Physical Sciences and Mathematics Commons^™

Measurement Of The Helicity Asymmetry E In Ω → Π+Π−Π0 Photoproduction, Z. Akbar, P. Roy, S. Park, V. Crede, A. V. Anisovich, I. Denisenko, E. Klempt, V. A. Nikonov, A. V. Sarantsev, K. P. Adhikari, S. Adhikari, M. J. Amaryan, S. Anefalos Pereira, H. Avakian, J. Ball, M. Battaglieri, V. Batourine, I. Bedlinskiy, S. Boiarinov, W. J. Briscoe, J. Brock, W. K. Brooks, V. D. Burkert, F. T. Cao, C. Carlin, D. S. Carman, A. Celentano, G. Charles, T. Chetry, G. Ciullo, Wesley P. Gohn

Physics and Astronomy Faculty Publications

The double-polarization observable E was studied for the reaction γp → pω using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally polarized frozen-spin target (FROST). The observable was measured from the charged decay mode of the meson, ω → π⁺π⁻π⁰, using a circularly polarized tagged-photon beam with energies ranging from the ω threshold at 1.1 to 2.3 GeV. A partial-wave analysis within the Bonn-Gatchina framework found dominant contributions from the 3/2⁺ partial wave near threshold, which is identified with the subthreshold N …

Extraction Of The Neutron Electric Form Factor From Measurements Of Inclusive Double Spin Asymmetries, V. Sulkosky, G. Jin, E. Long, Y. -W. Zhang, M. Mihovilovic, A. Kelleher, B. Anderson, D. W. Higinbotham, S. Širca, K. Allada, J. R. M. Annand, T. Averett, W. Bertozzi, W. Boeglin, P. Bradshaw, A. Camsonne, M. Canan, G. D. Cates, C. Chen, J. -P. Chen, E. Chudakov, R. De Leo, X. Deng, A. Deur, C. Dutta, L. El Fassi, D. Flay, S. Frullani, F. Garibaldi, Wolfgang Korsch

Physics and Astronomy Faculty Publications

Background: Measurements of the neutron charge form factor, Gⁿ_E, are challenging because the neutron has no net charge. In addition, measurements of the neutron form factors must use nuclear targets which require accurately accounting for nuclear effects. Extracting Gⁿ_E with different targets and techniques provides an important test of our handling of these effects.

Purpose: The goal of the measurement was to use an inclusive asymmetry measurement technique to extract the neutron charge form factor at a four-momentum transfer of 1 (GeV/c)². This technique has very different systematic uncertainties …

Sea Quarks Contribution To The Nucleon Magnetic Moment And Charge Radius At The Physical Point, Raza Sabbir Sufian, Yi-Bo Yang, Jian Liang, Terrence Draper, Keh-Fei Liu

Physics and Astronomy Faculty Publications

We report a comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon magnetic moment, charge radius, and the electric and magnetic form factors. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We adopt a model-independent extrapolation of the nucleon magnetic moment and the charge radius. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in a global fit to calculate results in the continuum limit. We find that the combined light and strange disconnected-sea quarks contribution to the nucleon …

Compton Scattering From 4He At 61 Mev, M. H. Sikora, M. W. Ahmed, A. Banu, C. Bartram, B. Crowe, E. J. Downie, G. Feldman, H. Gao, H. W. Grießhammer, H. Hao, C. R. Howell, H. J. Karwowski, D. P. Kendellen, Michael A. Kovash, X. Li, D. M. Markoff, S. Mikhailov, V. Popov, R. E. Pywell, J. A. Silano, M. C. Spraker, P. Wallace, H. R. Weller, C. S. Whisnant, Y. K. Wu, W. Xiong, X. Yan, Z. W. Zhao

