Nuclear Commons^™

Parton Energy Loss In Heavy-Ion Collisions Via Direct-Photon And Charged-Particle Azimuthal Correlations, B. I. Abelev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, B. D. Anderson, D. Arkhipkin, G. S. Averichev, S. Bueltmann, I. Koralt, Star Collaboration

Physics Faculty Publications

Charged-particle spectra associated with direct photon Ydir) and π⁰ are measured in p+p and Au+Au collisions at center-of-mass energy √sNN=200 GeV with the STAR detector at the Relativistic Heavy Ion Collider. A shower-shape analysis is used to partially discriminate between Ydirand π⁰. Assuming no associated charged particles in the γdir direction (near side) and small contribution from fragmentation photons (Yfrag), the associated charged-particle yields opposite to Ydir(away side) are extracted. In central Au+Au collisions, the charged-particle yields at midrapidity (|η|<1) and high transverse momentum (3 < P_T^assoc < 16 GeV/c) associated with γdir and π⁰ (|η|<0.9, 8 < P_T^trig <16 GeV/c) are suppressed by a factor of 3–5 compared with p+p collisions. The observed suppression of the associated charged particles is similar for Ydir and π⁰ and …

Electromagnetic Structure And Reactions Of Few-Nucleon Systems In Χeft, L. Girlanda, S. Pastore, R. Schiavilla, M. Viviani

Physics Faculty Publications

We summarize our recent work dealing with the construction of the nucleon-nucleon potential and associated electromagnetic currents up to one loop in chiral effective field theory (χEFT). The magnetic dipole operators derived from these currents are then used in hybrid calculations of static properties and low-energy radiative capture processes in few-body nuclei. A preliminary set of results are presented for the magnetic moments of the deuteron and trinucleons and thermal neutron captures on p, d, and ³He.

Hard Photodisintegration Of A Proton Pair, I. Pomerantz, N. Bubis, K. Allada, A. Beck, B. L. Berman, W. Boeglin, A. Camsonne, M. Canan, K. Chirapatpimol, E. Cisbani

Physics Faculty Publications

We present a study of high energy photodisintegration of proton-pairs through the γ + ³He → p + p + n channel. Photon energies, Eγ , from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. The s⁻¹¹ scaling of the cross section, as predicted by the constituent counting rule for two nucleon photodisintegration, was observed for the first time. The onset of the scaling is at a higher energy and the cross section is significantly lower than for deuteron (pn pair) photodisintegration. …

High-Energy Amplitudes In Gauge Theories In The Next-To-Leading-Order, Giovanni Antonio Chirilli

Physics Theses & Dissertations

Scattering processes play a central role in physics, and high-energies experiments give us an insight into the fine structure of matter. The high-energy behavior of amplitudes in gauge theories can be reformulated in terms of the evolution of Wilson-line operators. In the leading order this evolution is governed by the non-linear Balitsky-Kovchegov (BK) equation. In order to see if this equation is relevant for existing or future deep inelastic scattering (DIS) accelerators (like Electron Ion Collider (EIC) or Large Hadron electron Collider (LHeC)) one needs to know how large are the next-to-leading order (NLO) corrections. In addition, the NLO corrections …

Effects Of Hze Irradiation On Chemical Neurotransmission In Rodent Hippocampus, Mayumi Machida

Theses and Dissertations in Biomedical Sciences

Space radiation represents a significant risk to the CNS (central nervous system) during space missions. Most harmful are the HZE (high mass, highly charged (Z), high energy) particles, e.g. ⁵⁶Fe, which possess high ionizing ability, dense energy deposition pattern, and high penetrance.

Accumulating evidence suggests that radiation has significant impact on cognitive functions. In ground-base experiments, HZE radiation induces pronounced deficits in hippocampus dependent learning and memory in rodents. However, the mechanisms underlying these impairments are mostly unknown.

Exposure to HZE radiation elevates the level of oxidation, resulting in cell loss, tissue damage and functional deficits through direct ionization …

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 + …

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.

