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14 results on '"V. M. Gray"'

1. Deep Exclusive Electroproduction of π0 at High Q2 in the Quark Valence Regime

Author

N. H. Saylor, D. Bulumulla, Wouter Deconinck, E. Pooser, L. Ye, B. Crowe, Weidong Li, B. P. Quinn, Y. Huang, Douglas Higinbotham, E. Fuchey, C. Ayerbe Gayoso, Y. Zhao, S. A. Wood, M. K. Jones, Darko Androić, Jie Liu, A. J. Sarty, Z. Ye, K. Hamilton, E. McClellan, M. E. Christy, A. Liyanage, J. Bane, F. Georges, O. F. Obretch, C. Gal, S. F. Ali, Bogdan Wojtsekhowski, P. M. King, C. Palatchi, F. Hauenstein, J. Roche, T. Averett, P. E. Reimer, J. P. Chen, G. M. Urciuoli, Franco Meddi, M. H. Shabestari, C. Fanelli, K. A. Aniol, R. I. Pomatsalyuk, B. Aljawrneh, Shams Rahman, C. E. Hyde, R. Beminiwattha, X. Yan, Andrew Puckett, E. Voutier, E. Cisbani, S. J. Nazeer, Chunhui Chen, C. Desnault, M. Carmignotto, O. Glamazdin, J. Castellano, Z. Ahmed, L. Ou, F. De Persio, Olfred Hansen, S. Allison, J. R. M. Annand, Simon Širca, T. Gautam, D. Nguyen, B. Sawatzky, G. M. Huber, S. Danagoulian, J. C. Cornejo, Tanja Horn, C. M. Jen, F. Tortorici, T. Su, S. Alsalmi, Yicheng Wang, G. Hamad, B. Duran, Kalyan Allada, Maxime Defurne, R. Michaels, Hongjun Liu, D. Gaskell, Juliette Mammei, David Hamilton, Pete Markowitz, L. A. Thorne, E. J. Brash, V. M. Gray, C. Munoz Camacho, D. Adikaram, T. W. Danley, Y. Tian, K. Park, Ping Zhu, L. S. Myers, M. N. H. Rashad, Rolf Ent, R. A. Montgomery, D. Biswas, S. Malace, W. Henry, A. Sun, M. Dlamini, H. Atac, N. Israel, R. Trotta, X. Bai, V. Bellini, N. Ton, R. Spies, Alexandre Camsonne, A. Stefanko, C. Gu, K. Bartlett, K. Jin, B. A. Clary, Kondo Gnanvo, M. Nycz, T. Holmstrom, P.-J. Lin, Shanfeng Li, C. Yero, T. Hague, Taya Chetry, Jie Zhang, J. Bericic, J. Campbell, A. Mkrtchyan, Nikos Sparveris, K. Mesik, I. Sapkota, Vladimir Nelyubin, A. Shahinyan, N. Compton, D. Di, Eliahu Cohen, S. Sooriyaarachchilage, Cynthia Keppel, H. S. Ko, A. Kabir, V. A. Punjabi, D. G. Meekins, S. Barcus, V. Khachatryan, G. B. Franklin, P. Nadel-Turonski, N. Nuruzzaman, Chao Peng, G. R. Smith, H. F. Ibrahim, B. Karki, M. Duer, H. Albataineh, A. Subedi, S. Park, B. Schmookler, B. Pandey, Vincent Sulkosky, J. A. Magee, B. Waidyawansa, and S. Covrig Dusa

Subjects
Quark, Physics, Particle physics, 010308 nuclear & particles physics, Momentum transfer, General Physics and Astronomy, Sigma, Virtual particle, Parton, 01 natural sciences, Helicity, Pion, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of $x_B$ (0.36, 0.48 and 0.60) and $Q^2$ (3.1 to 8.4 GeV$^2$) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions $d\sigma_L/dt+\epsilon d\sigma_T/dt$, $d\sigma_{TT}/dt$, $d\sigma_{LT}/dt$ and $d\sigma_{LT'}/dt$ are extracted as a function of the proton momentum transfer $t-t_{min}$. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross-section throughout this kinematic range. The data are well described by calculations based on transversity Generalized Parton Distributions coupled to a helicity flip Distribution Amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Published
2021
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2. Measurement of the beam-normal single-spin asymmetry for elastic electron scattering from C12 and Al27

