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108 results on '"A J, Sarty"'

1. Measurement of R=σL/σT and the separated longitudinal and transverse structure functions in the nucleon-resonance region

Author

Y. Liang, V. Tvaskis, M. E. Christy, A. Ahmidouch, C. S. Armstrong, J. Arrington, R. Asaturyan, S. Avery, O. K. Baker, D. H. Beck, H. P. Blok, C. W. Bochna, W. Boeglin, P. Bosted, M. Bouwhuis, H. Breuer, D. S. Brown, A. Bruell, R. D. Carlini, J. Cha, N. S. Chant, A. Cochran, L. Cole, S. Danagoulian, D. B. Day, J. Dunne, D. Dutta, R. Ent, H. C. Fenker, B. Fox, L. Gan, H. Gao, K. Garrow, D. Gaskell, A. Gasparian, D. F. Geesaman, R. Gilman, P. L. J. Guèye, M. Harvey, R. J. Holt, X. Jiang, M. Jones, C. E. Keppel, E. Kinney, W. Lorenzon, A. Lung, D. J. Mack, P. Markowitz, J. W. Martin, K. McIlhany, D. McKee, D. Meekins, M. A. Miller, R. G. Milner, J. H. Mitchell, H. Mkrtchyan, B. A. Mueller, A. Nathan, G. Niculescu, I. Niculescu, T. G. O'Neill, V. Papavassiliou, S. F. Pate, R. B. Piercey, D. Potterveld, R. D. Ransome, J. Reinhold, E. Rollinde, O. Rondon, P. Roos, A. J. Sarty, R. Sawafta, E. C. Schulte, E. Segbefia, C. Smith, S. Stepanyan, S. Strauch, V. Tadevosyan, L. Tang, R. Tieulent, A. Uzzle, W. F. Vulcan, S. A. Wood, F. Xiong, L. Yuan, M. Zeier, B. Zihlmann, and V. Ziskin

Published
2022
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2. 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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3. Extracting the spin polarizabilities of the proton by measurement of Compton double-polarization observables

Author

Susanna Costanza, A. G. Denig, V. L. Kashevarov, V. Metag, C. Sfienti, W. Gradl, G. M. Huber, M. Oberle, D. Werthmüller, J. Wettig, M. Biroth, F. Afzal, P. B. Otte, V. Lisin, A. Polonski, V. Sokhoyan, A. B. Lazarev, Anthony W. Thomas, D. I. Glazier, K. Livingston, S. Lutterer, K. Spieker, J. Mancell, S. Gardner, N. S. Borisov, A. Käser, D. Hornidge, C. Collicott, A. Braghieri, A. B. Neganov, Th. Strub, A. Rajabi, D. P. Watts, Patrick Achenbach, J. R. M. Annand, H. J. Arends, P. Drexler, M. Ostrick, R. Kondratiev, Michaela Thiel, Lena Heijkenskjöld, M. I. Ferretti-Bondy, D. Glowa, M. Bashkanov, R. A. Miskimen, M. Korolija, S. N. Prakhov, Yu. A. Usov, O. Steffen, A. Thiel, G. M. Gurevich, David Manley, P. Pedroni, Lorenzo Zana, P. P. Martel, S. Garni, A. Neiser, I. Keshelashvili, David Hamilton, W. Meyer, B. Krusche, J. Linturi, M. Dieterle, Lilian Witthauer, S. Kay, S. Günther, S. Wagner, G. Reicherz, S. Abt, C. S. Akondi, A. J. Sarty, Reinhard Beck, I. Supek, I. Gorodnov, M. H. Sikora, Roderick M. Macrae, W. J. Briscoe, A. N. Mushkarenkov, T. Rostomyan, Guy Ron, E. J. Downie, M. Unverzagt, F. Cividini, P. Adlarson, Z. Ahmed, I. I. Strakovsky, C. Mullen, Durga Paudyal, M. Wolfes, A. Powell, N. K. Walford, E. Mornacchi, and I. J. D. MacGregor

Subjects
Nuclear reaction, Physics, Chiral perturbation theory, Proton, 010308 nuclear & particles physics, Resonance, 16. Peace & justice, 01 natural sciences, Baryon, 0103 physical sciences, Proton spin crisis, Atomic physics, 010306 general physics, Microtron, Spin-½
Abstract

The Compton double-polarization observable \ud Σ\ud 2\ud z\ud has been measured for the first time in the \ud Δ\ud (\ud 1232\ud )\ud resonance region using a circularly polarized photon beam incident on a longitudinally polarized proton target at the Mainz Microtron. This paper reports these results, together with the model-dependent extraction of four proton spin polarizabilities from fits to additional asymmetry data using either a dispersion relation calculation or a baryon chiral perturbation theory calculations with the weighted average of these two fits resulting in \ud γ\ud E\ud 1\ud E\ud 1\ud =\ud −\ud 2.87\ud ±\ud 0.52\ud ,\ud \ud γ\ud M\ud 1\ud M\ud 1\ud =\ud 2.70\ud ±\ud 0.43\ud ,\ud \ud γ\ud E\ud 1\ud M\ud 2\ud =\ud −\ud 0.85\ud ±\ud 0.72\ud , and \ud γ\ud M\ud 1\ud E\ud 2\ud =\ud 2.04\ud ±\ud 0.43\ud , in units of \ud 10\ud −\ud 4\ud fm\ud 4\ud .

Published
2020
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4. Erratum to: Dispersive corrections in elastic electron-nucleus scattering: an investigation in the intermediate energy regime and their impact on the nuclear matter

Author

R. I. Pomatsalyuk, Yannick Rousseau, A. J. R. Puckett, C. E. Hyde, Ishay Pomerantz, A. P. Freyberger, M. Olson, A. Shahinyan, Kent Paschke, Karl Slifer, E. Piasetzky, S. Strauch, X. Jiang, Fatiha Benmokhtar, H. Arenaövel, A. T. Katramatou, J. R. Calarco, H. F. Ibrahim, T. Holmstrom, S. Frullani, Bryan J. Moffit, W.U. Boeglin, F. Cusanno, E. Chudakov, D. G. Meekins, Asghar Askarpour Kabir, Simon Širca, F. Garibaldi, M. H. Shabestari, Ronald Ransome, E. J. Brash, Guy Ron, Z. E. Meziani, R. Shneor, M. Potokar, Yordanka Ilieva, Young Do Oh, Xin Qian, E. Schulte, Whitney Armstrong, B. Craver, L. Coman, J. P. Chen, C. F. Perdrisat, A. J. Sarty, J.-O. Hansen, M. Reyhan, C. Dutta, B. E. Norum, B. Sawatzky, E. Kuchina, J. Dumas, Emily M. McCullough, Bumsung Lee, M. Meziane, J. Song, R. Michaels, B. L. Berman, G. G. Petratos, J. Roche, G. J. Kumbartzki, P. Giuliani, M. Schwamb, Smt Beck, Douglas Higinbotham, M. K. Jones, Ronald Gilman, Pete Markowitz, Michael Paolone, A. Adeyemi, A. Beck, Yujie Qiang, P. Solvignon, E. Khrosinkova, S. Choi, J. Arrington, Kalyan Allada, R. J. Feuerbach, Alexandre Camsonne, R. A. Lindgren, J. J. LeRose, Punjabi, Paul Gueye, A. Kelleher, and J. Glister

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Hardware_MEMORYSTRUCTURES, medicine.anatomical_structure, Intermediate energy, Scattering, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, medicine, Elastic electron, Nuclear matter, Nucleus
Abstract

In the original PDF online version of this article, the references 22–26 were missing.These are the missing references.

Published
2020
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5. Dispersive corrections in elastic electron-nucleus scattering: an investigation in the intermediate energy regime and their impact on the nuclear matter

Author

L. Coman, Karl Slifer, E. Schulte, Guy Ron, P. Solvignon, S. May-Tal Beck, J. Song, R. Subedi, E. Piasetzky, R. Michaels, C. F. Perdrisat, B. Craver, Young Do Oh, M. Olson, P. Gueye, C. E. Hyde, G. G. Petratos, V. A. Punjabi, E. McCullough, G. M. Urciuoli, Asghar Askarpour Kabir, Pete Markowitz, A. Kelleher, Ronald Ransome, Ishay Pomerantz, J. J. LeRose, M. Potokar, A. J. Sarty, A. J. R. Puckett, R. Pomatsalyuk, J. Dumas, Xin Qian, C. Dutta, H. F. Ibrahim, A. P. Freyberger, R. Lindgren, M. Meziane, Kent Paschke, A. Shahinyan, B. Sawatzky, E. Kuchina, R. Sparks, Xiaofeng Zhu, S. Strauch, D. G. Meekins, B. L. Berman, F. Cusanno, Z. E. Meziani, A. T. Katramatou, J. Glister, T. Holmstrom, X. Yan, R. J. Feuerbach, J. Arrington, E. Chudakov, Y. Qiang, Fatiha Benmokhtar, B. E. Norum, H. Arenaövel, M. Paolone, J. O. Hansen, J. Roche, W. U. Boeglin, Bryan J. Moffit, A. Camsonne, Franco Garibaldi, H. Yao, M. Schwamb, Byounghoon Lee, Simon Širca, X. Zhan, S. Choi, X. Jiang, R. Shneor, Whitney Armstrong, Kalyan Allada, E. J. Brash, G. J. Kumbartzki, P. Giuliani, Y. Ilieva, M. H. Shabestari, A. Beck, M. Reyhan, Salvatore Frullani, Ronald Gilman, J. P. Chen, Douglas Higinbotham, M. K. Jones, J. R. Calarco, Yannick Rousseau, K. Wang, A. Adeyemi, Bogdan Wojtsekhowski, E. Khrosinkova, Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Jefferson Lab Hall A, and Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Diffraction, Elastic scattering, Physics, Nuclear and High Energy Physics, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 010308 nuclear & particles physics, Scattering, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear matter, 01 natural sciences, 7. Clean energy, Effective nuclear charge, Cross section (physics), 0103 physical sciences, Nuclear fusion, Atomic physics, Born approximation, 010306 general physics
Abstract

Measurements of elastic electron scattering data within the past decade have highlighted two-photon exchange contributions as a necessary ingredient in theoretical calculations to precisely evaluate hydrogen elastic scattering cross sections. This correction can modify the cross section at the few percent level. In contrast, dispersive effects can cause significantly larger changes from the Born approximation. The purpose of this experiment is to extract the carbon-12 elastic cross section around the first diffraction minimum, where the Born term contributions to the cross section are small to maximize the sensitivity to dispersive effects. The analysis uses the LEDEX data from the high resolution Jefferson Lab Hall A spectrometers to extract the cross sections near the first diffraction minimum of $$^{12}$$ C at beam energies of 362 MeV and 685 MeV. The results are in very good agreement with previous world data, although with less precision. The average deviation from a static nuclear charge distribution expected from linear and quadratic fits indicate a 30.6% contribution of dispersive effects to the cross section at 1 GeV. The magnitude of the dispersive effects near the first diffraction minimum of $$^{12}$$ C has been confirmed to be large with a strong energy dependence and could account for a large fraction of the magnitude for the observed quenching of the longitudinal nuclear response. These effects could also be important for nuclei radii extracted from parity-violating asymmetries measured near a diffraction minimum.

Published
2020
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6. Cross section for γn→π0n measured at the Mainz A2 experiment

Author

K. Livingston, S. Lutterer, S. Gardner, N. S. Borisov, M. Unverzagt, V. V. Kulikov, H. J. Arends, A. B. Lazarev, A. Neiser, Alfred Švarc, F. Cividini, A. Braghieri, F. Afzal, D. G. Middleton, B. Oussena, C. Collicott, D. P. Watts, K. Spieker, K. Bantawa, M. Bashkanov, R. A. Miskimen, M. Ostrick, S. Kay, C. Sfienti, V. E. Tarasov, Patrick Achenbach, Yu. A. Usov, G. M. Huber, A. E. Kudryavtsev, A. Käser, O. Steffen, P. Aguar-Bartolomé, V. L. Kashevarov, A. G. Denig, E. J. Downie, N. K. Walford, J. Wettig, E. Mornacchi, A. Thiel, J. Stahov, S. Fegan, Durga Paudyal, J. C. McGeorge, Nicholas Zachariou, V. Sokhoyan, I. J. D. MacGregor, M. I. Ferretti Bondy, M. A. Martemianov, D. Gurevich, D. Hornidge, D. Ghosal, S. Wagner, M. Wolfes, Anthony W. Thomas, D. I. Glazier, Guy Ron, Z. Ahmed, Susanna Costanza, Michaela Thiel, W. J. Briscoe, A. Powell, M. Günther, L. Tiator, I. I. Strakovsky, A. N. Mushkarenkov, S. A. Bulychjov, D. M. Manley, Lena Heijkenskjöld, P. P. Martel, R. Omerović, M. Korolija, R. Beck, C. Mullen, J. R. M. Annand, D. Werthmüller, M. Biroth, M. Hadžimehmedović, P. B. Otte, A. B. Neganov, P. Pedroni, W. Gradl, S. N. Prakhov, B. Krusche, P. Drexler, H. Osmanović, T. Rostomyan, I. Supek, I. Gorodnov, Ron L. Workman, Roderick M. Macrae, S. Abt, C. S. Akondi, and A. J. Sarty

Subjects
Physics, 010308 nuclear & particles physics, Nuclear Theory, 7. Clean energy, 01 natural sciences, Resonance (particle physics), Nuclear physics, Cross section (physics), Pion, Amplitude, Deuterium, Reaction dynamics, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, Microtron
Abstract

The γ n → π 0 n differential cross section evaluated for 27 energy bins span the photon-energy range 290–813 MeV ( W = 1.195 –1.553 GeV) and the pion c.m. polar production angles, ranging from 18 ∘ to 162 ∘ , making use of model-dependent nuclear corrections to extract π 0 production data on the neutron from measurements on the deuteron target. Additionally, the total photoabsorption cross section was measured. The tagged photon beam produced by the 883 MeV electron beam of the Mainz Microtron MAMI was used for the π 0 -meson production. Our accumulation of 3.6 × 10 6 γ n → π 0 n events allowed a detailed study of the reaction dynamics. Our data are in reasonable agreement with previous A2 measurements and extend them to lower energies. The data are compared with predictions of previous said, maid, and BnGa partial-wave analyses and to the latest said fit MA19 that included our data. Selected photon-decay amplitudes N ∗ → γ n at the resonance poles are determined for the first time.

Published
2019
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7. Exclusive π+ electroproduction off the proton from low to high -t

Author

R. J. Holt, S. Basnet, L. G. Tang, X. Zheng, MathML\\'> F, V. Tadevosyan, H. Breuer, A. J. Sarty, Tanja Horn, Glen A. Warren, S. Jin, W. B. Li, A. Matsumura, V. A. Punjabi, D. G. Meekins, J. Volmer, G. M. Huber, P. M. King, Rolf Ent, Jin Liu, M. E. Christy, C. E. Keppel, C. C. Chang, C. F. Perdrisat, K. A. Aniol, E. J. Beise, I. Niculescu, Y. Okayasu, W. Kim, D. Gaskell, Geoffrey Smith, H. P. Blok, msub, D. J. Margaziotis, G. J. Lolos, Pete Markowitz, S. A. Wood, C. Xu, W.U. Boeglin, J. Reinhold, E. F. Gibson, D. J. Mack, H. Mkrtchyan, W. F. Vulcan, E. J. Brash, M. K. Jones, V. Kovaltchouk, Lubomir Pentchev, J. Arrington, V. Tvaskis, mrow> π, P. E. Reimer, J. Roche, Toshinobu Miyoshi, D. H. Potterveld, and Student Lab and Education

Subjects
SDG 16 - Peace, generalized parton distribution, Proton, accelerator, Hadron, Degrees of freedom (physics and chemistry), interference, Regge, Parton, nonperturbative, 01 natural sciences, 7. Clean energy, energy [beam], High Energy Physics - Experiment, Nuclear physics, Cross section (physics), 0103 physical sciences, ddc:530, structure, 010306 general physics, Nuclear Experiment, production [meson], Quantum chromodynamics, Physics, Range (particle radiation), 010308 nuclear & particles physics, background, momentum transfer, SDG 16 - Peace, Justice and Strong Institutions, electroproduction, Justice and Strong Institutions, Amplitude, kinematics, High Energy Physics::Experiment, distribution function [parton], Jefferson Lab, photoproduction
Abstract

Background: Measurements of exclusive meson production are a useful tool in the study of hadronic structure. In particular, one can discern the relevant degrees of freedom at different distance scales through these studies. Purpose: To study the transition between non-perturbative and perturbative Quantum Chromodyanmics as the square of four momentum transfer to the struck proton, -t, is increased. Method: Cross sections for the $^1$H(e,e'$\pi^+$)n reaction were measured over the -t range of 0.272 to 2.127 GeV$^2$ with limited azimuthal coverage at fixed beam energy of 4.709 GeV, Q$^2$ of 2.4 GeV$^2$ and W of 2.0 GeV at the Thomas Jefferson National Accelerator Facility (JLab) Hall C. Results: The -t dependence of the measured $\pi^+$ electroproduction cross section generally agrees with prior data from JLab Halls B and C. The data are consistent with a Regge amplitude based theoretical model, but show poor agreement with a Generalized Parton Distribution (GPD) based model. Conclusion: The agreement of cross sections with prior data implies small contribution from the interference terms, and the confirmation of the change in t-slopes between the low and high -t regions previously observed in photoproduction indicates the changing nature of the electroproduction reaction in our kinematic regime., Comment: 9 pages, 5 figures Physical Review C, in press