Moments Of The Spin Structure Functions G(1)(P) And G(1)(D) For 0.05 < Q2 < 3.0 Gev2, Clas Collaboration, Y. Prok, K. V. Dharmawardane, G. E. Dodge, S. E. Kuhn, M. J. Amaryan, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, N. Kalantarians, A. Klein, J. Lachniet, R. A. Niyazov, L. M. Qin, S. Sabatie, S. Tkachenko, L. B. Weinstein, J. Zhang

Physics Faculty Publications

The spin structure functions g1 for the proton and the deuteron have been measured over a wide kinematic range in x and Q² using 1.6 and 5.7 GeV longitudinally polarized electrons incident upon polarized NH3 and ND3 targets at Jefferson Lab. Scattered electrons were detected in the CEBAF Large Acceptance Spectrometer, for 0.05 < Q² < 5GeV² and W < 3 GeV. The first moments of g1 for the proton and deuteron are presented – both have a negative slope at low Q², as predicted by the extended Gerasimov–Drell–Hearn sum rule. The first extraction of the generalized forward spin polarizability of the proton γ p 0 the Q² evolution of the first moment of g1 shows agreement in leading order with Heavy …

Beam-Energy And System-Size Dependence Of Dynamical Net Charge Fluctuations, B. I. Abelev, M. M. Aggarwal, Z. Ahammed, B. D. Anderson, D. Arkhipkin, G. S. Averichev, Y. Bai, J. Balewski, S. Bueltmann, Star Collaboration

Physics Faculty Publications

We present measurements of net charge fluctuations in Au+Au collisions at √sNN=19.6, 62.4, 130, and 200 GeV, Cu+Cu collisions at √sNN=62.4 and 200 GeV, and p+p collisions at √s=200GeV using the dynamical net charge fluctuations measure ν_+−,dyn. We observe that the dynamical fluctuations are nonzero at all energies and exhibit a modest dependence on beam energy. A weak system size dependence is also observed. We examine the collision centrality dependence of the net charge fluctuations and find that dynamical net charge fluctuations violate 1/N_ch scaling but display approximate 1/N_part scaling. We also study the azimuthal and …

Beam Spin Asymmetries In Deeply Virtual Compton Scattering (Dvcs) With Clas At 4.8 Gev, G. Gavalian, M. J. Amaryan, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, N. Guler, C. E. Hyde, H. G. Juengst, N. Kalantarians, A. Klein, S. E. Kuhn, J. Lachniet, M. R. Niroula, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang, Clas Collaboration

Physics Faculty Publications

We report measurements of the beam spin asymmetry in deeply virtual Compton scattering (DVCS) at an electron beam energy of 4.8 GeV using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The DVCS beam spin asymmetry has been measured in a wide range of kinematics, 1.02<2.8 (GeV/c)², 0.12<_xB<0.48, and 0.1<−t<0.8 (GeV/c)², using the reaction →ep→e′pX. The number of H(e,e′γp) and H(e,e′π⁰p) events are separated in each (Q²,_xB,t) bin by a fit to the line shape of the H(e,e′p)X M²_x distribution. The validity of the method was studied in detail …

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 …

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 …

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 …

Spin Structure Of The Deuteron, Nevzat Guler

Physics Theses & Dissertations

Double spin asymmetries for the proton and the deuteron have been measured in the EG1b experiment using the CLAS detector at Jefferson Lab. Longitudinally polarized electrons at energies 1.6, 2.5, 4.2 and 5.7 GeV were scattered from longitudinally polarized NH3 and ND3 targets. The double spin asymmetry A|| for the proton and the deuteron has been extracted from these data as a function of W and Q² with unprecedented precision. The virtual photon asymmetry A₁ and the spin structure function g1 can be calculated from these measurements by using parametrization to the world data for the virtual …

Neutron Structure Functions Measured With Spectator Tagging, Svyatoslav Tkachenko