Author

R. W. Radloff, S. A. Page, John M. Finn, L. Lee, V. Tvaskis, L. Z. Ndukum, K. E. Mesick, S. Kowalski, Jongmin Lee, W. S. Duvall, A. Mkrtchyan, A. R. Lee, C. A. Davis, P. Solvignon, William A. Tobias, J. Leacock, Jay Benesch, J. A. Dunne, F. Guo, H. Mkrtchyan, M. M. Dalton, R. D. Carlini, B. Sawatzky, S. MacEwan, T. Seva, W. D. Ramsay, E. Korkmaz, D. G. Meekins, Kent Paschke, P. M. King, V. M. Gray, V. Tadevosyan, D. C. Jones, J. C. Cornejo, Jean-Francois Rajotte, J. Pan, M. H. Shabestari, P. Wang, J. A. Magee, R. S. Beminiwattha, Michael Gericke, R. Michaels, Fatiha Benmokhtar, Wouter Deconinck, B. Waidyawansa, D. S. Armstrong, Jonathan W. Martin, R. Subedi, S. Covrig Dusa, M. Kargiantoulakis, J. Leckey, Dipanwita Dutta, S. P. Wells, W. R. Falk, S. A. Wood, P. Zang, Darko Androić, D. T. Spayde, Vladimir Nelyubin, D. J. Mack, S. Zhamkochyan, M. E. Christy, A. Asaturyan, R. Silwal, J. F. Dowd, S. K. Phillips, T. A. Forest, J. Birchall, M. Elaasar, Geoffrey Smith, A. Subedi, R. Mahurin, M. J. McHugh, Riad Suleiman, Michael Pitt, Amrendra Narayan, D. Gaskell, V. Owen, C. Gal, W. T. H. van Oers, Nuruzzaman, J. R. Hoskins, Juliette Mammei, K. Bartlett, J. Roche, and Neven Simicevic

Subjects
Elastic scattering, Physics, Range (particle radiation), 010308 nuclear & particles physics, Scattering, media_common.quotation_subject, 01 natural sciences, Asymmetry, Nuclear physics, Momentum, Transverse plane, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Beam (structure), Spin-½, media_common
Abstract

We report measurements of the parity-conserving beam-normal single-spin elastic scattering asymmetries $B_n$ on $^{12}$C and $^{27}$Al, obtained with an electron beam polarized transverse to its momentum direction. These measurements add an additional kinematic point to a series of previous measurements of $B_n$ on $^{12}$C and provide a first measurement on $^{27}$Al. The experiment utilized the Qweak apparatus at Jefferson Lab with a beam energy of 1.158 GeV. The average lab scattering angle for both targets was 7.7 degrees, and the average $Q^2$ for both targets was 0.02437 GeV$^2$ (Q=0.1561 GeV). The asymmetries are $B_n$ = -10.68 $\pm$ 0.90 stat) $\pm$ 0.57 (syst) ppm for $^{12}$C and $B_n$ = -12.16 $\pm$ 0.58 (stat) $\pm$ 0.62 (syst) ppm for $^{27}$Al. The results are consistent with theoretical predictions, and are compared to existing data. When scaled by Z/A, the Q-dependence of all the far-forward angle (theta < 10 degrees) data from $^{1}$H to $^{27}$Al can be described by the same slope out to $Q \approx 0.35$ GeV. Larger-angle data from other experiments in the same Q range are consistent with a slope about twice as steep.

Published
2021
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3. Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering

Author

Wouter Deconinck, Riad Suleiman, M. H. Shabestari, L. Z. Ndukum, William A. Tobias, C. A. Davis, J. Leckey, J. A. Magee, S. Yang, Jongmin Lee, Amrendra Narayan, P. Solvignon, mrow, J. Roche, V. Tvaskis, M. M. Dalton, W. D. Ramsay, A. Mkrtchyan, S. MacEwan, D. Gaskell, M. Elaasar, Nuruzzaman, J. Beaufait, T. Seva, E. Korkmaz, V. M. Gray, A. R. Lee, B. Waidyawansa, D. T. Spayde, S. Covrig Dusa, Jean-Francois Rajotte, Roger Carlini, S. K. Phillips, mrow> weak, R. Subedi, M. K. Jones, Kent Paschke, K. Bartlett, S. A. Wood, P. Wang, Neven Simicevic, V. Owen, A. Asaturyan, W. R. Falk, J. Leacock, R. W. Radloff, R. Mahurin, P. Zang, Dipangkar Dutta, V. Tadevosyan, C. Gal, Fatiha Benmokhtar, J.C. Cornejo, K. E. Mesick, L. Lee, Vladimir Nelyubin, P. M. King, A. M. Micherdzinska, S. A. Page, F. Guo, H. Mkrtchyan, D. J. Mack, Darko Androić, R. S. Beminiwattha, mtext, A. Subedi, S. Zhamkochyan, W. T. H. van Oers, M. Kargiantoulakis, T. A. Forest, Michael Gericke, J. F. Dowd, Joseph Grames, S. Wells, J. M. Finn, K. Grimm, J. Pan, R. Silwal, J. A. Dunne, B. Sawatzky, D. C. Jones, R. Michaels, J. R. Hoskins, J. Birchall, Juliette Mammei, S. Kowalski, W. S. Duvall, J. W. Martin, J. Mei, N. Morgan, msub, R. T. Jones, Jay Benesch, Michael Pitt, D. G. Meekins, D. S. Armstrong, G. R. Smith, and M. J. McHugh