Published
2019
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8. Experimental study of the $ \gamma p \rightarrow K^{0}\Sigma^{+}$, $ \gamma n \rightarrow K^{0} \Lambda$, and $ \gamma n \rightarrow K^{0} \Sigma^{0}$ reactions at the Mainz Microtron

Author

Anthony W. Thomas, D. I. Glazier, A. Mushkarenkov, M. Biroth, B. Krusche, H. J. Arends, I. Gorodnov, S. Abt, C. S. Akondi, E. J. Downie, Th. Strub, R. Beck, M. Unverzagt, A. J. Sarty, V. L. Kashevarov, M. Bashkanov, F. Cividini, D. G. Middleton, D. Gurevich, M. Wolfes, David Manley, Yu. A. Usov, O. Steffen, M. Ostrick, A. B. Neganov, Concettina Sfienti, Jrm Annand, W. Gradl, E. Mornacchi, M. Käser, S. Kay, C. Mullen, J. C. McGeorge, Igor Strakovsky, Lena Heijkenskjöld, P. Aguar-Bartolomé, I. J. D. MacGregor, A. Powell, A. Braghieri, J. Wettig, N. K. Walford, A. Thiel, M. Günther, M. I. Ferretti Bondy, A. Denig, P. P. Martel, M. Oberle, S. Costanza, S. N. Prakhov, S. Wagner, G. Ron, A. Lazarev, M. Thiel, D. Hornidge, M. Korolija, I. Supek, Lilian Witthauer, D. Werthmüller, A. Neiser, K. Spieker, W. J. Briscoe, F. Afzal, K. Livingston, S. Lutterer, S. Gardner, M. Dieterle, N. S. Borisov, P. Drexler, P. B. Otte, P. Pedroni, V. Sokhoyan, T. Rostomyan, B. Oussena, C. Collicott, D. P. Watts, K. Bantawa, Z. Ahmed, Patrick Achenbach, R. Miskimen, D. Paudyal, and G. M. Huber

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Hadron, Sigma, Nuclear fusion, Lambda, Nuclear Experiment, Legendre polynomials, Microtron
Abstract

This work measured $d\sigma/d\Omega$ for neutral kaon photoproduction reactions from threshold up to a c.m.\ energy of 1855MeV, focussing specifically on the $\gamma p\rightarrow K^0\Sigma^+$, $\gamma n\rightarrow K^0\Lambda$, and $\gamma n\rightarrow K^0 \Sigma^0$ reactions. Our results for $\gamma n\rightarrow K^0 \Sigma^0$ are the first-ever measurements for that reaction. These data will provide insight into the properties of $N^*$ resonances and, in particular, will lead to an improved knowledge about those states that couple only weakly to the $\pi N$ channel. Integrated cross sections were extracted by fitting the differential cross sections for each reaction as a series of Legendre polynomials and our results are compared with prior experimental results and theoretical predictions., Comment: 16 pages, 13 figures, 7 tables

Published
2019
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9. Electroexcitation of the Δ+(1232) at low momentum transfer

Author

V. Bellini, C.M. Camacho, E. Schulte, H. Albataineh, J. W. Watson, M. Huang, M. Hashemi Shabestari, J. Sjoegren, C. Gu, Simon Širca, F. Garibaldi, I. Yaron, L. Selvy, M. Khandaker, V. A. Punjabi, T. Holmstrom, E. Fuchey, B. D. Anderson, M. Defurne, W. Tireman, D. J. Margaziotis, R. A. Lindgren, Or Hen, J. P. Chen, I. Korover, E. Piasetzky, Z. E. Meziani, A. Blomberg, H. Baghdasaryan, Olfred Hansen, K. Chirapatpimol, J. R. M. Annand, Juliette Mammei, A. Polychronopoulou, Salvatore Frullani, M. Posik, N. Muangma, X. Zhan, S. K. Phillips, John Arrington, X. Bai, J. Leckey, D. Flay, Nikos Sparveris, Ping Zhu, B. Zhao, Guy Ron, David Hamilton, W. B. Yan, A. Kelleher, X. Zheng, N. Kalantarians, R. Shneor, S. Riordan, Abdurahim Rakhman, A. Saha, Kalyan Allada, Vincent Sulkosky, Z. W. Zhao, Z. Ye, E. Long, Xin Qian, R. Subedi, D. G. Meekins, Bogdan Wojtsekhowski, B. E. Norum, J. LeRose, R. De Leo, M. Mihovilovič, A. Martí Jiménez-Argüello, E. Cisbani, S. Iqbal, M. M. Dalton, W. U. Boeglin, Chunhui Chen, H. Kang, A. Camsonne, Nuruzzaman, Michael Paolone, C. Hanretty, D. Anez, N. Fomin, Shalev Gilad, K. A. Aniol, T. Averett, Wouter Deconinck, Ishay Pomerantz, Z. Ahmed, A. J. Sarty, Fatiha Benmokhtar, D. Wang, S. Beck, Ronald Gilman, Douglas Higinbotham, K. Pan, Yiyang Zhang, A. Beck, Jie Zhang, M. Friend, P. E. Reimer, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Ecole Centrale Paris, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Angular momentum, Nuclear and High Energy Physics, High Energy Physics::Lattice, Nuclear Theory, Constituent quark, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nucleon deformation, 01 natural sciences, 7. Clean energy, Atomic, Nuclear physics, Pion, Particle and Plasma Physics, 0103 physical sciences, Coulomb, Effective field theory, Nuclear, CMR, 010306 general physics, Nuclear Experiment, Mathematical Physics, Physics, 010308 nuclear & particles physics, Momentum transfer, Pion electroproduction, Molecular, Nuclear & Particles Physics, lcsh:QC1-999, Quantum electrodynamics, Quadrupole, Nucleon, Astronomical and Space Sciences, lcsh:Physics
Abstract

International audience; We report on new p(e,e′p)π∘p(e,e′p)π∘ measurements at the Δ+(1232)Δ+(1232) resonance at the low momentum transfer region, where the mesonic cloud dynamics is predicted to be dominant and rapidly changing, offering a test bed for chiral effective field theory calculations. The new data explore the Q2Q2 dependence of the resonant quadrupole amplitudes and for the first time indicate that the Electric and the Coulomb quadrupole amplitudes converge as Q2→0Q2→0. The measurements of the Coulomb quadrupole amplitude have been extended to the lowest momentum transfer ever reached, and suggest that more than half of its magnitude is attributed to the mesonic cloud in this region. The new data disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations that include pion cloud effects, chiral effective field theory and lattice calculations. The measurements indicate that improvement is required to the theoretical calculations and provide valuable input that will allow their refinements.

Published
2016
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10. Measurement of the beam-helicity asymmetry in photoproduction of π0η pairs on carbon, aluminum, and lead

Author

R. A. Miskimen, A. G. Denig, Durga Paudyal, M. Wolfes, I. Keshelashvili, Yu. A. Usov, O. Steffen, K. Spieker, P. Pedroni, Susanna Costanza, P. Aguar-Bartolomé, Concettina Sfienti, A. N. Mushkarenkov, M. Ostrick, D. G. Middleton, M. Günther, S. Garni, A. Powell, I. Supek, A. Käser, R. Beck, I. Gorodnov, M. Unverzagt, V. L. Kashevarov, F. Cividini, Roderick M. Macrae, L. V. Fil'kov, P. Adlarson, M. Oberle, S. Abt, E. J. Downie, Patrick Achenbach, D. P. Watts, S. Cherepnya, A. J. Sarty, K. Bantawa, G. M. Huber, Z. Ahmed, S. Kay, I. I. Strakovsky, T. Rostomyan, K. Livingston, S. Lutterer, B. Strandberg, S. Gardner, N. S. Borisov, C. Mullen, Guy Ron, D. I. Glazier, S. Wagner, H. J. Arends, W. J. Briscoe, A. B. Lazarev, Michaela Thiel, A. Neiser, A. Fix, A. Braghieri, Th. Strub, P. Drexler, F. Afzal, A. B. Neganov, Nicholas Zachariou, W. Gradl, J. Wettig, J. C. McGeorge, V. Sokhoyan, P. P. Martel, J. R. M. Annand, D. Hornidge, E. Mornacchi, I. J. D. MacGregor, M. Korolija, David Manley, N. K. Walford, B. Krusche, K. Altangerel, E. Rickert, M. Biroth, P. B. Otte, R. Kondratiev, G. M. Gurevich, S. N. Prakhov, Lilian Witthauer, M. Dieterle, Lena Heijkenskjöld, M. I. Ferretti Bondy, Andy Thomas, A. Thiel, D. Werthmüller, C. Collicott, and M. Bashkanov

Subjects
Nuclear and High Energy Physics, Proton, media_common.quotation_subject, Nuclear Theory, chemistry.chemical_element, 7. Clean energy, 01 natural sciences, Asymmetry, Nuclear physics, Aluminium, 0103 physical sciences, Intermediate state, Nuclear Experiment, 010306 general physics, QC, media_common, Physics, 010308 nuclear & particles physics, Helicity, lcsh:QC1-999, 3. Good health, chemistry, High Energy Physics::Experiment, Nucleon, Carbon, lcsh:Physics, Beam (structure)
Abstract

The beam-helicity asymmetry was measured, for the first time, in photoproduction of $\pi^{0}\eta$ pairs on carbon, aluminum, and lead, with the A2 experimental setup at MAMI. The results are compared to an earlier measurement on a free proton and to the corresponding theoretical calculations. The Mainz model is used to predict the beam-helicity asymmetry for the nuclear targets. The present results indicate that the photoproduction mechanism for $\pi^{0}\eta$ pairs on nuclei is similar to photoproduction on a free nucleon. This process is dominated by the $D_{33}$ partial wave with the $\eta\Delta(1232)$ intermediate state., Comment: Accepted for publication in Physics Letters B (2020)

Published
2020
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11. Measurement of the decay η′→π0π0η at MAMI

Author

Z. Ahmed, David Manley, K. Livingston, S. Gardner, David Hamilton, N. S. Borisov, I. Supek, I. Keshelashvili, H. J. Arends, Ron L. Workman, T. Rostomyan, A. G. Denig, Michaela Thiel, Durga Paudyal, J. C. McGeorge, S. Wagner, M. Ostrick, M. Wolfes, A. B. Lazarev, Lorenzo Zana, B. Oussena, C. Collicott, K. Spieker, A. B. Neganov, M. Korolija, P. P. Martel, D. P. Watts, A. Braghieri, Th. Strub, P. Ott, J. R. M. Annand, R. Kondratiev, D. G. Middleton, C. S. Akondi, G. M. Gurevich, D. Hornidge, S. Kay, C. Sfienti, A. J. Sarty, I. J. D. MacGregor, A. Käser, V. L. Kashevarov, B. Krusche, A. Neiser, W. Gradl, Lilian Witthauer, Yu. A. Usov, O. Steffen, S. N. Prakhov, R. Miskimen, Andy Thomas, A. Thiel, P. Pedroni, A. Polonski, Igor Strakovsky, Susanna Costanza, J. Linturi, Reinhard Beck, M. Dieterle, M. I. Ferretti Bondy, D. Glowa, Guy Ron, S. Garni, L. Tiator, W. J. Briscoe, P. B. Otte, D. I. Glazier, J. Wettig, V. Sokhoyan, F. Afzal, G. M. Huber, M. Oberle, M. Unverzagt, A. Rajabi, F. Cividini, P. Adlarson, A. N. Mushkarenkov, E. J. Downie, and D. Werthmüller

Subjects
Cusp (singularity), Physics, Meson, 010308 nuclear & particles physics, Resolution (electron density), Magnitude (mathematics), Scattering length, 01 natural sciences, Nuclear physics, 0103 physical sciences, 010306 general physics, Microtron, Parametrization, Sign (mathematics)
Abstract

An experimental study of the η′→π0π0η→6γ decay has been conducted with the best up-to-date statistical accuracy, by measuring η′ mesons produced in the γp→η′p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The results obtained for the standard parametrization of the η′→π0π0η matrix element are consistent with the most recent results for η′→ππη decays, but have smaller uncertainties. The available statistics and experimental resolution allowed, for the first time, an observation of a structure below the π+π- mass threshold, the magnitude and sign of which, checked within the framework of the nonrelativistic effective-field theory, demonstrated good agreement with the cusp that was predicted based on the ππ scattering length combination, a0-a2, extracted from K→3π decays.

Published
2018
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12. High-statistics measurement of the η→3π0 decay at the Mainz Microtron

Author

D. Paudyal, E. Mornacchi, V. L. Kashevarov, Lena Heijkenskjöld, I. J. D. MacGregor, J. Ahrens, Igor Strakovsky, R. Kondratiev, R. Miskimen, C. B. Hamill, M. Oberle, M. Biroth, F. Afzal, A. Käser, A. Lazarev, D. I. Glazier, G. M. Gurevich, I. Supek, C. Sfienti, F. Cividini, M. Bashkanov, P. Drexler, M. Dieterle, L. Zana, I. Gorodnov, A. Mushkarenkov, M. I. Ferretti Bondy, N. K. Walford, A. Thiel, Patrick Achenbach, S. Cherepnya, Yu. A. Usov, O. Steffen, I. Keshelashvili, E. J. Downie, S. Kay, Reinhard Beck, A. Braghieri, D. Hornidge, J. R. M. Annand, P. Aguar-Bartolomé, David Manley, V. Lisin, A. Fix, A. Denig, A. Polonski, P. Pedroni, M. Wolfes, A. B. Neganov, D. Werthmüller, S. Costanza, A. Neiser, M. Unverzagt, S. Abt, S. Wagner, Th. Strub, D. G. Middleton, W. J. Briscoe, S. N. Prakhov, Z. Ahmed, G. Ron, A. Thomas, G. M. Huber, P. Adlarson, Lilian Witthauer, A. J. Sarty, P. B. Otte, C. Collicott, D. P. Watts, J. C. McGeorge, K. Bantawa, P. P. Martel, M. Korolija, B. Krusche, K. Livingston, S. Lutterer, V. Sokhoyan, B. Strandberg, S. Gardner, N. S. Borisov, T. Rostomyan, H. J. Arends, L. V. Fil'kov, W. Gradl, J. Wettig, M. Thiel, M. Ostrick, S. Garni, and K. Spieker

Subjects
Cusp (singularity), Physics, Meson, 010308 nuclear & particles physics, Dalitz plot, 01 natural sciences, 7. Clean energy, Moment (mathematics), Nonlinear system, Quadratic equation, 0103 physical sciences, Statistics, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Microtron, Parametrization
Abstract

The largest, at the moment, statistics of 7×106η→3π0 decays, based on 6.2×107η mesons produced in the γp→ηp reaction, has been accumulated by the A2 Collaboration at the Mainz Microtron, MAMI. It allowed a detailed study of the η→3π0 dynamics beyond its conventional parametrization with just the quadratic slope parameter α and enabled, for the first time, a measurement of the second-order term and a better understanding of the cusp structure in the neutral decay. The present data are also compared to recent theoretical calculations that predict a nonlinear dependence along the quadratic distance from the Dalitz-plot center.

Published
2018
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13. Experimental study of the γp→π0ηp reaction with the A2 setup at the Mainz Microtron

Author

C. B. Hamill, K. Livingston, S. Lutterer, S. Garni, W. Gradl, B. Strandberg, S. Gardner, N. S. Borisov, N. K. Walford, D. Paudyal, A. Polonski, C. Sfienti, B. Krusche, E. J. Downie, A. Lazarev, K. Spieker, S. Wagner, M. Günther, M. Biroth, P. Pedroni, M. Bashkanov, D. Werthmüller, S. Abt, M. Dieterle, M. Ostrick, M. Oberle, C. Collicott, D. P. Watts, L. Zana, M. I. Ferretti Bondy, J. Wettig, Yu. A. Usov, M. Unverzagt, O. Steffen, A. Thomas, R. Kondratiev, K. Bantawa, Z. Ahmed, F. Cividini, David Manley, A. Fix, A. J. Sarty, V. L. Kashevarov, Lena Heijkenskjöld, G. M. Huber, P. Adlarson, S. Kay, M. Thiel, P. Aguar-Bartolomé, I. Gorodnov, S. N. Prakhov, P. Drexler, A. Braghieri, D. Hornidge, G. Ron, V. Sokhoyan, V. Lisin, F. Afzal, T. Rostomyan, Th. Strub, H. J. Arends, Reinhard Beck, D. G. Middleton, E. Mornacchi, Lilian Witthauer, J. Ahrens, Patrick Achenbach, R. Miskimen, Igor Strakovsky, L. V. Fil'kov, W. J. Briscoe, I. J. D. MacGregor, I. Supek, A. B. Neganov, G. M. Gurevich, J. R. M. Annand, D. I. Glazier, A. Thiel, A. Denig, A. Mushkarenkov, S. Costanza, A. Neiser, J. C. McGeorge, M. Wolfes, P. B. Otte, A. Käser, P. P. Martel, M. Korolija, I. Keshelashvili, and S. Cherepnya

Subjects
Physics, Particle physics, Basis (linear algebra), 010308 nuclear & particles physics, Observable, 7. Clean energy, 01 natural sciences, Reaction dynamics, 0103 physical sciences, Photon polarization, Range (statistics), Photon beam, Nuclear Experiment, 010306 general physics, Microtron, Energy (signal processing)
Abstract

The data available from the A2 Collaboration at MAMI were analyzed to select the γp→π0ηp reaction on an event-by-event basis, which allows for partial-wave analyses of three-body final states to obtain more reliable results, compared to fits to measured distributions. These data provide the world's best statistical accuracy in the energy range from threshold to Eγ=1.45 GeV, allowing a finer energy binning in the measurement of all observables needed for understanding the reaction dynamics. The results obtained for the measured observables are compared to existing models, and the impact from the new data is checked by the fit with the revised Mainz model.