Physics and Astronomy Faculty Publications

The Compton scattering cross section from ⁴He has been measured with high statistical accuracy over a scattering angle range of 40^∘−159^∘ using a quasimonoenergetic 61-MeV photon beam at the High Intensity Gamma-Ray Source. The data are interpreted using a phenomenological model sensitive to the dipole isoscalar electromagnetic polarizabilities (α_s and β_s) of the nucleon. These data can be fit with the model using values of α_s and β_s that are consistent with the currently accepted values. These data will serve as benchmarks of future calculations from effective field theories and …

First Exclusive Measurement Of Deeply Virtual Compton Scattering Off 4He: Toward The 3d Tomography Of Nuclei, M. Hattawy, N. A. Baltzell, R. Dupré, K. Hafidi, S. Stepanyan, S. Bültmann, R. De Vita, A. El Alaoui, L. El Fassi, H. Egiyan, F. X. Girod, M. Guidal, D. Jenkins, S. Liuti, Y. Perrin, B. Torayev, E. Voutier, K. P. Adhikari, S. Adhikari, D. Adikaram, Z. Akbar, M. J. Amaryan, S. Anefalos Pereira, Whitney R. Armstrong, H. Avakian, J. Ball, M. Bashkanov, M. Battaglieri, V. Batourine, I. Bedlinskiy, Wesley P. Gohn

Physics and Astronomy Faculty Publications

We report on the first measurement of the beam-spin asymmetry in the exclusive process of coherent deeply virtual Compton scattering off a nucleus. The experiment uses the 6 GeV electron beam from the Continuous Electron Beam Accelerator Facility (CEBAF) accelerator at Jefferson Lab incident on a pressurized ⁴He gaseous target placed in front of the CEBAF Large Acceptance Spectrometer (CLAS). The scattered electron is detected by CLAS and the photon by a dedicated electromagnetic calorimeter at forward angles. To ensure the exclusivity of the process, a specially designed radial time projection chamber is used to detect the recoiling ^{4 …}

Coherent Diffractive Photoproduction Of Ρ0 Mesons On Gold Nuclei At 200 Gev/Nucleon-Pair At The Relativistic Heavy Ion Collider, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

The STAR Collaboration reports on the photoproduction of π⁺π⁻ pairs in gold-gold collisions at a center-of-mass energy of 200 GeV/nucleon-pair. These pion pairs are produced when a nearly real photon emitted by one ion scatters from the other ion.

We fit the π⁺π⁻ invariant-mass spectrum with a combination of ρ⁰ and ω resonances and a direct π⁺π⁻ continuum. This is the first observation of the ω in ultraperipheral collisions, and the first measurement of ρ−ω interference at energies where photoproduction is dominated by Pomeron exchange. The ω amplitude is consistent …

First Direct Constraints On Fierz Interference In Free-Neutron Β Decay, K. P. Hickerson, X. Sun, Y. Bagdasarova, D. Bravo-Berguño, L. J. Broussard, M. A. -P. Brown, R. Carr, S. Currie, X. Ding, B. W. Filippone, A. García, P. Geltenbort, J. Hoagland, A. T. Holley, R. Hong, T. M. Ito, A. Knecht, C. -Y. Liu, J. L. Liu, M. Makela, R. R. Mammei, J. W. Martin, D. Melconian, M. P. Mendenhall, S. D. Moore, C. L. Morris, R. W. Pattie Jr., A. Pérez Galván, R. Picker, M. L. Pitt, Bradley R. Plaster

Physics and Astronomy Faculty Publications

Precision measurements of free-neutron β decay have been used to precisely constrain our understanding of the weak interaction. However, the neutron Fierz interference term b_n, which is particularly sensitive to beyond-standard-model tensor currents at the TeV scale, has thus far eluded measurement. Here we report the first direct constraints on this term, finding b_n = 0.067 ± 0.005_{stat^+0.090-0.061sys}, consistent with the standard model. The uncertainty is dominated by absolute energy reconstruction and the linearity of the β spectrometer energy response.