Physics Theses & Dissertations

We know much less about the neutron than the proton due to the absence of free neutron targets. Neutron information has to be extracted from data on nuclear targets like deuterium. This requires corrections for off-shell and binding effects which are not known from first principles and therefore are model-dependent. As a consequence, the same data can be interpreted in different ways, leading to different conclusions about important questions such as the value of the d/u quark ratio at large momentum fraction x. The Barely Off-shell NUcleon Structure (BONUS) experiment at Jefferson Lab addressed this problem by tagging spectator protons …

3he Spin-Dependent Cross Sections And Sum Rules, K. Slifer, M. Amarian, L. Auerbach, T. Averett, J. Berthot, P. Bertin, B. Bertozzi, K. Mccormick, F. Sabatié, L. Todor

Physics Faculty Publications

We present a measurement of the spin-dependent cross sections for the ^3→He(→e,e′)X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1≤Q²≤0.9  GeV². The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt-Cottingham and extended Gerasimov-Drell-Hearn sum rules for the first time. The data are also compared to an impulse approximation calculation and an exact three-body Faddeev calculation in the quasielastic region.

Studies Of Breakdown In A Pressurized Rf Cavity, M. Bastaninejad, A. A. Elmustafa, C. M. Ankenbrandt, A. Moretti, M. Popovic, K. Yonehara, D. M. Kaplan, M. Alsharo'a, P. M. Hanlet, R. P. Johnson, M. Kuchnir, D. Newsham, D. V. Rose, C. Thoma, D. R. Welch

Mechanical & Aerospace Engineering Faculty Publications

Microscopic images of the surfaces of metallic electrodes used in high-pressure gas-filled 805 MHz RF cavity experiments [1] have been used to investigate the mechanism of RF breakdown [2]. The images show evidence for melting and boiling in small regions of ∼10 micron diameter on tungsten, molybdenum, and beryllium electrode surfaces. In these experiments, the dense hydrogen gas in the cavity prevents electrons or ions from being accelerated to high enough energy to participate in the breakdown process so that the only important variables are the fields and the metallic surfaces. The distributions of breakdown remnants on the electrode surfaces …

Ratios Of 15N/12C And 4He/12C Inclusive Electroproduction Cross Sections In The Nucleon Resonance Region, P. E. Bosted, R. Fersch, G. Adams, M. Amaryan, S. Anefalos, M. Anghinolfi, G. Asryan, H. Avakian, H. Badasaryan, N. Baillie, M. Bektasoglu, S. Bültmann, S. L. Careccia, G. E. Dodge, K. V. Dharmawardane, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, N. Kalantarians, A. Klein, S. E. Kuhn, J. Lachniet, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Zhang, Clas Collaboration

Physics Faculty Publications

The (W,Q²) dependence of the ratio of inclusive electron scattering cross sections for ¹⁵N/¹²C was determined in the kinematic ranges 0.8 < W < 2 GeV and 0.2 < Q² < 1 GeV² using 2.285 GeV electrons and the CLAS detector at Jefferson Lab. The ratios exhibit only slight resonance structure, in agreement with a simple phenomenological model and an extrapolation of deep-inelastic scattering ratios to low Q². Ratios of ⁴He/¹²C using 1.6 to 2.5 GeV electrons were measured with very high statistical precision and were used to correct for He in the N and C targets. …

Light Vector Mesons In The Nuclear Medium, M. H. Wood, M. J. Amaryan, H. Bagdasaryan, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, N. Kalantarians, A. Klein, K. V. Klimenko, S. E. Kuhn, J. Lachniet, M. R. Niroula, R. A. Niyazov, S. Tkachenko, L. B. Weinstein, J. Zhang, Clas Collaboration

Physics Faculty Publications

The light vector mesons (ρ,ω, and ϕ) were produced in deuterium, carbon, titanium, and iron targets in a search for possible in-medium modifications to the properties of the ρ meson at normal nuclear densities and zero temperature. The vector mesons were detected with the CEBAF Large Acceptance Spectrometer (CLAS) via their decays to e+e−. The rare leptonic decay was chosen to reduce final-state interactions. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing technique. The ρ-meson mass spectrum was extracted after the ω and ϕ signals were removed in a nearly model-independent way. Comparisons …

Parmela Based Simulations On Jefferson Lab Free Electron Laser Injector, Deepesh Kumar Koppunuru