Published
2018
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14. Threshold π0 photoproduction on transverse polarised protons at MAMI

Author

V. Sokhoyan, S. Costanza, B. Krusche, H. J. Arends, G. M. Huber, T. Rostomyan, Lothar Tiator, V. L. Kashevarov, M. H. Sikora, M. Ostrick, L. V. Fil'kov, P. Hall-Barrientos, S. N. Prakhov, C. S. Akondi, W. Gradl, A. Polonski, S. Garni, D. I. Glazier, A. J. Sarty, A. Braghieri, D. Hornidge, B. Oussena, C. Collicott, E. J. Downie, A. Thomas, A. Mushkarenkov, V. Lisin, E. F. McNicoll, D. P. Watts, K. Livingston, Durga Paudyal, I. Keshelashvili, David Hamilton, R. Miskimen, Lilian Witthauer, N. S. Borisov, W. Meyer, M. Wolfes, P. Pedroni, V. V. Polyanski, R. Kondratiev, J. Mancel, G. Reicherz, Igor Strakovsky, A. B. Neganov, César Fernández-Ramírez, A. B. Lazarev, A. Nikolaev, G. M. Gurevich, B. M. K. Nefkens, D. G. Middleton, Th. Strub, H. Ortega, M. Dieterle, Reinhard Beck, Yu. A. Usov, O. Steffen, J. R. M. Annand, W. J. Briscoe, S. Cherepnya, P. Ott, I. J. D. MacGregor, David Manley, A. Fix, D. Werthmüller, P. P. Martel, Aron M. Bernstein, I. Supek, M. Oberle, M. Unverzagt, D. Howdle, M. Korolija, S. Schumann, and P. B. Otte

Subjects
Physics, Nuclear and High Energy Physics, Photon, Chiral perturbation theory, Scattering, media_common.quotation_subject, Asymmetry, Nuclear physics, Cross section (physics), Transverse plane, Atomic physics, Nuclear Experiment, Multipole expansion, Microtron, media_common
Abstract

Polarisation-dependent differential cross sections σ T associated with the target asymmetry T have been measured for the reaction γ p → → p π 0 with transverse target polarisation from π 0 threshold to photon energies of 190 MeV. The data were obtained using a frozen-spin butanol target with the Crystal Ball / TAPS detector set-up and the Glasgow photon tagging system at the Mainz Microtron MAMI. Results for σ T have been used in combination with our previous measurements of the unpolarised cross section σ 0 and the beam asymmetry Σ for a model-independent determination of S- and P-wave multipoles in the π 0 threshold region, which includes for the first time a direct determination of the imaginary part of the E 0 + multipole.

Published
2015
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15. First measurement of helicity-dependent cross sections in π0η photoproduction from quasi-free nucleons

Author

J. Wettig, A. Käser, M. Bashkanov, S. Costanza, M. Dieterle, R. Miskimen, S. Wagner, M. Thiel, G. Reicherz, P. Adlarson, F. Cividini, Yu. A. Usov, O. Steffen, R. Kondratiev, H. J. Arends, B. Krusche, V. L. Kashevarov, Lena Heijkenskjöld, P. P. Martel, M. Korolija, M. Unverzagt, E. Mornacchi, I. Supek, F. Afzal, A. Lazarev, S. Abt, C. Collicott, D. P. Watts, G. M. Huber, M. Ostrick, I. J. D. MacGregor, S. N. Prakhov, G. Ron, J. Ahrens, G. M. Gurevich, A. B. Neganov, A. Thiel, M. Günther, P. B. Otte, D. Paudyal, L. Zana, N. K. Walford, W. Gradl, E. J. Downie, Lilian Witthauer, K. Livingston, S. Lutterer, M. Biroth, W. Meyer, C. Sfienti, A. Braghieri, V. Sokhoyan, N. S. Borisov, D. Hornidge, Igor Strakovsky, V. Lisin, T. Rostomyan, A. J. Sarty, D. Werthmüller, Reinhard Beck, David Manley, A. Fix, Th. Strub, S. Kay, D. I. Glazier, A. Mushkarenkov, A. Polonski, A. Thomas, I. Gorodnov, W. J. Briscoe, M. Wolfes, M. Oberle, P. Drexler, P. Pedroni, Volker Metag, Z. Ahmed, Patrick Achenbach, J. R. M. Annand, A. Denig, A. Neiser, S. Garni, K. Spieker, and I. Keshelashvili

Subjects
Nuclear and High Energy Physics, Photon, Nuclear Theory, FOS: Physical sciences, 7. Clean energy, 01 natural sciences, Nuclear physics, Pion, 0103 physical sciences, Neutron, ddc:530, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Spin-½, Physics, 010308 nuclear & particles physics, Helicity, lcsh:QC1-999, 3. Good health, Deuterium, Nucleon, lcsh:Physics, Crystal Ball, reaction gamma-p, polarization, eta, mesons, mami, Pi(0)-pairs, photon, proton, pairs
Abstract

The helicity-dependent cross sections for the photoproduction of $\pi^0\eta$ pairs have been measured for the first time. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball - TAPS calorimeter. The experiment used a polarized deuterated butanol target and a circularly polarized photon beam. This arrangement allowed the $\sigma_{1/2}$ (photon and target spin antiparallel) and $\sigma_{3/2}$ (parallel spins) components to be measured for quasi-free production of $\pi^0\eta$ pairs off protons and neutrons. The main finding is that the two helicity components contribute identically, within uncertainties, for both participant protons and neutrons. The absolute couplings for protons and neutrons are also identical. This means that nucleon resonances contributing to this reaction in the investigated energy range have almost equal electromagnetic helicity couplings, $A_{1/2}^{n,p}$ and $A_{3/2}^{n,p}$. Identical couplings for protons and neutrons are typical for $\Delta$ resonances and identical $A_{1/2}$ and $A_{3/2}$ components are only possible for $J\geq 3/2$ states, which constrains possible contributions of nucleon resonances., Comment: accepted for publication in Phys. Lett. B

Published
2018
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16. Separated Kaon Electroproduction Cross Section and the Kaon Form Factor from 6 GeV JLab Data

Author

L. G. Tang, S. Jin, W. Kim, H. Breuer, Tanja Horn, H. P. Blok, C. E. Keppel, E. F. Gibson, Glen A. Warren, A. Vargas, A. Matsumura, D. J. Margaziotis, W. F. Vulcan, H. C. Fenker, C. Xu, P. E. Reimer, Jin Liu, R. J. Holt, M. E. Christy, S. A. Wood, C. C. Chang, S. Vidakovic, V. Tadevosyan, W.U. Boeglin, I. Niculescu, V. Tvaskis, D. J. Mack, V. Kovaltchouk, Jlab Fpi, Lubomir Pentchev, G. J. Lolos, J. Reinhold, A. J. Sarty, Rolf Ent, G. Niculescu, J. Volmer, J. Roche, Toshinobu Miyoshi, G. M. Huber, V. A. Punjabi, D. G. Meekins, E. J. Brash, E. J. Beise, M. Carmignotto, D. H. Potterveld, J. Arrington, K. A. Aniol, Richard Trotta, Y. Okayasu, Ian L. Pegg, P. M. King, Pete Markowitz, M. K. Jones, Brynle Barrett, C. F. Perdrisat, A. Dittmann, Geoffrey Smith, H. Mkrtchyan, D. Gaskell, X. Zheng, Shaikh Faruque Ali, and Student Lab and Education

Subjects
perturbation theory [quantum chromodynamics], Particle physics, Meson, interference, Regge, FOS: Physical sciences, Parton, nucl-ex, Atomic, 01 natural sciences, Cross section (physics), momentum transfer [form factor], Particle and Plasma Physics, Pion, Factorization, 0103 physical sciences, ddc:530, Nuclear, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, form factor [K], Quantum chromodynamics, Physics, distribution amplitude [parton], +electron+K%2B+Lambda%22">electron p --> electron K+ Lambda, model, factorization [quantum chromodynamics], 010308 nuclear & particles physics, Form factor (quantum field theory), Molecular, Perturbative QCD, Nuclear & Particles Physics, transverse [cross section], electroproduction [K], High Energy Physics::Experiment, longitudinal [cross section], distribution function [parton], experimental results, Jefferson Lab
Abstract

The H1(e,e′K+)Λ reaction was studied as a function of the Mandelstam variable -t using data from the E01-004 (FPI-2) and E93-018 experiments that were carried out in Hall C at the 6 GeV Jefferson Laboratory. The cross section was fully separated into longitudinal and transverse components, and two interference terms at four-momentum transfers Q2 of 1.00, 1.36, and 2.07GeV2. The kaon form factor was extracted from the longitudinal cross section using the Regge model by Vanderhaeghen et al. [Phys. Rev. C 57, 1454 (1998)PRVCAN0556-281310.1103/PhysRevC.57.1454]. The results establish the method, previously used successfully for pion analyses, for extracting the kaon form factor. Data from 12 GeV Jefferson Laboratory experiments are expected to have sufficient precision to distinguish between theoretical predictions, for example, recent perturbative QCD calculations with modern parton distribution amplitudes. The leading-twist behavior for light mesons is predicted to set in for values of Q2 between 5 and 10GeV2, which makes data in the few-GeV regime particularly interesting. The Q2 dependence at fixed x and -t of the longitudinal cross section that we extracted seems consistent with the QCD factorization prediction within the experimental uncertainty.

Published
2018
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17. Photoproduction of π 0 mesons off protons and neutrons in the second and third nucleon resonance regions

Author

S. Kay, D. Gurevich, V. Metag, M. Wolfes, M. Bashkanov, H. J. Arends, Igor Strakovsky, S. N. Prakhov, G. Ron, B. Krusche, Lilian Witthauer, A. B. Neganov, M. Dieterle, M. Günther, R. Kondratiev, L. V. Fil'kov, S. Cherepnya, J. Ahrens, R. Miskimen, Yu. A. Usov, V. Sokhoyan, O. Steffen, F. Afzal, S. Wagner, I. Gorodnov, M. Oberle, D. I. Glazier, P. Drexler, F. Cividini, T. Rostomyan, M. Ostrick, M. Unverzagt, C. Sfienti, A. Thiel, G. M. Huber, K. Livingston, S. Lutterer, David Manley, A. Mushkarenkov, A. Lazarev, N. S. Borisov, A. Braghieri, D. Hornidge, J. R. M. Annand, V. Lisin, K. Spieker, J. C. McGeorge, N. K. Walford, A. Denig, S. Costanza, A. Neiser, D. Paudyal, A. Polonski, I. Keshelashvili, S. Abt, Th. Strub, I. Supek, D. G. Middleton, A. Thomas, A. J. Sarty, V. L. Kashevarov, Lena Heijkenskjöld, S. Garni, B. Oussena, P. Pedroni, L. Zana, C. Collicott, D. P. Watts, Z. Ahmed, E. J. Downie, D. Werthmüller, Reinhard Beck, W. J. Briscoe, P. P. Martel, M. Korolija, A. Käser, P. B. Otte, W. Gradl, P. Aguar Bartolomé, J. Wettig, M. Thiel, M. Biroth, E. Mornacchi, and I. J. D. MacGregor

Subjects
Physics, Nuclear reaction, Proton, Meson, 010308 nuclear & particles physics, Hadron, Nuclear Theory, 7. Clean energy, 01 natural sciences, 3. Good health, Nuclear physics, Pion, Isospin, 0103 physical sciences, tagged photon spectrometer, polarization observable E, cross-sections, pion-photoproduction, baryon resonances, deuteron, MAMI, asymmetry, microtron, threshold, Neutron, ddc:530, 010306 general physics, Nucleon, Nuclear Experiment
Abstract

Photoproduction of mesons off quasi-free nucleons bound in the deuteron allows to study the electromagnetic excitation spectrum of the neutron and the isospin structure of the excitation of nucleon resonances. The database for such reactions is much more sparse than for free proton targets. Single $\pi^0$ photoproduction off quasi-free nucleons from the deuteron was experimentally studied. Nuclear effects were investigated by a comparison of the results for free protons and quasi-free protons and used as a correction for the quasi-free neutron data. The experiment was performed at the tagged photon beam of the Mainz MAMI accelerator for photon energies between 0.45~GeV and 1.4~GeV, using an almost $4\pi$ electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. A complete kinematic reconstruction of the final state removed the effects of Fermi motion. Reaction model predictions and PWA for $\gamma n\rightarrow n\pi^{0}$, based on fits to data for the other isospin channels, disagreed between themselves and no model provided a good description of the new data. The results demonstrate clearly the importance of a measurement of the fully neutral final state for the isospin decomposition of the cross section. Model refits, for example from the Bonn-Gatchina analysis, show that the new and the previous data for the other three isospin channels can be simultaneously described when the contributions of several partial waves are modified. The results are also relevant for the suppression of the higher resonance bumps in total photoabsorption on nuclei, which are not well understood., Comment: excepted for publication in Phys. Rev. C

Published
2018
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18. Study of η and η′ Photoproduction at MAMI

Author

H. J. Arends, T. Rostomyan, F. Afzal, S. Garni, P. Pedroni, A. Rajabi, Reinhard Beck, S. Costanza, M. Oberle, K. Spieker, B. Oussena, E. McNicol, A. Thomas, G. M. Huber, C. Collicott, J. C. McGeorge, D. P. Watts, D. I. Glazier, M. Unverzagt, K. Livingston, B. Strandberg, S. Gardner, A. Mushkarenkov, R. Kondratiev, Concettina Sfienti, R. Miskimen, A. Thiel, J. R. M. Annand, V. V. Polyanski, J. Wettig, G. M. Gurevich, S. Schumann, M. F. Taragin, Th. Strub, Michaela Thiel, V. L. Kashevarov, F. Cividini, B. Krusche, V. Sokhoyan, A. Neiser, L. Tiator, Igor Strakovsky, W. J. Briscoe, A. Braghieri, D. Hornidge, David Manley, V. Lisin, David Hamilton, A. Fix, D. Glowa, J. Mancell, M. Ostrick, P. B. Otte, M. Dieterle, O. Steffen, J. Linturi, W. Gradl, D. G. Middleton, I. Keshelashvili, S. N. Prakhov, P. Ott, P. P. Martel, S. Kay, M. Korolija, Ron L. Workman, Roderick M. Macrae, L. V. Fil'kov, L. Zana, G. Rosner, A. Käser, D. Howdle, C. S. Akondi, Lilian Witthauer, D. M. Schott, A. J. Sarty, S. Wagner, I. Supek, G. Reicherz, M. I. Ferretti Bondy, Z. Ahmed, P. Adlarson, E. J. Downie, D. Werthmüller, C. Mullen, A. G. Denig, Durga Paudyal, M. Wolfes, R. F. B. Codling, E. Mornacchi, I. J. D. MacGregor, and J. Robinson

Subjects
Cusp (singularity), Physics, Particle physics, Photon, Proton, 010308 nuclear & particles physics, General Physics and Astronomy, 01 natural sciences, Nuclear physics, Cross section (physics), Excited state, 0103 physical sciences, Isobar, 010306 general physics, Microtron, Crystal Ball
Abstract

The reactions γp→ηp and γp→η′p are measured from their thresholds up to the center-of-mass energy W=1.96 GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section for η photoproduction at the energies in the vicinity of the η′ threshold, W=1896 MeV (Eγ=1447 MeV). Within the framework of a revised ηMAID isobar model, the cusp, in connection with a steep rise of the η′ total cross section from its threshold, can only be explained by a strong coupling of the poorly known N(1895)1/2− state to both ηp and η′p. Including the new high-accuracy results in the ηMAID fit to available η and η′ photoproduction data allows the determination of the N(1895)1/2− properties.

