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8 results on '"Beminiwattha RS"'

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. Precision Determination of the Neutral Weak Form Factor of ^{48}Ca.

Author

Adhikari D, Albataineh H, Androic D, Aniol KA, Armstrong DS, Averett T, Ayerbe Gayoso C, Barcus SK, Bellini V, Beminiwattha RS, Benesch JF, Bhatt H, Bhatta Pathak D, Bhetuwal D, Blaikie B, Boyd J, Campagna Q, Camsonne A, Cates GD, Chen Y, Clarke C, Cornejo JC, Covrig Dusa S, Dalton MM, Datta P, Deshpande A, Dutta D, Feldman C, Fuchey E, Gal C, Gaskell D, Gautam T, Gericke M, Ghosh C, Halilovic I, Hansen JO, Hassan O, Hauenstein F, Henry W, Horowitz CJ, Jantzi C, Jian S, Johnston S, Jones DC, Kakkar S, Katugampola S, Keppel C, King PM, King DE, Kumar KS, Kutz T, Lashley-Colthirst N, Leverick G, Liu H, Liyanage N, Mammei J, Mammei R, McCaughan M, McNulty D, Meekins D, Metts C, Michaels R, Mihovilovic M, Mondal MM, Napolitano J, Narayan A, Nikolaev D, Owen V, Palatchi C, Pan J, Pandey B, Park S, Paschke KD, Petrusky M, Pitt ML, Premathilake S, Quinn B, Radloff R, Rahman S, Rashad MNH, Rathnayake A, Reed BT, Reimer PE, Richards R, Riordan S, Roblin YR, Seeds S, Shahinyan A, Souder P, Thiel M, Tian Y, Urciuoli GM, Wertz EW, Wojtsekhowski B, Yale B, Ye T, Yoon A, Xiong W, Zec A, Zhang W, Zhang J, and Zheng X

Abstract

We report a precise measurement of the parity-violating (PV) asymmetry A&#95;{PV} in the elastic scattering of longitudinally polarized electrons from ^{48}Ca. We measure A&#95;{PV}=2668±106(stat)±40(syst) parts per billion, leading to an extraction of the neutral weak form factor F&#95;{W}(q=0.8733  fm^{-1})=0.1304±0.0052(stat)±0.0020(syst) and the charge minus the weak form factor F&#95;{ch}-F&#95;{W}=0.0277±0.0055. The resulting neutron skin thickness R&#95;{n}-R&#95;{p}=0.121±0.026(exp)±0.024(model)  fm is relatively thin yet consistent with many model calculations. The combined CREX and PREX results will have implications for future energy density functional calculations and on the density dependence of the symmetry energy of nuclear matter.

Published
2022
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4. New Measurements of the Beam-Normal Single Spin Asymmetry in Elastic Electron Scattering over a Range of Spin-0 Nuclei.

Author

Adhikari D, Albataineh H, Androic D, Aniol K, Armstrong DS, Averett T, Ayerbe Gayoso C, Barcus S, Bellini V, Beminiwattha RS, Benesch JF, Bhatt H, Bhatta Pathak D, Bhetuwal D, Blaikie B, Boyd J, Campagna Q, Camsonne A, Cates GD, Chen Y, Clarke C, Cornejo JC, Covrig Dusa S, Dalton MM, Datta P, Deshpande A, Dutta D, Feldman C, Fuchey E, Gal C, Gaskell D, Gautam T, Gericke M, Ghosh C, Halilovic I, Hansen JO, Hauenstein F, Henry W, Horowitz CJ, Jantzi C, Jian S, Johnston S, Jones DC, Karki B, Kakkar S, Katugampola S, Keppel CE, King PM, King DE, Knauss M, Kumar KS, Kutz T, Lashley-Colthirst N, Leverick G, Liu H, Liyange N, Malace S, Mammei J, Mammei R, McCaughan M, McNulty D, Meekins D, Metts C, Michaels R, Mihovilovic M, Mondal MM, Napolitano J, Nikolaev D, Rashad MNH, Owen V, Palatchi C, Pan J, Pandey B, Park S, Paschke KD, Petrusky M, Pitt ML, Premathilake S, Puckett AJR, Quinn B, Radloff R, Rahman S, Rathnayake A, Reed BT, Reimer PE, Richards R, Riordan S, Roblin Y, Seeds S, Shahinyan A, Souder PA, Tang L, Thiel M, Tian Y, Urciuoli GM, Wertz EW, Wojtsekhowski B, Xiong W, Yale B, Ye T, Zec A, Zhang W, Zhang J, and Zheng X

Abstract

We report precision determinations of the beam-normal single spin asymmetries (A&#95;{n}) in the elastic scattering of 0.95 and 2.18 GeV electrons off ^{12}C, ^{40}Ca, ^{48}Ca, and ^{208}Pb at very forward angles where the most detailed theoretical calculations have been performed. The first measurements of A&#95;{n} for ^{40}Ca and ^{48}Ca are found to be similar to that of ^{12}C, consistent with expectations and thus demonstrating the validity of theoretical calculations for nuclei with Z≤20. We also report A&#95;{n} for ^{208}Pb at two new momentum transfers (Q^{2}) extending the previous measurement. Our new data confirm the surprising result previously reported, with all three data points showing significant disagreement with the results from the Z≤20 nuclei. These data confirm our basic understanding of the underlying dynamics that govern A&#95;{n} for nuclei containing ≲50 nucleons, but point to the need for further investigation to understand the unusual A&#95;{n} behavior discovered for scattering off ^{208}Pb.

