill, Climate, And Contrasting Future Scenarios For Arctic And Antarctic Fisheries, Margaret M. Mcbride, Padmini Dalpadado, Kenneth F. Drinkwater, Olav Rune Godø, Alistair J. Hobday, Anne B. Hollowed, Trond Kristiansen, Eugene J. Murphy, Patrick H. Ressler, Sam Subbey, Eileen E. Hofmann, Harald Loeng

CCPO Publications

Arctic and Antarcticmarine systems have incommon high latitudes, large seasonal changes in light levels, cold air and sea temperatures, and sea ice. In other ways, however, they are strikingly different, including their: age, extent, geological structure, ice stability, and foodweb structure. Both regions contain very rapidly warming areas and climate impacts have been reported, as have dramatic future projections. However, the combined effects of a changing climate on oceanographic processes and foodweb dynamics are likely to influence their future fisheries in very different ways. Differences in the life-history strategies of the key zooplankton species (Antarctic krill in the Southern Ocean …

A Comparative Study Of Sea Level Reconstruction Techniques Using 20 Years Of Satellite Altimetry Data, M. W. Strassburg, B. D. Hamlington, R. R. Leben, K.-Y. Kim

CCPO Publications

Sea level reconstructions extend spatially dense data sets, such as those from satellite altimetry, by decomposing the data set into basis functions and fitting those functions to in situ tide gauge measurements with a longer temporal record. We compare and evaluate two methods for reconstructing sea level through an idealized study. The compared sea level reconstruction methods differ in the technique for calculating basis functions, i.e., empirical orthogonal functions (EOFs) versus cyclostationary EOFs (CSEOFs). Reconstructions are created using Archiving, Validation, and Interpretation of Satellite Oceanographic (AVISO) satellite altimetry data and synthetic tide gauges. Synthetic tide gauge records are simulated using …

Template-Based C8-Scorpion: A Protein 8 State Secondary Structure Prediction Method Using Structural Information And Context-Based Features, Ashraf Yaseen, Yaohang Li

Computer Science Faculty Publications

Background: Secondary structures prediction of proteins is important to many protein structure modeling applications. Correct prediction of secondary structures can significantly reduce the degrees of freedom in protein tertiary structure modeling and therefore reduces the difficulty of obtaining high resolution 3D models.

Methods: In this work, we investigate a template-based approach to enhance 8-state secondary structure prediction accuracy. We construct structural templates from known protein structures with certain sequence similarity. The structural templates are then incorporated as features with sequence and evolutionary information to train two-stage neural networks. In case of structural templates absence, heuristic structural information is incorporated instead. …

A Scalable Backward Chaining-Based Reasoner For A Semantic Web, Hui Shi, Kurt Maly, Steven Zeil

Computer Science Faculty Publications

In this paper we consider knowledge bases that organize information using ontologies. Specifically, we investigate reasoning over a semantic web where the underlying knowledge base covers linked data about science research that are being harvested from the Web and are supplemented and edited by community members. In the semantic web over which we want to reason, frequent changes occur in the underlying knowledge base, and less frequent changes occur in the underlying ontology or the rule set that governs the reasoning. Interposing a backward chaining reasoner between a knowledge base and a query manager yields an architecture that can support …

Did A Submarine Landslide Contribute To The 2011 Tohoku Tsunami?, David R. Tappin, Stephan T. Grilli, Jeffrey C. Harris, Robert J. Geller, Timothy Masterlark, James T. Kirby, Fengyan Shi, Gangfeng Ma, K.K.S. Thingbaijam, P. Martin Mai

Civil & Environmental Engineering Faculty Publications

Many studies have modeled the Tohoku tsunami of March 11, 2011 as being due entirely to slip on an earthquake fault, but the following discrepancies suggest that further research is warranted. (1) Published models of tsunami propagation and coastal impact underpredict the observed runup heights of up to 40. m measured along the coast of the Sanriku district in the northeast part of Honshu Island. (2) Published models cannot reproduce the timing and high-frequency content of tsunami waves recorded at three nearshore buoys off Sanriku, nor the timing and dispersion properties of the waveforms at offshore DART buoy #21418. (3) …