Electrical & Computer Engineering Theses & Dissertations

Free Electron Lasers (FELs) have many applications and are under continuing development to meet various needs and in areas from materials processing to life sciences research. This is because of its unique capability of generating high-average power, coherent, and wavelength tunable light by employing relativistic beam of un-bounded electrons. The main challenge in FEL development is the generation of a high intensity, high-quality electron beam in an injector. Further acceleration to relativistic energies is accomplished in a linear accelerator (LINAC) for producing laser light in a device known as wiggler. The Jefferson Lab FEL team intents to increase the injector …

Measurements Of Correlated Pair Momentum Distributions In -3he(E,E',P,P)N With Clas, Hovhannes Baghdasaryan

Physics Theses & Dissertations

Nucleon-Nucleon (NN) Short Range Correlations (SRC) represent a valuable part of the nuclear wave function. Improved knowledge of SRC will give us a better understanding of nuclear matter and nuclear interactions in extreme conditions. A study of the effects of short-range correlations using the ³He(e, e'pp)n reaction measured at Jefferson Lab is presented. Two different approaches were selected to investigate SRC. The first approach consists of the kinematics when we investigate the two active protons and neutron is the spectator (was not involved in the interaction). This kinematics dominates by Final State Interactions which are reasonably …

Quark-Hadron Duality In Spin Structure Functions G(1)(P) And G(1)(D), P. E. Bosted, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, S. E. Kuhn, Y. Prok, G. Adams, M. Amarian, P. Ambrozewicz, M. Anghinolfi, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, A. Klein, J. Lachniet, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang

Physics Faculty Publications

New measurements of the spin structure functions of the proton and deuteron g(1)(p)(x,Q²) and g(1)(d)(x,Q²) in the nucleon resonance region are compared with extrapolations of target-mass-corrected next-to-leading-order (NLO) QCD fits to higher energy data. Averaged over the entire resonance region (W <2 >GeV), the data and QCD fits are in good agreement in both magnitude and Q² dependence for Q² >1.7 GeV²/c². This "global" duality appears to result from cancellations among the prominent "local" resonance regions: in particular strong ^{σ …}

Form Factors And Wave Functions Of Vector Mesons In Holographic Qcd, Hovhannes R. Grigoryan, Anatoly V. Radyushkin

Physics Faculty Publications

Within the framework of a holographic dual model of QCD, we develop a formalism for calculating form factors of vector mesons. We show that the holographic bound states can be described not only in terms of eigenfunctions of the equation of motion, but also in terms of conjugate wave functions that are close analogues of quantum-mechanical bound state wave functions. We derive a generalized VMD representation for form factors, and find a very specific VMD pattern, in which form factors are essentially given by contributions due to the first two bound states in the Q² -channel. We calculate electric …

Experimental Study Of Exclusive ²H(E,E'P)N Reaction Mechanisms At High Q², S. E. Kuhn, M. J. Amaryan, H. Bagdasaryan, M. Bektasoglu, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, N. Guler, C. E. Hyde-Wright, H. G. Juengst, N. Kalantarians, A. Klein, M. R. Niroula, R. A. Niyazov, S. Tkachenko, L. B. Weinstein, J. Zhang, Et. Al., Clas Collaboration

Physics Faculty Publications

The reaction ²H(e,e(')p)n has been studied with full kinematic coverage for photon virtuality 1.75 < Q²< 5.5 GeV². Comparisons of experimental data with theory indicate that for very low values of neutron recoil momentum (p_n< 100 MeV/c) the neutron is primarily a spectator and the reaction can be described by the plane-wave impulse approximation. For 100 < p_n< 750 MeV/c, proton-neutron rescattering dominates the cross section, while Delta production followed by the NΔ → NN transition is the primary contribution at higher momenta.