Published
2022
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5. 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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6. Accurate Determination of the Neutron Skin Thickness of ^{208}Pb through Parity-Violation in Electron Scattering.

Author

Adhikari D, Albataineh H, Androic D, Aniol K, Armstrong DS, Averett T, Ayerbe Gayoso C, Barcus S, Bellini V, Beminiwattha RS, Benesch JF, Bhatt H, Bhatta Pathak D, Bhetuwal D, Blaikie B, Campagna Q, Camsonne A, Cates GD, Chen Y, Clarke C, Cornejo JC, Covrig Dusa S, Datta P, Deshpande A, Dutta D, Feldman C, Fuchey E, Gal C, Gaskell D, Gautam T, Gericke M, Ghosh C, Halilovic I, Hansen JO, Hauenstein F, Henry W, Horowitz CJ, Jantzi C, Jian S, Johnston S, Jones DC, Karki B, Katugampola S, Keppel C, King PM, King DE, Knauss M, Kumar KS, Kutz T, Lashley-Colthirst N, Leverick G, Liu H, Liyange N, Malace S, Mammei R, Mammei J, McCaughan M, McNulty D, Meekins D, Metts C, Michaels R, Mondal MM, Napolitano J, Narayan A, Nikolaev D, Rashad MNH, Owen V, Palatchi C, Pan J, Pandey B, Park S, Paschke KD, Petrusky M, Pitt ML, Premathilake S, Puckett AJR, Quinn B, Radloff R, Rahman S, Rathnayake A, Reed BT, Reimer PE, Richards R, Riordan S, Roblin Y, Seeds S, Shahinyan A, Souder P, Tang L, Thiel M, Tian Y, Urciuoli GM, Wertz EW, Wojtsekhowski B, Yale B, Ye T, Yoon A, Zec A, Zhang W, Zhang J, and Zheng X

Abstract

We report a precision measurement of the parity-violating asymmetry A&#95;{PV} in the elastic scattering of longitudinally polarized electrons from ^{208}Pb. We measure A&#95;{PV}=550±16(stat)±8(syst) parts per billion, leading to an extraction of the neutral weak form factor F&#95;{W}(Q^{2}=0.00616  GeV^{2})=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is R&#95;{n}-R&#95;{p}=0.283±0.071  fm. The result also yields the first significant direct measurement of the interior weak density of ^{208}Pb: ρ&#95;{W}^{0}=-0.0796±0.0036(exp)±0.0013(theo)  fm^{-3} leading to the interior baryon density ρ&#95;{b}^{0}=0.1480±0.0036(exp)±0.0013(theo)  fm^{-3}. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.

Published
2021
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7. 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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8. First determination of the weak charge of the proton.

Author

Androic D, Armstrong DS, Asaturyan A, Averett T, Balewski J, Beaufait J, Beminiwattha RS, Benesch J, Benmokhtar F, Birchall J, Carlini RD, Cates GD, Cornejo JC, Covrig S, Dalton MM, Davis CA, Deconinck W, Diefenbach J, Dowd JF, Dunne JA, Dutta D, Duvall WS, Elaasar M, Falk WR, Finn JM, Forest T, Gaskell D, Gericke MT, Grames J, Gray VM, Grimm K, Guo F, Hoskins JR, Johnston K, Jones D, Jones M, Jones R, 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, Mei J, Michaels R, Micherdzinska A, Mkrtchyan A, Mkrtchyan H, Morgan N, Myers KE, Narayan A, Ndukum LZ, Nelyubin V, Nuruzzaman, van Oers WT, Opper AK, Page SA, Pan J, Paschke KD, Phillips SK, Pitt ML, Poelker M, 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, Young RD, and Zhamkochyan S

Abstract

The Q(weak) experiment has measured the parity-violating asymmetry in ep elastic scattering at Q(2)=0.025(GeV/c)(2), employing 145 μA of 89% longitudinally polarized electrons on a 34.4 cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run, constituting approximately 4% of the data collected in the experiment, are reported here. From these initial results, the measured asymmetry is A(ep)=-279±35 (stat) ± 31 (syst) ppb, which is the smallest and most precise asymmetry ever measured in ep scattering. The small Q(2) of this experiment has made possible the first determination of the weak charge of the proton Q(W)(p) by incorporating earlier parity-violating electron scattering (PVES) data at higher Q(2) to constrain hadronic corrections. The value of Q(W)(p) obtained in this way is Q(W)(p)(PVES)=0.064±0.012, which is in good agreement with the standard model prediction of Q(W)(p)(SM)=0.0710±0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be Q(W)(n)(PVES+APV)=-0.975±0.010.

Published
2013
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