Measurement Of The Vector And Tensor Asymmetries At Large Missing Momentum In Quasielastic (E→,E'P Electron Scattering From Deuterium, A. Degrush, A. Maschinot, T. Akdogan, R. Alarcon, W. Bertozzi, E. Booth, T. Botto, J. R. Calarco, B. Clasie, Christopher Crawford, K. Dow, M. Farkhondeh, Renee H. Fatemi, O. Filoti, W. Franklin, H. Gao, E. Geis, S. Gilad, D. K. Hasell, P. Karpius, M. Kohl, H. Kolster, T. Lee, J. Matthews, K. Mcilhany, N. Meitanis, R. Milner, J. Rapaport, R. Redwine, J. Seely

Physics and Astronomy Faculty Publications

We report the measurement of the beam-vector and tensor asymmetries A^V_ed and A^T_d in quasielastic (e^→,e′p) electrodisintegration of the deuteron at the MIT-Bates Linear Accelerator Center up to missing momentum of 500  MeV/c. Data were collected simultaneously over a momentum transfer range 0.1 < Q² < 0.5  (GeV/c)² with the Bates Large Acceptance Spectrometer Toroid using an internal deuterium gas target polarized sequentially in both vector and tensor states. The data are compared with calculations. The beam-vector asymmetry AVed is found to be directly sensitive to the D-wave …

Opportunities For Undergraduate Research In Nuclear Physics, S. F. Hicks, T. D. Nguyen, D. T. Jackson, S. G. Block, S. T. Byrd, M. T. Nickel, J. R. Vanhoy, Erin E. Peters, Anthony Paul Ramirez, Marcus T. Mcellistrem, Sharmistha Mukhopadhyay, Steven W. Yates

Chemistry Faculty Publications

University of Dallas (UD) physics majors are offered a variety of undergraduate research opportunities in nuclear physics through an established program at the University of Kentucky Accelerator Laboratory (UKAL). The 7-MV Model CN Van de Graaff accelerator and the neutron production and detection facilities located there are used by UD students to investigate how neutrons scatter from materials that are important in nuclear energy production and for our basic understanding of how neutrons interact with matter. Recent student projects include modeling of the laboratory using the neutron transport code MCNP to investigate the effectiveness of laboratory shielding, testing the long-term …

Bulk Properties Of The Medium Produced In Relativistic Heavy-Ion Collisions From The Beam Energy Scan Program, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

We present measurements of bulk properties of the matter produced in Au+Au collisions at √S_NN = 7.7, 11.5, 19.6, 27, and 39 GeV using identified hadrons (π^±, K^±, p, and p¯) from the STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC). Midrapidity (|y| < 0.1) results for multiplicity densities dN/dy, average transverse momenta ⟨p_T⟩, and particle ratios are presented. The chemical and kinetic freeze-out dynamics at these energies are discussed and presented as a function of collision centrality and energy. These results constitute the systematic …

Lattice Calculation Of Nucleon Isovector Axial Charge With Improved Currents, Jian Liang, Yi-Bo Yang, Keh-Fei Liu, Andrei Alexandru, Terrence Draper, Raza Sabbir Sufian

Physics and Astronomy Faculty Publications

We employ dimension-4 operators to improve the local vector and axial-vector currents and calculate the nucleon isovector axial coupling g³_A with overlap valence on 2 + 1-flavor domain wall fermion (DWF) sea. Using the equality of g³_A from the spatial and temporal components of the axial-vector current as a normalization condition, we find that g³_A is increased by a few percent towards the experimental value. The excited-state contamination has been taken into account with three time separations between the source and sink. The improved axial charges g³_A(24I) = 1.22(4)(3) …

Measurement Of Jet Quenching With Semi-Inclusive Hadron+Jet Distributions In Au + Au Collisions At √SNn = 200 Gev, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

The STAR Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum hadron trigger, in central and peripheral Au + Au collisions at √^s_NN = 200 GeV. Charged jets are reconstructed with the anti-k_T algorithm for jet radii R between 0.2 and 0.5 and with low infrared cutoff of track constituents (p_T > 0.2 GeV/c). A novel mixed-event technique is used to correct the large uncorrelated background present in heavy ion collisions. Corrected recoil jet distributions are reported at midrapidity, for charged-jet transverse momentum p^ch_T,jet < GeV/c. Comparison is made to similar measurements for Pb + Pb collisions at √s = …

