I. J. MacGregor - The CLAS Collaboration

I. J. MacGregor
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I. J. MacGregor
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The CLAS Collaboration
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Nuclear Experiment (50)
 
High Energy Physics - Experiment (16)
 
Nuclear Theory (5)
 
High Energy Physics - Phenomenology (3)
 
Physics - Instrumentation and Detectors (2)

Publications Authored By I. J. MacGregor

2017May
Authors: D. Ho, P. Peng, C. Bass, P. Collins, A. D'Angelo, A. Deur, J. Fleming, C. Hanretty, T. Kageya, M. Khandaker, F. J. Klein, E. Klempt, V. Laine, M. M. Lowry, H. Lu, C. Nepali, V. A. Nikonov, T. O'Connell, A. M. Sandorfi, A. V. Sarantsev, R. A. Schumacher, I. I. Strakovsky, A. Švarc, N. K. Walford, X. Wei, C. S. Whisnant, R. L. Workman, I. Zonta, K. P. Adhikari, D. Adikaram, Z. Akbar, M. J. Amaryan, S. Anefalos Pereira, H. Avakian, J. Ball, M. Bashkanov, M. Battaglieri, V. Batourine, I. Bedlinskiy, W. J. Briscoe, V. D. Burkert, D. S. Carman, A. Celentano, G. Charles, T. Chetry, G. Ciullo, L. Clark, L. Colaneri, P. L. Cole, M. Contalbrigo, V. Crede, N. Dashyan, E. De Sanctis, R. De Vita, C. Djalali, R. Dupre, A. El Alaoui, L. El Fassi, L. Elouadrhiri, G. Fedotov, S. Fegan, R. Fersch, A. Filippi, A. Fradi, Y. Ghandilyan, G. P. Gilfoyle, F. X. Girod, D. I. Glazier, C. Gleason, W. Gohn, E. Golovatch, R. W. Gothe, K. A. Griffioen, M. Guidal, L. Guo, H. Hakobyan, N. Harrison, K. Hicks, M. Holtrop, S. M. Hughes, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, D. Jenkins, H. Jiang, H. S. Jo, K. Joo, S. Joosten, D. Keller, G. Khachatryan, A. Kim, W. Kim, A. Klein, V. Kubarovsky, S. V. Kuleshov, L. Lanza, P. Lenisa, K. Livingston, I . J . D. MacGregor, N. Markov, B. McKinnon, T. Mineeva, V. Mokeev, R. A. Montgomery, A Movsisyan, C. Munoz Camacho, G. Murdoch, S. Niccolai, G. Niculescu, M. Osipenko, M. Paolone, R. Paremuzyan, K. Park, E. Pasyuk, W. Phelps, O. Pogorelko, J. W. Price, S. Procureur, D. Protopopescu, M. Ripani, D. Riser, B. G. Ritchie, A. Rizzo, G. Rosner, F. Sabatié, C. Salgado, Y. G. Sharabian, Iu. Skorodumina, G. D. Smith, D. I. Sober, D. Sokhan, N. Sparveris, S. Strauch, Ye Tian, B. Torayev, M. Ungaro, H. Voskanyan, D. P. Watts, M. H. Wood, N. Zachariou, J. Zhang, Z. W. Zhao

We report the first beam-target double-polarization asymmetries in the $\gamma + n(p) \rightarrow \pi^- + p(p)$ reaction spanning the nucleon resonance region from invariant mass $W$= $1500$ to $2300$ MeV. Circularly polarized photons and longitudinally polarized deuterons in $H\!D$ have been used with the CLAS detector at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the {\it{E}} polarization observable for an effective neutron target. Read More

Precise helicity-dependent cross sections and the double-polarization observable $E$ were measured for $\eta$ photoproduction from quasi-free protons and neutrons bound in the deuteron. The $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0\rightarrow 6\gamma$ 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. Read More

2017Mar
Authors: CLAS Collaboration, I. Bedlinskiy, V. Kubarovsky, P. Stoler, K. P. Adhikari, Z. Akbar, S. Anefalos Pereira, H. Avakian, J. Ball, N. A. Baltzell, M. Battaglieri, V. Batourine, A. S. Biselli, S. Boiarinov, W. J. Briscoe, V. D. Burkert, T. Cao, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, G. Ciullo, L. Clark, L. Colaneri, P. L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, R. Dupre, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, E. Fanchini, G. Fedotov, R. Fersch, A. Filippi, J. A. Fleming, T. A. Forest, M. Garçon, N. Gevorgyan, Y. Ghandilyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, C. Gleason, E. Golovatch, R. W. Gothe, K. A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, N. Harrison, M. Hattawy, K. Hicks, S. M. Hughes, C. E. Hyde, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, D. Jenkins, H. Jiang, H. S. Jo, K. Joo, S. Joosten, D. Keller, G. Khachatryan, M. Khachatryan, M. Khandaker, A. Kim, W. Kim, F. J. Klein, S. E. Kuhn, S. V. Kuleshov, L. Lanza, P. Lenisa, K. Livingston, I. J. D. MacGregor, N. Markov, B. McKinnon, Z. E. Meziani, M. Mirazita, V. Mokeev, R. A. Montgomery, A. Movsisyan, C. Munoz Camacho, P. Nadel-Turonski, L. A. Net, A. Ni, S. Niccolai, G. Niculescu, M. Osipenko, A. I. Ostrovidov, M. Paolone, R. Paremuzyan, K. Park, E. Pasyuk, P. Peng, W. Phelps, S. Pisano, O. Pogorelko, J. W. Price, Y. Prok, D. Protopopescu, A. J. R. Puckett, B. A. Raue, M. Ripani, A. Rizzo, G. Rosner, P. Rossi, P. Roy, F. Sabatié, M. S. Saini, C. Salgado, R. A. Schumacher, Y. G. Sharabian, Iu. Skorodumina, G. D. Smith, D. Sokhan, N. Sparveris, S. Stepanyan, I. I. Strakovsky, S. Strauch, M. Taiuti, Ye Tian, B. Torayev, M. Turisini, M. Ungaro, H. Voskanyan, E. Voutier, N. K. Walford, D. P. Watts, X. Wei, L. B. Weinstein, M. H. Wood, M. Yurov, N. Zachariou, J. Zhang, I. Zonta

The cross section of the exclusive $\eta$ electroproduction reaction $ep\to e^\prime p^\prime \eta$ was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections $d^4\sigma/dtdQ^2dx_Bd\phi_\eta$ and structure functions $\sigma_U = \sigma_T+\epsilon\sigma_L, \sigma_{TT}$ and $\sigma_{LT}$, as functions of $t$ were obtained over a wide range of $Q^2$ and $x_B$. Read More

2017Mar
Authors: P. Collins, B. G. Ritchie, M. Dugger, A. V. Anisovich, M. Döring, E. Klempt, V. A. Nikonov, D. Rönchen, D. Sadasivan, A. Sarantsev, K. P. Adhikaria, Z. Akbar, M. J. Amaryana, S. Anefalos Pereira, H. Avakiana, J. Ball, I. Balossino, M. Bashkanova, M. Battaglieri, I. Bedlinskiy, A. S. Bisellik, W. J. Briscoe, W. K. Brooks, V. D. Burkert, Frank Thanh Cao, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, T. Chetry, G. Ciullo, L. Clark, L. Colaneri, P. L. Cole, N. Compton, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, E. Fanchini, G. Fedotov, A. Filippi, J. A. Fleming, Y. Ghandilyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, D. I. Glazier, C. Gleason, E. Golovatch, R. W. Gothe, K. A. Griffioen, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, N. Harrison, D. Heddle, K. Hicks, M. Holtrop, S. M. Hughes, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, D. Jenkins, H. S. Jo, S. Joosten, D. Keller, G. Khachatryan, M. Khachatryan, M. Khandaker, A. Kim, W. Kim, A. Klein, F. J. Klein, V. Kubarovsky, L. Lanza, P. Lenisa, K. Livingston, I. J. D. MacGregor, N. Markov, B. McKinnon, C. A. Meyer, M. Mirazita, V. Mokeev, R. A. Montgomery, A Movsisyan, C. Munoz Camacho, G. Murdoch, P. Nadel-Turonski, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A. I. Ostrovidov, M. Paolone, R. Paremuzyan, K. Park, E. Pasyuk, W. Phelps, S. Pisano, O. Pogorelko, J. W. Price, Y. Prok, D. Protopopescu, B. A. Raue, M. Ripani, A. Rizzo, G. Rosner, P. Roy, F. Sabatié, C. Salgado, R. A. Schumacher, Y. G. Sharabian, Iu. Skorodumina, G. D. Smith, D. Sokhan, N. Sparveris, S. Stepanyan, I. I. Strakovsky, S. Strauch, M. Taiuti, Ye Tian, B. Torayev, M. Ungaro, H. Voskanyan, E. Voutier, N. K. Walford, X. Wei, N. Zachariou, J. Zhang

Measurements of the linearly-polarized photon beam asymmetry $\Sigma$ for photoproduction from the proton of $\eta$ and $\eta^\prime$ mesons are reported. A linearly-polarized tagged photon beam produced by coherent bremsstrahlung was incident on a cryogenic hydrogen target within the CEBAF Large Acceptance Spectrometer. Results are presented for the $\gamma p \to \eta p$ reaction for incident photon energies from 1. Read More

The double polarization observable $E$ and the helicity dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$ were measured for $\eta$ photoproduction from quasi-free protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost $4\pi$ detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0$. Read More

The reactions $\gamma p\to \eta p$ and $\gamma p\to \eta' p$ have been 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 were obtained with unprecedented accuracy, providing fine energy binning and full production-angle coverage. Read More

The Dalitz decay pi^0 -> e^+e^-gamma has been measured in the gamma p -> pi^0 p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the pi^0 electromagnetic transition form factor, a_pi = 0.030+/-0. Read More