Subjects
Physics, Scattering, media_common.quotation_subject, General Physics and Astronomy, FOS: Physical sciences, Observable, Electron, beam-normalization, single-spin asymmetry, scattering, transversaly polarized electrons, unpolarized nucleons, 01 natural sciences, Asymmetry, 0103 physical sciences, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment (nucl-ex), 010306 general physics, Nucleon, Nuclear Experiment, Energy (signal processing), Beam (structure), Spin-½, media_common
Abstract

A beam-normal single-spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable related to the imaginary part of the two-photon exchange process. We report a 2% precision measurement of the beam-normal single-spin asymmetry in elastic electron-proton scattering with a mean scattering angle of theta_lab = 7.9 degrees and a mean energy of 1.149 GeV. The asymmetry result is B_n = -5.194 +- 0.067 (stat) +- 0.082 (syst) ppm. This is the most precise measurement of this quantity available to date and therefore provides a stringent test of two-photon exchange models at far-forward scattering angles (theta_lab -> 0) where they should be most reliable., 6 pages, 3 figures; Slightly revised version, after referee's comments; accepted in PRL

Published
2020

4. Precision Measurement of the Weak Charge of the Proton

Author

K. Bartlett, K. E. Mesick, W. R. Falk, P. M. King, R. S. Beminiwattha, A. Asaturyan, J. Leckey, P. Zang, J. Leacock, T. Averett, D. T. Spayde, M. M. Dalton, Ross D. Young, W. D. Ramsay, Vladimir Nelyubin, J. Balewski, J. F. Dowd, J. Roche, S. Yang, Darko Androić, A. Micherdzinska, M. Kargiantoulakis, John M. Finn, J. A. Magee, Kent Paschke, Jongmin Lee, R. W. L. Jones, P. Solvignon, S. Kowalski, L. Z. Ndukum, W. S. Duvall, S. Zhamkochyan, J. Birchall, V. Tvaskis, Riad Suleiman, A. R. Lee, B. Waidyawansa, J. Pan, D. C. Jones, Fatiha Benmokhtar, Wouter Deconinck, Jonathan W. Martin, S. Covrig Dusa, L. Lee, A. Mkrtchyan, Amrendra Narayan, R. Michaels, S. P. Wells, M. H. Shabestari, Geoffrey Smith, D. Gaskell, C. A. Davis, William A. Tobias, Jay Benesch, H. Mkrtchyan, Matthew Jones, Joseph Grames, S. A. Page, A. K. Opper, S. MacEwan, T. Seva, E. Korkmaz, Jean-Francois Rajotte, V. M. Gray, M. Poelker, C. Gal, D. S. Armstrong, J. A. Dunne, S. A. Wood, J. Mei, J. Beaufait, R. D. Carlini, Kathryn Grimm, F. Guo, S. K. Phillips, J. Diefenbach, P. Wang, D. J. Mack, N. Morgan, Michael Gericke, B. Sawatzky, T. A. Forest, R. Silwal, M. J. McHugh, M. Elaasar, R. Mahurin, J. C. Cornejo, Michael Pitt, R. Subedi, W. T. H. van Oers, Nuruzzaman, H. Nuhait, J. R. Hoskins, D. G. Meekins, Juliette Mammei, V. Tadevosyan, Dipangkar Dutta, Neven Simicevic, and A. Subedi

Subjects
Physics, Particle physics, Multidisciplinary, Large Hadron Collider, 010308 nuclear & particles physics, media_common.quotation_subject, Electroweak interaction, Dark matter, FOS: Physical sciences, Elementary particle, Parity (physics), Weak interaction, 7. Clean energy, 01 natural sciences, Asymmetry, 0103 physical sciences, Higgs boson, Nuclear Experiment (nucl-ex), 010306 general physics, weak charge of proton, parity violation, polarized electron beam, Nuclear Experiment, media_common
Abstract

The fields of particle and nuclear physics have undertaken extensive programs to search for evidence of physics beyond that explained by current theories. The observation of the Higgs boson at the Large Hadron Collider completed the set of particles predicted by the Standard Model (SM), currently the best description of fundamental particles and forces. However, the theory's limitations include a failure to predict fundamental parameters and the inability to account for dark matter/energy, gravity, and the matter-antimater asymmetry in the universe, among other phenomena. Given the lack of additional particles found so far through direct searches in the post-Higgs era, indirect searches utilizing precise measurements of well predicted SM observables allow highly targeted alternative tests for physics beyond the SM. Indirect searches have the potential to reach mass/energy scales beyond those directly accessible by today's high-energy accelerators. The value of the weak charge of the proton Q_W^p is an example of such an indirect search, as it sets the strength of the proton's interaction with particles via the well-predicted neutral electroweak force. Parity violation (invariance under spatial inversion (x,y,z) -> (-x,-y,-z)) is violated only in the weak interaction, thus providing a unique tool to isolate the weak interaction in order to measure the proton's weak charge. Here we report Q_W^p=0.0719+-0.0045, as extracted from our measured parity-violating (PV) polarized electron-proton scattering asymmetry, A_ep=-226.5+-9.3 ppb. Our value of Q_W^p is in excellent agreement with the SM, and sets multi-TeV-scale constraints on any semi-leptonic PV physics not described within the SM., Direct link to Nature Version "https://rdcu.be/954U"