Dijet Imbalance Measurements In Au + Au And Pp Collisions At √SNn = 200 Gev At Star, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, I. Bunzarov, J. Butterworth, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

We report the first dijet transverse momentum asymmetry measurements from Au + Au and pp collisions at RHIC. The two highest-energy back-to-back jets reconstructed from fragments with transverse momenta above 2  GeV/c display a significantly higher momentum imbalance in heavy-ion collisions than in the pp reference. When reexamined with correlated soft particles included, we observe that these dijets then exhibit a unique new feature—momentum balance is restored to that observed in pp for a jet resolution parameter of R = 0.4, while rebalancing is not attained with a smaller value of R = 0.2.

Level Lifetimes And The Structure Of 134Xe From Inelastic Neutron Scattering, Erin E. Peters, Anagha Chakraborty, Benjamin P. Crider, S. F. Ashley, E. Elhami, S. F. Hicks, A. Kumar, Marcus T. Mcellistrem, Sharmistha Mukhopadhyay, J. N. Orce, Francisco M. Prados-Estévez, Steven W. Yates

Chemistry Faculty Publications

The level structure of ¹³⁴Xe was studied with the inelastic neutron scattering reaction followed by γ-ray detection. A number of level lifetimes were determined for the first time with the Doppler-shift attenuation method and the low-lying excited states were characterized. From this new spectroscopic information, the third excited state, a 0⁺ level which had only been observed in a previous inelastic neutron scattering study, was verified. Reduced transition probabilities were calculated; comparisons were drawn with a vibrational description of the nucleus and found lacking. The 3⁻ octupole phonon has been confirmed, and the complete negative-parity multiplet …

Lifetime Measurements Of Low-Spin Negative-Parity Levels In 160Gd, S. R. Lesher, C. Casarella, L. M. Robledo, Benjamin P. Crider, R. Ikeyama, I. R. Marsh, Marcus T. Mcellistrem, Erin E. Peters, Francisco M. Prados-Estévez, M. K. Smith, Z. R. Tully, J. R. Vanhoy, Steven W. Yates

Physics and Astronomy Faculty Publications

¹⁶⁰Gd(n,n′γ) experiments were performed with accelerator-produced monoenergetic neutrons. Excitation functions at neutron energies from 1.5 to 2.8 MeV aided in the placement of γ rays in the level scheme and angular distributions at three neutron energies resulted in the determination of 28 excited-level lifetimes or limits in ¹⁶⁰Gd, including the lifetimes of several negative-parity levels attributed to octupole vibrations.

Neutron Scattering Cross Section Measurements For 56Fe, Anthony Paul D. Ramirez, J. Vanhoy, S. F. Hicks, Marcus T. Mcellistrem, Erin E. Peters, Sharmistha Mukhopadhyay, T. D. Harrison, T. J. Howard, D. T. Jackson, P. D. Lenzen, T. D. Nguyen, R. L. Pecha, B. G. Rice, B. K. Thompson, Steven W. Yates

Chemistry Faculty Publications

Elastic and inelastic differential cross sections for neutron scattering from ⁵⁶Fe have been measured for several incident energies from 1.30 to 7.96 MeV at the University of Kentucky Accelerator Laboratory. Scattered neutrons were detected using a C₆D₆ liquid scintillation detector using pulse-shape discrimination and time-of-flight techniques. The deduced cross sections have been compared with previously reported data, predictions from evaluation databases ENDF, JENDL, and JEFF, and theoretical calculations performed using different optical model potentials using the TALYS and EMPIRE nuclear reaction codes. The coupled-channel calculations based on the vibrational and soft-rotor models are found to describe …