Published
2017
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19. First measurement of the polarization observable E and helicity-dependent cross sections in single π 0 photoproduction from quasi-free nucleons

Author

David Hamilton, T. Rostomyan, M. Bashkanov, W. Meyer, D. I. Glazier, P. B. Otte, R. Miskimen, L. Zana, Concettina Sfienti, Yu. A. Usov, O. Steffen, V. L. Kashevarov, I. Supek, A. G. Denig, P. P. Martel, V. Lisin, Durga Paudyal, K. Livingston, Reinhard Beck, Susanna Costanza, A. Polonski, M. H. Sikora, A. B. Lazarev, S. Lutterer, A. Käser, M. Wolfes, F. Afzal, R. Kondratiev, S. N. Prakhov, A. Braghieri, S. Gardner, S. Kay, Michaela Thiel, Guy Ron, Th. Strub, F. Cividini, N. S. Borisov, A. Rajabi, C. Collicott, S. Abt, W. J. Briscoe, G. M. Gurevich, D. P. Watts, Z. Ahmed, Andy Thomas, A. Thiel, E. J. Downie, E. Mornacchi, D. M. Manley, M. Korolija, G. M. Huber, H. J. Arends, D. Glowa, C. S. Akondi, Patrick Achenbach, S. Wagner, G. Reicherz, B. Krusche, A. J. Sarty, I. Keshelashvili, I. J. D. MacGregor, Igor Strakovsky, D. Werthmüller, J. R. M. Annand, M. Unverzagt, V. Sokhoyan, J. Wettig, J. Linturi, K. Spieker, M. Dieterle, M. Ostrick, J. Mancell, P. Pedroni, S. Garni, M. Biroth, N. K. Walford, P. Adlarson, P. Drexler, M. Oberle, Volker Metag, A. N. Mushkarenkov, A. Neiser, M. I. Ferretti-Bondy, D. Hornidge, Lilian Witthauer, A. B. Neganov, W. Gradl, and M. Günther

Subjects
Nuclear and High Energy Physics, Photon, Meson, Proton, Nuclear Theory, 01 natural sciences, 7. Clean energy, Nuclear physics, Recoil, 0103 physical sciences, Neutron, ddc:530, 010306 general physics, Nuclear Experiment, Physics, 010308 nuclear & particles physics, lcsh:QC1-999, 3. Good health, Nuclear cross section, Atomic physics, Nucleon, i-circle-dot, meson photoproduction, eta-photoproduction, baryon resonances, deuteron, neutrons, protons, asymmetry, photon, pairs, Crystal Ball, lcsh:Physics
Abstract

The double-polarization observable $E$ and the helicity-dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$ have been measured for the first time for single $\pi^{0}$ photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the $\pi^0$ meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Effects from nuclear Fermi motion were removed by a kinematic reconstruction of the $\pi^{0}N$ final state. A comparison to data measured with a free proton target showed that the absolute scale of the cross sections is significantly modified by nuclear final-state interaction (FSI) effects. However, there is no significant effect on the asymmetry $E$ since the $\sigma_{1/2}$ and $\sigma_{3/2}$ components appear to be influenced in a similar way. Thus, the best approximation of the two helicity-dependent cross sections for the free neutron is obtained by combining the asymmetry $E$ measured with quasi-free neutrons and the unpolarized cross section corrected for FSI effects under the assumption that the FSI effects are similar for neutrons and protons., Comment: accepted for publication in Phys. Lett. B

Published
2017
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20. Helicity-dependent cross sections and double-polarization observable E in η photoproduction from quasifree protons and neutrons

Author

H. J. Arends, V. Metag, S. Kay, David Manley, S. Garni, R. Kondratiev, J. R. M. Annand, K. Spieker, G. M. Huber, David Hamilton, K. Livingston, S. Lutterer, P. Pedroni, S. Gardner, A. Denig, N. S. Borisov, M. Biroth, F. Afzal, M. Oberle, W. Meyer, S. Wagner, C. Sfienti, F. Cividini, R. Miskimen, M. Unverzagt, G. Reicherz, A. Neiser, Igor Strakovsky, G. M. Gurevich, Z. Ahmed, Th. Strub, A. Rajabi, E. Mornacchi, D. I. Glazier, W. Gradl, I. Supek, Patrick Achenbach, I. J. D. MacGregor, M. Bashkanov, M. Günther, V. L. Kashevarov, A. Mushkarenkov, N. K. Walford, I. Keshelashvili, J. Wettig, M. Dieterle, P. Drexler, M. I. Ferretti-Bondy, M. Thiel, Yu. A. Usov, J. Mancell, O. Steffen, D. Paudyal, D. Glowa, A. Käser, P. B. Otte, Reinhard Beck, P. P. Martel, M. Korolija, W. J. Briscoe, A. Lazarev, L. Zana, V. Sokhoyan, T. Rostomyan, M. H. Sikora, C. Collicott, D. P. Watts, S. Abt, C. S. Akondi, A. B. Neganov, J. Linturi, A. J. Sarty, A. Polonski, M. Wolfes, B. Krusche, M. Ostrick, A. Thomas, A. Thiel, S. N. Prakhov, G. Ron, S. Costanza, Lilian Witthauer, A. Braghieri, D. Hornidge, V. Lisin, E. J. Downie, and D. Werthmüller

Subjects
Physics, Excitation function, Photon, 010308 nuclear & particles physics, Nuclear Theory, Bremsstrahlung, Polarization (waves), 01 natural sciences, Helicity, Nuclear physics, 0103 physical sciences, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon, Crystal Ball
Abstract

Precise helicity-dependent cross sections and the double-polarization observable E were measured for η photoproduction from quasifree protons and neutrons bound in the deuteron. The η→2γ and η→3π0→6γ decay modes were used to optimize the statistical quality of the data and to estimate systematic uncertainties. The measurement used the A2 detector setup at the tagged photon beam of the electron accelerator MAMI in Mainz. A longitudinally polarized deuterated butanol target was used in combination with a circularly polarized photon beam from bremsstrahlung of a longitudinally polarized electron beam. The reaction products were detected with the electromagnetic calorimeters Crystal Ball and TAPS, which covered 98% of the full solid angle. The results show that the narrow structure observed earlier in the unpolarized excitation function of η photoproduction off the neutron appears only in reactions with antiparallel photon and nucleon spin (σ1/2). It is absent for reactions with parallel spin orientation (σ3/2) and thus very probably related to partial waves with total spin 1/2. The behavior of the angular distributions of the helicity-dependent cross sections was analyzed by fitting them withLegendre polynomials. The results are in good agreement with a model from the Bonn-Gatchina group, which uses an interference of P11 and S11 partial waves to explain the narrow structure.

Published
2017
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21. The double spin asymmetry of nitrogen in elastic and quasielastic kinematics from a solid ammonia dynamically polarized target

Author

M. Friedman, Guy Ron, J. Campbell, Donal Day, Douglas Higinbotham, and A. J. Sarty

Subjects
Physics, Nuclear and High Energy Physics, Muon, Proton, 010308 nuclear & particles physics, Scattering, media_common.quotation_subject, Momentum transfer, Electron, 01 natural sciences, Asymmetry, 0103 physical sciences, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, 010306 general physics, Instrumentation, Beam (structure), media_common, Spin-½
Abstract

Solid ammonia (NH 3 ) is commonly used as a dynamically polarized proton target for electron and muon scattering cross-section asymmetry measurements. As spin 1 + particles, the 14N nuclei in the target are also polarized and contribute a non-trivial asymmetry background that should be addressed. We describe here a method to extract the nitrogen contribution to the asymmetry, and report the cross-section asymmetries of electron–nitrogen scattering at beam energies of E = 1 . 7 GeV and E = 2 . 2 GeV, and momentum transfer of Q 2 = 0 . 023 − 0 . 080 GeV2.

Published
2019
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22. Determination of the scalar polarizabilities of the proton using beam asymmetry $\Sigma_{3}$ Σ 3 in Compton scattering

Author

A. Käser, C. S. Akondi, Michaela Thiel, D. Hornidge, I. J. D. MacGregor, P. Ott, A. J. Sarty, D. M. Manley, R. Kondratiev, G. M. Gurevich, B. Krusche, M. Korolija, J. Ahrens, Durga Paudyal, M. Unverzagt, N. Krupina, M. Wolfes, M. Ostrick, P. P. Martel, Judith A. McGovern, S. N. Prakhov, F. Cividini, T. Rostomyan, J. Wettig, H. Ortega Spina, D. I. Glazier, D. Werthmüller, V. Sokhoyan, Lilian Witthauer, B. Oussena, A. Polonski, C. Collicott, A. Rajabi, A. G. Denig, I. Supek, V. Lensky, D. P. Watts, V. L. Kashevarov, I. Keshelashvili, Roderick M. Macrae, S. Schumann, M. Oberle, Andy Thomas, P. B. Otte, I. I. Strakovsky, S. Wagner, D. Glowa, V. Polyansky, E. Mornacchi, W. J. Briscoe, A. N. Mushkarenkov, M. Ferretti, J. Linturi, F. Afzal, P. Pedroni, M. Dieterle, W. Gradl, V. Lisin, A. Braghieri, Th. Strub, E. J. Downie, D. G. Middleton, G. M. Huber, S. Garni, R. A. Miskimen, K. Livingston, O. Steffen, B. Strandberg, S. Gardner, H. J. Arends, David Hamilton, Lorenzo Zana, A. Neiser, J. R. M. Annand, Susanna Costanza, and R. Beck

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, media_common.quotation_subject, Nuclear Theory, Scalar (physics), Compton scattering, Sigma, 01 natural sciences, Asymmetry, Nuclear physics, Dipole, Pion, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Nucleon, Microtron, media_common
Abstract

The scalar dipole polarizabilities, $\alpha_{E1}$ and $\beta_{M1}$, are fundamental properties related to the internal dynamics of the nucleon. The currently accepted values of the proton polarizabilities were determined by fitting to unpolarized proton Compton scattering cross section data. The measurement of the beam asymmetry $\Sigma_{3}$ in a certain kinematical range provides an alternative approach to the extraction of the scalar polarizabilities. At the Mainz Microtron (MAMI) the beam asymmetry was measured for Compton scattering below pion photoproduction threshold for the first time. The results are compared with model calculations and the influence of the experimental data on the extraction of the scalar polarizabilities is determined.

Published
2017
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23. TandFasymmetries inπ0photoproduction on the proton

Author

A. Nikolaev, I. J. D. MacGregor, G. Reicherz, P. Ott, D. Hornidge, J. R. M. Annand, B. Oussena, S. Cherepnya, D. I. Glazier, Reinhard Beck, P. Pedroni, A. B. Lazarev, V. L. Kashevarov, I. I. Strakovsky, E. F. McNicoll, M. Dieterle, T. Rostomyan, D. M. Manley, S. Garni, M. Korolija, L. V. Fil'kov, L. Tiator, D. G. Middleton, D. Howdle, C. Collicott, K. Livingston, I. Keshelashvili, D. P. Watts, W. Gradl, M. Oberle, N. S. Borisov, A. Braghieri, Th. Strub, M. Wolfes, A. J. Sarty, I. Supek, H. J. Arends, S. N. Prakhov, S. Schumann, M. Ostrick, David Hamilton, P. B. Otte, A. Fix, Andy Thomas, R. A. Miskimen, V. Lisin, W. Meyer, B. Krusche, H. Ortega, A. B. Neganov, G. M. Huber, Yu. A. Usov, O. Steffen, P. Hall Barrientos, W. J. Briscoe, A. N. Mushkarenkov, M. Unverzagt, E. J. Downie, R. Kondratiev, G. M. Gurevich, V. V. Polyanski, A. Polonski, Lilian Witthauer, D. Werthmüller, P. P. Martel, J. Mancel, and S. Costanza

Subjects
Physics, Particle physics, Photon, 010308 nuclear & particles physics, media_common.quotation_subject, Bremsstrahlung, Photon energy, 01 natural sciences, Asymmetry, Resonance (particle physics), Baryon, Nuclear physics, 0103 physical sciences, Physics::Accelerator Physics, Nuclear Experiment, 010306 general physics, Microtron, Crystal Ball, media_common
Abstract

The γp→π0p reaction was studied at laboratory photon energies from 425 to 1445 MeV with a transversely polarized target and a longitudinally polarized beam. The beam-target asymmetry F was measured for the first time and new high precision data for the target asymmetry T were obtained. The experiment was performed at the photon tagging facility of the Mainz Microtron (MAMI) using the Crystal Ball and TAPS photon spectrometers. The polarized cross sections were expanded in terms of associated Legendre functions and compared to recent predictions from several partial-wave analyses. The impact of the new data on our understanding of the underlying partial-wave amplitudes and baryon resonance contributions is discussed.

Published
2016
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24. High-precision measurement of the proton elastic form factor ratio μpGE/GM at low Q2

Author

F. Itard, P. E. Reimer, T. Holmstrom, William Bertozzi, John Arrington, S. Choi, A. Saha, Kalyan Allada, C. Dutta, Bogdan Wojtsekhowski, S. Strauch, Ronald Ransome, Xin Qian, Ishay Pomerantz, D. G. Meekins, X. Zhan, S. Riordan, R. Shneor, M. H. Shabestari, I. Vilardi, P. Solvignon, R. De Leo, W. U. Boeglin, R. Subedi, D. J. Margaziotis, R. Michaels, R. J. Holt, E. Piasetzky, J. P. Chen, M. Olson, B. Hahn, J. Glister, A. J. Sarty, E. Schulte, Simon Širca, J. Huang, Yujie Qiang, G. M. Huber, F. Garibaldi, K. Chirapatpimol, K. Hafidi, E. Chudakov, Yingxiao Wang, M. Johnson, S. May-Tal Beck, E. Cisbani, J. O. Hansen, Abdurahim Rakhman, Nikolaos Sparveris, Shalev Gilad, E. Fuchey, C. W. de Jager, Z. Ye, B. E. Norum, Y. Zhang, X. Jiang, E. Long, D. S. Armstrong, J. Reinhold, S. Frullani, D. Protopopescu, B. Moffit, A. Shahinyan, Douglas Higinbotham, R. A. Lindgren, J. J. LeRose, Guy Ron, Joseph M. Katich, B. Sawatzky, Vincent Sulkosky, P. Decowski, and Ronald Gilman

Subjects
Physics, Nuclear and High Energy Physics, Recoil, Proton, Hydrogen, chemistry, Charge radius, chemistry.chemical_element, Electron, Atomic physics, Polarization (waves), Exotic atom, Lamb shift
Abstract

We report a new, high-precision measurement of the proton elastic form factor ratio μ p G E / G M for the four-momentum transfer squared Q 2 = 0.3 – 0.7 ( GeV / c ) 2 . The measurement was performed at Jefferson Lab (JLab) in Hall A using recoil polarimetry. With a total uncertainty of approximately 1%, the new data clearly show that the deviation of the ratio μ p G E / G M from unity observed in previous polarization measurements at high Q 2 continues down to the lowest Q 2 value of this measurement. The updated global fit that includes the new results yields an electric (magnetic) form factor roughly 2% smaller (1% larger) than the previous global fit in this Q 2 range. We obtain new extractions of the proton electric and magnetic radii, which are 〈 r E 2 〉 1 / 2 = 0.875 ± 0.010 fm and 〈 r M 2 〉 1 / 2 = 0.867 ± 0.020 fm . The charge radius is consistent with other recent extractions based on the electron–proton interaction, including the atomic hydrogen Lamb shift measurements, which suggests a missing correction in the comparison of measurements of the proton charge radius using electron probes and the recent extraction from the muonic hydrogen Lamb shift.