Published
2019

5. The ${Q^{p}_{\rm Weak}}$ experiment

Author

P. Solvignon, Wouter Deconinck, Riad Suleiman, D. G. Meekins, V. M. Gray, M. Poelker, J. A. Magee, S. Yang, S. Wells, Amrendra Narayan, R. T. Jones, T. Averett, B. Waidyawansa, D. Gaskell, Jean-Francois Rajotte, K. E. Myers, S. Kowalski, W. S. Duvall, William A. Tobias, M. K. Jones, W. T. H. van Oers, J. W. Martin, F. Guo, Joseph Grames, W. R. Falk, Kent Paschke, K. Grimm, J. Balewski, D. S. Armstrong, G. R. Smith, S. Covrig, J. A. Dunne, K. Johnston, V. Tadevosyan, P. Wang, Fatiha Benmokhtar, J. Mei, Vladimir Nelyubin, T. A. Forest, M. Kargiantoulakis, J. Leacock, J.C. Cornejo, M. M. Dalton, A.K. Opper, A. Mkrtchyan, Darko Androić, R. Silwal, V. Tvaskis, M. J. McHugh, W. D. Ramsay, L. Lee, Neven Simicevic, P. M. King, R. Mahurin, R. S. Beminiwattha, Michael Gericke, D. Zou, S. Zhamkochyan, J. Diefenbach, N. Nuruzzaman, Dipangkar Dutta, Roger Carlini, S. K. Phillips, D. T. Spayde, A. M. Micherdzinska, S. A. Page, M. H. Shabestari, J. R. Hoskins, D. C. Jones, Michael Pitt, Ross D. Young, Jongmin Lee, J. Birchall, Jay Benesch, K. A. Dow, L. Z. Ndukum, J. F. Dowd, A. R. Lee, Juliette Mammei, R. Michaels, J. M. Finn, J. Pan, J. Leckey, A. Asaturyan, A. Subedi, S. A. Wood, M. Elaasar, H. Mkrtchyan, C. A. Davis, D. J. Mack, S. MacEwan, T. Seva, E. Korkmaz, B. Sawatzky, J. Beaufait, R. Subedi, and J. Roche

Subjects
Quark, Physics, Nuclear and High Energy Physics, Particle physics, Proton, media_common.quotation_subject, Physics beyond the Standard Model, Momentum transfer, Weinberg angle, Parity (physics), Electron, Condensed Matter Physics, Asymmetry, Atomic and Molecular Physics, and Optics, Nuclear physics, Physical and Theoretical Chemistry, media_common
Abstract

In May 2012, the $Q^{p}_{\rm Weak}$ collaboration completed a two year measurement program to determine the weak charge of the proton ${Q^{p}_W} = ( 1 - 4\sin^2{\theta_{W}})$ at the Thomas Jefferson National Accelerator Facility (TJNAF). The experiment was designed to produce a 4.0 % measurement of the weak charge, via a 2.5 % measurement of the parity violating asymmetry in the number of elastically scattered 1.165 GeV electrons from protons, at forward angles. At the proposed precision, the experiment would produce a 0.3 % measurement of the weak mixing angle at a momentum transfer of Q 2 = 0.026 GeV2, making it the most precise stand alone measurement of the weak mixing angle at low momentum transfer. In combination with other parity measurements, $Q^{p}_{\rm Weak}$ will also provide a high precision determination of the weak charges of the up and down quarks. At the proposed precision, a significant deviation from the Standard Model prediction could be a signal of new physics at mass scales up to ≃ 6 TeV, whereas agreement would place new and significant constraints on possible Standard Model extensions at mass scales up to ≃ 2 TeV. This paper provides an overview of the physics and the experiment, as well as a brief look at some preliminary diagnostic and analysis data.

Published
2013
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6. The tracking analysis in the Q-weak experiment