2016Nov
Authors: P. E. Bosted1, A. Kim2, K. P. Adhikari3, D. Adikaram4, Z. Akbar5, M. J. Amaryan6, S. Anefalos Pereira7, H. Avakian8, R. A. Badui9, J. Ball10, I. Balossino11, M. Battaglieri12, I. Bedlinskiy13, A. S. Biselli14, S. Boiarinov15, W. J. Briscoe16, W. K. Brooks17, S. Bültmann18, V. D. Burkert19, T. Cao20, D. S. Carman21, A. Celentano22, S. Chandavar23, G. Charles24, T. Chetry25, G. Ciullo26, L. Clark27, L. Colaneri28, P. L. Cole29, M. Contalbrigo30, O. Cortes31, V. Crede32, A. D'Angelo33, N. Dashyan34, R. De Vita35, E. De Sanctis36, A. Deur37, C. Djalali38, R. Dupre39, H. Egiyan40, A. El Alaoui41, L. El Fassi42, L. Elouadrhiri43, P. Eugenio44, E. Fanchini45, G. Fedotov46, S. Fegan47, R. Fersch48, A. Filippi49, J. A. Fleming50, T. A. Forest51, A. Fradi52, Y. Ghandilyan53, G. P. Gilfoyle54, F. X. Girod55, D. I. Glazier56, W. Gohn57, E. Golovatch58, R. W. Gothe59, K. A. Griffioen60, M. Guidal61, N. Guler62, H. Hakobyan63, L. Guo64, K. Hafidi65, H. Hakobyan66, C. Hanretty67, N. Harrison68, M. Hattawy69, D. Heddle70, K. Hicks71, G. Hollis72, M. Holtrop73, S. M. Hughes74, D. G. Ireland75, E. L. Isupov76, D. Jenkins77, H. Jiang78, H. S. Jo79, K. Joo80, D. Keller81, G. Khachatryan82, M. Khandaker83, W. Kim84, A. Klei85, F. J. Klein86, S. Koirala87, V. Kubarovsky88, S. E. Kuhn89, L. Lanza90, P. Lenisa91, K. Livingston92, H. Y. Lu93, I. J. D. MacGregor94, N. Markov95, M. Mayer96, M. E. McCracken97, B. McKinnon98, T. Mineeva99, M. Mirazita100, V. I. Mokeev101, R. A. Montgomery102, A Movsisyan103, C. Munoz Camacho104, G. Murdoch105, P. Nadel-Turonski106, A. Ni107, S. Niccolai108, G. Niculescu109, M. Osipenko110, A. I. Ostrovidov111, M. Paolone112, R. Paremuzyan113, K. Park114, E. Pasyuk115, W. Phelps116, S. Pisano117, O. Pogorelko118, J. W. Price119, Y. Prok120, D. Protopopescu121, A. J. R. Puckett122, B. A. Raue123, M. Ripani124, A. Rizzo125, G. Rosner126, P. Rossi127, P. Roy128, F. Sabatié129, M. S. Saini130, R. A. Schumacher131, E. Seder132, Y. G. Sharabian133, Iu. Skorodumina134, G. D. Smith135, D. Sokhan136, N. Sparveris137, I. Stankovic138, S. Stepanyan139, P. Stoler140, I. I. Strakovsky141, S. Strauch142, M. Taiuti143, Ye Tian144, B. Torayev145, M. Ungaro146, H. Voskanyan147, E. Voutier148, N. K. Walford149, D. P. Watts150, X. Wei151, L. B. Weinstein152, N. Zachariou153, J. Zhang154, Z. W. Zhao155, I. Zonta156
Affiliations: 1The CLAS Collaboration, 2The CLAS Collaboration, 3The CLAS Collaboration, 4The CLAS Collaboration, 5The CLAS Collaboration, 6The CLAS Collaboration, 7The CLAS Collaboration, 8The CLAS Collaboration, 9The CLAS Collaboration, 10The CLAS Collaboration, 11The CLAS Collaboration, 12The CLAS Collaboration, 13The CLAS Collaboration, 14The CLAS Collaboration, 15The CLAS Collaboration, 16The CLAS Collaboration, 17The CLAS Collaboration, 18The CLAS Collaboration, 19The CLAS Collaboration, 20The CLAS Collaboration, 21The CLAS Collaboration, 22The CLAS Collaboration, 23The CLAS Collaboration, 24The CLAS Collaboration, 25The CLAS Collaboration, 26The CLAS Collaboration, 27The CLAS Collaboration, 28The CLAS Collaboration, 29The CLAS Collaboration, 30The CLAS Collaboration, 31The CLAS Collaboration, 32The CLAS Collaboration, 33The CLAS Collaboration, 34The CLAS Collaboration, 35The CLAS Collaboration, 36The CLAS Collaboration, 37The CLAS Collaboration, 38The CLAS Collaboration, 39The CLAS Collaboration, 40The CLAS Collaboration, 41The CLAS Collaboration, 42The CLAS Collaboration, 43The CLAS Collaboration, 44The CLAS Collaboration, 45The CLAS Collaboration, 46The CLAS Collaboration, 47The CLAS Collaboration, 48The CLAS Collaboration, 49The CLAS Collaboration, 50The CLAS Collaboration, 51The CLAS Collaboration, 52The CLAS Collaboration, 53The CLAS Collaboration, 54The CLAS Collaboration, 55The CLAS Collaboration, 56The CLAS Collaboration, 57The CLAS Collaboration, 58The CLAS Collaboration, 59The CLAS Collaboration, 60The CLAS Collaboration, 61The CLAS Collaboration, 62The CLAS Collaboration, 63The CLAS Collaboration, 64The CLAS Collaboration, 65The CLAS Collaboration, 66The CLAS Collaboration, 67The CLAS Collaboration, 68The CLAS Collaboration, 69The CLAS Collaboration, 70The CLAS Collaboration, 71The CLAS Collaboration, 72The CLAS Collaboration, 73The CLAS Collaboration, 74The CLAS Collaboration, 75The CLAS Collaboration, 76The CLAS Collaboration, 77The CLAS Collaboration, 78The CLAS Collaboration, 79The CLAS Collaboration, 80The CLAS Collaboration, 81The CLAS Collaboration, 82The CLAS Collaboration, 83The CLAS Collaboration, 84The CLAS Collaboration, 85The CLAS Collaboration, 86The CLAS Collaboration, 87The CLAS Collaboration, 88The CLAS Collaboration, 89The CLAS Collaboration, 90The CLAS Collaboration, 91The CLAS Collaboration, 92The CLAS Collaboration, 93The CLAS Collaboration, 94The CLAS Collaboration, 95The CLAS Collaboration, 96The CLAS Collaboration, 97The CLAS Collaboration, 98The CLAS Collaboration, 99The CLAS Collaboration, 100The CLAS Collaboration, 101The CLAS Collaboration, 102The CLAS Collaboration, 103The CLAS Collaboration, 104The CLAS Collaboration, 105The CLAS Collaboration, 106The CLAS Collaboration, 107The CLAS Collaboration, 108The CLAS Collaboration, 109The CLAS Collaboration, 110The CLAS Collaboration, 111The CLAS Collaboration, 112The CLAS Collaboration, 113The CLAS Collaboration, 114The CLAS Collaboration, 115The CLAS Collaboration, 116The CLAS Collaboration, 117The CLAS Collaboration, 118The CLAS Collaboration, 119The CLAS Collaboration, 120The CLAS Collaboration, 121The CLAS Collaboration, 122The CLAS Collaboration, 123The CLAS Collaboration, 124The CLAS Collaboration, 125The CLAS Collaboration, 126The CLAS Collaboration, 127The CLAS Collaboration, 128The CLAS Collaboration, 129The CLAS Collaboration, 130The CLAS Collaboration, 131The CLAS Collaboration, 132The CLAS Collaboration, 133The CLAS Collaboration, 134The CLAS Collaboration, 135The CLAS Collaboration, 136The CLAS Collaboration, 137The CLAS Collaboration, 138The CLAS Collaboration, 139The CLAS Collaboration, 140The CLAS Collaboration, 141The CLAS Collaboration, 142The CLAS Collaboration, 143The CLAS Collaboration, 144The CLAS Collaboration, 145The CLAS Collaboration, 146The CLAS Collaboration, 147The CLAS Collaboration, 148The CLAS Collaboration, 149The CLAS Collaboration, 150The CLAS Collaboration, 151The CLAS Collaboration, 152The CLAS Collaboration, 153The CLAS Collaboration, 154The CLAS Collaboration, 155The CLAS Collaboration, 156The CLAS Collaboration

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive $\pi^0$ electroproduction reaction $\gamma^* p \to p \pi^0$, expanding an analysis of the $\gamma^* p \to n \pi^+$ reaction from the same experiment. The results were obtained from scattering of 6 GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Lab. The kinematic range covered is $1. Read More

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. Read More

The Dalitz decays eta -> e^+e^-g and omega -> pi^0 e^+e^- have been measured in the g p -> eta p and g p -> omega p reactions, respectively, with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the electromagnetic transition form factor of eta, Lambda^{-2}_eta=(1.97+/-0. Read More

2016Jul
Authors: P. E. Bosted1, M. J. Amaryan2, S. Anefalos Pereira3, H. Avakian4, R. A. Badui5, J. Ball6, N. A. Baltzell7, M. Battaglieri8, V. Batourine9, I. Bedlinskiy10, A. S. Biselli11, W. J. Briscoe12, S. Bültmann13, V. D. Burkert14, D. S. Carman15, A. Celentano16, S. Chandavar17, G. Charles18, L. Clark19, L. Colaneri20, P. L. Cole21, M. Contalbrigo22, V. Crede23, A. D'Angelo24, R. De Vita25, A. Deur26, E. De Sanctis27, C. Djalali28, R. Dupre29, H. Egiyan30, A. El Alaoui31, L. El Fassi32, L. Elouadrhiri33, P. Eugenio34, E. Fanchini35, G. Fedotov36, A. Filippi37, J. A. Fleming38, T. Forest39, A. Fradi40, N. Gevorgyan41, G. P. Gilfoyle42, F. X. Girod43, C. Gleason44, W. Gohn45, E. Golovatch46, R. W. Gothe47, K. A. Griffioen48, M. Guidal49, H. Hakobyan50, M. Hattawy51, K. Hicks52, M. Holtrop53, S. M. Hughes54, Y. Ilieva55, D. G. Ireland56, B. S. Ishkhanov57, E. L. Isupov58, H. Jiang59, H. S. Jo60, K. Joo61, S. Joosten62, G. Khachatryan63, M. Khandaker64, A. Kim65, W. Kim66, F. J. Klein67, S. Koirala68, V. Kubarovsky69, S. E. Kuhn70, L. Lanza71, L. A. Net72, P. Lenisa73, K. Livingston74, I. J. D. MacGregor75, M. E. McCracken76, B. McKinnon77, C. A. Meyer78, M. Mirazita79, V. I. Mokeev80, R. A. Montgomery81, E. Munevar82, C. Munoz Camacho83, G. Murdoch84, P. Nadel-Turonski85, S. Niccolai86, M. Osipenko87, A. I. Ostrovidov88, K. Park89, E. Pasyuk90, P. Peng91, W. Phelps92, S. Pisano93, O. Pogorelko94, J. W. Price95, Y. Prok96, D. Protopopescu97, B. A. Raue98, M. Ripani99, G. Rosner100, P. Rossi101, R. A. Schumacher102, Iu. Skorodumina103, G. D. Smith104, D. Sokhan105, N. Sparveris106, I. Stankovic107, I. I. Strakovsky108, S. Strauch109, M. Taiuti110, B. Torayev111, M. Ungaro112, H. Voskanyan113, E. Voutier114, X. Wei115, L. B. Weinstein116, J. Zhang117, I. Zonta118
Affiliations: 1CLAS Collaboration, 2CLAS Collaboration, 3CLAS Collaboration, 4CLAS Collaboration, 5CLAS Collaboration, 6CLAS Collaboration, 7CLAS Collaboration, 8CLAS Collaboration, 9CLAS Collaboration, 10CLAS Collaboration, 11CLAS Collaboration, 12CLAS Collaboration, 13CLAS Collaboration, 14CLAS Collaboration, 15CLAS Collaboration, 16CLAS Collaboration, 17CLAS Collaboration, 18CLAS Collaboration, 19CLAS Collaboration, 20CLAS Collaboration, 21CLAS Collaboration, 22CLAS Collaboration, 23CLAS Collaboration, 24CLAS Collaboration, 25CLAS Collaboration, 26CLAS Collaboration, 27CLAS Collaboration, 28CLAS Collaboration, 29CLAS Collaboration, 30CLAS Collaboration, 31CLAS Collaboration, 32CLAS Collaboration, 33CLAS Collaboration, 34CLAS Collaboration, 35CLAS Collaboration, 36CLAS Collaboration, 37CLAS Collaboration, 38CLAS Collaboration, 39CLAS Collaboration, 40CLAS Collaboration, 41CLAS Collaboration, 42CLAS Collaboration, 43CLAS Collaboration, 44CLAS Collaboration, 45CLAS Collaboration, 46CLAS Collaboration, 47CLAS Collaboration, 48CLAS Collaboration, 49CLAS Collaboration, 50CLAS Collaboration, 51CLAS Collaboration, 52CLAS Collaboration, 53CLAS Collaboration, 54CLAS Collaboration, 55CLAS Collaboration, 56CLAS Collaboration, 57CLAS Collaboration, 58CLAS Collaboration, 59CLAS Collaboration, 60CLAS Collaboration, 61CLAS Collaboration, 62CLAS Collaboration, 63CLAS Collaboration, 64CLAS Collaboration, 65CLAS Collaboration, 66CLAS Collaboration, 67CLAS Collaboration, 68CLAS Collaboration, 69CLAS Collaboration, 70CLAS Collaboration, 71CLAS Collaboration, 72CLAS Collaboration, 73CLAS Collaboration, 74CLAS Collaboration, 75CLAS Collaboration, 76CLAS Collaboration, 77CLAS Collaboration, 78CLAS Collaboration, 79CLAS Collaboration, 80CLAS Collaboration, 81CLAS Collaboration, 82CLAS Collaboration, 83CLAS Collaboration, 84CLAS Collaboration, 85CLAS Collaboration, 86CLAS Collaboration, 87CLAS Collaboration, 88CLAS Collaboration, 89CLAS Collaboration, 90CLAS Collaboration, 91CLAS Collaboration, 92CLAS Collaboration, 93CLAS Collaboration, 94CLAS Collaboration, 95CLAS Collaboration, 96CLAS Collaboration, 97CLAS Collaboration, 98CLAS Collaboration, 99CLAS Collaboration, 100CLAS Collaboration, 101CLAS Collaboration, 102CLAS Collaboration, 103CLAS Collaboration, 104CLAS Collaboration, 105CLAS Collaboration, 106CLAS Collaboration, 107CLAS Collaboration, 108CLAS Collaboration, 109CLAS Collaboration, 110CLAS Collaboration, 111CLAS Collaboration, 112CLAS Collaboration, 113CLAS Collaboration, 114CLAS Collaboration, 115CLAS Collaboration, 116CLAS Collaboration, 117CLAS Collaboration, 118CLAS Collaboration