Published
2011
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25. Polarization observables in deuteron photodisintegration below 360 MeV

Author

L. Coman, Karl Slifer, M. H. Shabestari, E. Kuchina, J. Dumas, J. Song, R. Michaels, Bogdan Wojtsekhowski, M. Olson, Young Do Oh, Hartmuth Arenhövel, Douglas Higinbotham, T. Holmstrom, M. K. Jones, R. Shneor, B. L. Berman, J. Glister, Arijit Saha, Yannick Rousseau, S. Choi, H. F. Ibrahim, Franco Garibaldi, W. Armstrong, K. Wang, Kalyan Allada, John Arrington, R. Sparks, E. J. Brash, M. Paolone, C. E. Hyde, Guy Ron, Salvatore Frullani, B. E. Norum, E. Chudakov, Hyekoo Kang, J. R. Calarco, H. Yao, P. Solvignon, J. O. Hansen, S. Širca, Ronald Ransome, E. Schulte, Ishay Pomerantz, Yujie Qiang, R. J. Feuerbach, B. Sawatzky, A. Beck, Andrew Puckett, J. Roche, J. P. Chen, Xin Qian, X. Zhu, G. Kumbartzki, R. Subedi, A. P. Freyberger, Byounghoon Lee, B. Craver, D. G. Meekins, C. F. Perdrisat, Kent Paschke, C. W. de Jager, R. Pomatsalyuk, Emily M. McCullough, F. Cusanno, M. Reyhan, Bryan J. Moffit, A. Shahinyan, C. Dutta, M. Potokar, Ronald Gilman, W. U. Boeglin, A. Camsonne, S. Strauch, E. Khrosinkova, M. Meziane, Pete Markowitz, G. M. Urciuoli, F. Benmokhtar, R. A. Lindgren, J. J. LeRose, A. Kelleher, Z. E. Meziani, X. Yan, E. Piasetzky, X. Jiang, S. May-Tal Beck, V. A. Punjabi, M. Schwamb, X. Zhan, Y. Ilieva, and A. J. Sarty

Subjects
Physics, Nuclear and High Energy Physics, Photon, Meson, 010308 nuclear & particles physics, Nuclear Theory, Polarization observables, FOS: Physical sciences, Polarization (waves), 01 natural sciences, Recoil proton, Nuclear physics, Baryon, Deuterium, Photodisintegration, 0103 physical sciences, Nuclear Experiment (nucl-ex), Atomic physics, Nuclear Experiment, 010306 general physics
Abstract

High precision measurements of induced and transferred recoil proton polarization in d(polarized gamma, polarized p})n have been performed for photon energies of 277--357 MeV and theta_cm = 20 degrees -- 120 degrees. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. At the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used., Comment: 5 pages, 2 figures

Published
2011
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26. First measurement of target and beam-target asymmetries in theγp→π0ηpreaction

Author

A. Nikolaev, S. N. Prakhov, Andy Thomas, P. P. Martel, V. L. Kashevarov, J. R. M. Annand, I. I. Strakovsky, C. Collicott, L. V. Fil'kov, D. P. Watts, T. Rostomyan, D. I. Glazier, Lilian Witthauer, D. M. Manley, M. Korolija, M. Ostrick, D. Howdle, D. G. Middleton, M. Oberle, B. Krusche, V. Lisin, V. V. Polyanski, D. Hornidge, M. Wolfes, A. B. Neganov, I. J. D. MacGregor, D. Werthmüller, A. J. Sarty, I. Supek, E. F. McNicoll, E. J. Downie, G. M. Huber, W. Gradl, G. Reicherz, J. Mancel, A. Polonski, R. Beck, H. Ortega, I. Keshelashvili, R. Kondratiev, S. Cherepnya, M. Unverzagt, S. Costanza, G. M. Gurevich, P. Pedroni, S. Schumann, David Hamilton, S. Garni, M. Dieterle, B. Oussena, K. Livingston, W. Meyer, P. B. Otte, N. S. Borisov, W. J. Briscoe, A. N. Mushkarenkov, H. J. Arends, A. Fix, L. Tiator, P. Hall Barrientos, A. B. Lazarev, A. Braghieri, Th. Strub, P. Ott, R. A. Miskimen, Yu. A. Usov, and O. Steffen

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Photon, Meson, Partial wave analysis, Bremsstrahlung, Physics::Accelerator Physics, Photon energy, Nuclear Experiment, Nucleon, Microtron, Crystal Ball
Abstract

The first data on target and beam-target asymmetries for the gamma p -> pi(0)eta p reaction at photon energies from 1050 up to 1450 MeV are presented. The measurements were performed using the Crystal Ball and TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. The general assumption that the reaction is dominated by the Delta 3/2-amplitude is confirmed. The data are in particular sensitive to small contributions from other partial waves.

Published
2015
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27. Spectroscopy ofLiΛ9by electroproduction

Author

T. Miyoshi, P. Brindza, V. A. Punjabi, W. U. Boeglin, X. Jiang, Bogdan Wojtsekhowski, L. Lagamba, D. J. Millener, E. Cisbani, L. Coman, V. Sulkosky, Pete Markowitz, H. Ueno, S. Marrone, R. Michaels, V. M. Rodriguez, Jaideep Singh, B. E. Norum, P. E. Reimer, K. Kino, B. Reitz, R. De Leo, Pavlo Baturin, S. K. Nanda, Yujie Qiang, P. Bydžovský, P.Y. Bertin, S. Colilli, C. Munoz Camacho, H. Breuer, Y. Okasyasu, Vladimir Nelyubin, Z. E. Meziani, Salvatore Frullani, M. Lucentini, J. P. Chen, G. de Cataldo, L. J. Kaufman, G. M. Urciuoli, A. Shahinyan, K. A. Aniol, Franco Garibaldi, Joerg Reinhold, C. E. Hyde, F. Cusanno, A. Deur, Simon Širca, B. Kross, Douglas Higinbotham, Kent Paschke, Tohru Suzuki, E. Piasetzky, M. Gricia, Eugenio Nappi, J. Gomez, A. Acha, D. J. Margaziotis, P. E. Ulmer, C. Zorn, Mauro Iodice, C. C. Chang, D. Hayes, H. Benaoum, H. F. Ibrahim, R. A. Lindgren, J. J. LeRose, A. Saha, X. Zheng, R. J. Feuerbach, P. Veneroni, R. Fratoni, P. Ambrozewicz, Seonho Choi, K. I. Blomqvist, E. Chudakov, C. Ferdi, T. Holmstrom, J. O. Hansen, K. McCormick, J. Segal, A. Camsonne, A. J. Sarty, R. Subedi, Maryam Moteabbed, M. Sotona, Olivier Gayou, R. Snyder, C. W. de Jager, Bryan J. Moffit, R. Roche, F. Giuliani, P. Monaghan, B. Craver, C. F. Perdrisat, E. Folts, F. Santavenere, E. Voutier, and P. Solvignon

Subjects
Superconductivity, Physics, Nuclear and High Energy Physics, Nuclear Theory, Order (ring theory), Atomic physics, Nuclear Experiment, Ground state, Hypernucleus, Spectroscopy, Lambda, Energy (signal processing), Spectral line
Abstract

Background: In the absence of accurate data on the free two-body hyperon-nucleon interaction, the spectra of hypernuclei provides information on the details of the effective hyperon-nucleon interaction.Purpose: To obtain a high-resolution binding-energy spectrum for the ${}^{9}\mathrm{Be}(e,{e}^{\ensuremath{'}}{K}^{+})_{\ensuremath{\Lambda}}^{9}\mathrm{Li}$ reaction.Method: Electroproduction of the hypernucleus $_{\ensuremath{\Lambda}}^{9}\mathrm{Li}$ has been studied for the first time with sub-MeV energy resolution in Hall A at Jefferson Lab on a $^{9}\mathrm{Be}$ target. In order to increase the counting rate and to provide unambiguous kaon identification, two superconducting septum magnets and a ring imaging Cherenkov detector were added to the Hall A standard equipment.Results: The cross section to low-lying states of $_{\ensuremath{\Lambda}}^{9}\mathrm{Li}$ is concentrated within 3 MeV of the ground state and can be fit with four peaks. The positions of the doublets agree with theory while a disagreement could exist with respect to the relative strengths of the peaks in the doublets. The $\ensuremath{\Lambda}$ separation energy, ${B}_{\ensuremath{\Lambda}}$, of $8.36\ifmmode\pm\else\textpm\fi{}0.08$ (stat.) $\ifmmode\pm\else\textpm\fi{}0.08$ (syst.) MeV was measured, in agreement with an earlier experiment.

Published
2015
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28. A new measurement of the neutron detection efficiency for the NaI Crystal Ball detector

Author

D. Hornidge, Th. Strub, J. Linturi, Steffen Schumann, R. Miskimen, V. Sokhoyan, A. Lazarev, B. Krusche, T. Rostomyan, R. Kondratiev, I. Supek, H. J. Arends, I. J. D. MacGregor, D. Glowa, W. Gradl, M. I. Ferretti Bondy, S. Wagner, A. B. Neganov, D. Schott, C. S. Akondi, David Manley, P. Pedroni, Yu. A. Usov, O. Steffen, M. Ostrick, A. J. Sarty, S. Cherepnya, B. Demissie, G. M. Gurevich, P. P. Martel, J. Wettig, S. N. Prakhov, P. Ott, A. Braghieri, B. Oussena, M. Korolija, L. V. Fil'kov, V. L. Kashevarov, Reinhard Beck, C. Collicott, S. Costanza, K. Livingston, D. P. Watts, A. Kaeser, Lilian Witthauer, M. Thiel, N. S. Borisov, Guy Ron, A. Neiser, V. Lisin, A. Polonski, M. Oberle, W. J. Briscoe, M. Dieterle, P. B. Otte, M. A. Martemianov, M. Unverzagt, D. G. Middleton, S. Garni, Z. Marinides, Anthony W. Thomas, D. I. Glazier, A. Mushkarenkov, G. M. Huber, Igor Strakovsky, M. Wolfes, E. J. Downie, Jrm Annand, V. V. Kulikov, D. Werthmüller, and I. Keshelashvili

Subjects
Physics, Physics - Instrumentation and Detectors, Physics::Instrumentation and Detectors, Detector, Nuclear Theory, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), Neutron temperature, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion beam, Deuterium, Neutron detection, Physics::Accelerator Physics, High Energy Physics::Experiment, Photon beam, Nuclear Experiment (nucl-ex), Nuclear Experiment, Instrumentation, Microtron, Mathematical Physics, Crystal Ball
Abstract

We report on a measurement of the neutron detection efficiency in NaI crystals in the Crystal Ball detector obtained from a study of single π0 photoproduction on deuterium using the tagged photon beam at the Mainz Microtron. The results were obtained up to a neutron energy of 400 MeV . They are compared to previous measurements made more than 15 years ago at the pion beam at the BNL AGS.

Published
2015

29. Performance of a compact detector package for the out-of-plane spectrometer system

Author

Nilanga Liyanage, Ricardo Alarcon, S. Dolfini, J. R. Comfort, S. Kowalski, J. Zhao, Shalev Gilad, C. Vellidis, S. Sobczynski, K. Joo, P. Bourgeois, K. A. Dow, J. Kirkpatrick, R. S. Hicks, T. McIlvain, A. Dooley, Costas N. Papanicolas, D. S. Dale, S. Georgakopoulos, C. Mertz, C. Tschalaer, S. B. Soong, I. Nakagawa, Jian-Ping Chen, E. Six, R. A. Miskimen, M. Farkhondeh, D. J. Margaziotis, J. R. Calarco, G. A. Peterson, W. Turchinetz, C. Kunz, Nikolaos Sparveris, M. O. Distler, D. R. Tieger, N. I. Kaloskamis, A. Hotta, Glen A. Warren, D. Jordan, J. Shaw, A. J. Sarty, Ross Milner, S. Stiliaris, F. Casagrande, T. Zwart, Tancredi Botto, M. Pavan, Aron M. Bernstein, Z.-L. Zhou, Joseph B. Mandeville, S. E. Williamson, Tadaaki Tamae, X. Jiang, M. Holtrop, S. Širca, W. Boeglin, Larry Weinstein, William Bertozzi, G. Tsentalovich, A. F. Ramirez, G. W. Dodson, Yutaro Sato, S. Stave, A. Karabarbounis, R. Beck, M. B. Epstein, A. Young, and D. Rowntree

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Pion, Spectrometer, Detector, Compton scattering, Electron, Nuclear Experiment, Instrumentation, Electron scattering, Linear particle accelerator, Particle identification
Abstract

We report on the design and performance of compact detector packages currently installed in the four magnetic out-of-plane spectrometers for electron scattering experiments at the MIT-Bates Linear Accelerator Center. The detector packages have been designed to meet the mechanical requirements arising from out-of-plane particle detection. They offer good trajectory and momentum reconstruction, particle identification and time-of-flight measurements for electrons, pions, protons, and deuterons with large momentum bites and in broad kinematical ranges and high luminosities. The detectors have so far been used with great success in out-of-plane measurements of 12 C ( e → , e ′ p ) , 2 H ( e → , e ′ p ) , virtual Compton scattering below pion threshold and in studies of the N → Δ transition in both exclusive reaction channels 1 H ( e → , e ′ p ) π 0 and 1 H ( e → , e ′ π + )n .

Published
2002
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30. Measurements of Double-Polarized Compton Scattering Asymmetries and Extraction of the Proton Spin Polarizabilities

Author

B. Oussena, D. P. Watts, I. Keshelashvili, I. I. Strakovsky, A. B. Lazarev, A. Nikolaev, I. Supek, D. Howdle, A. Braghieri, S. N. Prakhov, G. Reicherz, K. Livingston, T. C. Jude, M. H. Sikora, B. M. K. Nefkens, Th. Strub, M. Unverzagt, S. Schrauf, N. S. Borisov, Michaela Thiel, V. L. Kashevarov, David Hamilton, C. S. Akondi, D. M. Manley, M. Korolija, L. Tiator, W. J. Briscoe, P. Hall Barrientos, Anthony W. Thomas, D. Hornidge, M. Ostrick, D. I. Glazier, W. Meyer, P. P. Martel, P. Pedroni, I. J. D. MacGregor, A. Starostin, A. J. Sarty, A. Rajabi, S. Garni, R. Kondratiev, R. A. Miskimen, A. Kaeser, A. N. Mushkarenkov, S. Schumann, B. Krusche, J. Ahrens, G. M. Gurevich, G. M. Huber, J. R. M. Annand, A. G. Denig, Yu. A. Usov, E. J. Downie, Lilian Witthauer, P. Aguar-Bartolomé, P. B. Otte, A. B. Neganov, T. Rostomyan, L. V. Fil'kov, W. Barnes, C. Collicott, D. Werthmüller, S. Cherepnya, M. Wolfes, A. Polonski, W. Gradl, J. Mancell, Susanna Costanza, M. Oberle, R. Beck, M. Dieterle, Aron M. Bernstein, H. J. Arends, D. G. Middleton, O. Steffen, V. Polyansky, V. Lisin, H. Ortega Spina, and P. Ott

Subjects
Physics, Photon, Proton, Nuclear Theory, Compton scattering, General Physics and Astronomy, FOS: Physical sciences, 7. Clean energy, 3. Good health, Baryon, Nuclear physics, Proton spin crisis, spin polarizabilities, nucleon, photon, ∆(1232) region, MAMI, Nuclear Experiment (nucl-ex), Nucleon, Nuclear Experiment, Microtron, Spin-½
Abstract

The spin polarizabilities of the nucleon describe how the spin of the nucleon responds to an incident polarized photon. The most model-independent way to measure the nucleon spin polarizabilities is through polarized Compton scattering. Double-polarized Compton scattering asymmetries on the proton were measured in the $\Delta(1232)$ region using circularly polarized incident photons and a transversely polarized proton target at the Mainz Microtron. Fits to asymmetry data were performed using a dispersion model calculation and a baryon chiral perturbation theory calculation, and a separation of all four proton spin polarizabilities in the multipole basis was achieved. The analysis based on a dispersion model calculation yields $\gamma_{E1E1} = -3.5 \pm 1.2$, $\gamma_{M1M1}= 3.16 \pm 0.85$, $\gamma_{E1M2} = -0.7 \pm 1.2$, and $\gamma_{M1E2} = 1.99 \pm 0.29$, in units of $10^{-4}$ fm$^4$., Comment: 5 pages, 3 figures, 2 tables

Published
2014

31. Dynamics of the16O(e,e′p)Reaction at High Missing Energies

Author

C. Cavata, A. Soldi, A. J. Sarty, Y. Roblin, Paul Souder, T. Pussieux, K. Wijesooriya, Ronald Ransome, S. Malov, Shalev Gilad, E. Burtin, M. Liang, C. W. de Jager, K. A. Aniol, M. Holtrop, E. A.J.M. Offermann, Wolfgang Korsch, B. Doyle, G. Quéméner, P. Djawotho, T. Terasawa, Vincent Breton, A. Gasparian, A. V. Glamazdin, K. Joo, D. Rowntree, R. Holmes, C. R. Howell, D. M. Manley, J. R. Calarco, R. W. Lourie, O. Ravel, J. W. Watson, Justin I. McIntyre, J. Gao, E. J. Brash, W. U. Boeglin, B. D. Anderson, G. J. Lolos, M. B. Epstein, G. M. Urciuoli, J. A. Templon, W. Kahl, C. E. Hyde-Wright, S. Kerhoas, A. Serdarevic-Offermann, N. d'Hose, F. T. Baker, C. F. Perdrisat, S. Platchkov, Kazushige Maeda, A. Deur, G. M. Huber, T. Saito, J. Martino, L. Auerbach, Bogdan Wojtsekhowski, J. Domingo, J. Berthot, J. Y. Mougey, R. I. Pomatsalyuk, A. Saha, L. Bimbot, H. Ueno, Kevin Fissum, Z. Papandreou, T. P. Smith, Jian-Ping Chen, L. Todor, A. Leone, James J. Kelly, Seigo Kato, P.Y. Bertin, Nilanga Liyanage, G. Rutledge, Hiroaki Tsubota, Z. L. Zhou, Richard Wilson, Branislav Vlahovic, H. Fonvieille, Gordon D. Cates, Mauro Iodice, Larry Weinstein, G. Laveissière, R. Suleiman, E. Cisbani, William Bertozzi, S. Nanda, G. Kumbartzki, Jing Zhao, R. Madey, D. G. Zainea, Ronald Gilman, R. Roche, D. S. Dale, K. McCormick, R. Michaels, L. Cardman, P. E. Ulmer, V. Zeps, S. van Verst, Pete Markowitz, J. M. Finn, S. Jaminion, H. Breuer, J. Gomez, J.E. Ducret, M. Khandaker, R. A. Lindgren, J. J. LeRose, M. Khayat, H. Voskanyan, C. Jutier, D. Neyret, V. Gorbenko, Roberto Perrino, R. De Leo, F. W. Hersman, L. A. Ewell, B. Diederich, Laird Kramer, M. K. Jones, G. G. Petratos, J. S. McCarthy, T. P. Gorringe, Z. E. Meziani, P. M. Rutt, Leonid Levchuk, David L. Prout, F. Garibaldi, V. A. Punjabi, S. Frullani, P. Vernin, R. L.J. van der Meer, D. J. Margaziotis, C. C. Chang, K. S. Kumar, Pavel Sorokin, K. Kino, B. Frois, and Charles Glashausser

Subjects
Physics, Proton, 010308 nuclear & particles physics, Nuclear Theory, General Physics and Astronomy, 01 natural sciences, Nuclear physics, Cross section (geometry), Pion, 0103 physical sciences, Isobar, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract

We measured the cross section and response functions for the quasielastic 16O(e,e'p) reaction for missing energies 25< or =E(m)< or =120 MeV at missing momenta P(m)< or =340 MeV/c. For 25

Published
2001
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32. Search for Quadrupole Strength in the Electroexcitation of theΔ+(1232)

Author

A. J. Sarty, C. Mertz, B. D. Milbrath, J. Chen, C. F. Perdrisat, K. Joo, R. W. Lourie, K. Dow, J. J. Kelly, A. Bernstein, W. Bertozzi, G. A. Warren, D. H. Barkhuff, J. H. Mitchell, P. E. Ulmer, N. Kaloskamis, D. Tieger, R. J. Woo, C. Papanicolas, J. R. Comfort, J. M. Finn, J. I. McIntyre, S. Dolfini, C. Tschalær, W. Turchinetz, R. Miskimen, C. Kunz, G. Dodson, V. Burkert, L. Weinstein, M. Farkhondeh, A. Karabarbounis, S. Kowalski, J. Shaw, A. Young, S. E. Williamson, C. Vellidis, S. Van Verst, S. Soong, S. Gilad, Ricardo Alarcon, X. Jiang, and R. W. Gothe

Subjects
Delta, Nuclear physics, Physics, Cross section.transverse, Amplitude, Quadrupole, General Physics and Astronomy, Angular dependence, Excitation
Abstract

High precision 1H(e, e'p)pi0 measurements at Q2 = 0.126. (GeV/c)2 are reported, which allow the determination of quadrupole amplitudes in the gamma*N --> Delta transition; they simultaneously test the reliability of electroproduction models. The derived quadrupole-to-dipole (I = 3/2) amplitude ratios, RSM = (-6.5 +/- 0.2stat+sys+/-2.5mod)% and REM = 9-2.1 +/-0.2stat+sys +/-2.0mod)%, are dominated by model error. Previous RSM and REM results should be reconsidered after the model uncertainties associated with the method of their extraction are taken into account.