Atomic Layer Deposition Of Nanolaminate Structures Of Alternating Pbte And Pbse Thermoelectric Films, K. Zhang, A. D. Ramalingom Pillai, K. Bollenbach, D. Nminibapiel, W. Cao, H. Baumgart

Electrical & Computer Engineering Faculty Publications

For this study PbTe and PbSe thin film nanolaminates have been prepared on silicon substrates with native oxide by Atomic Layer Deposition (ALD) using lead(II)bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (Pb(C₁₁H₁₉O₂)(₂), (trimethylsilyl) telluride ((Me₃Si)₂Te) and bis-(triethyl silyl) selane ((Et₃Si)₂Se) as ALD precursors for lead, tellurium and selenium. The experimental evidence revealed the ALD growth of lead telluride and lead selenide followed the Vollmer-Weber island growth mode. We found a strong dependence of the nucleation process on the temperature. In this paper, we present the optimized conditions for growing PbTe …

Optical And Hybrid Imaging And Processing For Big Data Problems, Khan Iftekharuddin, Abdul A. S. Awwal, S. Susan Young, Ghaleb M. Abdulla

Electrical & Computer Engineering Faculty Publications

(First paragraph) The scientific community has been dealing with big data for a long time. Due to advancement in sensing, networking, and storage technology, other domains such as business, health, and social media followed. Data are considered the gold of the 21st century and are being collected, stored, and analyzed at a rapid pace. The amount of data being collected creates a compelling case for investing in hardware and software research to support generating even more data from new sensors and with better quality. It also creates a compelling case for investing in research and development of new hardware and …

Validation Of Mipas Imk/Iaa V5r_O3_224 Ozone Profiles, A. Laeng, U. Grabowski, T. Von Clarmann, G. Stiller, N. Glatthor, M. Höpfner, S. Kellmann, M. Kiefer, A. Linden, S. Lossow, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

We present the results of an extensive validation program of the most recent version of ozone vertical profiles retrieved with the IMK/IAA (Institute for Meteorology and Climate Research/Instituto de Astrofisica de Andalucia) MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) research level 2 processor from version 5 spectral level 1 data. The time period covered corresponds to the reduced spectral resolution period of the MIPAS instrument, i.e., January 2005-April 2012. The comparison with satellite instruments includes all post-2005 satellite limb and occultation sensors that have measured the vertical profiles of tropospheric and stratospheric ozone: ACE-FTS, GOMOS, HALOE, HIRDLS, MLS, OSIRIS, POAM, …

Synthesis And Characterization Of Ph Responsive D-Glucosamine Based Molecular Gelators, Navneet Goyal, Hari P.R. Mangunuru, Bargav Parikh, Sonu Shrestha, Guijun Wang

Chemistry & Biochemistry Faculty Publications

Small molecular gelators are a class of compounds with potential applications for soft biomaterials. Low molecular weight hydrogelators are especially useful for exploring biomedical applications. Previously, we found that 4,6-O-benzylidene acetal protected D-glucose and D-glucosamine are well-suited as building blocks for the construction of low molecular weight gelators. To better understand the scope of D-glucosamine derivatives as gelators, we synthesized and screened a novel class of N-acetylglucosamine derivatives with a p-methoxybenzylidene acetal protective group. This modification did not exert a negative influence on the gelation. On the contrary, it actually enhanced the gelation tendency for many derivatives. The …

Middle Atmospheric Changes Caused By The January And March 2012 Solar Proton Events, C. H. Jackman, C. E. Randall, V. L. Harvey, S. Wang, E. L. Fleming, M. López-Puertas, B. Funke, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

The recent 23-30 January and 7-11 March 2012 solar proton event (SPE) periods were substantial and caused significant impacts on the middle atmosphere. These were the two largest SPE periods of solar cycle 24 so far. The highly energetic solar protons produced considerable ionization of the neutral atmosphere as well as HOx (H, OH, HO2) and NOx (N, NO, NO2). We compute a NOx production of 1.9 and 2.1 Gigamoles due to these SPE periods in January and March 2012, respectively, which places these SPE periods among the 12 largest in the past 50 yr. Aura Microwave Limb Sounder (MLS) …