Measurement Of Two-Photon Exchange Effect By Comparing Elastic E±P Cross Sections, P. Rimal, D. Adikaram, B. A. Raue, L. B. Weinstein, J. Arrington, W. K. Brooks, M. Ungaro, K. P. Adhikari, A. V. Afanasev, Z. Akbar, S. Anefalos Pereira, R. A. Badui, J. Ball, N. A. Baltzell, M. Battaglieri, V. Batourine, I. Bedlinskiy, A. S. Biselli, S. Boiarinov, W. J. Briscoe, S. Bültmann, V. D. Burkert, D. S. Carman, A. Celentano, T. Chetry, G. Ciullo, L. Clark, L. Colaneri, P. L. Cole, N. Compton, Wesley P. Gohn

Physics and Astronomy Faculty Publications

Background: The electromagnetic form factors of the proton measured by unpolarized and polarized electron scattering experiments show a significant disagreement that grows with the squared four-momentum transfer (Q²). Calculations have shown that the two measurements can be largely reconciled by accounting for the contributions of two-photon exchange (TPE). TPE effects are not typically included in the standard set of radiative corrections since theoretical calculations of the TPE effects are highly model dependent, and, until recently, no direct evidence of significant TPE effects has been observed.

Purpose: We measured the ratio of positron-proton to electron-proton elastic-scattering cross sections …

Measurement Of D0 Azimuthal Anisotropy At Midrapidity In Au + Au Collisions At √SNn = 200 Gev, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

We report the first measurement of the elliptic anisotropy (v²) of the charm meson D0 at midrapidity (|y| < 1) in Au+Au collisions at √s_NN = 200  GeV. The measurement was conducted by the STAR experiment at RHIC utilizing a new high-resolution silicon tracker. The measured D⁰ v₂ in 0%–80% centrality Au + Au collisions can be described by a viscous hydrodynamic calculation for a transverse momentum (p_T) of less than 4  GeV/c. The D⁰ v₂ as a function of transverse kinetic energy (m_T − m₀, where m …

Measurement Of The Cross Section And Longitudinal Double-Spin Asymmetry For Dijet Production In Polarized Pp Collisions At √S = 200 Gev, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, K. Barish, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

We report the first measurement of the longitudinal double-spin asymmetry A_LL for midrapidity dijet production in polarized pp collisions at a center-of-mass energy of √s = 200  GeV. The dijet cross section was measured and is shown to be consistent with next-to-leading order (NLO) perturbative QCD predictions. A_LL results are presented for two distinct topologies, defined by the jet pseudorapidities, and are compared to predictions from several recent NLO global analyses. The measured asymmetries, the first such correlation measurements, support those analyses that find positive gluon polarization at the level of roughly 0.2 over the region of …

Collective Quadrupole Behavior In 106Pd, Francisco M. Prados-Estévez, Erin E. Peters, A. Chakraborty, M. G. Mynk, D. Bandyopadhyay, N. Boukharouba, S. N. Choudry, Benjamin P. Crider, P. E. Garrett, S. F. Hicks, A. Kumar, S. R. Lesher, C. J. Mckay, Marcus T. Mcellistrem, Sharmistha Mukhopadhyay, J. N. Orce, M. Scheck, J. R. Vanhoy, J. L. Wood, Steven W. Yates

Chemistry Faculty Publications

Excited states in ¹⁰⁶Pd were studied with the (n,n′γ) reaction, and comprehensive information for excitations with spin ≤6ℏ was obtained. The data include level lifetimes in the femtosecond regime, spins and parities, transition multipolarities, and multipole mixing ratios, which allow the determination of reduced transition probabilities. The E2 decay strength to the low-lying states is mapped up to ≈2.4 MeV in excitation energy. The structures associated with quadrupole collectivity are elucidated and organized into bands.