Published
2001
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33. Theep→e′pηReaction at and above theS11(1535)Baryon Resonance

Author

M. J. Amaryan, M. Taiuti, S. K. Matthews, J. Ficenec, Gyurjyan, W. Kim, A. Longhi, R. A. Schumacher, B. E. Bonner, L. Elouadrhiri, A. P. Freyberger, R. Magahiz, Robert E. Welsh, S. Dytman, S. Whisnant, B. M. Preedom, Federico Ronchetti, R. J. Feuerbach, K. L. Giovanetti, B. Asavapibhop, Michael Dugger, Shalev Gilad, De Sanctis E, A. V. Vlassov, G. Ricco, J. R. Kane, H. Avakian, Philip L. Cole, J. P. Cummings, G. S. Adams, Larry Weinstein, R. A. Miskimen, K. Joo, J. Shaw, R. W. Major, Moshe Gai, M. Kossov, W. J. Briscoe, D. Rowntree, D. Doughty, K. Beard, W. K. Brooks, Friedrich Klein, R. S. Hicks, Brian Raue, Kevin Fissum, Kalvir S. Dhuga, Barry Ritchie, A. Coleman, K. A. Griffioen, M. M. Ito, G. Riccardi, L. M. Qin, J. J. Manak, M. Mirazita, J. M. Laget, C. E. Hyde-Wright, J. W C McNabb, M. S. Ohandjanyan, D. Heddle, C. Salgado, H. R. Weller, Roy Thompson, Curtis Smith, D. P. Weygand, Herbert O. Funsten, S. A. Philips, Patrick Girard, Y. Kuang, H. Egiyan, M. Witkowski, Bernhard Mecking, Mestayer, A. J. Sarty, Jing Zhao, S. Stepanyan, De Vita R, D. G. Jenkins, C. Djalali, Z. L. Zhou, M. Lucas, Airton Deppman, D. I. Sober, A. Shafi, D. Hancock, Avraham Klein, Leskin Ga, M. Battaglieri, S. McAleer, William Bertozzi, E. Polli, E. Anciant, L. Farhi, G. E. Dodge, Daniel S. Carman, V. B. Gavrilov, O. Pogorelko, A. K. Opper, G. Audit, J. W. Price, M. Khandaker, E. Wolin, P. V. Degtyarenko, Y. Patois, Gerard Gilfoyle, Dinko Pocanic, L.C. Dennis, K. Loukachine, N. Pivnyuk, M. Bektasoglu, S. E. Kuhn, S. M. Shuvalov, D. Lawrence, M. Eckhause, J. Napolitano, M. Ripani, M. Guillo, Jochen Heisenberg, Y. V. Efremenko, Volker D. Burkert, M. Sanzone, J. Connelly, Donal Day, M. Sargsyan, G. A. Peterson, M. Guidal, A. V. Skabelin, J. Yun, D. Cords, A. Yegneswaran, A. S. Biselli, Elton Smith, S. Barrow, M. Holtrop, Thomas E. Smith, G. S. Mutchler, M. Anghinolfi, Hall Crannell, D. G. Crabb, James Mueller, S. Taylor, P. D. Rubin, G. Capitani, F. Roudot, D. J. Tedeschi, Y. G. Sharabian, M. Spraker, Sapunenko, R. C. Minehart, M. Klusman, Nicola Bianchi, S. Boiarinov, C. A. Meyer, J. S. McCarthy, B. Carnahan, Thierry Auger, A. R. Reolon, Michael Vineyard, C. Marchand, P. Rossi, P. Dragovitsch, F. W. Hersman, R. A. Demirchyan, T. Y. Tung, J. Hardie, K. Y. Kim, Muccifora, R. A. Niyazov, John T. O'Brien, P. Corvisiero, K. S. Egiyan, Calarco, P. Stoler, and K. Hicks

Subjects
Baryon, Physics, Nuclear physics, Particle physics, Photon, Amplitude, Angular distribution, Meson, Momentum transfer, General Physics and Astronomy, Resonance, Invariant (physics), Nuclear Experiment
Abstract

New cross sections for the reaction e p-->e p eta are reported for total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 = 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction of important new information about response functions, photocouplings, and eta N coupling strengths of baryon resonances. Newly observed structure at W approximately 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.

Published
2001
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34. Dynamical Relativistic Effects in Quasielastic1p-Shell Proton Knockout fromO16

Author

C. E. Hyde-Wright, D. J. Margaziotis, J. Martino, Nilanga Liyanage, C. R. Howell, K. Kino, M. Liang, Richard Wilson, J. R. Calarco, G. Quéméner, T. P. Smith, A. V. Glamazdin, Kazushige Maeda, Branislav Vlahovic, R. Suleiman, E. Cisbani, G. M. Urciuoli, K. Joo, S. Frullani, R. W. Lourie, R. Roche, S. Platchkov, D. Rowntree, Paul Souder, Y. Roblin, T. Terasawa, Vincent Breton, Bogdan Wojtsekhowski, W. Kahl, P. Vernin, T. Pussieux, J. M. Finn, J. Gao, J. Gomez, C. F. Perdrisat, B. Frois, Jian-Ping Chen, K. Wijesooriya, W. Korsh, O. Ravel, Hiroaki Tsubota, Ronald Ransome, Seigo Kato, R. L.J. van der Meer, S. Malov, E. Burtin, J. A. Templon, S. Kerhoas, J. W. Watson, M. Holtrop, B. Doyle, S. van Verst, R. Holmes, Z. Papandreou, R. A. Lindgren, J. J. LeRose, H. Voskanyan, C. Jutier, P. M. Rutt, A. Gasparian, G. Rutledge, F. T. Baker, G. M. Huber, David L. Prout, V. Gorbenko, M. Khayat, Charles Glashausser, B. D. Anderson, G. J. Lolos, M. B. Epstein, Mauro Iodice, L. Auerbach, A. Saha, H. Ueno, L. Todor, A. Leone, J. Berthot, Larry Weinstein, William Bertozzi, D. S. Dale, L. Cardman, S. Jaminion, Pete Markowitz, L. Bimbot, G. G. Petratos, Z. E. Meziani, M. Khandaker, V. Zeps, W. U. Boeglin, Leonid Levchuk, Roberto Perrino, R. De Leo, D. Neyret, V. A. Punjabi, B. Diederich, D. G. Zainea, C. C. Chang, K. S. Kumar, T. Saito, Pavel Sorokin, H. Fonvieille, G. Kumbartzki, J. Y. Mougey, F. Garibaldi, T. P. Gorringe, P. E. Ulmer, Z. L. Zhou, G. Laveissière, J. S. McCarthy, P. Djawotho, P.Y. Bertin, J.E. Ducret, Ronald Gilman, K. McCormick, M. K. Jones, A. Serdarevic-Offermann, A. Deur, H. Breuer, F. W. Hersman, L. A. Ewell, James J. Kelly, R. I. Pomatsalyuk, S. Nanda, Shalev Gilad, D. M. Manley, C. W. de Jager, K. A. Aniol, E. A.J.M. Offermann, J. Domingo, K. A. Griffioen, C. Cavata, A. Soldi, A. J. Sarty, Gordon D. Cates, Laird Kramer, R. Madey, E. J. Brash, Kevin Fissum, Jing Zhao, R. Michaels, Justin I. McIntyre, and N. d'Hose

Subjects
Physics, Nuclear reaction, Proton, 010308 nuclear & particles physics, Hadron, General Physics and Astronomy, Elementary particle, 01 natural sciences, Omega, Baryon, 0103 physical sciences, Atomic physics, 010306 general physics, Nucleon, Relativistic quantum chemistry
Abstract

We have measured the cross section for quasielastic 1p -shell proton knockout in the {sup 16}O( e, e{sup '}p) reaction at {omega}=0.439 GeV and Q{sup 2}=0.8 (GeV/c){sup 2} for missing momentum P{sub miss}{

Published
2000
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35. GEp/GMpRatio by Polarization Transfer ine→p→ep→

Author

M. K. Jones, K. A. Aniol, F. T. Baker, J. Berthot, P. Y. Bertin, W. Bertozzi, A. Besson, L. Bimbot, W. U. Boeglin, E. J. Brash, D. Brown, J. R. Calarco, L. S. Cardman, C.-C. Chang, J.-P. Chen, E. Chudakov, S. Churchwell, E. Cisbani, D. S. Dale, R. De Leo, A. Deur, B. Diederich, J. J. Domingo, M. B. Epstein, L. A. Ewell, K. G. Fissum, A. Fleck, H. Fonvieille, S. Frullani, J. Gao, F. Garibaldi, A. Gasparian, G. Gerstner, S. Gilad, R. Gilman, A. Glamazdin, C. Glashausser, J. Gomez, V. Gorbenko, A. Green, J.-O. Hansen, C. R. Howell, G. M. Huber, M. Iodice, C. W. de Jager, S. Jaminion, X. Jiang, W. Kahl, J. J. Kelly, M. Khayat, L. H. Kramer, G. Kumbartzki, M. Kuss, E. Lakuriki, G. Lavessière, J. J. LeRose, M. Liang, R. A. Lindgren, N. Liyanage, G. J. Lolos, R. Macri, R. Madey, S. Malov, D. J. Margaziotis, P. Markowitz, K. McCormick, J. I. McIntyre, R. L. J. van der Meer, R. Michaels, B. D. Milbrath, J. Y. Mougey, S. K. Nanda, E. A. J. M. Offermann, Z. Papandreou, C. F. Perdrisat, G. G. Petratos, N. M. Piskunov, R. I. Pomatsalyuk, D. L. Prout, V. Punjabi, G. Quéméner, R. D. Ransome, B. A. Raue, Y. Roblin, R. Roche, G. Rutledge, P. M. Rutt, A. Saha, T. Saito, A. J. Sarty, T. P. Smith, P. Sorokin, S. Strauch, R. Suleiman, K. Takahashi, J. A. Templon, L. Todor, P. E. Ulmer, G. M. Urciuoli, P. Vernin, B. Vlahovic, H. Voskanyan, K. Wijesooriya, B. B. Wojtsekhowski, R. J. Woo, F. Xiong, G. D. Zainea, and Z.-L. Zhou

Subjects
Elastic scattering, Physics, Proton, 010308 nuclear & particles physics, Proton magnetic moment, General Physics and Astronomy, Electron, Polarization (waves), 01 natural sciences, Charged particle, Nuclear physics, Magnetization, 0103 physical sciences, Magnetic form factor, Physics::Accelerator Physics, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract

The ratio of the proton's elastic electromagnetic form factors was obtained by measuring the transverse and longitudinal polarizations of recoiling protons from the elastic scattering of polarized electrons with unpolarized protons. The ratio of the electric to magnetic form factor is proportional to the ratio of the transverse to longitudinal recoil polarizations. The ratio was measured over a range of four-momentum transfer squared between 0.5 and 3.5 GeV-squared. Simultaneous measurement of transverse and longitudinal polarizations in a polarimeter provides good control of the systematic uncertainty. The results for the ratio of the proton's electric to magnetic form factors show a systematic decrease with increasing four momentum squared, indicating for the first time a marked difference in the spatial distribution of charge and magnetization currents in the proton.

Published
2000
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36. The bremsstrahlung tagged photon beam in Hall B at JLab

Author

W. R. Dodge, Hall Crannell, B. L. Berman, M. Khandaker, M. Klusman, D. I. Sober, Barry Ritchie, E. Anciant, D. Lawrence, C. Salgado, Elton Smith, Philip L. Cole, Michael Dugger, Thierry Auger, S. A. Philips, J.M. Lambert, A. Longhi, Jim Napolitano, A. J. Sarty, J. Connelly, C. Marchand, L. Y. Murphy, S. K. Matthews, G. Audit, John T. O'Brien, and W. J. Briscoe

Subjects
Physics, Nuclear and High Energy Physics, Photon, Physics::Instrumentation and Detectors, Bremsstrahlung, Scintillator, Photon energy, Nuclear physics, Beamline, Hodoscope, Dipole magnet, Physics::Accelerator Physics, Instrumentation, Beam (structure)
Abstract

We describe the design and commissioning of the photon tagging beamline installed in experimental Hall B at the Thomas Jefferson National Accelerator Facility (JLab). This system can tag photon energies over a range from 20% to 95% of the incident electron energy, and is capable of operation with beam energies up to 6.1 GeV. A single dipole magnet is combined with a hodoscope containing two planar arrays of plastic scintillators to detect energy-degraded electrons from a thin bremsstrahlung radiator. The first layer of 384 partially overlapping small scintillators provides photon energy resolution, while the second layer of 61 larger scintillators provides the timing resolution necessary to form a coincidence with the corresponding nuclear interaction triggered by the tagged photon. The definitions of overlap channels in the first counter plane and of geometric correlation between the two planes are determined using digitized time information from the individual counters. Auxiliary beamline devices are briefly described, and performance results to date under real operating conditions are presented. The entire photon-tagging system has met or exceeded its design goals.

Published
2000
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37. Measurement of recoil proton polarizations in the electrodisintegration of deuterium by polarized electrons

Author

Shalev Gilad, C. Vellidis, K. A. Dow, K. Joo, J. M. Finn, C. Tschalaer, C. S. Armstrong, A. J. Sarty, Paul Ulmer, D. R. Tieger, D. Liu, Jiahao Chen, P. M. Rutt, D. S. Dale, L.M. Qin, John C. Mitchell, P. Markowitz, S. Kowalski, D.H. Barkhuff, M. Farkhondeh, C. Mertz, R.W. Lourie, Richard Madey, Larry Weinstein, William Bertozzi, M. K. Jones, S.P. Van Verst, B.D. Milbrath, D. J. Margaziotis, Glen A. Warren, V. A. Punjabi, S. Mukhopadhyay, M. Epstein, G. W. Dodson, J. McIntyre, James J. Kelly, W. Turchinetz, C. F. Perdrisat, and R. J. Woo

Subjects
Physics, Nuclear and High Energy Physics, Spin polarization, Scattering, Nuclear Theory, Electron, Polarization (waves), Induced polarization, Nuclear physics, Recoil, Deuterium, Neutron, Atomic physics, Nuclear Experiment
Abstract

In order to test modern theories of two-nucleon bound and scattering states, we have measured the spin polarization of ejectile protons in the electrodisintegration reaction d( e → ,e′ p → )n . Compared with spin-averaged observations, these observables offer the potential of enhanced sensitivity to details of the reaction process. The experiment was carried out in quasielastic kinematics ( q μ q μ =−2m p ω=−0.38 GeV2/c2). Protons were detected at two angles corresponding to neutron recoil momenta pr of 0 and 100 MeV/c. Full nonrelativistic calculations of the polarization transfer components sl and st, including leading order relativistic contributions, describe our measurements well, but calculations of the induced polarization sn at pr=100 MeV/c underpredict the experimental result.