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive $\pi^+$ electroproduction reaction $\gamma^* p \to n \pi^+$. The results were obtained from scattering of 6 GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Lab. The kinematic range covered is $1. Read More

2016Jul
Authors: X. Zheng1, K. P. Adhikari2, P. Bosted3, A. Deur4, V. Drozdov5, L. El Fassi6, Hyekoo Kang7, K. Kovacs8, S. Kuhn9, E. Long10, S. K. Phillips11, M. Ripani12, K. Slifer13, L. C. Smith14, D. Adikaram15, Z. Akbar16, M. J. Amaryan17, S. Anefalos Pereira18, G. Asryan19, H. Avakian20, R. A. Badui21, J. Ball22, N. A. Baltzell23, M. Battaglieri24, V. Batourine25, I. Bedlinskiy26, A. S. Biselli27, W. J. Briscoe28, S. Bültmann29, V. D. Burkert30, D. S. Carman31, A. Celentano32, S. Chandavar33, G. Charles34, J. -P. Chen35, T. Chetry36, Seonho Choi37, G. Ciullo38, L. Clark39, L. Colaneri40, P. L. Cole41, N. Compton42, M. Contalbrigo43, V. Crede44, A. D'Angelo45, N. Dashyan46, R. De Vita47, E. De Sanctis48, C. Djalali49, G. E. Dodge50, R. Dupre51, H. Egiyan52, A. El Alaoui53, L. Elouadrhiri54, P. Eugenio55, E. Fanchini56, G. Fedotov57, R. Fersch58, A. Filippi59, J. A. Fleming60, N. Gevorgyan61, Y. Ghandilyan62, G. P. Gilfoyle63, K. L. Giovanetti64, F. X. Girod65, C. Gleason66, E. Golovach67, R. W. Gothe68, K. A. Griffioen69, M. Guidal70, N. Guler71, L. Guo72, C. Hanretty73, N. Harrison74, M. Hattawy75, K. Hicks76, M. Holtrop77, S. M. Hughes78, Y. Ilieva79, D. G. Ireland80, B. S. Ishkhanov81, E. L. Isupov82, D. Jenkins83, H. Jiang84, H. S. Jo85, S. Joosten86, D. Keller87, G. Khachatryan88, M. Khandaker89, A. Kim90, W. Kim91, F. J. Klein92, V. Kubarovsky93, L. Lanza94, P. Lenisa95, K. Livingston96, I . J . D. MacGregor97, N. Markov98, B. McKinnon99, M. Mirazita100, V. Mokeev101, A. Movsisyan102, E. Munevar103, C. Munoz Camacho104, G. Murdoch105, P. Nadel-Turonski106, L. A. Net107, A. Ni108, S. Niccolai109, G. Niculescu110, I. Niculescu111, M. Osipenko112, A. I. Ostrovidov113, M. Paolone114, R. Paremuzyan115, K. Park116, E. Pasyuk117, P. Peng118, S. Pisano119, O. Pogorelko120, J. W. Price121, A. J. R. Puckett122, B. A. Raue123, A. Rizzo124, G. Rosner125, P. Rossi126, P. Roy127, F. Sabatié128, C. Salgado129, R. A. Schumacher130, Y. G. Sharabian131, Iu. Skorodumina132, G. D. Smith133, D. Sokhan134, N. Sparveris135, I. Stankovic136, I. I. Strakovsky137, S. Strauch138, M. Taiuti139, Ye Tian140, M. Ungaro141, H. Voskanyan142, E. Voutier143, N. K. Walford144, D. P. Watts145, X. Wei146, L. B. Weinstein147, M. H. Wood148, N. Zachariou149, J. Zhang150
Affiliations: 1The CLAS Collaboration, 2The CLAS Collaboration, 3The CLAS Collaboration, 4The CLAS Collaboration, 5The CLAS Collaboration, 6The CLAS Collaboration, 7The CLAS Collaboration, 8The CLAS Collaboration, 9The CLAS Collaboration, 10The CLAS Collaboration, 11The CLAS Collaboration, 12The CLAS Collaboration, 13The CLAS Collaboration, 14The CLAS Collaboration, 15The CLAS Collaboration, 16The CLAS Collaboration, 17The CLAS Collaboration, 18The CLAS Collaboration, 19The CLAS Collaboration, 20The CLAS Collaboration, 21The CLAS Collaboration, 22The CLAS Collaboration, 23The CLAS Collaboration, 24The CLAS Collaboration, 25The CLAS Collaboration, 26The CLAS Collaboration, 27The CLAS Collaboration, 28The CLAS Collaboration, 29The CLAS Collaboration, 30The CLAS Collaboration, 31The CLAS Collaboration, 32The CLAS Collaboration, 33The CLAS Collaboration, 34The CLAS Collaboration, 35The CLAS Collaboration, 36The CLAS Collaboration, 37The CLAS Collaboration, 38The CLAS Collaboration, 39The CLAS Collaboration, 40The CLAS Collaboration, 41The CLAS Collaboration, 42The CLAS Collaboration, 43The CLAS Collaboration, 44The CLAS Collaboration, 45The CLAS Collaboration, 46The CLAS Collaboration, 47The CLAS Collaboration, 48The CLAS Collaboration, 49The CLAS Collaboration, 50The CLAS Collaboration, 51The CLAS Collaboration, 52The CLAS Collaboration, 53The CLAS Collaboration, 54The CLAS Collaboration, 55The CLAS Collaboration, 56The CLAS Collaboration, 57The CLAS Collaboration, 58The CLAS Collaboration, 59The CLAS Collaboration, 60The CLAS Collaboration, 61The CLAS Collaboration, 62The CLAS Collaboration, 63The CLAS Collaboration, 64The CLAS Collaboration, 65The CLAS Collaboration, 66The CLAS Collaboration, 67The CLAS Collaboration, 68The CLAS Collaboration, 69The CLAS Collaboration, 70The CLAS Collaboration, 71The CLAS Collaboration, 72The CLAS Collaboration, 73The CLAS Collaboration, 74The CLAS Collaboration, 75The CLAS Collaboration, 76The CLAS Collaboration, 77The CLAS Collaboration, 78The CLAS Collaboration, 79The CLAS Collaboration, 80The CLAS Collaboration, 81The CLAS Collaboration, 82The CLAS Collaboration, 83The CLAS Collaboration, 84The CLAS Collaboration, 85The CLAS Collaboration, 86The CLAS Collaboration, 87The CLAS Collaboration, 88The CLAS Collaboration, 89The CLAS Collaboration, 90The CLAS Collaboration, 91The CLAS Collaboration, 92The CLAS Collaboration, 93The CLAS Collaboration, 94The CLAS Collaboration, 95The CLAS Collaboration, 96The CLAS Collaboration, 97The CLAS Collaboration, 98The CLAS Collaboration, 99The CLAS Collaboration, 100The CLAS Collaboration, 101The CLAS Collaboration, 102The CLAS Collaboration, 103The CLAS Collaboration, 104The CLAS Collaboration, 105The CLAS Collaboration, 106The CLAS Collaboration, 107The CLAS Collaboration, 108The CLAS Collaboration, 109The CLAS Collaboration, 110The CLAS Collaboration, 111The CLAS Collaboration, 112The CLAS Collaboration, 113The CLAS Collaboration, 114The CLAS Collaboration, 115The CLAS Collaboration, 116The CLAS Collaboration, 117The CLAS Collaboration, 118The CLAS Collaboration, 119The CLAS Collaboration, 120The CLAS Collaboration, 121The CLAS Collaboration, 122The CLAS Collaboration, 123The CLAS Collaboration, 124The CLAS Collaboration, 125The CLAS Collaboration, 126The CLAS Collaboration, 127The CLAS Collaboration, 128The CLAS Collaboration, 129The CLAS Collaboration, 130The CLAS Collaboration, 131The CLAS Collaboration, 132The CLAS Collaboration, 133The CLAS Collaboration, 134The CLAS Collaboration, 135The CLAS Collaboration, 136The CLAS Collaboration, 137The CLAS Collaboration, 138The CLAS Collaboration, 139The CLAS Collaboration, 140The CLAS Collaboration, 141The CLAS Collaboration, 142The CLAS Collaboration, 143The CLAS Collaboration, 144The CLAS Collaboration, 145The CLAS Collaboration, 146The CLAS Collaboration, 147The CLAS Collaboration, 148The CLAS Collaboration, 149The CLAS Collaboration, 150The CLAS Collaboration

We report measurements of target- and double-spin asymmetries for the exclusive channel $\vec e\vec p\to e\pi^+ (n)$ in the nucleon resonance region at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). These asymmetries were extracted from data obtained using a longitudinally polarized NH$_3$ target and a longitudinally polarized electron beam with energies 1.1, 1. Read More

High statistics measurements of the photon asymmetry $\mathrm{\Sigma}$ for the $\overrightarrow{\gamma}$p$\rightarrow\pi^{0}$p reaction have been made in the center of mass energy range W=1214-1450 MeV. The data were measured with the MAMI A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The results significantly improve the existing world data and are shown to be in good agreement with previous measurements, and with the MAID, SAID, and Bonn-Gatchina predictions. Read More