Drift Corrected Trends And Periodic Variations In Mipas Imk/Iaa Ozone Measurements, E. Eckert, T. Von Clarmann, M. Kiefer, G. P. Stiller, S. Lossow, N. Glatthor, D. A. Degenstein, L. Froidevaux, S. Godin-Beekmann, T. Leblanc, S. Mcdermid, M. Pastel, W. Steinbrcht, D.P.J. Swart, K. A. Walker, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Drifts, trends and periodic variations were calculated from monthly zonally averaged ozone profiles. The ozone profiles were derived from level-1b data of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) by means of the scientific level-2 processor run by the Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK). All trend and drift analyses were performed using a multilinear parametric trend model which includes a linear term, several harmonics with period lengths from 3 to 24 months and the quasi-biennial oscillation (QBO). Drifts at 2-sigma significance level were mainly negative for ozone relative to Aura MLS and …

Spectrometric Monitoring Of Atmospheric Carbon Tetrafluoride (Cf4) Above The Jungfraujoch Station Since 1989: Evidence Of Continued Increase But At A Slowing Rate, E. Mahieu, R. Zander, G. C. Toon, M. K. Vollmer, S. Reimann, J. Muhle, W. Bader, B. Bovy, B. Lejune, C. Servais, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

The long-term evolution of the vertical column abundance of carbon tetrafluoride (CF₄) above the high-altitude Jungfraujoch station (Swiss Alps, 46.5 ° N, 8.0 ° E, 3580 ma.s.l.) has been derived from the spectrometric analysis of Fourier transform infrared solar spectra recorded at that site between 1989 and 2012. The investigation is based on a multi-microwindow approach, two encompassing pairs of absorption lines belonging to the R-branch of the strong ν₃ band of CF₄ centered at 1283 cm^-1, and two additional ones to optimally account for weak but overlapping HNO₃ interferences. The analysis reveals …

Ch In Stellar Atmospheres: An Extensive Linelist, T. Masseron, B. Plez, S. Van Eck, R. Colin, I. Daoutidis, M. Godefroid, P.-F. Coheur, P. Bernath, A. Jorissen, N. Christleib

Chemistry & Biochemistry Faculty Publications

The advent of high-resolution spectrographs and detailed stellar atmosphere modelling has strengthened the need for accurate molecular data. Carbon-enhanced metal-poor (CEMP) stars spectra are interesting objects with which to study transitions from the CH molecule. We combine programs for spectral analysis of molecules and stellar-radiative transfer codes to build an extensive CH linelist, including predissociation broadening as well as newly identified levels. We show examples of strong predissociation CH lines in CEMP stars, and we stress the important role played by the CH features in the Bond-Neff feature depressing the spectra of barium stars by as much as 0.2 mag …

A Database Of Water Transitions From Experiment And Theory (Iupac Technical Report), Jonathan Tennyson, Peter F. Bernath, Linda R. Brown, Alain Campargue, Attila G. Császár, Ludovic Daumont

Chemistry & Biochemistry Faculty Publications

The report and results of an IUPAC Task Group (TG) formed in 2004 on "A Database of Water Transitions from Experiment and Theory" (Project No. 2004-035-1-100) are presented. Energy levels and recommended labels involving exact and approximate quantum numbers for the main isotopologues of water in the gas phase, H₂¹⁶O, H₂¹⁸0, H₂¹⁷O, HD¹⁶O, HD¹⁸O, HD¹⁷O, D₂¹⁶O, D₂¹⁸O, and D₂¹⁷O, are determined from measured transition frequencies. The transition frequencies and energy levels are validated using first-principles nuclear …

Recommended Isolated-Line Profile For Representing High-Resolution Spectroscopic Transitions (Iupac Technical Report), Jonathan Tennyson, Peter F. Bernath, Alain Campargue, Attila G. Császár, Ludovic Daumont, Robert R. Gamache, Joseph T. Hodges, Daniel Lisak, Olga V. Naumenko, Laurence S. Rothman

Chemistry & Biochemistry Faculty Publications

The report of an IUPAC Task Group, formed in 2011 on "Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory" (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety alternative line-profile models. These models capture more of the physics of the influence of pressure …