Lifetimes In 124Te: Examining Critical-Point Symmetry In The Te Nuclei, S. F. Hicks, J. R. Vanhoy, P. G. Burkett, B. R. Champine, S. J. Etzkorn, P. E. Garrett, Steven W. Yates, Minfang Yeh

Physics and Astronomy Faculty Publications

The Doppler-shift attenuation method following inelastic neutron scattering was used to determine the lifetimes of nuclear levels to 3.3-MeV excitation in ¹²⁴Te. Level energies and spins, γ-ray energies and branching ratios, and multipole-mixing ratios were deduced from measured γ-ray angular distributions at incident neutron energies of 2.40 and 3.30 MeV, γ-ray excitation functions, and γγ coincidence measurements. The newly obtained reduced transition probabilities and level energies for ¹²⁴Te were compared to critical-point symmetry model predictions. The E(5) and β⁴ potential critical-point symmetries were also investigated in ¹²²Te and ¹²⁶Te.

First Measurement Of Unpolarized Semi-Inclusive Deep-Inelastic Scattering Cross Sections From A 3He Target, X. Yan, K. Allada, K. Aniol, J. R. M. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, P. C. Bradshaw, P. Bosted, A. Camsonne, M. Canan, G. D. Cates, C. Chen, J. -P. Chen, W. Chen, K. Chirapatpimol, E. Chudakov, E. Cisbani, J. C. Cornejo, F. Cusanno, M. M. Dalton, W. Deconinck, C. W. De Jager, R. De Leo, X. Deng, A. Deur, H. Ding, P. A. M. Dolph, C. Dutta, D. Dutta, A. Kolarkar, Wolfgang Korsch

Physics and Astronomy Faculty Publications

The unpolarized semi-inclusive deep-inelastic scattering (SIDIS) differential cross sections in ³He(e,e′π^±)X have been measured for the first time in Jefferson Lab experiment E06-010 with a 5.9 GeV e⁻ beam on a ³He gas target. The experiment focuses on the valence quark region, covering a kinematic range 0.12 < x_bj < 0.45, 1 < Q² < 4 (GeV/c)², 0.45 < z_h < 0.65, and 0.05 < P_t < 0.55 GeV/c. The extracted SIDIS differential cross sections of π^± production are compared with existing phenomenological models while the ³He nucleus approximated as two protons and one …

Target And Beam-Target Spin Asymmetries In Exclusive Pion Electroproduction For Q2 > 1 Gev2. Ii. Ep → Eπ0P, P. E. Bosted, A. Kim, K. P. Adhikari, D. Adikaram, Z. Akbar, M. J. Amaryan, S. Anefalos Pereira, H. Avakian, R. A. Badui, J. Ball, I. Balossino, M. Battaglieri, I. Bedlinskiy, A. S. Biselli, S. Boiarinov, W. J. Briscoe, W. K. Brooks, S. Bültmann, V. D. Burkert, T. Cao, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, T. Chetry, G. Ciullo, L. Clark, L. Colaneri, P. L. Cole, M. Contalbrigo, Wesley P. Gohn

Physics and Astronomy Faculty Publications

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π⁰ electroproduction reaction γ^∗p → pπ⁰, expanding an analysis of the γ^∗p → nπ⁺ reaction from the same experiment. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic ranges covered are 1.1 < W < 3 GeV and 1 < Q² < 6 GeV². Results were obtained for about 5700 bins in W, Q², cos(θ^∗), and ϕ^∗. The beam-target asymmetries were found …

Elliptic Flow Of Electrons From Heavy-Flavor Hadron Decays In Au + Au Collisions At √SNn = 200, 62.4, And 39 Gev, L. Adamczyk, J. Kevin Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

We present measurements of elliptic flow (ν₂) of electrons from the decays of heavy-flavor hadrons (e_HF) by the STAR experiment. For Au+Au collisions at √s_NN = 200 GeV we report v₂, for transverse momentum (p_T) between 0.2 and 7 GeV/c, using three methods: the event plane method (v₂{EP}), two-particle correlations (v₂{2}), and four-particle correlations (v₂{4}). For Au+Au collisions at √s_NN = 62.4 and 39 GeV we report v₂{2} for p_T < 2 GeV/c …