Author

T. Averett, M. M. Dalton, A.K. Opper, W. D. Ramsay, D. T. Spayde, K. Johnston, Kent Paschke, J. Mei, J.C. Cornejo, William A. Tobias, F. Guo, P. M. King, W. R. Falk, Vladimir Nelyubin, S. A. Wood, R. Mahurin, J. Leacock, Fatiha Benmokhtar, D. J. Mack, Jean-Francois Rajotte, S. A. Page, D. G. Meekins, J. Pan, Michael Gericke, S. Wells, S. Kowalski, J. Balewski, W. S. Duvall, J. Leckey, R. T. Jones, A. Mkrtchyan, M. H. Shabestari, J. W. Martin, Nuruzzaman, M. Elaasar, C. A. Davis, L. Z. Ndukum, B. Sawatzky, M. Kargiantoulakis, J. Grames, J. A. Magee, Roger Carlini, S. K. Phillips, P. Solvignon, G. D. Cates, S. Yang, Jongmin Lee, D. C. Jones, J. Diefenbach, N. Morgan, Wouter Deconinck, W. T. H. van Oers, Darko Androić, R. Michaels, V. M. Gray, A. R. Lee, B. Waidyawansa, S. MacEwan, T. Seva, E. Korkmaz, Jay Benesch, V. Tvaskis, J. Beaufait, R. Subedi, A. Asaturyan, R. Suleiman, S. Zhamkochyan, K. E. Myers, H. Mkrtchyan, D. S. Armstrong, G. R. Smith, J. A. Dunne, P. Wang, L. Lee, Dipangkar Dutta, K. Grimm, A. Subedi, S. Covrig, M. J. McHugh, Michael Pitt, Neven Simicevic, J. M. Finn, J. R. Hoskins, J. Roche, J. Birchall, T. A. Forest, Juliette Mammei, A. Micherdzinska, V. Tadevosyan, M. K. Jones, R. Silwal, Amrendra Narayan, M. Poelker, D. Gaskell, R. S. Beminiwattha, Ross D. Young, and J. F. Dowd

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Spectrometer, business.industry, Scattering, media_common.quotation_subject, Momentum transfer, Tracking system, Parity (physics), Kinematics, Electron, Condensed Matter Physics, 01 natural sciences, Asymmetry, Atomic and Molecular Physics, and Optics, 010305 fluids & plasmas, Nuclear physics, q-weak experiment, 0103 physical sciences, Physical and Theoretical Chemistry, 010306 general physics, business, Nuclear Experiment, media_common
Abstract

The Q-weak experiment at Jefferson Laboratory measured the parity violating asymmetry (A P V ) in elastic electron-proton scattering at small momentum transfer squared (Q 2=0.025 (G e V/c)2), with the aim of extracting the proton’s weak charge ( ${Q^p_W}$ ) to an accuracy of 5 %. As one of the major uncertainty contribution sources to ${Q^p_W}$ , Q 2 needs to be determined to ∼1 % so as to reach the proposed experimental precision. For this purpose, two sets of high resolution tracking chambers were employed in the experiment, to measure tracks before and after the magnetic spectrometer. Data collected by the tracking system were then reconstructed with dedicated software into individual electron trajectories for experimental kinematics determination. The Q-weak kinematics and the analysis scheme for tracking data are briefly described here. The sources that contribute to the uncertainty of Q 2 are discussed, and the current analysis status is reported.

Published
2016

7. The Qweak experimental apparatus

Author

J. R. Hoskins, R. S. Beminiwattha, J. Birchall, J. Diefenbach, Juliette Mammei, J. Balewski, Erik Urban, J. F. Dowd, K. Johnston, G. Clark, P.W. Rose, B. Sawatzky, P. Solvignon, M. Kargiantoulakis, M. Elaasar, J. Mei, S. Sobczynski, A. Micherdzinska, A. Kubera, M. K. Jones, R.B. Zielinski, Mitchell D. Anderson, T. Averett, R. Suleiman, V. M. Gray, E. Henderson, R.D. Carlini, S. A. Wood, Neven Simicevic, J. D. Bowman, A. Mkrtchyan, Amber McCreary, Darko Androić, V. Tvaskis, E. Bonnell, N. Morgan, R. Mahurin, Kent Paschke, R. Averill, J. Beaufait, J. Roche, S. Zhamkochyan, D. J. Mack, C. A. Davis, Fatiha Benmokhtar, S. A. Page, D.C. Dean, J. M. Finn, P. Medeiros, Jean-Francois Rajotte, R. Subedi, G. D. Cates, S. Wells, F. Guo, S. MacEwan, P. Wang, J. A. Dunne, Jongmin Lee, T. Seva, E. Korkmaz, S. K. Phillips, D. C. Jones, P. Brindza, Amrendra Narayan, M. Poelker, J. Pan, J. Leacock, A. R. Lee, V. Tadevosyan, D. Gaskell, Y. Liang, R. Michaels, M. M. Dalton, D.J. Harrison, A.K. Opper, J. Grames, M. McDonald, S. Kowalski, J.C. Cornejo, W. S. Duvall, W. D. Ramsay, A. Asaturyan, J. Leckey, K. Grimm, J. W. Martin, B. Stokes, P. M. King, Michael Gericke, K. E. Mesick, H. Mkrtchyan, E. Ihloff, J. A. Magee, Nadeem A. Khan, L. Lee, J. Kelsey, Trent Allison, Jay Benesch, S. Yang, D. T. Spayde, B. Waidyawansa, D.B. Brown, S. Covrig Dusa, Dipangkar Dutta, W. R. Falk, R. Silwal, A. Subedi, Vladimir Nelyubin, J. Bessuille, D. G. Meekins, R. T. Jones, J. Hansknecht, Nuruzzaman, W. T. H. van Oers, K.D. Finelli, Michael Pitt, J.R. Echols, D. S. Armstrong, G. R. Smith, Douglas Storey, M. J. McHugh, M. H. Shabestari, J. Musson, K. A. Dow, L. Z. Ndukum, Wouter Deconinck, W.R. Roberts, William A. Tobias, and B. S. Cavness