Published
1999
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38. High-Precision Studies of theH3e(e,e′p)Reaction at the Quasielastic Peak

Author

M. Kahrau, J. P. Chen, Jing Zhao, Th. Walcher, J. A. Templon, J.M. Friedrich, R. Geiges, G. Rosner, Achim Richter, D. J. Margaziotis, R. E. J. Florizone, P. Bartsch, William Bertozzi, U. Müller, R. Böhm, Klemen Bohinc, K. Merle, Konrad Aniol, E. A. J. M. Offermann, I. Ewald, K. W. Krygier, A. Wagner, W.U. Boeglin, M. O. Distler, M. B. Epstein, Simon Širca, Z. L. Zhou, D. S. Dale, R. Neuhausen, Th. Pospischil, S.P. Van Verst, G. Schrieder, P. Jennewein, A. J. Sarty, Shalev Gilad, M. Kuss, M. Potokar, H. Schmieden, A. Liesenfeld, and Harald Merkel

Subjects
Baryon, Nuclear reaction, Physics, Nuclear physics, Momentum, Nuclear Theory, Hadron, Momentum transfer, General Physics and Astronomy, Elementary particle, Nuclear Experiment, Nucleon, Microtron
Abstract

Precision studies of the reaction [sup 3]He( e,thinspe[sup [prime]]p) using the three-spectrometer facility at the Mainz microtron MAMI are presented. All data are for quasielastic kinematics at [vert bar][rvec q][vert bar]=685 MeV/c . Absolute cross sections were measured at three electron kinematics. For the measured missing momenta range from 10 to 165 MeV/c , no strength is observed for missing energies higher than 20thinspthinspMeV. Distorted momentum distributions were extracted for the two-body breakup and the continuum. The longitudinal and transverse nature of the cross sections is well described by a widely used prescription of the off-shell electron-nucleon cross section. The results are compared to modern three-body calculations and to previous data. [copyright] [ital 1999] [ital The American Physical Society]

Published
1999
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39. Measurements of the Deuteron Elastic Structure FunctionA(Q2)for0.7≤Q2≤6.0(GeV/c)2at Jefferson Laboratory

Author

Paul Souder, Z. L. Zhou, E. Burtin, R. I. Pomatsalyuk, D. S. Dale, N. d'Hose, Ch. Hyde-Wright, J. O. Hansen, T. Saito, H. Breuer, K. Arundell, Seigo Kato, W. M. Zhang, C. R. Howell, J. R. Calarco, S. Nanda, L. Auerbach, K. Wijesooriya, Kevin Fissum, G. M. Huber, G. Rutledge, R. W. Lourie, J. Domingo, Y. Roblin, H. Fonvieille, L. Bimbot, T. P. Smith, S. Frullani, E. Chudakov, P. E. Ulmer, L. A. Ewell, Nilanga Liyanage, Pierre Bertin, Mauro Iodice, S. Mehrabyan, G. W. Miller, S. Malov, P. Vernin, Bogdan Wojtsekhowski, Larry Weinstein, L. C. Alexa, R. Madey, W. Kahl, R. A. Lindgren, Richard Wilson, H. Voskanyan, Branislav Vlahovic, Charles Glashausser, C. Jutier, J. J. LeRose, M. Holtrop, A. Saha, D. Neyret, A. Gasparian, R. L.J. van der Meer, T. Terasawa, Vincent Breton, R. Suleiman, E. Cisbani, V. Gorbenko, G. M. Urciuoli, M. Liang, G. Quéméner, S. Platchkov, L. Cardman, D. J. Margaziotis, David L. Prout, C. Cavata, K. Soldi, A. Serdarevic, K. Kino, Z. Papandreou, A. Leone, S. Jaminion, F. T. Baker, P. M. Rutt, A. J. Sarty, J. Gomez, D. Rowntree, William Bertozzi, Jing Zhao, Ronald Ransome, James J. Kelly, J. Jardillier, J. M. Finn, T. Pussieux, Pete Markowitz, R. Michaels, J. Gao, D. M. Manley, H. Ueno, Jian-Ping Chen, A. Ketikyan, G. Lavessiere, D. G. Zainea, V. A. Punjabi, E. J. Brash, J. W. Watson, A. T. Katramatou, Roberto Perrino, C. C. Chang, R. De Leo, S. Kerhoas, K. S. Kumar, A. V. Glamazdin, B. Diederich, Shalev Gilad, M. Khayat, L. Van Hoorebeke, O. Ravel, Justin I. McIntyre, Pavel Sorokin, L. Todor, J. A. Templon, R. Holmes, C. W. de Jager, W. U. Boeglin, K. A. Aniol, G. G. Petratos, Z. E. Meziani, B. D. Anderson, G. J. Lolos, M. B. Epstein, J. Berthot, A. Deur, J. Martino, C. F. Perdrisat, E. A.J.M. Offermann, Kazushige Maeda, Haiyan Gao, J. Marroncle, Laird Kramer, J. Y. Mougey, C. J. Martoff, F. Garibaldi, G. Kumbartzki, Ronald Gilman, Hiroaki Tsubota, K. McCormick, B. Frois, N Degrande, M. K. Jones, and M. Kuss

Subjects
Quantum chromodynamics, Quark, Physics, Particle physics, 010308 nuclear & particles physics, Scattering, High Energy Physics::Lattice, Nuclear Theory, Quark model, General Physics and Astronomy, Elementary particle, 7. Clean energy, 01 natural sciences, Gluon, Nuclear physics, 0103 physical sciences, High Energy Physics::Experiment, Quantum field theory, Nuclear Experiment, 010306 general physics, Boson
Abstract

The deuteron elastic structure function A(Q2) has been extracted in the range 0.7≤Q2≤6.0(GeV/c)2 from cross section measurements of elastic electron-deuteron scattering in coincidence using the Hall A Facility of Jefferson Laboratory. The data are compared to theoretical models, based on the impulse approximation with the inclusion of meson-exchange currents, and to predictions of quark dimensional scaling and perturbative quantum chromodynamics.

Published
1999
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40. Measurement of the interference structure functionRLTfor the12C(e,e′p)reaction in the quasielastic region

Author

V. Bhushan, D. S. Dale, S. Dolfini, Joseph B. Mandeville, T. McIlvain, D. J. Margaziotis, William Bertozzi, D. Martinez, Glen A. Warren, J. Görgen, W. W. Sapp, D. R. Tieger, G. W. Dodson, D. Jordan, Shalev Gilad, K. A. Dow, M. Holtrop, M. B. Epstein, Jiahao Chen, W. Turchinetz, J. Kelsey, J. Dzengeleski, W. Boeglin, C. Tschalaer, A. J. Sarty, Costas N. Papanicolas, K. Joo, Ricardo Alarcon, R. M. Laszewski, W. Kim, M. Farkhondeh, R. Beck, R.W. Lourie, Larry Weinstein, S. Penn, R. A. Miskimen, and S. E. Williamson

Subjects
Physics, Nuclear and High Energy Physics, Nuclear Theory, Structure function, Momentum transfer, Hartree–Fock method, Hartree, Atomic physics
Abstract

The coincidence cross section and the interference structure function, ${R}_{\mathrm{LT}},$ were measured for the ${}^{12}\mathrm{C}{(e,e}^{\ensuremath{'}}p){}^{11}\mathrm{B}$ reaction at quasielastic kinematics and central momentum transfer of $|\stackrel{\ensuremath{\rightarrow}}{q}|=400\mathrm{M}\mathrm{e}\mathrm{V}/\mathrm{c}.$ The measurement was at an opening angle of ${\ensuremath{\theta}}_{\mathrm{pq}}=11\ifmmode^\circ\else\textdegree\fi{},$ covering a range in missing energy of ${E}_{m}=0$ to 65 MeV. The ${R}_{\mathrm{LT}}$ structure function is found to be consistent with zero for ${E}_{m}g50\mathrm{MeV},$ confirming an earlier study which indicated that ${R}_{L}$ vanishes in this region. The integrated strengths of the $p$- and $s$-shell are compared with a distorted wave impulse approximation (DWIA) calculation. The $s$-shell strength and shape are also compared with a Hartree Fock--random phase approximation (HF-RPA) calculation. The DWIA calculation does not succeed in giving a consistent description of both the cross section data and the extracted ${R}_{\mathrm{LT}}$ response for either shell. The HF-RPA calculation describes the data more consistently, which may be due to the inclusion of 2-body currents in this calculation.

Published
1998
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41. Induced proton polarization forπ0electroproduction atQ2=0.126 GeV2/c2around theΔ(1232)resonance

Author

S. E. Williamson, X. Jiang, B. Asavapibhop, G. W. Dodson, Glen A. Warren, Larry Weinstein, A. J. Sarty, S. B. Soong, K. Joo, D. J. Margaziotis, S. Kowalski, James J. Kelly, Shalev Gilad, C. Vellidis, K. A. Dow, C. S. Armstrong, L. M. Qin, P. Markowitz, Jiunn-Wei Chen, A. Young, R. W. Gothe, D. S. Dale, Justin I. McIntyre, Volker D. Burkert, P. M. Rutt, Ricardo Alarcon, J. P. Chen, M. B. Epstein, D. Liu, R. J. Woo, C. Tschalaer, V. A. Punjabi, D. H. Barkhuff, M. K. Jones, William Bertozzi, D. R. Tieger, J. M. Finn, A. Karabarbounis, J. R. Comfort, M. Farkhondeh, S. Van Verst, B. D. Milbrath, Richard Madey, R. A. Miskimen, S. Mukhopadhyay, S. Dolfini, C. Kunz, C. F. Perdrisat, J. Shaw, Costas N. Papanicolas, P. E. Ulmer, R.W. Lourie, W. Turchinetz, John C. Mitchell, and C. Mertz

Subjects
Physics, Baryon, Nuclear and High Energy Physics, Particle physics, Pion, Proton, Meson, Hadron, Elementary particle, Nucleon, Delta baryon
Abstract

We present a measurement of the induced proton polarization ${P}_{n}$ in ${\ensuremath{\pi}}^{0}$ electroproduction on the proton around the $\ensuremath{\Delta}$ resonance. The measurement was made at a central invariant mass and a squared four-momentum transfer of $W=1231 \mathrm{MeV}$ and ${Q}^{2}=0.126 {\mathrm{GeV}}^{2}{/c}^{2},$ respectively. We measured a large induced polarization, ${P}_{n}=\ensuremath{-}0.397\ifmmode\pm\else\textpm\fi{}0.055\ifmmode\pm\else\textpm\fi{}0.009.$ The data suggest that the scalar background is larger than expected from a recent effective Hamiltonian model.

Published
1998
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42. Measurement of the Induced Proton PolarizationPnin theC12(e,e′p→)Reaction

Author

Glen A. Warren, C. Mertz, V. A. Punjabi, P. Markowitz, W. Turchinetz, K. Joo, Shalev Gilad, C. Vellidis, John M. Finn, K. A. Dow, M. Farkhondeh, D. J. Margaziotis, S.P. Van Verst, D. Dale, P. E. Ulmer, P. M. Rutt, M. B. Epstein, B. D. Milbrath, A. J. Sarty, James J. Kelly, S. Kowalski, M. K. Jones, C. F. Perdrisat, Justin I. McIntyre, Richard Madey, D. Barkhuff, R. W. Lourie, G. W. Dodson, D. Tieger, Larry Weinstein, William Bertozzi, J. P. Chen, R. J. Woo, John C. Mitchell, and C. Tschalaer

Subjects
Physics, Nuclear reaction, Proton, Nuclear Theory, Momentum transfer, Hadron, General Physics and Astronomy, Born approximation, Atomic physics, Nuclear Experiment, Nucleon, Helicity, Induced polarization
Abstract

The first measurements of the induced proton polarization Pn for the 12C(e,e',p) reaction are reported. The experiment was performed at quasifree kinematics for energy and momentum transfer (w,q) = (294 MeV, 765 MeV/c) and sampled a missing momentum range of 0-250 MeV/c. The induced polarization arises from final-state interactions and for these kinematics is dominated by the real part of the spin-orbit optical potential. The distorted-wave impulse approximation provides good agreement with data for the 1 p3/2 shell. The data for the continuum suggest that both the 1s1/2 shell and underlying l > 1 configurations contribute.

Published
1998
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43. Helicity dependence of the γ 3He → πX reactions in the Δ(1232) resonance region

Author

M. Unverzagt, I. J. D. MacGregor, R. Beck, F. Pheron, V. L. Kashevarov, F. Rigamonti, S. Cherepnya, B. M. K. Nefkens, W. J. Briscoe, A. N. Mushkarenkov, R. Kondratiev, J. R. M. Annand, G. Rosner, D. M. Manley, A. Starostin, M. Korolija, A. Nikolaev, P. Aguar Bartolomé, M. Oberle, B. Krusche, Giuseppe Mandaglio, A. Polonski, A. Kulbardis, M. Thiel, E. J. Downie, I. Jaegle, D. Hornidge, M. Ostrick, S. Costanza, A. J. Sarty, J. Ahrens, D. Howdle, B. Oussena, D. P. Watts, J. Mancell, D. Werthmüller, L. V. Fil'kov, D. G. Middleton, J. C. McGeorge, V. S. Bekrenev, H. Berghäuser, K. Livingston, T. C. Jude, J. Krimmer, T. Rostomyan, I. Supek, S. Schumann, H. J. Arends, P. B. Otte, A. Fix, P. Pedroni, I. Keshelashvili, A. Braghieri, M. Romaniuk, David Hamilton, S. P. Kruglov, V. Lisin, O. Jahn, Werner Heil, G. M. Huber, D. I. Glazier, S. N. Prakhov, Andy Thomas, C. Collicott, P. Drexler, H. Ortega, Volker Metag, and E. Heid

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, Meson, 010308 nuclear & particles physics, Nuclear Theory, Hadron, Elementary particle, 7. Clean energy, 01 natural sciences, Helicity, Nuclear physics, Pion, 0103 physical sciences, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics, Crystal Ball
Abstract

The helicity dependences of the differential cross sections for the semi-inclusive γ 3He → π0 X and γ 3He → π± X reactions have been measured for the first time in the energy region 200 < E γ 450 MeV. The experiment was performed at the tagged photon beam facility of the MAMI accelerator in Mainz using a longitudinally polarised high-pressure 3He gas target. Hadronic products were measured with the large-acceptance Crystal Ball detector complemented with additional devices for charged-particle tracking and identification. Unpolarised differential cross sections and their helicity dependence are compared with theoretical calculations using the Fix-Arenhovel model. The effect of the intermediate excitation of the Δ(1232) resonance can be clearly seen from this comparison, especially for the polarised case, where nuclear effects are relatively small. The model provides a better theoretical description of the unpolarised charged pion photoproduction data than the neutral pion channel. It does significantly better in describing the helicity-dependent data in both channels. These comparisons provide new information on the mechanisms involved in pion photoproduction on 3He and suggest that a polarised 3He target can provide valuable information on the corresponding polarised quasi-free neutron reactions.