Running Coupling Constant And Transition From Low To High Energies In Quantum Chromodynamics, Alexander Babansky

Physics Theses & Dissertations

The remarkable feature of QCD is that the coupling constant (the strength of the interaction) depends on the energy of the interacting particles. At high energies, the coupling constant vanishes and QCD becomes asymptotically free. However, at lower energy, the running coupling constant increases, leading to the confining strong-coupling theory at energies of the order of hadron masses. We study the essential effects of the running coupling constant and analyze the transition from high to low energies in different processes.

The ²H(E, E'P)N Reaction At High Four-Momentum Transfer, Hassan F. Ibrahim

Physics Theses & Dissertations

This dissertation presents the highest four-momentum transfer, Q², quasielastic (x_Bj = 1) results from Experiment E01-020 which systematically explored the 2H(e, e'p)n reaction ("Electro-disintegration" of the deuteron) at three different four-momentum transfers, Q² = 0.8, 2.1, and 3.5 GeV² and missing momenta, p_miss = 0, 100, 200, 300, 400, and 500 GeV including separations of the longitudinal-transverse interference response function, R_LT, and extraction of the longitudinal-transverse asymmetry, A_LT. This systematic approach will help to understand the reaction mechanism and the deuteron structure down to the short …

Constraints On The Nucleon Strange Form Factors At Q2 ∼ 0.1 Gev2, K. A. Aniol, D. S. Armstrong, T. Averett, H. Benaoum, P. Y. Bertin, E. Burtin, J. Cahoon, G. D. Cates, C. C. Chang, Y.-C. Chao, D. Deepa, H. Ibrahim

Mechanical & Aerospace Engineering Faculty Publications

We report the most precise measurement to date of a parity-violating asymmetry in elastic electron–proton scattering. The measurement was carried out with a beam energy of 3.03 GeV and a scattering angle (θ_lab) = 6.0○ , with the result A PV = ( − 1.14 ± 0.24 ( stat ) ± 0.06 ( syst ) ) × 10⁻⁶ . From this we extract, at Q² = 0.099 GeV² , the strange form factor combination G^s_E + 0.080 G^s_M = 0.030 ± 0.025 ( stat ) ± 0.006 ( syst ) ± …

Measurement Of The X- And Q2 -Dependence Of The Asymmetry A1 On The Nucleon, K. V. Dharmawardane, S. E. Kuhn, P. Bosted, Y. Prok, G. Adams, P. Ambrozewicz, M. Anghinolfi, G. Asryan, H. Avakian, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, G. E. Dodge, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, A. Klein, J. Lachniet, M. R. Niroula, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Zhang

Physics Faculty Publications

We report results for the virtual photon asymmetry A₁ on the nucleon from new Jefferson Lab measurements. The experiment, which used the CEBAF Large Acceptance Spectrometer and longitudinally polarized proton (¹⁵NH₃) and deuteron (¹⁵ND₃) targets, collected data with a longitudinally polarized electron beam at energies between 1.6 GeV and 5.7 GeV. In the present Letter, we concentrate on our results for A₁ ( x , Q² ) and the related ratio g1 / F₁ ( x , Q² ) in the resonance and the deep inelastic …

Measurement Of Deeply Virtual Compton Scattering With A Polarized-Proton Target, S. Chen, M. Amarian, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, A. Klein, S. E. Kuhn, J. Lachniet, M. R. Niroula, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang, Clas Collaboration

Physics Faculty Publications

The longitudinal target-spin asymmetry A_UL for the exclusive electroproduction of high-energy photons was measured for the first time in e→p→e′pγ. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH₃ target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sinϕ moment is 0.252±0.042^stat±0.020^sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions …

Η’ Photoproduction On The Proton For Photon Energies From 1.527 To 2.227 Gev, M. Bektasoglu, S.L. Careccia, K. V. Dharmawardane, G. E. Dodge, C. E. Hyde-Wright, H. G. Juengst, A. Klein, S. E. Kuhn, A. V. Klimenko, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang, Et Al., Clas Collaboration

Physics Faculty Publications

Differential cross sections for the reaction γp→η′p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the η′N channel to both the S₁₁(1535) and P₁₁(1710) resonances, known to couple strongly to the ηN channel in photoproduction on the proton, and the importance of J=3/2 resonances in the process.