Subjects
Physics, Nuclear and High Energy Physics, business.industry, Compton scattering, Collimator, Electron, Helicity, law.invention, Nuclear physics, Optics, Beamline, law, Scintillation counter, Cathode ray, Physics::Accelerator Physics, Parity violation, Electron scattering, Liquid hydrogen target, business, Instrumentation, Cherenkov radiation
Abstract

The Jefferson Lab Q weak experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum transfer. A custom apparatus was designed for this experiment to meet the technical challenges presented by the smallest and most precise e → p asymmetry ever measured. Technical milestones were achieved at Jefferson Lab in target power, beam current, beam helicity reversal rate, polarimetry, detected rates, and control of helicity-correlated beam properties. The experiment employed 180 μA of 89% longitudinally polarized electrons whose helicity was reversed 960 times per second. The electrons were accelerated to 1.16 GeV and directed to a beamline with extensive instrumentation to measure helicity-correlated beam properties that can induce false asymmetries. Moller and Compton polarimetry were used to measure the electron beam polarization to better than 1%. The electron beam was incident on a 34.4 cm liquid hydrogen target. After passing through a triple collimator system, scattered electrons between 5.8° and 11.6° were bent in the toroidal magnetic field of a resistive copper-coil magnet. The electrons inside this acceptance were focused onto eight fused silica Cherenkov detectors arrayed symmetrically around the beam axis. A total scattered electron rate of about 7 GHz was incident on the detector array. The detectors were read out in integrating mode by custom-built low-noise pre-amplifiers and 18-bit sampling ADC modules. The momentum transfer Q 2 =0.025 GeV 2 was determined using dedicated low-current ( ~ 100 pA ) measurements with a set of drift chambers before (and a set of drift chambers and trigger scintillation counters after) the toroidal magnet.

Published
2015

8. Early Results from the Qweak Experiment

Author

J. Beaufait, H. Mkrtchyan, J. Roche, J. A. Dunne, Jean-Francois Rajotte, Kathryn Grimm, S. K. Phillips, J. Diefenbach, S. Covrig, S. MacEwan, T. Seva, E. Korkmaz, D. G. Meekins, Matthew Jones, M. M. Dalton, T. Averett, D. C. Jones, Kent Paschke, R. W. L. Jones, Fatiha Benmokhtar, J. A. Magee, R. Michaels, P. M. King, W. D. Ramsay, R. S. Beminiwattha, M. H. Shabestari, Wouter Deconinck, V. Tadevosyan, A. Asaturyan, R. D. Carlini, S. Kowalski, W. S. Duvall, Jay Benesch, F. Guo, J. Birchall, A. Micherdzinska, Joseph Grames, Ross D. Young, J. W. Martin, B. Waidyawansa, J. F. Dowd, Michael Pitt, S. Yang, Geoffrey Smith, S. A. Page, V. M. Gray, M. Poelker, Nuruzzaman, R. Silwal, G. D. Cates, P. Wang, S. P. Wells, T. A. Forest, Jongmin Lee, Dipangkar Dutta, K. Johnston, A. R. Lee, J. Leacock, B. Sawatzky, M. Elaasar, J. Mei, D. S. Armstrong, Riad Suleiman, A. Subedi, S. A. Wood, R. Mahurin, Amrendra Narayan, L. Lee, J. Balewski, P. Solvignon, D. J. Mack, R. Subedi, John M. Finn, W. R. Falk, M. Kargiantoulakis, N. Morgan, L. Z. Ndukum, Vladimir Nelyubin, M. J. McHugh, Neven Simicevic, W. T. H. van Oers, C. A. Davis, William A. Tobias, D. Gaskel, Michael Gericke, J. C. Cornejo, J. R. Hoskins, J. Pan, Darko Androić, Juliette Mammei, S. Zhamkochyan, J. Leckey, D. T. Spayde, A. K. Opper, K. E. Myers, V. Tvaskis, and A. Mkrtchyan

Subjects
Physics, Quark, Scattering, media_common.quotation_subject, Physics beyond the Standard Model, QC1-999, FOS: Physical sciences, Electron, Measure (mathematics), Asymmetry, Nuclear physics, Neutron, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment, Beam (structure), media_common
Abstract

A subset of results from the recently completed Jefferson Lab Qweak experiment are reported. This experiment, sensitive to physics beyond the Standard Model, exploits the small parity-violating asymmetry in elastic ep scattering to provide the first determination of the protons weak charge Qweak(p). The experiment employed a 180 uA longitudinally polarized 1.16 GeV electron beam on a 35 cm long liquid hydrogen target. Scattered electrons corresponding to Q2 of 0.025 GeV2 were detected in eight Cerenkov detectors arrayed symmetrically around the beam axis. The goals of the experiment were to provide a measure of Qweak(p) to 4.2 percent (combined statistical and systematic error), which implies a measure of sin2(thetaw) at the level of 0.3 percent, and to help constrain the vector weak quark charges C1u and C1d. The experimental method is described, with particular focus on the challenges associated with the worlds highest power LH2 target. The new constraints on C1u and C1d provided by the subset of the experiments data analyzed to date will also be shown, together with the extracted weak charge of the neutron., Comment: 8 pages, 4 figures, INPC2013