Published
2014

44. Measurement of the transverse target and beam-target asymmetries in η meson photoproduction at MAMI

Author

M. Oberle, P. P. Martel, M. Dieterle, B. Oussena, Aron M. Bernstein, C. Collicott, D. P. Watts, A. B. Neganov, E. F. McNicoll, S. Cherepnya, H. Ortega, David Hamilton, W. Gradl, A. N. Mushkarenkov, W. Meyer, W. J. Briscoe, J. Mancel, D. Hornidge, G. Reicherz, P. Hall Barrientos, B. Krusche, V. Lisin, E. J. Downie, I. J. D. MacGregor, V. L. Kashevarov, Lothar Tiator, K. Livingston, N. S. Borisov, P. Pedroni, D. Werthmüller, R. A. Miskimen, R. Kondratiev, G. M. Gurevich, A. Fix, D. M. Manley, M. Korolija, P. Ott, A. Polonski, S. Costanza, S. N. Prakhov, Yu. A. Usov, O. Steffen, V. V. Polyanski, R. Beck, M. Wolfes, A. B. Lazarev, A. Braghieri, Th. Strub, S. Garni, I. I. Strakovsky, H. J. Arends, D. G. Middleton, Lilian Witthauer, G. M. Huber, Anthony W. Thomas, D. I. Glazier, I. Keshelashvili, J. R. M. Annand, S. Schumann, P. B. Otte, A. Nikolaev, B. M. K. Nefkens, D. Howdle, L. V. Fil'kov, C. S. Akondi, M. Ostrick, A. J. Sarty, I. Supek, T. Rostomyan, and M. Unverzagt

Subjects
Physics, Particle physics, Photon, Proton, Meson, Nuclear Theory, media_common.quotation_subject, Partial wave analysis, General Physics and Astronomy, Asymmetry, High Energy Physics - Experiment, Nuclear physics, beam-target asymmetry F, γ⃗ p⃗ →ηp reaction, Mainz Microtron MAMI, High Energy Physics::Experiment, Nucleon, Nuclear Experiment, Microtron, Crystal Ball, media_common
Abstract

We present new data for the transverse target asymmetry T and the very first data for the beam-target asymmetry F in the $\vec \gamma \vec p\to\eta p$ reaction up to a center-of-mass energy of W=1.9 GeV. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. All existing model predictions fail to reproduce the new data indicating a significant impact on our understanding of the underlying dynamics of $\eta$ meson photoproduction. The peculiar nodal structure observed in existing T data close to threshold is not confirmed., Comment: 5 pages, 3 figures, accepted for publication in PRL

Published
2014
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45. Measurement of the Longitudinal, Transverse, and Longitudinal-Transverse Structure Functions in theH2(e,e′p)nReaction

Author

R. A. Miskimen, William Bertozzi, D. J. Margaziotis, W. Kim, S. Dolfini, M. Epstein, S. Penn, W.W. Sapp, J. Görgen, R. Beck, Shalev Gilad, K. Joo, W. Turchinetz, K. A. Dow, Ricardo Alarcon, A. J. Sarty, Larry Weinstein, D. Martinez, C. Tschalaer, Jiahao Chen, D. S. Dale, D. Jordan, R. M. Laszewski, J. Kelsey, Glen A. Warren, M. Holtrop, J. Dzengeleski, Joseph B. Mandeville, R.W. Lourie, W. Boeglin, M. Farkhondeh, S. E. Williamson, G. W. Dodson, Costas N. Papanicolas, D. R. Tieger, V. Bhushan, and T. McIlvain

Subjects
Physics, Transverse plane, Meson, Condensed matter physics, Structure function, Isobar, General Physics and Astronomy, Atomic physics, Omega
Abstract

We have separated the longitudinal ({ital f}{sub 00}), transverse ({ital f}{sub 11}), and longitudinal-transverse interference ({ital f}{sub 01}) structure functions in the {sup 2}H({ital e},{ital e}{prime}{ital p}){ital n} reaction at {ital q}{searrow}{parallel}{approx_equal} 400 MeV/{ital c} and {omega}{approx_equal}110 MeV. A nonrelativistic calculation which includes effects due to final state interactions, meson exchange currents, and isobar configurations agrees with the measured {ital f}{sub 11} and {ital f}{sub 01} but overpredicts {ital f}{sub 00} by 25{percent} (2{sigma}). The data are also compared to the results of previous structure function measurements. {copyright} {ital 1996 The American Physical Society.}

Published
1996
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46. Hard Two-body Photodisintegration of 3He

Author

G. Niculescu, N. Dashyan, D. Protopopescu, E. Cisbani, S. Pozdniakov, G. Rosner, S. Tkachenko, C. Djalali, Yujie Qiang, C. S. Nepali, X. Yan, Idaykis Rodriguez, F. X. Girod, Yordanka Ilieva, L. Guo, Andrew Puckett, G. Charles, Yingxiao Wang, H. Baghdasaryan, Victor Mokeev, S. Beck, Martin K. Mayer, M. S. Saini, Nikolaos Sparveris, X. Zhan, E. Voutier, J. A. Fleming, Ronald Gilman, E. L. Isupov, J. T. Goetz, E. De Sanctis, Dustin Keller, E. Piasetzky, Diane Schott, R. Shneor, G. Ricco, C. W. de Jager, W. Tang, Franco Garibaldi, M. Aghasyan, A. I. Ostrovidov, K. Park, G. G. Petratos, Bryan J. Moffit, Michael Wood, K. Hafidi, T. Mineeva, N. Harrison, A. Deur, Barry Ritchie, P. L. Cole, M. Osipenko, M. Contalbrigo, N. A. Saylor, J. Bono, P. Nadel-Turonski, S. Boiarinov, D. G. Ireland, M. Anghinolfi, H. Seraydaryan, X. Zheng, D. Doughty, I. Zonta, B. S. Ishkhanov, H. Yao, W. K. Brooks, C. E. Taylor, R. A. Schumacher, R. Dupre, N. Bubis, X. Jiang, A. El Alaoui, D. Martinez, M. Battaglieri, V. Crede, B. Lee, K. Joo, Volker D. Burkert, A. S. Biselli, George Davey Smith, D. Heddle, S. Koirala, Guy Ron, V. P. Kubarovsky, K. A. Griffioen, R. De Vita, A. Kim, E. Golovatch, A. Beck, N. A. Baltzell, O. Pogorelko, M. Ungaro, N. D. Kvaltine, Xin Qian, W. J. Briscoe, J. P. Ball, R. A. Montgomery, S. Chandavar, Y. Mao, Friedrich Klein, K. Chirapatpimol, P. Khetarpal, D. S. Carman, P. Stoler, O. Geagla, Nicholas Zachariou, A. Camsonne, S. Anefalos Pereira, Michael Vineyard, A. J. Sarty, N. K. Walford, P. Eugenio, D. G. Meekins, A. D'Angelo, H. Voskanyan, A. T. Katramatou, R. Michaels, Douglas Higinbotham, M. Taiuti, K. Hicks, C. Dutta, Vincent Sulkosky, S. Stepanyan, E. Schulte, E. Munevar, Bogdan Wojtsekhowski, D. Rimal, E. Seder, A. Fradi, B. Vernarsky, S. Lewis, M. J. Amaryan, B. Guegan, C. E. Hyde, F. Sabatié, L. El Fassi, W. U. Boeglin, G. E. Dodge, S. Procureur, R. Nasseripour, C. Munoz Camacho, H. Y. Lu, S. Fegan, R. A. Lindgren, S. Strauch, H. S. Jo, Ishay Pomerantz, J. J. LeRose, C. A. Meyer, S. Pisano, G. V. Fedotov, H. Moutarde, D. P. Watts, H. Egiyan, C. Bookwalter, F. Cusanno, K. Livingston, K. L. Giovanetti, I. Niculescu, I. J. D. MacGregor, K. P. Adhikari, D. P. Weygand, Larry Weinstein, W. Gohn, R. Paremuzyan, Jie Zhang, A. Celentano, R. W. Gothe, Z. W. Zhao, D. Ho, Emily M. McCullough, R. Subedi, D. Sokhan, M. Khandaker, B. McKinnon, B. L. Berman, J. Glister, M. Mirazita, E. Phelps, N. Gevorgyan, V. Batourine, S. Park, S. Niccolai, P. Rossi, H. Hakobyan, M. Guidal, M. Holtrop, A. Daniel, Luciano Pappalardo, S. S. Stepanyan, Mustafa Canan, Kalyan Allada, I. Bedlinskiy, A. Kubarovsky, Sergey Kuleshov, E. Khrosinkova, B. Sawatzky, M. Ripani, A. Saha, W. Kim, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), CLAS, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)

Subjects
Particle physics, Photon, Nuclear Theory, FOS: Physical sciences, General Physics and Astronomy, Few-body systems, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, Cross section (physics), ANGLE ELASTIC-SCATTERING, CROSS-SECTION, DEUTERON, 0103 physical sciences, medicine, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Scaling, Physics, 010308 nuclear & particles physics, medicine.anatomical_structure, Deuterium, Photodisintegration, Nucleus
Abstract

We have measured cross sections for the {gamma}+{sup 3}He->p+d reaction at photon energies of 0.4 - 1.4 GeV and a center-of-mass angle of 90 deg. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron.

Published
2013
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47. Virtual Compton scattering and the generalized polarizabilities of the proton atQ2=0.92and 1.76 GeV2

Author

L. B. Auerbach, C. Cavata, D. J. Margaziotis, K. Kino, A. J. Sarty, Seigo Kato, J. A. Templon, B. Frois, Ronald Ransome, D. Rowntree, R. W. Lourie, Christophe Furget, P. Grenier, M. K. Jones, D. S. Dale, G. W. Miller, H. Voskanyan, C. Jutier, S. Frullani, Z. L. Zhou, C. R. Howell, W. Kahl, M. Khayat, A. T. Katramatou, M. Kuss, J. W. Watson, K. Wijesooriya, W. M. Zhang, J. Jardillier, G.I. Smirnov, David L. Prout, G. Laveissière, A. Deur, G. E. Dodge, J. R. Calarco, G. Fournier, N. Degrande, R. A. Lindgren, J. J. LeRose, R. I. Pomatsalyuk, E. J. Brash, W. U. Boeglin, V. Gorbenko, R. Suleiman, F. T. Baker, S. Platchkov, G. M. Huber, F. Garibaldi, Ronald Gilman, K. McCormick, G. Rutledge, T. Saito, Richard Madey, G. G. Petratos, Z. E. Meziani, K. Arundell, Marc Vanderhaeghen, J. Martino, James J. Kelly, S. Kox, J. Marroncle, L. Cardman, C. E. Hyde, Raphael Noel Tieulent, Z. Papandreou, Pierre A.M. Guichon, F. Merchez, Bogdan Wojtsekhowski, D. Marchand, E. Tomasi-Gustaffson, M. Liang, P. M. Rutt, F. Renard, Shalev Gilad, S. Mehrabyan, G. Quéméner, V. A. Punjabi, D. M. Manley, C. W. de Jager, R. L.J. van der Meer, K. A. Aniol, Nilanga Liyanage, A. Gasparian, B. D. Anderson, G. J. Lolos, M. B. Epstein, Richard Wilson, Branislav Vlahovic, L. C. Alexa, A. Ketikyan, P. E. Ulmer, A. V. Glamazdin, E. A.J.M. Offermann, Jing Zhao, P. Y. Bertin, L. Van Hoorebeke, T. Pussieux, Mauro Iodice, Larry Weinstein, Laird Kramer, T. Terasawa, Vincent Breton, J. Gao, C. F. Perdrisat, C. Marchand, D. Neyret, William Bertozzi, R. Michaels, R. Holmes, H. Fonvieille, D. G. Zainea, Charles Glashausser, C. C. Chang, K. S. Kumar, J. Domingo, Pavel Sorokin, Haiyan Gao, Pete Markowitz, L. Bimbot, R. Di Salvo, J. M. Finn, J. S. Real, Justin I. McIntyre, S. Jaminion, G. Kumbartzki, E. Chudakov, Barbara Pasquini, Latifa Elouadrhiri, N. d'Hose, Roberto Perrino, R. De Leo, M. Baylac, J. O. Hansen, J. P. Chen, R. Van de Vyver, G. M. Urciuoli, J. Berthot, H. Breuer, Kevin Fissum, L. A. Ewell, G. Audit, Kazushige Maeda, J. Mougey, O. Ravel, S. Malov, E. Burtin, M. Holtrop, J. Gomez, Thomas E. Smith, Paul Souder, H. Ueno, S. K. Nanda, Hiroaki Tsubota, S. Kerhoas, L. Todor, A. Leone, A. Saha, E. Voutier, K. Soldi, A. Serdarevic, Sebastien Incerti, Y. Roblin, P. Vernin, and E. Cisbani

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Photon, Chiral perturbation theory, Proton, 010308 nuclear & particles physics, Structure function, Compton scattering, 01 natural sciences, Nuclear physics, Amplitude, Dispersion relation, 0103 physical sciences, Beta (velocity), 010306 general physics
Abstract

Virtual Compton Scattering (VCS) on the proton has been studied at Jefferson Lab using the exclusive photon electroproduction reaction (e p --> e p gamma). This paper gives a detailed account of the analysis which has led to the determination of the structure functions P{sub LL}-P{sub TT}/epsilon and P{sub LT}, and the electric and magnetic generalized polarizabilities (GPs) alpha{sub E}(Q{sup 2}) and beta{sub M}(Q{sup 2}) at values of the four-momentum transfer squared Q{sup 2} = 0.92 and 1.76 GeV{sup 2}. These data, together with the results of VCS experiments at lower momenta, help building a coherent picture of the electric and magnetic GPs of the proton over the full measured Q{sup 2}-range, and point to their non-trivial behavior.

Published
2012
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48. Low-Q2measurements of the proton form factor ratioμpGE/GM

Author

C. Dutta, J. P. Chen, Ronald Ransome, Xin Qian, A. Saha, L. Coman, W. U. Boeglin, Karl Slifer, B. Craver, G. M. Urciuoli, Douglas Higinbotham, M. K. Jones, S. Strauch, Yannick Rousseau, Xiaofeng Zhu, S. May Tal Beck, Olfred Hansen, F. Cusanno, E. Piasetzky, Emily M. McCullough, Young Do Oh, K. Wang, R. Pomatsalyuk, R. J. Feuerbach, M. Potokar, Yujie Qiang, R. Sparks, Guy Ron, C. W. de Jager, Bryan J. Moffit, Pete Markowitz, E. Khrosinkova, V. A. Punjabi, Kalyan Allada, A. Kelleher, Simon Širca, E. J. Brash, F. Garibaldi, A. Camsonne, X. Zhan, M. H. Shabestari, H. F. Ibrahim, A. J. Sarty, E. Schulte, Seonho Choi, M. Reyhan, P. Solvignon, G. J. Kumbartzki, J. Arrington, E. Chudakov, Ronald Gilman, A. Shahinyan, B. Sawatzky, F. Benmokhtar, X. Jiang, J. Dumas, B. L. Berman, J. Glister, M. Paolone, Z. E. Meziani, J. Roche, S. Frullani, R. Subedi, H. Yao, Y. Ilieva, A. Beck, C. F. Perdrisat, R. A. Lindgren, C. E. Hyde, J. J. LeRose, Ishay Pomerantz, A. P. Freyberger, Kent Paschke, X. Yan, Bogdan Wojtsekhowski, M. Meziane, J. R. Calarco, Bumsung Lee, J. Song, R. Michaels, M. Olson, B. E. Norum, T. Holmstrom, E. Kuchina, A. J. R. Puckett, R. Shneor, and Whitney Armstrong

Subjects
Nuclear physics, Baryon, Physics, Nuclear and High Energy Physics, Proton, Hadron, Form factor (quantum field theory), Analytical chemistry, Elementary particle, Fermion, Nucleon, Dimensionless quantity
Abstract

We present an updated extraction of the proton electromagnetic form factor ratio, {mu}{sub p}G{sub E}/G{sub M}, at low Q{sup 2}. The form factors are sensitive to the spatial distribution of the proton, and precise measurements can be used to constrain models of the proton. An improved selection of the elastic events and reduced background contributions yielded a small systematic reduction in the ratio {mu}{sub p}G{sub E}/G{sub M} compared to the original analysis.

Published
2011
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49. Measurement of the partial cross sectionsσTT,σLT, and(σT+ɛσL)of the1H(e,e′π+)nreaction in theΔ(1232)resonance

Author

P. Bourgeois, Z. L. Zhou, G. Tsentalivich, A. Hotta, S. Stave, Tancredi Botto, A. J. Sarty, Ross Milner, S. Širca, I. Nakagawa, William Bertozzi, W. Turchinetz, Efstathios Stiliaris, M. Farkondeh, C. Tschalaer, S. Georgakopoulos, J. R. Calarco, J. Kirkpatrick, R. S. Hicks, A. Karabarbounis, F. Casagrande, Ricardo Alarcon, Yukinori Sato, Shalev Gilad, A. Holtrop, R. A. Miskimen, J. Shaw, K. A. Dow, S. Kowalski, Nikos Sparveris, Tadaaki Tamae, E. Six, T. Zwart, M. O. Distler, Costas N. Papanicolas, Aron M. Bernstein, and X. Jiang

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Pion, Meson, Hadron, Resonance, Sigma, Elementary particle, Atomic physics, Nucleon
Abstract

We report precision {sup 1}H(e, e{sup '{pi}+})n measurements in the {Delta}(1232) resonance at Q{sup 2}=0.127(GeV/c){sup 2} obtained at the MIT-Bates out-of-plane scattering facility. These are the lowest, but nonzero, Q{sup 2} measurements in the {pi}{sup +} channel. The data offer tests of the theoretical calculations, particularly of the background amplitude contributions. The chiral effective field theory and Sato-Lee model calculations are not in agreement with this experiment.

Published
2011
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50. Precise Extraction of the Induced Polarization in theHe4(e,e′p→)H3Reaction

Author

P. Solvignon, Michael Paolone, E. Khrosinkova, Alexandre Camsonne, R. A. Lindgren, D. J. Margaziotis, J. R. Vignote, J. Glister, A. Saha, B. Craver, B. L. Berman, Bumsung Lee, Ronald Gilman, D. J. Tedeschi, C. E. Keppel, S. Strauch, X. Zhan, J. P. Chen, A. J. Sarty, C. E. Hyde-Wright, F. R. Wesselmann, R. Michaels, E. Cisbani, O. Glamazdin, E. Piasetzky, L. G. Tang, B. Briscoe, S. Malace, F. Cusanno, V. Tvaskis, Ronald Ransome, Yujie Qiang, Andrew Puckett, Xin Qian, E. J. Brash, X. Jiang, Bogdan Wojtsekhowski, E. Chudakov, K. Park, J. Arrington, E. Kuchina, C. W. de Jager, I. Albayrak, F. Garibaldi, C. F. Perdrisat, G. J. Kumbartzki, M. E. Christy, V. A. Punjabi, D. G. Meekins, Rolf Ent, P. E. Ulmer, Yordanka Ilieva, E. Schulte, Douglas Higinbotham, M. K. Jones, J. M. Udías, Lubomir Pentchev, and R. Subedi

Subjects
Physics, Quantum electrodynamics, General Physics and Astronomy, Impulse (physics), Atomic physics, Polarization (waves), Nuclear matter, Induced polarization, Charge exchange
Abstract

We measured with unprecedented precision the induced polarization P(y) in (4)He(e,e'p)(3)H at Q(2)=0.8 and 1.3 (GeV/c)(2). The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are overestimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin-independent charge-exchange term in the latter calculation.

Published
2011
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