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4 results on '"Duvall WS"'

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

Author

Androić, D, Armstrong, DS, Asaturyan, A, Bartlett, K, Beminiwattha, RS, Benesch, J, Benmokhtar, F, Birchall, J, Carlini, RD, Christy, ME, Cornejo, JC, Dusa, S Covrig, Dalton, MM, Davis, CA, Deconinck, W, Dowd, JF, Dunne, JA, Dutta, D, Duvall, WS, Elaasar, M, Falk, WR, Finn, JM, Forest, T, Gal, C, Gaskell, D, Gericke, MTW, Gray, VM, Guo, F, Hoskins, JR, Jones, DC, Kargiantoulakis, M, King, PM, Korkmaz, E, Kowalski, S, Leacock, J, Leckey, JP, Lee, AR, Lee, JH, Lee, L, MacEwan, S, Mack, D, Magee, JA, Mahurin, R, Mammei, J, Martin, JW, McHugh, MJ, Meekins, D, Mesick, KE, Michaels, R, Mkrtchyan, A, Mkrtchyan, H, Narayan, A, Ndukum, LZ, Nelyubin, V, Nuruzzaman, van Oers, WTH, Owen, VF, Page, SA, Pan, J, Paschke, KD, Phillips, SK, Pitt, ML, Radloff, RW, Rajotte, JF, Ramsay, WD, Roche, J, Sawatzky, B, Seva, T, Shabestari, MH, Silwal, R, Simicevic, N, Smith, GR, Solvignon, P, Spayde, DT, Subedi, A, Subedi, R, Suleiman, R, Tadevosyan, V, Tobias, WA, Tvaskis, V, Waidyawansa, B, Wang, P, Wells, SP, Wood, SA, Zang, P, and Zhamkochyan, S

Subjects
Clinical Research, nucl-ex
Abstract

We report measurements of the parity-conserving beam-normal single-spinelastic scattering asymmetries $B_n$ on $^{12}$C and $^{27}$Al, obtained withan electron beam polarized transverse to its momentum direction. Thesemeasurements add an additional kinematic point to a series of previousmeasurements 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 energyof 1.158 GeV. The average lab scattering angle for both targets was 7.7degrees, and the average $Q^2$ for both targets was 0.02437 GeV$^2$ (Q=0.1561GeV). The asymmetries are $B_n$ = -10.68 $\pm$ 0.90 stat) $\pm$ 0.57 (syst) ppmfor $^{12}$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 arecompared to existing data. When scaled by Z/A, the Q-dependence of all thefar-forward angle (theta < 10 degrees) data from $^{1}$H to $^{27}$Al can bedescribed by the same slope out to $Q \approx 0.35$ GeV. Larger-angle data fromother experiments in the same Q range are consistent with a slope about twiceas steep.

Published
2021

2. Measurement of the Beam-Normal Single-Spin Asymmetry for Elastic Electron Scattering from $^{12}$C and $^{27}$Al

Author

QWeak Collaboration, Androic, D, Armstrong, DS, Asaturyan, A, Bartlett, K, Beminiwattha, RS, Benesch, J, Benmokhtar, F, Birchall, J, Carlini, RD, Christy, ME, Cornejo, JC, Dusa, S Covrig, Dalton, MM, Davis, CA, Deconinck, W, Dowd, JF, Dunne, JA, Dutta, D, Duvall, WS, Elassar, M, Falk, WR, Finn, JM, Forest, T, Gal, C, Gaskell, D, Gericke, MTW, Gray, VM, Guo, F, Hoskins, JR, Jones, DC, Kargiantoulakis, M, King, PM, Korkmaz, E, Kowalski, S, Leacock, J, Leckey, JP, Lee, AR, Lee, JH, Lee, L, MacEwan, S, Mack, D, Magee, JA, Mahurin, R, Mammei, J, Martin, JW, McHugh, MJ, Meekins, D, Mesick, KE, Michaels, R, Mkrtchyan, A, Mkrtchyan, H, Narayan, A, Ndukum, LZ, Nuruzzaman, Nelyubin, V, van Oers, WTH, Owen, VF, Page, SA, Pan, J, Paschke, KD, Phillips, SK, Pitt, ML, Radloff, RW, Rajotte, JF, Ramsay, WD, Roche, J, Sawatzky, B, Seva, T, Shabestari, MH, Silwal, R, Simicevic, N, Smith, GR, Solvignon, P, Spayde, DT, Subedi, A, Subedi, R, Tadevosyan, V, Tobias, WA, Waidyawansa, B, Wang, P, Wells, SP, Wood, SA, Zang, P, and Zhamkochyan, S

Subjects
Nuclear and Plasma Physics, Synchrotrons and Accelerators, Physical Sciences, Particle and High Energy Physics, nucl-ex, Nuclear and plasma physics
Abstract

We report measurements of the parity-conserving beam-normal single-spinelastic scattering asymmetries $B_n$ on $^{12}$C and $^{27}$Al, obtained withan electron beam polarized transverse to its momentum direction. Thesemeasurements add an additional kinematic point to a series of previousmeasurements 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 energyof 1.158 GeV. The average lab scattering angle for both targets was 7.7degrees, and the average $Q^2$ for both targets was 0.02437 GeV$^2$ (Q=0.1561GeV). The asymmetries are $B_n$ = -10.68 $\pm$ 0.90 stat) $\pm$ 0.57 (syst) ppmfor $^{12}$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 arecompared to existing data. When scaled by Z/A, the Q-dependence of all thefar-forward angle (theta < 10 degrees) data from $^{1}$H to $^{27}$Al can bedescribed by the same slope out to $Q \approx 0.35$ GeV. Larger-angle data fromother experiments in the same Q range are consistent with a slope about twiceas steep.