2016Apr
Authors: P. E. Bosted1, A. S. Biselli2, S. Careccia3, G. Dodge4, R. Fersch5, S. E. Kuhn6, J. Pierce7, Y. Prok8, X. Zheng9, K. P. Adhikari10, D. Adikaram11, Z. Akbar12, M. J. Amaryan13, S. Anefalos Pereira14, G. Asryan15, H. Avakian16, R. A. Badui17, J. Ball18, N. A. Baltzell19, M. Battaglieri20, V. Batourine21, I. Bedlinskiy22, S. Boiarinov23, W. J. Briscoe24, S. Bültmann25, V. D. Burkert26, T. Cao27, D. S. Carman28, A. Celentano29, S. Chandavar30, G. Charles31, T. Chetry32, G. Ciullo33, L. Clark34, L. Colaneri35, P. L. Cole36, M. Contalbrigo37, O. Cortes38, V. Crede39, A. D'Angelo40, N. Dashyan41, R. De Vita42, A. Deur43, C. Djalali44, R. Dupre45, H. Egiyan46, A. El Alaoui47, L. El Fassi48, P. Eugenio49, E. Fanchini50, G. Fedotov51, A. Filippi52, J. A. Fleming53, T. A. Forest54, A. Fradi55, M. Garçon56, N. Gevorgyan57, Y. Ghandilyan58, G. P. Gilfoyle59, K. L. Giovanetti60, F. X. Girod61, C. Gleason62, W. Gohn63, E. Golovatch64, R. W. Gothe65, K. A. Griffioen66, N. Guler67, L. Guo68, K. Hafidi69, C. Hanretty70, N. Harrison71, M. Hattawy72, D. Heddle73, K. Hicks74, M. Holtrop75, S. M. Hughes76, Y. Ilieva77, D. G. Ireland78, B. S. Ishkhanov79, E. L. Isupov80, D. Jenkins81, H. Jiang82, H. S. Jo83, K. Joo84, S. Joosten85, D. Keller86, M. Khandaker87, W. Kim88, A. Klein89, F. J. Klein90, V. Kubarovsky91, S. V. Kuleshov92, L. Lanza93, P. Lenisa94, K. Livingston95, H. Y. Lu96, I . J . D. MacGregor97, N. Markov98, M. E. McCracken99, B. McKinnon100, C. A. Meyer101, R. Minehart102, M. Mirazita103, V. Mokeev104, A Movsisyan105, E. Munevar106, C. Munoz Camacho107, P. Nadel-Turonski108, L. A. Net109, A. Ni110, S. Niccolai111, G. Niculescu112, I. Niculescu113, M. Osipenko114, A. I. Ostrovidov115, R. Paremuzyan116, K. Park117, E. Pasyuk118, P. Peng119, W. Phelps120, S. Pisano121, O. Pogorelko122, J. W. Price123, S. Procureur124, D. Protopopescu125, A. J. R. Puckett126, B. A. Raue127, M. Ripani128, A. Rizzo129, G. Rosner130, P. Rossi131, P. Roy132, F. Sabatié133, C. Salgado134, R. A. Schumacher135, E. Seder136, Y. G. Sharabian137, A. Simonyan138, Iu. Skorodumina139, G. D. Smith140, N. Sparveris141, Ivana Stankovic142, S. Stepanyan143, I. I. Strakovsky144, S. Strauch145, V. Sytnik146, M. Taiuti147, Ye Tian148, B. Torayev149, M. Ungaro150, H. Voskanyan151, E. Voutier152, N. K. Walford153, D. P. Watts154, X. Wei155, L. B. Weinstein156, M. H. Wood157, N. Zachariou158, L. Zana159, J. Zhang160, Z. W. Zhao161, I. Zonta162
Affiliations: 1CLAS Collaboration, 2CLAS Collaboration, 3CLAS Collaboration, 4CLAS Collaboration, 5CLAS Collaboration, 6CLAS Collaboration, 7CLAS Collaboration, 8CLAS Collaboration, 9CLAS Collaboration, 10CLAS Collaboration, 11CLAS Collaboration, 12CLAS Collaboration, 13CLAS Collaboration, 14CLAS Collaboration, 15CLAS Collaboration, 16CLAS Collaboration, 17CLAS Collaboration, 18CLAS Collaboration, 19CLAS Collaboration, 20CLAS Collaboration, 21CLAS Collaboration, 22CLAS Collaboration, 23CLAS Collaboration, 24CLAS Collaboration, 25CLAS Collaboration, 26CLAS Collaboration, 27CLAS Collaboration, 28CLAS Collaboration, 29CLAS Collaboration, 30CLAS Collaboration, 31CLAS Collaboration, 32CLAS Collaboration, 33CLAS Collaboration, 34CLAS Collaboration, 35CLAS Collaboration, 36CLAS Collaboration, 37CLAS Collaboration, 38CLAS Collaboration, 39CLAS Collaboration, 40CLAS Collaboration, 41CLAS Collaboration, 42CLAS Collaboration, 43CLAS Collaboration, 44CLAS Collaboration, 45CLAS Collaboration, 46CLAS Collaboration, 47CLAS Collaboration, 48CLAS Collaboration, 49CLAS Collaboration, 50CLAS Collaboration, 51CLAS Collaboration, 52CLAS Collaboration, 53CLAS Collaboration, 54CLAS Collaboration, 55CLAS Collaboration, 56CLAS Collaboration, 57CLAS Collaboration, 58CLAS Collaboration, 59CLAS Collaboration, 60CLAS Collaboration, 61CLAS Collaboration, 62CLAS Collaboration, 63CLAS Collaboration, 64CLAS Collaboration, 65CLAS Collaboration, 66CLAS Collaboration, 67CLAS Collaboration, 68CLAS Collaboration, 69CLAS Collaboration, 70CLAS Collaboration, 71CLAS Collaboration, 72CLAS Collaboration, 73CLAS Collaboration, 74CLAS Collaboration, 75CLAS Collaboration, 76CLAS Collaboration, 77CLAS Collaboration, 78CLAS Collaboration, 79CLAS Collaboration, 80CLAS Collaboration, 81CLAS Collaboration, 82CLAS Collaboration, 83CLAS Collaboration, 84CLAS Collaboration, 85CLAS Collaboration, 86CLAS Collaboration, 87CLAS Collaboration, 88CLAS Collaboration, 89CLAS Collaboration, 90CLAS Collaboration, 91CLAS Collaboration, 92CLAS Collaboration, 93CLAS Collaboration, 94CLAS Collaboration, 95CLAS Collaboration, 96CLAS Collaboration, 97CLAS Collaboration, 98CLAS Collaboration, 99CLAS Collaboration, 100CLAS Collaboration, 101CLAS Collaboration, 102CLAS Collaboration, 103CLAS Collaboration, 104CLAS Collaboration, 105CLAS Collaboration, 106CLAS Collaboration, 107CLAS Collaboration, 108CLAS Collaboration, 109CLAS Collaboration, 110CLAS Collaboration, 111CLAS Collaboration, 112CLAS Collaboration, 113CLAS Collaboration, 114CLAS Collaboration, 115CLAS Collaboration, 116CLAS Collaboration, 117CLAS Collaboration, 118CLAS Collaboration, 119CLAS Collaboration, 120CLAS Collaboration, 121CLAS Collaboration, 122CLAS Collaboration, 123CLAS Collaboration, 124CLAS Collaboration, 125CLAS Collaboration, 126CLAS Collaboration, 127CLAS Collaboration, 128CLAS Collaboration, 129CLAS Collaboration, 130CLAS Collaboration, 131CLAS Collaboration, 132CLAS Collaboration, 133CLAS Collaboration, 134CLAS Collaboration, 135CLAS Collaboration, 136CLAS Collaboration, 137CLAS Collaboration, 138CLAS Collaboration, 139CLAS Collaboration, 140CLAS Collaboration, 141CLAS Collaboration, 142CLAS Collaboration, 143CLAS Collaboration, 144CLAS Collaboration, 145CLAS Collaboration, 146CLAS Collaboration, 147CLAS Collaboration, 148CLAS Collaboration, 149CLAS Collaboration, 150CLAS Collaboration, 151CLAS Collaboration, 152CLAS Collaboration, 153CLAS Collaboration, 154CLAS Collaboration, 155CLAS Collaboration, 156CLAS Collaboration, 157CLAS Collaboration, 158CLAS Collaboration, 159CLAS Collaboration, 160CLAS Collaboration, 161CLAS Collaboration, 162CLAS Collaboration

Beam-target double spin asymmetries and target single-spin asymmetries in exclusive $\pi^+$ and $\pi^-$ electroproduction were obtained from scattering of 1.6 to 5.7 GeV longitudinally polarized electrons from longitudinally polarized protons (for $\pi^+$) and deuterons (for $\pi^-$) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Read More

2016Mar
Authors: D. Rimal, D. Adikaram, B. A. Raue, L. B. Weinstein, J. Arrington, W. K. Brooks, M. Ungaro, K. P. Adhikari, Z. Akbar, S. Anefalos Pereira, R. A. Badui, J. Ball, N. A. Baltzell, M. Battaglieri, V. Batourine, I. Bedlinskiy, R. P. Bennett, A. S. Biselli, S. Boiarinov, W. J. Briscoe, S. Bültmann, D. S. Carman, A. Celentano, T. Chetry, G. Ciullo, L. Clark, L. Colaneri, P. L. Cole, N. Compton, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, A. Deur, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, P. Eugenio, G. Fedotov, R. Fersch, A. Filippi, J. A. Fleming, T. A. Forest, A. Fradi, N. Gevorgyan, Y. Ghandilyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, C. Gleason, W. Gohn, E. Golovatch, R. W. Gothe, K. A. Griffioen, L. Guo, K. Hafidi, C. Hanretty, N. Harrison, M. Hattawy, D. Heddle, K. Hicks, M. Holtrop, S. M. Hughes, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, D. Jenkins, H. Jiang, S. Joosten, D. Keller, P. Khetarpal, G. Khachatryan, M. Khandaker, W. Kim, A. Klein, F. J. Klein, V. Kubarovsky, S. E. Kuhn, S. V. Kuleshov, L. Lanza, P. Lenisa, K. Livingston, H. Y. Lu, I . J . D. MacGregor, N. Markov, B. McKinnon, M. D. Mestayer, M. Mirazita, V. Mokeev, A Movsisyan, E. Munevar, C. Munoz Camacho, P. Nadel-Turonski, A. Ni, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A. I. Ostrovidov, M. Paolone, R. Paremuzyan, K. Park, E. Pasyuk, W. Phelps, S. Pisano, O. Pogorelko, J. W. Price, Y. Prok, D. Protopopescu, A. J. R. Puckett, A. Rizzo, G. Rosner, P. Rossi, P. Roy, F. Sabatié, C. Salgado, R. A. Schumacher, E. Seder, Y. G. Sharabian, Iu. Skorodumina, G. D. Smith, D. Sokhan, N. Sparveris, Ivana Stankovic, S. Stepanyan, S. Strauch, V. Sytnik, M. Taiuti, B. Torayev, H. Voskanyan, E. Voutier, N. K. Walford, D. P. Watts, X. Wei, M. H. Wood, N. Zachariou, L. Zana, J. Zhang, Z. W. Zhao, I. Zonta

[Background] The electromagnetic form factors of the proton measured by unpolarized and polarized electron scattering experiments show a significant disagreement that grows with the squared four momentum transfer ($Q^{2}$). Calculations have shown that the two measurements can be largely reconciled by accounting for the contributions of two-photon exchange (TPE). TPE effects are not typically included in the standard set of radiative corrections since theoretical calculations of the TPE effects are highly model dependent, and, until recently, no direct evidence of significant TPE effects has been observed. Read More

2015Nov
Authors: A. Kim, H. Avakian, V. Burkert, K. Joo, W. Kim, K. P. Adhikari, Z. Akbar, S. Anefalos Pereira, R. A. Badui, M. Battaglieri, V. Batourine, I. Bedlinskiy, A. S. Biselli, S. Boiarinov, P. Bosted, W. J. Briscoe, W. K. Brooks, S. Bültmann, T. Cao, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, T. Chetry, L. Colaneri, P. L. Cole, N. Compton, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, C. Djalali, H. Egiyan, A. El Alaoui, L. El Fassi, P. Eugenio, G. Fedotov, R. Fersch, A. Filippi, J. A. Fleming, A. Fradi, M. Garçon, Y. Ghandilyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, W. Gohn, E. Golovatch, R. W. Gothe, K. A. Griffioen, L. Guo, K. Hafidi, C. Hanretty, M. Hattawy, D. Heddle, K. Hicks, M. Holtrop, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, D. Jenkins, H. Jiang, H. S. Jo, S. Joosten, D. Keller, G. Khachatryan, M. Khandaker, A. Klein, F. J. Klein, V. Kubarovsky, S. E. Kuhn, S. V. Kuleshov, L. Lanza, P. Lenisa, H. Y. Lu, I . J . D. MacGregor, N. Markov, P. Mattione, M. E. McCracken, B. McKinnon, V. Mokeev, A Movsisyan, E. Munevar, P. Nadel-Turonski, L. A. Net, S. Niccolai, M. Osipenko, A. I. Ostrovidov, M. Paolone, K. Park, E. Pasyuk, W. Phelps, S. Pisano, O. Pogorelko, J. W. Price, Y. Prok, M. Ripani, A. Rizzo, G. Rosner, P. Rossi, P. Roy, C. Salgado, R. A. Schumacher, E. Seder, Y. G. Sharabian, Iu. Skorodumina, G. D. Smith, D. Sokhan, N. Sparveris, S. Stepanyan, P. Stoler, I. I. Strakovsky, S. Strauch, V. Sytnik, M. Taiuti, B. Torayev, M. Ungaro, H. Voskanyan, E. Voutier, D. P. Watts, X. Wei, L. B. Weinstein, N. Zachariou, L. Zana, J. Zhang, I. Zonta

The target and double spin asymmetries of the exclusive pseudoscalar channel $\vec e\vec p\to ep\pi^0$ were measured for the first time in the deep-inelastic regime using a longitudinally polarized 5.9 GeV electron beam and a longitudinally polarized proton target at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS). The data were collected over a large kinematic phase space and divided into 110 four-dimensional bins of $Q^2$, $x_B$, $-t$ and $\phi$. Read More

Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $\pi^0\pi^0$ pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557~MeV, which produced bremsstrahlung in thin radiator foils. Read More

2015Jul
Authors: M. E. McCracken, M. Bellis, K. P. Adhikari, D. Adikaram, Z. Akbar, S. Anefalos Pereira, R. A. Badui, J. Ball, N. A. Baltzell, M. Battaglieri, V. Batourine, I. Bedlinskiy, A. S. Biselli, S. Boiarinov, W. J. Briscoe, W. K. Brooks, V. D. Burkert, T. Cao, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P. L. Cole, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, G. E. Dodge, R. Dupre, A. El Alaoui, L. El Fassi, E. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, R. Fersch, A. Filippi, J. A. Fleming, B. Garillon, N. Gevorgyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, E. Golovatch, R. W. Gothe, K. A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, M. Hattawy, K. Hicks, M. Holtrop, S. M. Hughes, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, D. Jenkins, H. Jiang, H. S. Jo, D. Keller, G. Khachatryan, M. Khandaker, A. Kim, W. Kim, A. Klein, F. J. Klein, V. Kubarovsky, P. Lenisa, K. Livingston, H. Y. Lu, I. J. D. MacGregor, M. Mayer, B. McKinnon, M. D. Mestayer, C. A. Meyer, M. Mirazita, V. Mokeev, C. I. Moody, K. Moriya, C. Munoz Camacho, P. Nadel-Turonski, L. A. Net, S. Niccolai, M. Osipenko, A. I. Ostrovidov, K. Park, E. Pasyuk, S. Pisano, O. Pogorelko, J. W. Price, S. Procureur, Y. Prok, B. A. Raue, M. Ripani, A. Rizzo, G. Rosner, P. Roy, F. Sabatié, C. Salgado, R. A. Schumacher, E. Seder, Y. G. Sharabian, Iu. Skorodumina, D. Sokhan, N. Sparveris, P. Stoler, I. I. Strakovsky, S. Strauch, V. Sytnik, Ye Tian, M. Ungaro, H. Voskanyan, E. Voutier, N. K. Walford, D. P. Watts, X. Wei, M. H. Wood, N. Zachariou, L. Zana, J. Zhang, Z. W. Zhao, I. Zonta

