W. D. Ramsay

W. D. Ramsay
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W. D. Ramsay

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Nuclear Experiment (19)
Physics - Instrumentation and Detectors (5)
High Energy Physics - Phenomenology (5)
Physics - Accelerator Physics (2)
Nuclear Theory (2)
High Energy Physics - Experiment (1)
Physics - Popular Physics (1)

Publications Authored By W. D. Ramsay

We have performed a novel comparison between electron-beam polarimeters based on M{\o}ller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents ($<$ 5 $\mu$A) during the $Q_{\rm weak}$ experiment in Hall C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 $\mu$A) operation of the Compton polarimeter. Read More

We report on the highest precision yet achieved in the measurement of the polarization of a low energy, $\mathcal{O}$(1 GeV), electron beam, accomplished using a new polarimeter based on electron-photon scattering, in Hall~C at Jefferson Lab. A number of technical innovations were necessary, including a novel method for precise control of the laser polarization in a cavity and a novel diamond micro-strip detector which was able to capture most of the spectrum of scattered electrons. The data analysis technique exploited track finding, the high granularity of the detector and its large acceptance. Read More

Authors: MOLLER Collaboration, J. Benesch, P. Brindza, R. D. Carlini, J-P. Chen, E. Chudakov, S. Covrig, M. M. Dalton, A. Deur, D. Gaskell, A. Gavalya, J. Gomez, D. W. Higinbotham, C. Keppel, D. Meekins, R. Michaels, B. Moffit, Y. Roblin, R. Suleiman, R. Wines, B. Wojtsekhowski, G. Cates, D. Crabb, D. Day, K. Gnanvo, D. Keller, N. Liyanage, V. V. Nelyubin, H. Nguyen, B. Norum, K. Paschke, V. Sulkosky, J. Zhang, X. Zheng, J. Birchall, P. Blunden, M. T. W. Gericke, W. R. Falk, L. Lee, J. Mammei, S. A. Page, W. T. H. van Oers, K. Dehmelt, A. Deshpande, N. Feege, T. K. Hemmick, K. S. Kumar, T. Kutz, R. Miskimen, M. J. Ramsey-Musolf, S. Riordan, N. Hirlinger Saylor, J. Bessuille, E. Ihloff, J. Kelsey, S. Kowalski, R. Silwal, G. De Cataldo, R. De Leo, D. Di Bari, L. Lagamba, E. NappiV. Bellini, F. Mammoliti, F. Noto, M. L. Sperduto, C. M. Sutera, P. Cole, T. A. Forest, M. Khandekar, D. McNulty, K. Aulenbacher, S. Baunack, F. Maas, V. Tioukine, R. Gilman, K. Myers, R. Ransome, A. Tadepalli, R. Beniniwattha, R. Holmes, P. Souder, D. S. Armstrong, T. D. Averett, W. Deconinck, W. Duvall, A. Lee, M. L. Pitt, J. A. Dunne, D. Dutta, L. El Fassi, F. De Persio, F. Meddi, G. M. Urciuoli, E. Cisbani, C. Fanelli, F. Garibaldi, K. Johnston, N. Simicevic, S. Wells, P. M. King, J. Roche, J. Arrington, P. E. Reimer, G. Franklin, B. Quinn, A. Ahmidouch, S. Danagoulian, O. Glamazdin, R. Pomatsalyuk, R. Mammei, J. W. Martin, T. Holmstrom, J. Erler, Yu. G. Kolomensky, J. Napolitano, K. A. Aniol, W. D. Ramsay, E. Korkmaz, D. T. Spayde, F. Benmokhtar, A. Del Dotto, R. Perrino, S. Barkanova, A. Aleksejevs, J. Singh

The physics case and an experimental overview of the MOLLER (Measurement Of a Lepton Lepton Electroweak Reaction) experiment at the 12 GeV upgraded Jefferson Lab are presented. A highlight of the Fundamental Symmetries subfield of the 2007 NSAC Long Range Plan was the SLAC E158 measurement of the parity-violating asymmetry $A_{PV}$ in polarized electron-electron (M{\o}ller) scattering. The proposed MOLLER experiment will improve on this result by a factor of five, yielding the most precise measurement of the weak mixing angle at low or high energy anticipated over the next decade. Read More

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

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 ${\vec{e}}$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. Read More

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. Read More

The Qweak experiment has measured the parity-violating asymmetry in polarized e-p elastic scattering at Q^2 = 0.025(GeV/c)^2, employing 145 microamps of 89% longitudinally polarized electrons on a 34.4cm long liquid hydrogen target at Jefferson Lab. Read More

The parity-violating asymmetry arising from inelastic electron-nucleon scattering at backward angle (~95 degrees) near the Delta(1232) resonance has been measured using a hydrogen target. From this asymmetry, we extracted the axial transition form factor G^A_{N\Delta}, a function of the axial Adler form factors C^A_i. Though G^A_{N\Delta} has been previously studied using charged current reactions, this is the first measurement of the weak neutral current excitation of the Delta using a proton target. Read More

We propose a new precision measurement of parity-violating electron scattering on the proton at very low Q^2 and forward angles to challenge predictions of the Standard Model and search for new physics. A unique opportunity exists to carry out the first precision measurement of the proton's weak charge, $Q_W =1 - 4\sin^2\theta_W$. A 2200 hour measurement of the parity violating asymmetry in elastic ep scattering at Q^2=0. Read More

We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasi-elastic scattering on the deuteron, at backward angles (lab scattering angle of 108 degrees) for Q2 = 0.22 GeV^2/c^2 and 0.63 GeV^2/c^2 at beam energies of 362 MeV and 687 MeV, respectively. Read More