Published
2014

9. Qweak: First Direct Measurement of the Proton’s Weak Charge

Author

J. R. Hoskins, V. Tadevosyan, J. Diefenbach, K. Johnston, J. Birchall, S.A. Page, D. S. Armstrong, M. J. McHugh, J. Mei, H. Nuhait, C. A. Davis, M. Elaasar, Juliette Mammei, T. Averett, Wouter Deconinck, J. A. Magee, P. Wang, S. Yang, G.R. Smith, W. R. Falk, P. Zang, H. Mkrtchyan, W. T. H. van Oers, D. G. Meekins, J. Pan, F. Guo, J. Roche, Vladimir Nelyubin, W.D. Ramsay, J. Beaufait, B. Sawatzky, Fatiha Benmokhtar, M.L. Pitt, D. C. Jones, N. Morgan, R. Suleiman, N. Simicevic, V. Tvaskis, R. Michaels, Michael Gericke, B. Waidyawansa, Roger Carlini, J. Leckey, T. A. Forest, R. T. Jones, Jay Benesch, J. M. Finn, J. Balewski, M. M. Dalton, J. Grames, L. Lee, Jean-Francois Rajotte, Dipangkar Dutta, S. Kowalski, L. Z. Ndukum, W. S. Duvall, D. J. Mack, J. W. Martin, A.K. Opper, M. Kargiantoulakis, S.A. Wood, T. Seva, P. Solvignon, G. D. Cates, V. M. Gray, Jongmin Lee, K. Grimm, S. Covrig, A. R. Lee, J. Leacock, R. Mahurin, D.T. Spayde, R. Silwal, A. Mkrtchyan, S.K. Phillips, A. Asaturyan, S. Zhamkochyan, S. MacEwan, E. Korkmaz, J.C. Cornejo, K. E. Myers, P. M. King, K. Bartlett, Darko Androić, A. Subedi, J. A. Dunne, Amrendra Narayan, R. Subedi, D. Gaskell, K.D. Paschke, A. Micherdzinska, M.H. Shabestari, M. K. Jones, W.A. Tobias, C. Gal, R. S. Beminiwattha, M. Poelker, Ross D. Young, J. F. Dowd, and S.P. Wells

Subjects
Physics, Particle physics, Proton, 010308 nuclear & particles physics, QC1-999, media_common.quotation_subject, Hadron, Charge (physics), Elementary particle, 7. Clean energy, 01 natural sciences, Asymmetry, Standard Model, Nuclear physics, 0103 physical sciences, Physics::Accelerator Physics, Grand Unified Theory, Nuclear Experiment, 010306 general physics, Nucleon, media_common
Abstract

The Q weak experiment, which took data at Jefferson Lab in the period 2010 - 2012, will precisely determine the weak charge of the proton by measuring the parity-violating asymmetry in elastic e-p scattering at 1.1 GeV using a longitudinally polarized electron beam and a liquid hydrogen target at a low momentum transfer of Q 2 = 0.025 (GeV/c)2 . The weak charge of the proton is predicted by the Standard Model and any significant deviation would indicate physics beyond the Standard Model. The technical challenges and experimental apparatus for measuring the weak charge of the proton will be discussed, as well as the method of extracting the weak charge of the proton. The results from a small subset of the data, that has been published, will also be presented. Furthermore an update will be given of the current status of the data analysis.

Published
2017
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10. The ${Q^{p}_{\rm Weak}}$ experiment

Author

D. Androic, D. S. Armstrong, A. Asaturyan, T. Averett, J. Balewski, J. Beaufait, R. S. Beminiwattha, J. Benesch, F. Benmokhtar, J. Birchall, R. D. Carlini, J. C. Cornejo, S. Covrig, M. M. Dalton, C. A. Davis, W. Deconinck, J. Diefenbach, K. Dow, J. F. Dowd, J. A. Dunne, D. Dutta, W. S. Duvall, M. Elaasar, W. R. Falk, J. M. Finn, T. Forest, D. Gaskell, M. T. W. Gericke, J. Grames, V. M. Gray, K. Grimm, F. Guo, J. R. Hoskins, K. Johnston, D. Jones, M. Jones, R. Jones, M. Kargiantoulakis, P. M. King, E. Korkmaz, S. Kowalski, J. Leacock, J. Leckey, A. R. Lee, J. H. Lee, L. Lee, S. MacEwan, D. Mack, J. A. Magee, R. Mahurin, J. Mammei, J. Martin, M. McHugh, D. Meekins, J. Mei, R. Michaels, A. Micherdzinska, K. E. Myers, A. Mkrtchyan, H. Mkrtchyan, A. Narayan, L. Z. Ndukum, V. Nelyubin, N. Nuruzzaman, W. T. H van Oers, A. K. Opper, S. A. Page, J. Pan, K. Paschke, S. K. Phillips, M. L. Pitt, M. Poelker, J. F. Rajotte, W. D. Ramsay, J. Roche, B. Sawatzky, T. Seva, M. H. Shabestari, R. Silwal, N. Simicevic, G. Smith, P. Solvignon, D. T. Spayde, A. Subedi, R. Subedi, R. Suleiman, V. Tadevosyan, W. A. Tobias, V. Tvaskis, B. Waidyawansa, P. Wang, S. P. Wells, S. A. Wood, S. Yang, R. D. Young, S. Zhamkochyan, and D. Zou