We present a search for ten baryon-number violating decay modes of $\Lambda$ hyperons using the CLAS detector at Jefferson Laboratory. Nine of these decay modes result in a single meson and single lepton in the final state ($\Lambda \rightarrow m \ell$) and conserve either the sum or the difference of baryon and lepton number ($B \pm L$). The tenth decay mode ($\Lambda \rightarrow \bar{p}\pi^+$) represents a difference in baryon number of two units and no difference in lepton number. Read More

Photoproduction of $\pi\eta$-pairs from nucleons has been investigated from threshold up to incident photon energies of $\approx$~1.4~GeV. The quasi-free reactions $\gamma p\rightarrow p\pi^0\eta$, $\gamma n\rightarrow n\pi^0\eta$, $\gamma p\rightarrow n\pi^+\eta$, and $\gamma n\rightarrow p\pi^-\eta$ were for the first time measured from nucleons bound in the deuteron. Read More

2015Jul
Authors: I. Senderovich, B. T. Morrison, M. Dugger, B. G. Ritchie, E. Pasyuk, R. Tucker, J. Brock, C. Carlin, C. D. Keith, D. G. Meekins, M. L. Seely, D. R, M. D, P. Collins, K. P. Adhikari, D. Adikaram, Z. Akbar, M. D. Anderson, S. Anefalos Pereira, R. A. Badui, J. Ball, N. A. Baltzell, M. Battaglieri, V. Batourine, I. Bedlinskiy, A. S. Biselli, S. Boiarinov, W. J. Briscoe, W. K. Brooks, V. D. Burkert, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P. L. Cole, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, A. Fradi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, A. Filippi, J. A. Fleming, B. Garillon, Y. Ghandilyan, G. P. Gilfoyle, K. L. Giovanetti, F. -X. Girod, D. I. Glazier, J. T. Goetz, W. Gohn, E. Golovatch, R. W. Gothe, K. A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, M. Hattawy, K. Hicks, D. Ho, M. Holtrop, S. M. Hughes, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, D. Jenkins, H. Jiang, H. S. Jo, K. Joo, S. Joosten, D. Keller, G. Khachatryan, M. Khandaker, A. Kim, F. J. Klein, V. Kubarovsky, M. C. Kunkel, P. Lenisa, K. Livingston, H. Y. Lu, I. J. D. MacGregor, P. Mattione, B. McKinnon, C. A. Meyer, T. Mineeva, V. Mokeev, R. A. Montgomery, A. Movsisyan, C. Munoz Camacho, P. Nadel-Turonski, L. A. Net, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, K. Park, S. Park, P. Peng, W. Phelps, S. Pisano, O. Pogorelko, J. W. Price, Y. Prok, A. J. R. Puckett, M. Ripani, A. Rizzo, G. Rosner, P. Roy, F. Sabatie, C. Salgado, D. Schott, R. A. Schumacher, E. Seder, A. Simonyan, Iu. Skorodumina, G. D. Smith, D. I. Sober, D. Sokhan, N. Sparveris, S. Stepanyan, P. Stoler, I. I. Strakovsky, S. Strauch, V. Sytnik, Ye Tian, M. Ungaro, H. Voskanyan, E. Voutier, N. K. Walford, X. Wei, M. H. Wood, N. Zachariou, L. Zana, J. Zhang, Z. W. Zhao, I. Zonta

Results are presented for the first measurement of the double-polarization helicity asymmetry E for the $\eta$ photoproduction reaction $\gamma p \rightarrow \eta p$. Data were obtained using the FROzen Spin Target (FROST) with the CLAS spectrometer in Hall B at Jefferson Lab, covering a range of center-of-mass energy W from threshold to 2.15 GeV and a large range in center-of-mass polar angle. Read More

Differential cross sections for the gamma p -> pi^0 p reaction have been measured with the A2 tagged-photon facilities at the Mainz Microtron, MAMI C, up to the center-of-mass energy W=1.9 GeV. The new results, obtained with a fine energy and angular binning, increase the existing quantity of pi^0 photoproduction data by ~47%. Read More

The first data on target and beam-target asymmetries for the $\gamma p\to\pi^0\eta p$ 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. Read More

2015May
Authors: N. Guler, R. G. Fersch, S. E. Kuhn, P. Bosted, K. A. Griffioen, C. Keith, R. Minehart, Y. Prok, K. P. Adhikari, D. Adikaram, M. J. Amaryan, M. D. Anderson, S. Anefalos Pereira, J. Ball, M. Battaglieri, V. Batourine, I. Bedlinskiy, W. J. Briscoe, W. K. Brooks, S. Bultmann, V. D. Burkert, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P. L. Cole, M. Contalbrigo, D. Crabb, V. Crede, A. D Angelo, N. Dashyan, A. Deur, C. Djalali, G. E. Dodge, R. Dupre, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, A. Filippi, J. A. Fleming, T. A. Forest, B. Garillon, M. Garcon, N. Gevorgyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, J. T. Goetz, E. Golovatch, R. W. Gothe, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, N. Harrison, M. Hattawy, K. Hicks, D. Ho, M. Holtrop, S. M. Hughes, C. E. Hyde, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, H. S. Jo, K. Joo, S. Joosten, D. Keller, M. Khandaker, A. Kim, W. Kim, A. Klein, F. J. Klein, V. Kubarovsky, S. V. Kuleshov, K. Livingston, H. Y. Lu, I. J. D. MacGregor, B. McKinnon, M. Mirazita, V. Mokeev, R. A. Montgomery, A Movsisyan, C. Munoz Camacho, P. Nadel-Turonski, L. A. Net, I. Niculescu, M. Osipenko, A. I. Ostrovidov, K. Park, E. Pasyuk, S. Pisano, O. Pogorelko, J. W. Price, S. Procureur, M. Ripani, A. Rizzo, G. Rosner, P. Rossi, P. Roy, F. Sabatie, C. Salgado, D. Schott, R. A. Schumacher, E. Seder, A. Simonyan, Iu. Skorodumina, D. Sokhan, N. Sparveris, I. I. Strakovsky, S. Strauch, V. Sytnik, Ye Tian, S. Tkachenko, M. Ungaro, E. Voutier, N. K. Walford, X. Wei, L. B. Weinstein, M. H. Wood, N. Zachariou, L. Zana, J. Zhang, Z. W. Zhao, I. Zonta

We present the final results for the deuteron spin structure functions obtained from the full data set collected with Jefferson Lab's CLAS in 2000-2001. Polarized electrons with energies of 1.6, 2. Read More

2015Mar
Authors: Nicholas Zachariou, Yordanka Ilieva, Nikolay Ya. Ivanov, Misak M Sargsian, Robert Avakian, Gerald Feldman, Pawel Nadel-Turonski, K. P. Adhikari, D. Adikaram, M. D. Anderson, S. Anefalos Pereira, H. Avakian, R. A. Badui, N. A. Baltzell, M. Battaglieri, V. Baturin, I. Bedlinskiy, A. S. Biselli, W. J. Briscoe, W. K. Brooks, V. D. Burkert, T. Cao, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P. L. Cole, N. Compton, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, G. Fedotov, S. Fegan, A. Filippi, J. A. Fleming, T. A. Forest, A. Fradi, N. Gevorgyan, Y. Ghandilyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, D. I. Glazier, E. Golovatch, R. W. Gothe, K. A. Griffioen, M. Guidal, K. Hafidi, C. Hanretty, N. Harrison, M. Hattawy, K. Hicks, D. Ho, M. Holtrop, S. M. Hughes, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, H. Jiang, H. S. Jo, K. Joo, D. Keller, G. Khachatryan, M. Khandaker, A. Kim, W. Kim, F. J. Klein, V. Kubarovsky, P. Lenisa, K. Livingston, H. Y. Lu, I . J . D. MacGregor, N. Markov, P. T. Mattione, B. McKinnon, T. Mineeva, M. Mirazita, V. I. Mokeeev, R. A. Montgomery, H. Moutarde, C. Munoz Camacho, L. A. Net, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A. I. Ostrovidov, K. Park, E. Pasyuk, W. Phelps, J. J. Phillips, S. Pisano, O. Pogorelko, S. Pozdniakov, J. W. Price, S. Procureur, Y. Prok, D. Protopopescu, A. J. R. Puckett, M. Ripani, A. Rizzo, G. Rosner, P. Rossi, P. Roy, F. Sabatié, C. Salgado, D. Schott, R. A. Schumacher, E. Seder, I. Senderovich, Y. G. Sharabian, Iu. Skorodumina, G. D. Smith, D. I. Sober, D. Sokhan, N. Sparveris, S. Stepanyan, S. Strauch, V. Sytnik, M. Taiuti, Ye Tian, M. Ungaro, H. Voskanyan, E. Voutier, N. K. Walford, D. Watts, X. Wei, M. H. Wood, L. Zana, J. Zhang, Z. W. Zhao, I. Zonta, for the CLAS collaboration

The beam-spin asymmetry, $\Sigma$, for the reaction $\gamma d\rightarrow pn$ has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, $\theta_{c. Read More

A multi-cell He gas-scintillator active target, designed for the measurement of photoreaction cross sections, is described. The target has four main chambers, giving an overall thickness of 0.103 $\mathrm{g/cm^{2}}$ at an operating pressure of 2 MPa. Read More