Authors: G0 Collaboration, D. Androic, D. S. Armstrong, J. Arvieux, R. Asaturyan, T. D. Averett, S. L. Bailey, G. Batigne, D. H. Beck, E. J. Beise, J. Benesch, F. Benmokhtar, L. Bimbot, J. Birchall, A. Biselli, P. Bosted, H. Breuer, P. Brindza, C. L. Capuano, R. D. Carlini, R. Carr, N. Chant, Y. -C. Chao, R. Clark, A. Coppens, S. D. Covrig, A. Cowley, D. Dale, C. A. Davis, C. Ellis, W. R. Falk, H. Fenker, J. M. Finn, T. Forest, G. Franklin, R. Frascaria, C. Furget, D. Gaskell, M. T. W. Gericke, J. Grames, K. A. Griffioen, K. Grimm, G. Guillard, B. Guillon, H. Guler, K. Gustafsson, L. Hannelius, J. Hansknecht, R. D. Hasty, A. M. Hawthorne Allen, T. Horn, T. M. Ito, K. Johnston, M. Jones, P. Kammel, R. Kazimi, P. M. King, A. Kolarkar, E. Korkmaz, W. Korsch, S. Kox, J. Kuhn, J. Lachniet, R. Laszewski, L. Lee, J. Lenoble, E. Liatard, J. Liu, A. Lung, G. A. MacLachlan, J. Mammei, D. Marchand, J. W. Martin, D. J. Mack, K. W. McFarlane, D. W. McKee, R. D. McKeown, F. Merchez, M. Mihovilovic, A. Micherdzinska, H. Mkrtchyan, B. Moffit, M. Morlet, M. Muether, J. Musson, K. Nakahara, R. Neveling, S. Niccolai, D. Nilsson, S. Ong, S. A. Page, V. Papavassiliou, S. F. Pate, S. K. Phillips, P. Pillot, M. L. Pitt, M. Poelker, T. A. Porcelli, G. Quemener, B. P. Quinn, W. D. Ramsay, A. W. Rauf, J. -S. Real, T. Ries, J. Roche P. Roos, G. A. Rutledge, J. Schaub, J. Secrest, T. Seva, N. Simicevic, G. R. Smith, D. T. Spayde, S. Stepanyan, M. Stutzman, R. Suleiman, V. Tadevosyan, R. Tieulent, J. van de Wiele, W. T. H. van Oers, M. Versteegen, E. Voutier, W. F. Vulcan, S. P. Wells, G. Warren, S. E. Williamson, R. J. Woo, S. A. Wood, C. Yan, J. Yun, V. Zeps

In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. Read More

From a distance, the proton's weak charge is seen through the distorting effects of clouds of virtual particles. The effective weak charge can be calculated by starting with the measured weak coupling at the Z-pole and "running" the coupling to lower energy or, equivalently, longer distances. Because the "electroweak radiative corrections" or "loop diagrams" which give rise to the running depend not only on known particles, but on particles which have not yet been discovered, a difference between the calculated and measured weak charges may signal new physics. Read More

Parity-odd asymmetries in the electromagnetic decays of compound nuclei can sometimes be amplified above values expected from simple dimensional estimates by the complexity of compound nuclear states. In this work we use a statistical approach to estimate the root mean square (RMS) of the distribution of expected parity-odd correlations $\vec{s_{n}} \cdot \vec{k_{\gamma}}$, where $\vec {s_{n}}$ is the neutron spin and $\vec{k_{\gamma}}$ is the momentum of the gamma, in the integrated gamma spectrum from the capture of cold polarized neutrons on Al, Cu, and In and we present measurements of the asymmetries in these and other nuclei. Based on our calculations, large enhancements of asymmetries were not predicted for the studied nuclei and the statistical estimates are consistent with our measured upper bounds on the asymmetries. Read More

We have built a CsI(Tl) gamma-ray detector array for the NPDGamma experiment to search for a small parity-violating directional asymmetry in the angular distribution of 2.2 MeV gamma-rays from the capture of polarized cold neutrons by protons with a sensitivity of several ppb. The weak pion-nucleon coupling constant can be determined from this asymmetry. Read More

I start by reviewing existing $\vec{p}p$ measurements with particular emphasis on the recent 221 MeV $\vec{p}p$ measurement at TRIUMF which permitted the weak meson-nucleon coupling constants $h^{pp}_\rho$ and $h^{pp}_\omega$ to be determined separately for the first time. I then review $\vec{n}p$ experiments, with specific details of the $\vec{n}p \to d\gamma$ experiment now under preparation at Los Alamos National Laboratory. This experiment will provide a clean measurement of the weak pion nucleon coupling, $f_\pi$. Read More

Parity violation experiments involving only two nucleons provide a way to study the non-leptonic, strangeness conserving part of the weak interaction in a clean measurement free of nuclear structure uncertainties. Although simple in principle, the experiments are technically very demanding and great pains must be taken both in the preparation of the incident polarized beams and the measurement of the resultant parity violating asymmetries, which may be masked by a multitude of systematic effects. At low and intermediate energies, pp experiments are sensitive to the medium range part of the parity violating nucleon-nucleon force, usually parameterized in terms of rho and omega meson exchange. Read More

We measure the difference in the scattering probability when an experiment scattering longitudinally polarized 221 MeV protons from liquid hydrogen is replaced by its mirror image. The result depends on the interplay between the weak and strong interactions in the interesting region near the surface of the proton. The experiment is technically very challenging and requires elaborate precautions to measure and correct for various sources of systematic error. Read More

An experiment (E497) is underway at TRIUMF to measure the angle-integrated, parity violating longitudinal analyzing power, Az, in proton-proton elastic scattering, to a precision of +/- 0.2 x 10^-7. The experiment uses a 221 MeV longitudinally polarized proton beam incident on a 40 cm liquid hydrogen target. Read More