Published
2021

3. Determination of the ^{27}Al Neutron Distribution Radius from a Parity-Violating Electron Scattering Measurement.

Author

Androić D, Armstrong DS, Bartlett K, Beminiwattha RS, Benesch J, Benmokhtar F, Birchall J, Carlini RD, Cornejo JC, Covrig Dusa S, Dalton MM, Davis CA, Deconinck W, Dowd JF, Dunne JA, Dutta D, Duvall WS, Elaasar M, Falk WR, Finn JM, Forest T, Gal C, Gaskell D, Gericke MTW, Gray VM, Grimm K, Guo F, Hoskins JR, Jones DC, Jones MK, Kargiantoulakis M, King PM, Korkmaz E, Kowalski S, Leacock J, Leckey J, Lee AR, Lee JH, Lee L, MacEwan S, Mack D, Magee JA, Mahurin R, Mammei J, Martin JW, McHugh MJ, Meekins D, Mesick KE, Michaels R, Micherdzinska A, Mkrtchyan A, Mkrtchyan H, Narayan A, Ndukum LZ, Nelyubin V, Nuruzzaman, van Oers WTH, Owen VF, Page SA, Pan J, Paschke KD, Phillips SK, Pitt ML, Radloff RW, Rajotte JF, Ramsay WD, Roche J, Sawatzky B, Seva T, Shabestari MH, Silwal R, Simicevic N, Smith GR, Solvignon P, Spayde DT, Subedi A, Suleiman R, Tadevosyan V, Tobias WA, Tvaskis V, Waidyawansa B, Wang P, Wells SP, Wood SA, Yang S, Zang P, Zhamkochyan S, Christy ME, Horowitz CJ, Fattoyev FJ, and Lin Z

Abstract

We report the first measurement of the parity-violating elastic electron scattering asymmetry on ^{27}Al. The ^{27}Al elastic asymmetry is A&#95;{PV}=2.16±0.11(stat)±0.16(syst)  ppm, and was measured at ⟨Q^{2}⟩=0.02357±0.00010  GeV^{2}, ⟨θ&#95;{lab}⟩=7.61°±0.02°, and ⟨E&#95;{lab}⟩=1.157  GeV with the Q&#95;{weak} apparatus at Jefferson Lab. Predictions using a simple Born approximation as well as more sophisticated distorted-wave calculations are in good agreement with this result. From this asymmetry the ^{27}Al neutron radius R&#95;{n}=2.89±0.12  fm was determined using a many-models correlation technique. The corresponding neutron skin thickness R&#95;{n}-R&#95;{p}=-0.04±0.12  fm is small, as expected for a light nucleus with a neutron excess of only 1. This result thus serves as a successful benchmark for electroweak determinations of neutron radii on heavier nuclei. A tree-level approach was used to extract the ^{27}Al weak radius R&#95;{w}=3.00±0.15  fm, and the weak skin thickness R&#95;{wk}-R&#95;{ch}=-0.04±0.15  fm. The weak form factor at this Q^{2} is F&#95;{wk}=0.39±0.04.

Published
2022
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4. Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering.

Author

Androić D, Armstrong DS, Asaturyan A, Bartlett K, Beaufait J, Beminiwattha RS, Benesch J, Benmokhtar F, Birchall J, Carlini RD, Cornejo JC, Dusa SC, Dalton MM, Davis CA, Deconinck W, Dowd JF, Dunne JA, Dutta D, Duvall WS, Elaasar M, Falk WR, Finn JM, Forest T, Gal C, Gaskell D, Gericke MTW, Grames J, Gray VM, Grimm K, Guo F, Hoskins JR, Jones D, Jones MK, Jones RT, Kargiantoulakis M, King PM, Korkmaz E, Kowalski S, Leacock J, Leckey JP, Lee AR, Lee JH, Lee L, MacEwan S, Mack D, Magee JA, Mahurin R, Mammei J, Martin JW, McHugh MJ, Meekins D, Mei J, Mesick KE, Michaels R, Micherdzinska A, Mkrtchyan A, Mkrtchyan H, Morgan N, Narayan A, Ndukum LZ, Nelyubin V, Nuruzzaman, van Oers WTH, Owen VF, Page SA, Pan J, Paschke KD, Phillips SK, Pitt ML, Radloff RW, Rajotte JF, Ramsay WD, Roche J, Sawatzky B, Seva T, Shabestari MH, Silwal R, Simicevic N, Smith GR, Solvignon P, Spayde DT, Subedi A, Subedi R, Suleiman R, Tadevosyan V, Tobias WA, Tvaskis V, Waidyawansa B, Wang P, Wells SP, Wood SA, Yang S, Zang P, and Zhamkochyan S

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 θ&#95;{lab}=7.9° and a mean energy of 1.149 GeV. The asymmetry result is B&#95;{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 (θ&#95;{lab}→0) where they should be most reliable.

Published
2020
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