2015Mar
Authors: S. Strauch1, W. J. Briscoe2, M. Döring3, E. Klempt4, V. A. Nikonov5, E. Pasyuk6, D. Rönchen7, A. V. Sarantsev8, I. Strakovsky9, R. Workman10, K. P. Adhikari11, D. Adikaram12, M. D. Anderson13, S. Anefalos Pereira14, A. V. Anisovich15, R. A. Badui16, J. Ball17, V. Batourine18, M. Battaglieri19, I. Bedlinskiy20, N. Benmouna21, A. S. Biselli22, J. Brock23, W. K. Brooks24, V. D. Burkert25, T. Cao26, C. Carlin27, D. S. Carman28, A. Celentano29, S. Chandavar30, G. Charles31, L. Colaneri32, P. L. Cole33, N. Compton34, M. Contalbrigo35, O. Cortes36, V. Crede37, N. Dashyan38, A. D'Angelo39, R. De Vita40, E. De Sanctis41, A. Deur42, C. Djalali43, M. Dugger44, R. Dupre45, H. Egiyan46, A. El Alaoui47, L. El Fassi48, L. Elouadrhiri49, P. Eugenio50, G. Fedotov51, S. Fegan52, A. Filippi53, J. A. Fleming54, T. A. Forest55, A. Fradi56, N. Gevorgyan57, Y. Ghandilyan58, K. L. Giovanetti59, F. X. Girod60, D. I. Glazier61, W. Gohn62, E. Golovatch63, R. W. Gothe64, K. A. Griffioen65, M. Guidal66, L. Guo67, K. Hafidi68, H. Hakobyan69, C. Hanretty70, N. Harrison71, M. Hattawy72, K. Hicks73, D. Ho74, M. Holtrop75, S. M. Hughes76, Y. Ilieva77, D. G. Ireland78, B. S. Ishkhanov79, E. L. Isupov80, D. Jenkins81, H. Jiang82, H. S. Jo83, K. Joo84, S. Joosten85, C. D. Keith86, D. Keller87, G. Khachatryan88, M. Khandaker89, A. Kim90, W. Kim91, A. Klein92, F. J. Klein93, V. Kubarovsky94, S. E. Kuhn95, P. Lenisa96, K. Livingston97, H. Y. Lu98, I . J . D. MacGregor99, N. Markov100, B. McKinnon101, D. G. Meekins102, C. A. Meyer103, V. Mokeev104, R. A. Montgomery105, C. I. Moody106, H. Moutarde107, A Movsisyan108, E. Munevar109, C. Munoz Camacho110, P. Nadel-Turonski111, L. A. Net112, S. Niccolai113, G. Niculescu114, I. Niculescu115, M. Osipenko116, A. I. Ostrovidov117, K. Park118, P. Peng119, W. Phelps120, J. J. Phillips121, S. Pisano122, O. Pogorelko123, S. Pozdniakov124, J. W. Price125, S. Procureur126, Y. Prok127, D. Protopopescu128, A. J. R. Puckett129, B. A. Raue130, M. Ripani131, B. G. Ritchie132, A. Rizzo133, G. Rosner134, P. Roy135, F. Sabatié136, C. Salgado137, D. Schott138, R. A. Schumacher139, E. Seder140, M. L. Seely141, I Senderovich142, Y. G. Sharabian143, A. Simonyan144, Iu. Skorodumina145, G. D. Smith146, D. I. Sober147, D. Sokhan148, N. Sparveris149, P. Stoler150, S. Stepanyan151, V. Sytnik152, M. Taiuti153, Ye Tian154, A. Trivedi155, R. Tucker156, M. Ungaro157, H. Voskanyan158, E. Voutier159, N. K. Walford160, D. P. Watts161, X. Wei162, M. H. Wood163, N. Zachariou164, L. Zana165, J. Zhang166, Z. W. Zhao167, I. Zonta168
Affiliations: 1The CLAS Collaboration, 2The CLAS Collaboration, 3The CLAS Collaboration, 4The CLAS Collaboration, 5The CLAS Collaboration, 6The CLAS Collaboration, 7The CLAS Collaboration, 8The CLAS Collaboration, 9The CLAS Collaboration, 10The CLAS Collaboration, 11The CLAS Collaboration, 12The CLAS Collaboration, 13The CLAS Collaboration, 14The CLAS Collaboration, 15The CLAS Collaboration, 16The CLAS Collaboration, 17The CLAS Collaboration, 18The CLAS Collaboration, 19The CLAS Collaboration, 20The CLAS Collaboration, 21The CLAS Collaboration, 22The CLAS Collaboration, 23The CLAS Collaboration, 24The CLAS Collaboration, 25The CLAS Collaboration, 26The CLAS Collaboration, 27The CLAS Collaboration, 28The CLAS Collaboration, 29The CLAS Collaboration, 30The CLAS Collaboration, 31The CLAS Collaboration, 32The CLAS Collaboration, 33The CLAS Collaboration, 34The CLAS Collaboration, 35The CLAS Collaboration, 36The CLAS Collaboration, 37The CLAS Collaboration, 38The CLAS Collaboration, 39The CLAS Collaboration, 40The CLAS Collaboration, 41The CLAS Collaboration, 42The CLAS Collaboration, 43The CLAS Collaboration, 44The CLAS Collaboration, 45The CLAS Collaboration, 46The CLAS Collaboration, 47The CLAS Collaboration, 48The CLAS Collaboration, 49The CLAS Collaboration, 50The CLAS Collaboration, 51The CLAS Collaboration, 52The CLAS Collaboration, 53The CLAS Collaboration, 54The CLAS Collaboration, 55The CLAS Collaboration, 56The CLAS Collaboration, 57The CLAS Collaboration, 58The CLAS Collaboration, 59The CLAS Collaboration, 60The CLAS Collaboration, 61The CLAS Collaboration, 62The CLAS Collaboration, 63The CLAS Collaboration, 64The CLAS Collaboration, 65The CLAS Collaboration, 66The CLAS Collaboration, 67The CLAS Collaboration, 68The CLAS Collaboration, 69The CLAS Collaboration, 70The CLAS Collaboration, 71The CLAS Collaboration, 72The CLAS Collaboration, 73The CLAS Collaboration, 74The CLAS Collaboration, 75The CLAS Collaboration, 76The CLAS Collaboration, 77The CLAS Collaboration, 78The CLAS Collaboration, 79The CLAS Collaboration, 80The CLAS Collaboration, 81The CLAS Collaboration, 82The CLAS Collaboration, 83The CLAS Collaboration, 84The CLAS Collaboration, 85The CLAS Collaboration, 86The CLAS Collaboration, 87The CLAS Collaboration, 88The CLAS Collaboration, 89The CLAS Collaboration, 90The CLAS Collaboration, 91The CLAS Collaboration, 92The CLAS Collaboration, 93The CLAS Collaboration, 94The CLAS Collaboration, 95The CLAS Collaboration, 96The CLAS Collaboration, 97The CLAS Collaboration, 98The CLAS Collaboration, 99The CLAS Collaboration, 100The CLAS Collaboration, 101The CLAS Collaboration, 102The CLAS Collaboration, 103The CLAS Collaboration, 104The CLAS Collaboration, 105The CLAS Collaboration, 106The CLAS Collaboration, 107The CLAS Collaboration, 108The CLAS Collaboration, 109The CLAS Collaboration, 110The CLAS Collaboration, 111The CLAS Collaboration, 112The CLAS Collaboration, 113The CLAS Collaboration, 114The CLAS Collaboration, 115The CLAS Collaboration, 116The CLAS Collaboration, 117The CLAS Collaboration, 118The CLAS Collaboration, 119The CLAS Collaboration, 120The CLAS Collaboration, 121The CLAS Collaboration, 122The CLAS Collaboration, 123The CLAS Collaboration, 124The CLAS Collaboration, 125The CLAS Collaboration, 126The CLAS Collaboration, 127The CLAS Collaboration, 128The CLAS Collaboration, 129The CLAS Collaboration, 130The CLAS Collaboration, 131The CLAS Collaboration, 132The CLAS Collaboration, 133The CLAS Collaboration, 134The CLAS Collaboration, 135The CLAS Collaboration, 136The CLAS Collaboration, 137The CLAS Collaboration, 138The CLAS Collaboration, 139The CLAS Collaboration, 140The CLAS Collaboration, 141The CLAS Collaboration, 142The CLAS Collaboration, 143The CLAS Collaboration, 144The CLAS Collaboration, 145The CLAS Collaboration, 146The CLAS Collaboration, 147The CLAS Collaboration, 148The CLAS Collaboration, 149The CLAS Collaboration, 150The CLAS Collaboration, 151The CLAS Collaboration, 152The CLAS Collaboration, 153The CLAS Collaboration, 154The CLAS Collaboration, 155The CLAS Collaboration, 156The CLAS Collaboration, 157The CLAS Collaboration, 158The CLAS Collaboration, 159The CLAS Collaboration, 160The CLAS Collaboration, 161The CLAS Collaboration, 162The CLAS Collaboration, 163The CLAS Collaboration, 164The CLAS Collaboration, 165The CLAS Collaboration, 166The CLAS Collaboration, 167The CLAS Collaboration, 168The CLAS Collaboration

First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction $\vec \gamma \vec p \to \pi^+n$, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2. Read More

We report on a measurement of the neutron detection efficiency in NaI crystals in the Crystal Ball detector obtained from a study of single p0 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. Read More

2014Nov
Authors: O. Hen, M. Sargsian, L. B. Weinstein, E. Piasetzky, H. Hakobyan, D. W. Higinbotham, M. Braverman, W. K. Brooks, S. Gilad, K. P. Adhikari, J. Arrington, G. Asryan, H. Avakian, J. Ball, N. A. Baltzell, M. Battaglieri, A. Beck, S. May-Tal Beck, I. Bedlinskiy, W. Bertozzi, A. Biselli, V. D. Burkert, T. Cao, D. S. Carman, A. Celentano, S. Chandavar, L. Colaneri, P. L. Cole, V. Crede, A. DAngelo, R. De Vita, A. Deur, C. Djalali, D. Doughty, M. Dugger, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, G. Fedotov, S. Fegan, T. Forest, B. Garillon, M. Garcon, N. Gevorgyan, Y. Ghandilyan, G. P. Gilfoyle, F. X. Girod, J. T. Goetz, R. W. Gothe, K. A. Griffioen, M. Guidal, L. Guo, K. Hafidi, C. Hanretty, M. Hattawy, K. Hicks, M. Holtrop, C. E. Hyde, Y. Ilieva, D. G. Ireland, B. I. Ishkanov, E. L. Isupov, H. Jiang, H. S. Jo, K. Joo, D. Keller, M. Khandaker, A. Kim, W. Kim, F. J. Klein, S. Koirala, I. Korover, S. E. Kuhn, V. Kubarovsky, P. Lenisa, W. I. Levine, K. Livingston, M. Lowry, H. Y. Lu, I. J. D. MacGregor, N. Markov, M. Mayer, B. McKinnon, T. Mineeva, V. Mokeev, A. Movsisyan, C. Munoz Camacho, B. Mustapha, P. Nadel-Turonski, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, L. L. Pappalardo, R. Paremuzyan, K. Park, E. Pasyuk, W. Phelps, S. Pisano, O. Pogorelko, J. W. Price, S. Procureur, Y. Prok, D. Protopopescu, A. J. R. Puckett, D. Rimal, M. Ripani, B. G. Ritchie, A. Rizzo, G. Rosner, P. Rossi, P. Roy, F. Sabatie, D. Schott, R. A. Schumacher, Y. G. Sharabian, G. D. Smith, R. Shneor, D. Sokhan, S. S. Stepanyan, S. Stepanyan, P. Stoler, S. Strauch, V. Sytnik, M. Taiuti, S. Tkachenko, M. Ungaro, A. V. Vlassov, E. Voutier, D. Watts, N. K. Walford, X. Wei, M. H. Wood, S. A. Wood, N. Zachariou, L. Zana, Z. W. Zhao, X. Zheng, I. Zonta

The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe and 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Read More

2014Nov
Authors: D. Adikaram, D. Rimal, L. B. Weinstein, B. Raue, P. Khetarpal, R. P. Bennett, J. Arrington, W. K. Brooks, K. P. Adhikari, A. V. Afanasev, M. J. Amaryan, M. D. Anderson, J. Ball, M. Battaglieri, I. Bedlinskiy, A. S. Biselli, J. Bono, S. Boiarinov, W. J. Briscoe, V. D. Burkert, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P. L. Cole, M. Contalbrigo, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, G. E. Dodge, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, P. Eugenio, G. Fedotov, S. Fegan, A. Filippi, J. A. Fleming, A. Fradi, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, J. T. Goetz, W. Gohn, E. Golovatch, R. W. Gothe, K. A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, N. Harrison, M. Hattawy, K. Hicks, M. Holtrop, S. M. Hughes, C. E. Hyde, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, D. Jenkins, H. Jiang, K. Joo, S. Joosten, M. Khandaker, W. Kim, A. Klein, F. J. Klein, S. Koirala, V. Kubarovsky, S. E. Kuhn, H. Y. Lu, I . J . D. MacGregor, N. Markov, M. Mayer, B. McKinnon, M. D. Mestayer, C. A. Meyer, M. Mirazita, V. Mokeev, R. A. Montgomery, C. I. Moody, H. Moutarde, A Movsisyan, C. Munoz Camacho, P. Nadel-Turonski, S. Niccolai, G. Niculescu, M. Osipenko, A. I. Ostrovidov, K. Park, E. Pasyuk, S. Pisano, O. Pogorelko, S. Procureur, Y. Prok, D. Protopopescu, A. J. R. Puckett, M. Ripani, A. Rizzo, G. Rosner, P. Rossi, F. Sabatié, D. Schott, R. A. Schumacher, Y. G. Sharabian, A. Simonyan, I. Skorodumina, E. S. Smith, G. D. Smith, D. I. Sober, N. Sparveris, S. Stepanyan, S. Strauch, V. Sytnik, M. Taiuti, Ye Tian, A. Trivedi, M. Ungaro, H. Voskanyan, E. Voutier, N. K. Walford, D. P. Watts, X. Wei, M. H. Wood, N. Zachariou, L. Zana, J. Zhang, Z. W. Zhao, I. Zonta, The CLAS Collaboration

There is a significant discrepancy between the values of the proton electric form factor, $G_E^p$, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of $G_E^p$ from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. Read More

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. Read More

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. Read More

Differential and total cross sections for the quasifree reactions $\gamma p\rightarrow\eta p$ and $\gamma n\rightarrow\eta n$ have been determined at the MAMI-C electron accelerator using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy-tagged with the Glasgow photon tagger. Read More

An experimental study of $\omega$ photoproduction on the proton was conducted by using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. The $\gamma p\to\omega p$ differential cross sections are measured from threshold to the incident-photon energy $E_\gamma=1.40$ GeV ($W=1. Read More