Published
2013
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11. Control of nitrate and nitrite assimilation by carbohydrate reserves, adenosine nucleotides and pyridine nucleotides in leaves of Zea mays L. under dark conditions

Author

C. F. Cresswell, V. M. Gray, and M. P. Watt

Subjects
Chemistry, Adenylate kinase, chemistry.chemical_element, Plant Science, Metabolism, Carbohydrate, Nitrate reductase, Oxygen, chemistry.chemical_compound, Biochemistry, Nitrate, Genetics, Nitrite, Anaerobic exercise
Abstract

The rate of in-vivo nitrate reduction by leaf segments of Zea mays L. was found to decline during the second hour of dark anaerobic treatment. On transfer to oxygen the capacity to reduce nitrate under dark conditions was restored. These observations led to the proposal that nitrate reductase is a regulatory enzyme with ADP acting as a negative effector. The effect of ADP on the invitro activity of nitrate reductase and the changes in the in-vivo adenylate pool under dark-N2 and dark-O2 were investigated. It was found that ADP inhibited the activity of partially purified nitrate reductase. Similarly, the in-vivo anaerobic inhibition of nitrate reduction was associated with a build-up of ADP in the leaf tissue. Under anaerobic conditions nitrite accumulated and on transfer to oxygen the accumulated nitrite was reduced. To explain this phenomenon the following hypothesis was proposed and tested. Under anaerobic conditions the supply of reducing equivalents for nitrite reduction in the plastid becomes restricted and nitrite accumulates as a consequence. On transfer to oxygen this restriction is removed and nitrite disappears. This capacity to reduce accumulated nitrite was found to be dependent on the carbohydrate status of the leaf tissue.

Published
1987
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12. The effect of oxygen on nitrate and nitrite assimilation in leaves of Zea mays L. under dark conditions

Author

C. F. Cresswell, V. M. Gray, and M. P. Watt

Subjects
genetic structures, Chemistry, Nitrogen assimilation, Oxygene, chemistry.chemical_element, Plant Science, Metabolism, Nitrogen, Oxygen, Horticulture, chemistry.chemical_compound, Nitrate, Botany, Genetics, sense organs, Nitrite, computer, Nitrogen cycle, computer.programming_language
Abstract

The assimilation of nitrate under dark-N2 and dark-O2 conditions in Zea mays leaf tissue was investigated using colourimetric and (15)N techniques for the determination of organic and inorganic nitrogen. Studies using (15)N indicated that nitrate was assimilated under dark conditions. However, the rate of nitrate assimilation in the dark was only 28% of the rate under non-saturating light conditions. No nitrite accumulated under dark aerobiosis, even though nitrate reduction occurred under these conditions. The pattern of nitrite accumulation in leaf tissue in response to dark-N2 conditions consisted of three phases: an initial lag phase, followed by a period of rapid nitrite accumulation and finally a phase during which the rate of nitrite accumulation declined. After a 1-h period of dark-anaerobiosis, both nitrate reduction and nitrite accumulation declined considerably. However, when O2 was supplied, nitrate reduction was stimulated and the accumulated nitrite was rapidly reduced. Anaerobic conditions stimulated nitrate reduction in leaf tissue after a period of dark-aerobic pretreatment.

Published
1986
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13. The influence of light and dark conditions on the reduction of nitrate in leaves and roots of maize

Author

C. F. Cresswell and V. M. Gray

Subjects
Ecophysiology, chemistry.chemical_compound, Nitrate, chemistry, Nitrogen assimilation, Botany, chemistry.chemical_element, DCMU, Metabolism, Nitrite, Photosynthesis, Nitrogen
Abstract

Anaerobiosis stimulated nitrate reduction and nitrite accumulation in maize roots and leaves under dark in vivo conditions. Inhibitors of photosynthetic electron transport and respiratory electron transport stimulated the accumulation of nitrite in maize leaves under light conditions, and inhibited the utilization of exogenous nitrite. In all cases where nitrite accumulated in leaf and root tissue no corresponding stoichiometry between nitrate reduction and nitrite accumulation was observed. The assimilation of nitrate by leaf tissue in the dark suggests the operation of a system of nitrate metabolism independent of photosynthesis and similar to that operative in the root system.

Published
1986
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