2014Jun
Authors: M. Gabrielyan, B. A. Raue, D. S. Carman, K. Park, K. P. Adhikari, D. Adikaram, M. J. Amaryan, S. Anefalos Pereira, H. Avakian, J. Ball, N. A. Baltzell, M. Battaglieri, V. Baturin, I. Bedlinskiy, A. S. Biselli, J. Bono, S. Boiarinov, W. J. Briscoe, W. K. Brooks, V. D. Burkert, T. Cao, A. Celentano, S. Chandavar, G. Charles, P. L. Cole, M. Contalbrigo, O. Cortes, V. Crede, A. DAngelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, D. Doughty, R. Dupre, L. El Fassi, P. Eugenio, G. Fedotov, S. Fegan, J. A. Fleming, T. A. Forest, B. Garillon, N. Gevorgyan, Y. Ghandilyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, J. T. Goetz, E. Golovatch, R. W. Gothe, K. A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, M. Hattawy, K. Hicks, D. Ho, M. Holtrop, S. M. Hughes, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, D. Jenkins, H. Jiang, H. S. Jo, K. Joo, D. Keller, M. Khandaker, W. Kim, F. J. Klein, S. Koirala, V. Kubarovsky, S. E. Kuhn, S. V. Kuleshov, P. Lenisa, W. I. Levine, K. Livingston, I. J. D. MacGregor, M. Mayer, B. McKinnon, C. A. Meyer, M. D. Mestayer, M. Mirazita, V. Mokeev, C. I. Moody, H. Moutarde, A Movsisyan, E. Munevar, C. Munoz Camacho, P. Nadel-Turonski, S. Niccolai, G. Niculescu, M. Osipenko, L. L. Pappalardo, R. Paremuzyan, E. Pasyuk, P. Peng, W. Phelps, J. J. Phillips, S. Pisano, O. Pogorelko, S. Pozdniakov, J. W. Price, S. Procureur, D. Protopopescu, D. Rimal, M. Ripani, A. Rizzo, F. Sabatie, C. Salgado, D. Schott, R. A. Schumacher, A. Simonyan, G. D. Smith, D. I. Sober, D. Sokhan, S. S. Stepanyan, S. Stepanyan, I. I. Strakovsky, S. Strauch, V. Sytnik, W. Tang, M. Ungaro, A. V. Vlassov, H. Voskanyan, E. Voutier, N. K. Walford, D. P. Watts, X. Wei, L. B. Weinstein, N. Zachariou, L. Zana, J. Zhang

We have measured the induced polarization of the ${\Lambda}(1116)$ in the reaction $ep\rightarrow e'K^+{\Lambda}$, detecting the scattered $e'$ and $K^+$ in the final state along with the proton from the decay $\Lambda\rightarrow p\pi^-$.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy $W$ ($1.6\leq W \leq 2. Read More

2014May
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI, 77A2 Collaboration at MAMI, 78A2 Collaboration at MAMI, 79A2 Collaboration at MAMI

A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0. Read More

2014May
Authors: I. Bedlinskiy1, V. Kubarovsky2, S. Niccolai3, P. Stoler4, K. P. Adhikari5, M. D. Anderson6, S. Anefalos Pereira7, H. Avakian8, J. Ball9, N. A. Baltzell10, M. Battaglieri11, V. Batourine12, A. S. Biselli13, S. Boiarinov14, J. Bono15, W. J. Briscoe16, W. K. Brooks17, V. D. Burkert18, D. S. Carman19, A. Celentano20, S. Chandavar21, L. Colaneri22, P. L. Cole23, M. Contalbrigo24, O. Cortes25, V. Crede26, A. D'Angelo27, N. Dashyan28, R. De Vita29, E. De Sanctis30, A. Deur31, C. Djalali32, D. Doughty33, R. Dupre34, H. Egiyan35, A. El Alaoui36, L. El Fassi37, L. Elouadrhiri38, P. Eugenio39, G. Fedotov40, S. Fegan41, J. A. Fleming42, T. A. Forest43, B. Garillon44, M. Garçon45, G. Gavalian46, N. Gevorgyan47, Y. Ghandilyan48, G. P. Gilfoyle49, K. L. Giovanetti50, F. X. Girod51, E. Golovatch52, R. W. Gothe53, K. A. Griffioen54, B. Guegan55, L. Guo56, K. Hafidi57, H. Hakobyan58, N. Harrison59, M. Hattawy60, K. Hicks61, M. Holtrop62, D. G. Ireland63, B. S. Ishkhanov64, E. L. Isupov65, D. Jenkins66, H. S. Jo67, K. Joo68, D. Keller69, M. Khandaker70, A. Kim71, W. Kim72, A. Klein73, F. J. Klein74, S. Koirala75, S. E. Kuhn76, S. V. Kuleshov77, P. Lenisa78, W. I. Levine79, K. Livingston80, H. Y. Lu81, I . J . D. MacGregor82, N. Markov83, M. Mayer84, B. McKinnon85, M. Mirazita86, V. Mokeev87, R. A. Montgomery88, C. I. Moody89, H. Moutarde90, A Movsisyan91, C. Munoz Camacho92, P. Nadel-Turonski93, I. Niculescu94, M. Osipenko95, A. I. Ostrovidov96, L. L. Pappalardo97, K. Park98, S. Park99, E. Pasyuk100, E. Phelps101, W. Phelps102, J. J. Phillips103, S. Pisano104, O. Pogorelko105, J. W. Price106, Y. Prok107, D. Protopopescu108, S. Procureur109, A. J. R. Puckett110, B. A. Raue111, M. Ripani112, B. G. Ritchie113, A. Rizzo114, P. Rossi115, P. Roy116, F. Sabatié117, C. Salgado118, D. Schott119, R. A. Schumacher120, E. Seder121, I. Senderovich122, Y. G. Sharabian123, A. Simonyan124, G. D. Smith125, D. I. Sober126, D. Sokhan127, S. S. Stepanyan128, S. Strauch129, V. Sytnik130, W. Tang131, Ye Tian132, M. Ungaro133, A. V. Vlassov134, H. Voskanyan135, E. Voutier136, N. K. Walford137, D. Watts138, X. Wei139, L. B. Weinstein140, M. Yurov141, N. Zachariou142, L. Zana143, J. Zhang144, Z. W. Zhao145, I. Zonta146, for the CLAS Collaboration
Affiliations: 1Institute of Theoretical and Experimental Physics, 2Thomas Jefferson National Accelerator Facility, 3Institut de Physique Nucléaire ORSAY, 4Rensselaer Polytechnic Institute, 5Old Dominion University, 6University of Glasgow, 7INFN, 8Thomas Jefferson National Accelerator Facility, 9CEA, 10Argonne National Laboratory, 11INFN, 12Thomas Jefferson National Accelerator Facility, 13Thomas Jefferson National Accelerator Facility, 14Thomas Jefferson National Accelerator Facility, 15Florida International University, 16The George Washington University, 17Universidad Técnica Federico Santa María, 18Thomas Jefferson National Accelerator Facility, 19Thomas Jefferson National Accelerator Facility, 20INFN, 21Ohio University, 22INFN, 23Idaho State University, 24INFN, 25Idaho State University, 26Florida State University, 27INFN, 28Yerevan Physics Institute, 29INFN, 30INFN, 31Thomas Jefferson National Accelerator Facility, 32University of South Carolina, 33Christopher Newport University, 34Institut de Physique Nucléaire ORSAY, 35Thomas Jefferson National Accelerator Facility, 36Argonne National Laboratory, 37Old Dominion University, 38Thomas Jefferson National Accelerator Facility, 39Florida State University, 40University of South Carolina, 41INFN, 42Edinburgh University, 43Idaho State University, 44Institut de Physique Nucléaire ORSAY, 45CEA, 46Old Dominion University, 47Yerevan Physics Institute, 48Yerevan Physics Institute, 49University of Richmond, 50James Madison University, 51Thomas Jefferson National Accelerator Facility, 52Skobeltsyn Institute of Nuclear Physics, 53University of South Carolina, 54Institut de Physique Nucléaire ORSAY, 55Institut de Physique Nucléaire ORSAY, 56Florida International University, 57Argonne National Laboratory, 58Universidad Técnica Federico Santa María, 59University of Connecticut, 60Institut de Physique Nucléaire ORSAY, 61Ohio University, 62University of New Hampshire, 63University of Glasgow, 64Skobeltsyn Institute of Nuclear Physics, 65Skobeltsyn Institute of Nuclear Physics, 66Institut de Physique Nucléaire ORSAY, 67Institut de Physique Nucléaire ORSAY, 68University of Connecticut, 69University of Virginia, 70Idaho State University, 71University of Connecticut, 72Kyungpook National University, 73Old Dominion University, 74Catholic University of America, 75Old Dominion University, 76Old Dominion University, 77Universidad Técnica Federico Santa María, 78INFN, 79Carnegie Mellon University, 80University of Glasgow, 81University of South Carolina, 82University of Glasgow, 83University of Connecticut, 84Old Dominion University, 85University of Glasgow, 86INFN, 87Thomas Jefferson National Accelerator Facility, 88INFN, 89Argonne National Laboratory, 90CEA, 91INFN, 92Institut de Physique Nucléaire ORSAY, 93Thomas Jefferson National Accelerator Facility, 94James Madison University, 95INFN, 96Florida State University, 97INFN, 98Thomas Jefferson National Accelerator Facility, 99Florida State University, 100Thomas Jefferson National Accelerator Facility, 101University of South Carolina, 102Florida International University, 103University of Glasgow, 104INFN, 105Institute of Theoretical and Experimental Physics, 106California State University, 107Old Dominion University, 108University of Glasgow, 109CEA, 110University of Connecticut, 111Florida International University, 112INFN, 113Arizona State University, 114INFN, 115INFN, 116Florida State University, 117CEA, 118Norfolk State University, 119The George Washington University, 120Carnegie Mellon University, 121University of Connecticut, 122Arizona State University, 123Thomas Jefferson National Accelerator Facility, 124Yerevan Physics Institute, 125Edinburgh University, 126Catholic University of America, 127University of Glasgow, 128Kyungpook National University, 129University of South Carolina, 130Universidad Técnica Federico Santa María, 131Ohio University, 132University of South Carolina, 133Thomas Jefferson National Accelerator Facility, 134Institute of Theoretical and Experimental Physics, 135Yerevan Physics Institute, 136LPSC, 137Catholic University of America, 138University of Glasgow, 139Thomas Jefferson National Accelerator Facility, 140Old Dominion University, 141University of Virginia, 142University of South Carolina, 143Edinburgh University, 144Thomas Jefferson National Accelerator Facility, 145University of Virginia, 146INFN

Exclusive neutral-pion electroproduction ($ep\to e^\prime p^\prime \pi^0$) was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections $d^4\sigma/dtdQ^2dx_Bd\phi_\pi$ and structure functions $\sigma_T+\epsilon\sigma_L, \sigma_{TT}$ and $\sigma_{LT}$ as functions of $t$ were obtained over a wide range of $Q^2$ and $x_B$. Read More

2014Apr
Authors: Y. Prok, P. Bosted, N. Kvaltine, K. P. Adhikari, D. Adikaram, M. Aghasyan, M. J. Amaryan, M. D. Anderson, S. Anefalos Pereira, H. Avakian, H. Baghdasaryan, J. Ball, N. A. Baltzell, M. Battaglieri, A. S. Biselli, J. Bono, W. J. Briscoe, J. Brock, W. K. Brooks, S. Bültmann, V. D. Burkert, C. Carlin, D. S. Carman, A. Celentano, S. Chandavar, L. Colaneri, P. L. Cole, M. Contalbrigo, O. Cortes, D. Crabb, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, G. E. Dodge, D. Doughty, R. Dupre, A. El Alaoui, L. El Fassi, L. Elouadrhiri, G. Fedotov, S. Fegan, R. Fersch, J. A. Fleming, T. A. Forest, M. Garcon, N. Gevorgyan, Y. Ghandilyan, G. P. Gilfoyle, F. X. Girod, K. L. Giovanetti, J. T. Goetz, W. Gohn, R. W. Gothe, K. A. Griffioen, B. Guegan, N. Guler, K. Haffidi, C. Hanretty, N. Harrison, M. Hattawy, K. Hicks, D. Ho, M. Holtrop, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, S. Jawalkar, X. Jiang, H. S. Jo, K. Joo, N. Kalantarians, C. Keith, D. Keller, M. Khandaker, A. Kim, W. Kim, A. Klein, F. J. Klein, S. Koirala, V. Kubarovsky, S. E. Kuhn, S. V. Kuleshov, P. Lenisa, K. Livingston, H. Y. Lu, I . J. D. MacGregor, N. Markov, M. Mayee, B. McKinnon, D. Meekins, T. Mineeva, M. Mirazita, V. Mokeev, R. A. Montgomery, H. Moutarde, A Movsisyan, E. Munevar, C. Munoz Camacho, P. Nadel-Turonski, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A. I. Ostrovidov, L. L. Pappalardo, R. Paremuzyan, K. Park, P. Peng, J. J. Phillips, J. Pierce, S. Pisano, O. Pogorelko, S. Pozdniakov, J. W. Price, S. Procureur, D. Protopopescu, A. J. R. Puckett, B. A. Raue, D. Rimal, M. Ripani, A. Rizzo, G. Rosner, P. Rossi, P. Roy, F. Sabatié, M. S. Saini, C. Salgado, D. Schott, R. A. Schumacher, E. Seder, Y. G. Sharabian, A. Simonyan, C. Smith, G. Smith, D. I. Sober, D. Sokhan, S. S. Stepanyan, S. Stepanyan, I. I. Strakovsky, S. Strauch, V. Sytnik, M. Taiuti, W. Tang, S. Tkachenko, M. Ungaro, B . Vernarsky, A. V. Vlassov, H. Voskanyan, E. Voutier, N. K. Walford, D . P. Watts, L. B. Weinstein, N. Zachariou, L. Zana, J. Zhang, B. Zhao, Z. W. Zhao, I. Zonta, for the CLAS collaboration

The inclusive polarized structure functions of the proton and deuteron, g1p and g1d, were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at lab angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual DIS kinematics, Q^2>1 GeV^2 and the final-state invariant mass W>2 GeV, the ratio of polarized to unpolarized structure functions g1/F1 is found to be nearly independent of Q^2 at fixed x. Read More

Precise angular distributions have been measured for the first time for the photoproduction of $\pi^{0}$-mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasi-free protons bound in the deuteron to the results for free protons and then applied as a correction to the quasi-free neutron data. Read More

Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of mixed-charge pion pairs in the reactions $\boldsymbol{\gamma}p\rightarrow n\pi^0\pi^+$ off free protons and $\boldsymbol{\gamma}d\rightarrow (p)p\pi^0\pi^-$ and $\boldsymbol{\gamma}d\rightarrow (n)n\pi^0\pi^+$ off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow-Mainz magnetic spectrometer. Read More

2014Feb
Authors: S. Tkachenko1, N. Baillie2, S. E. Kuhn3, J. Zhang4, J. Arrington5, P. Bosted6, S. Bültmann7, M. E. Christy8, D. Dutta9, R. Ent10, H. Fenker11, K. A. Griffioen12, M. Ispiryan13, N. Kalantarians14, C. E. Keppel15, W. Melnitchouk16, V. Tvaskis17, K. P. Adhikari18, M. Aghasyan19, M. J. Amaryan20, S. Anefalos Pereira21, H. Avakian22, J. Ball23, N. A. Baltzell24, M. Battaglieri25, I. Bedlinskiy26, A. S. Biselli27, W. J. Briscoe28, W. K. Brooks29, V. D. Burkert30, D. S. Carman31, A. Celentano32, S. Chandavar33, G. Charles34, P. L. Cole35, M. Contalbrigo36, O. Cortes37, V. Crede38, A. D'Angelo39, N. Dashyan40, R. De Vita41, E. De Sanctis42, A. Deur43, C. Djalali44, G. E. Dodge45, D. Doughty46, R. Dupre47, H. Egiyan48, A. El Alaoui49, L. El Fassi50, L. Elouadrhiri51, P. Eugenio52, G. Fedotov53, J. A. Fleming54, B. Garillon55, N. Gevorgyan56, Y. Ghandilyan57, G. P. Gilfoyle58, K. L. Giovanetti59, F. X. Girod60, J. T. Goetz61, E. Golovatch62, R. W. Gothe63, M. Guidal64, L. Guo65, K. Hafidi66, H. Hakobyan67, C. Hanretty68, N. Harrison69, M. Hattawy70, K. Hicks71, D. Ho72, M. Holtrop73, C . E. Hyde74, Y. Ilieva75, D. G. Ireland76, B. S. Ishkhanov77, H. S. Jo78, D. Keller79, M. Khandaker80, A. Kim81, W. Kim82, P. M. King83, A. Klein84, F. J. Klein85, S. Koirala86, V. Kubarovsky87, S. V. Kuleshov88, P. Lenisa89, S. Lewis90, K. Livingston91, H. Lu92, M. MacCormick93, I. J. D. MacGregor94, N. Markov95, M. Mayer96, B. McKinnon97, T. Mineeva98, M. Mirazita99, V. Mokeev100, R. A. Montgomery101, H. Moutarde102, C. Munoz Camacho103, P. Nadel-Turonski104, S. Niccolai105, G. Niculescu106, I. Niculescu107, M. Osipenko108, L. L. Pappalardo109, R. Paremuzyan110, K. Park111, E. Pasyuk112, J. J. Phillips113, S. Pisano114, O. Pogorelko115, S. Pozdniakov116, J. W. Price117, S. Procureur118, D. Protopopescu119, A. J . R. Puckett120, D. Rimal121, M. Ripani122, A. Rizzo123, G. Rosner124, P. Rossi125, P. Roy126, F. Sabatié127, D. Schott128, R. A. Schumacher129, E. Seder130, I. Senderovich131, Y. G. Sharabian132, A. Simonyan133, G. D. Smith134, D. I. Sober135, D. Sokhan136, S. Stepanyan137, S. S. Stepanyan138, S. Strauch139, W. Tang140, M. Ungaro141, A. V. Vlassov142, H. Voskanyan143, E. Voutier144, N. K. Walford145, D. Watts146, X. Wei147, L. B. Weinstein148, M. H. Wood149, L. Zana150, I. Zonta151
Affiliations: 1The CLAS collaboration, 2The CLAS collaboration, 3The CLAS collaboration, 4The CLAS collaboration, 5The CLAS collaboration, 6The CLAS collaboration, 7The CLAS collaboration, 8The CLAS collaboration, 9The CLAS collaboration, 10The CLAS collaboration, 11The CLAS collaboration, 12The CLAS collaboration, 13The CLAS collaboration, 14The CLAS collaboration, 15The CLAS collaboration, 16The CLAS collaboration, 17The CLAS collaboration, 18The CLAS collaboration, 19The CLAS collaboration, 20The CLAS collaboration, 21The CLAS collaboration, 22The CLAS collaboration, 23The CLAS collaboration, 24The CLAS collaboration, 25The CLAS collaboration, 26The CLAS collaboration, 27The CLAS collaboration, 28The CLAS collaboration, 29The CLAS collaboration, 30The CLAS collaboration, 31The CLAS collaboration, 32The CLAS collaboration, 33The CLAS collaboration, 34The CLAS collaboration, 35The CLAS collaboration, 36The CLAS collaboration, 37The CLAS collaboration, 38The CLAS collaboration, 39The CLAS collaboration, 40The CLAS collaboration, 41The CLAS collaboration, 42The CLAS collaboration, 43The CLAS collaboration, 44The CLAS collaboration, 45The CLAS collaboration, 46The CLAS collaboration, 47The CLAS collaboration, 48The CLAS collaboration, 49The CLAS collaboration, 50The CLAS collaboration, 51The CLAS collaboration, 52The CLAS collaboration, 53The CLAS collaboration, 54The CLAS collaboration, 55The CLAS collaboration, 56The CLAS collaboration, 57The CLAS collaboration, 58The CLAS collaboration, 59The CLAS collaboration, 60The CLAS collaboration, 61The CLAS collaboration, 62The CLAS collaboration, 63The CLAS collaboration, 64The CLAS collaboration, 65The CLAS collaboration, 66The CLAS collaboration, 67The CLAS collaboration, 68The CLAS collaboration, 69The CLAS collaboration, 70The CLAS collaboration, 71The CLAS collaboration, 72The CLAS collaboration, 73The CLAS collaboration, 74The CLAS collaboration, 75The CLAS collaboration, 76The CLAS collaboration, 77The CLAS collaboration, 78The CLAS collaboration, 79The CLAS collaboration, 80The CLAS collaboration, 81The CLAS collaboration, 82The CLAS collaboration, 83The CLAS collaboration, 84The CLAS collaboration, 85The CLAS collaboration, 86The CLAS collaboration, 87The CLAS collaboration, 88The CLAS collaboration, 89The CLAS collaboration, 90The CLAS collaboration, 91The CLAS collaboration, 92The CLAS collaboration, 93The CLAS collaboration, 94The CLAS collaboration, 95The CLAS collaboration, 96The CLAS collaboration, 97The CLAS collaboration, 98The CLAS collaboration, 99The CLAS collaboration, 100The CLAS collaboration, 101The CLAS collaboration, 102The CLAS collaboration, 103The CLAS collaboration, 104The CLAS collaboration, 105The CLAS collaboration, 106The CLAS collaboration, 107The CLAS collaboration, 108The CLAS collaboration, 109The CLAS collaboration, 110The CLAS collaboration, 111The CLAS collaboration, 112The CLAS collaboration, 113The CLAS collaboration, 114The CLAS collaboration, 115The CLAS collaboration, 116The CLAS collaboration, 117The CLAS collaboration, 118The CLAS collaboration, 119The CLAS collaboration, 120The CLAS collaboration, 121The CLAS collaboration, 122The CLAS collaboration, 123The CLAS collaboration, 124The CLAS collaboration, 125The CLAS collaboration, 126The CLAS collaboration, 127The CLAS collaboration, 128The CLAS collaboration, 129The CLAS collaboration, 130The CLAS collaboration, 131The CLAS collaboration, 132The CLAS collaboration, 133The CLAS collaboration, 134The CLAS collaboration, 135The CLAS collaboration, 136The CLAS collaboration, 137The CLAS collaboration, 138The CLAS collaboration, 139The CLAS collaboration, 140The CLAS collaboration, 141The CLAS collaboration, 142The CLAS collaboration, 143The CLAS collaboration, 144The CLAS collaboration, 145The CLAS collaboration, 146The CLAS collaboration, 147The CLAS collaboration, 148The CLAS collaboration, 149The CLAS collaboration, 150The CLAS collaboration, 151The CLAS collaboration

Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. Read More

Elastic scattering of photons from 12C has been investigated using quasi-monoenergetic tagged photons with energies in the range 65 - 115 MeV at laboratory angles of 60 deg, 120 deg, and 150 deg at the Tagged-Photon Facility at the MAX IV Laboratory in Lund, Sweden. A phenomenological model was employed to provide an estimate of the sensitivity of the 12C(g,g)12C cross section to the bound-nucleon polarizabilities. Read More

Information on the size and shape of the neutron skin on $^{208}$Pb has been extracted from coherent pion photoproduction cross sections measured using the Crystal Ball together with the Glasgow tagger at the MAMI electron beam facility. On exploitation of an interpolated fit of a theoretical model to the measured cross sections the half-height radius and diffuseness of the neutron distribution are found to be 6.70$\pm 0. Read More

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon, pioneering a novel polarimetry technique with wide application to future nuclear and hadronic physics experiments. The commissioning measurement of polarization transfer in the $^{1}H$($\vec{\gamma}$,$\vec{p}$)$\pi^{0}$ reaction in the range $0.4Read More

2013Sep
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI

The Dalitz decay eta -> e^+ e^- gamma has been measured in the gamma p -> eta p reaction with the Crystal Ball and TAPS multiphoton spectrometers, together with the photon tagging facility at the Mainz Microtron MAMI. The experimental statistic used in this work is one order of magnitude greater than in any previous measurement of eta -> e^+ e^- gamma. The value obtained for the slope parameter 1/Lambda^2 of the eta transition form factor, 1/Lambda^2 = (1. Read More

Measurements of $\gamma p \rightarrow K^{+} \Lambda$ and $\gamma p \rightarrow K^{+} \Sigma^0$ cross-sections have been obtained with the photon tagging facility and the Crystal Ball calorimeter at MAMI-C. The measurement uses a novel $K^+$ meson identification technique in which the weak decay products are characterized using the energy and timing characteristics of the energy deposit in the calorimeter, a method that has the potential to be applied at many other facilities. The fine center-of-mass energy ($W$) resolution and statistical accuracy of the new data results in a significant impact on partial wave analyses aiming to better establish the excitation spectrum of the nucleon. Read More