B. G. Ritchie - The CLAS Collaboration

B. G. Ritchie
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B. G. Ritchie
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The CLAS Collaboration
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Nuclear Experiment (21)
 
High Energy Physics - Experiment (15)
 
Solar and Stellar Astrophysics (14)
 
Physics - Instrumentation and Detectors (4)
 
Astrophysics of Galaxies (2)
 
Astrophysics (2)
 
Nuclear Theory (1)

Publications Authored By B. G. Ritchie

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

We report on the design and construction of a high-energy photon polarimeter for measuring the degree of polarization of a linearly-polarized photon beam. The photon polarimeter uses the process of pair production on an atomic electron (triplet production). The azimuthal distribution of scattered atomic electrons following triplet production yields information regarding the degree of linear polarization of the incident photon beam. 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

2017Jan
Authors: GlueX Collaboration, H. Al Ghoul, E. G. Anassontzis, A. Austregesilo, F. Barbosa, A. Barnes, T. D. Beattie, D. W. Bennett, V. V. Berdnikov, T. Black, W. Boeglin, W. J. Briscoe, W. K. Brooks, B. E. Cannon, O. Chernyshov, E. Chudakov, V. Crede, M. M. Dalton, A. Deur, S. Dobbs, A. Dolgolenko, M. Dugger, R. Dzhygadlo, H. Egiyan, P. Eugenio, C. Fanelli, A. M. Foda, J. Frye, S. Furletov, L. Gan, A. Gasparian, A. Gerasimov, N. Gevorgyan, K. Goetzen, V. S. Goryachev, L. Guo, H. Hakobyan, J. Hardin, A. Henderson, G. M. Huber, D. G. Ireland, M. M. Ito, N. S. Jarvis, R. T. Jones, V. Kakoyan, M. Kamel, F. J. Klein, R. Kliemt, C. Kourkoumeli, S. Kuleshov, I. Kuznetsov, M. Lara, I. Larin, D. Lawrence, W. I. Levine, K. Livingston, G. J. Lolos, V. Lyubovitskij, D. Mack, P. T. Mattione, V. Matveev, M. McCaughan, M. McCracken, W. McGinley, J. McIntyre, R. Mendez, C. A. Meyer, R. Miskimen, R. E. Mitchell, F. Mokaya, K. Moriya, F. Nerling, G. Nigmatkulov, N. Ochoa, A. I. Ostrovidov, Z. Papandreou, M. Patsyuk, R. Pedroni, M. R. Pennington, L. Pentchev, K. J. Peters, E. Pooser, B. Pratt, Y. Qiang, J. Reinhold, B. G. Ritchie, L. Robison, D. Romanov, C. Salgado, R. A. Schumacher, C. Schwarz, J. Schwiening, A. Yu. Semenov, I. A. Semenova, K. K. Seth, M. R. Shepherd, E. S. Smith, D. I. Sober, A. Somov, S. Somov, O. Soto, N. Sparks, M. J. Staib, J. R. Stevens, I. I. Strakovsky, A. Subedi, V. Tarasov, S. Taylor, A. Teymurazyan, I. Tolstukhin, A. Tomaradze, A. Toro, A. Tsaris, G. Vasileiadis, I. Vega, N. K. Walford, D. Werthmuller, T. Whitlatch, M. Williams, E. Wolin, T. Xiao, J. Zarling, Z. Zhang, B. Zihlmann, V. Mathieu, J. Nys

We report measurements of the photon beam asymmetry $\Sigma$ for the reactions $\vec{\gamma}p\to p\pi^0$ and $\vec{\gamma}p\to p\eta $ from the GlueX experiment using a 9 GeV linearly-polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous $\pi^0$ measurements and are the first $\eta$ measurements in this energy regime. The results are compared with theoretical predictions based on $t$-channel, quasi-particle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models. Read More

2015Dec

The GlueX experiment at Jefferson Lab ran with its first commissioning beam in late 2014 and the spring of 2015. Data were collected on both plastic and liquid hydrogen targets, and much of the detector has been commissioned. All of the detector systems are now performing at or near design specifications and events are being fully reconstructed, including exclusive production of $\pi^{0}$, $\eta$ and $\omega$ mesons. 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

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

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

We propose to enhance the kaon identification capabilities of the GlueX detector by constructing an FDIRC (Focusing Detection of Internally Reflected Cherenkov) detector utilizing the decommissioned BaBar DIRC components. The GlueX FDIRC would significantly enhance the GlueX physics program by allowing one to search for and study hybrid mesons decaying into kaon final states. Such systematic studies of kaon final states are essential for inferring the quark flavor content of hybrid and conventional mesons. Read More

The first soft gamma-ray repeater was discovered over three decades ago, and subsequently identified as a magnetar. However there is currently no consenus on the formation channel(s) of these objects. The presence of a magnetar in the starburst cluster Westerlund 1 implies a >40Msun progenitor, favouring formation in a binary that was disrupted at supernova. 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

The location of the supergiant (sg)B[e] star Wd1-9 within the coeval starburst cluster Westerlund 1 allows for its placement in a detailed post-Main Sequence evolutionary scheme and hence we have utilised a comprehensive multiwavelength dataset to determine its physical properties and relation to other sgB[e] stars and the evolved stellar population of Wd1. Wd1-9 is found to exhibit the rich optical emission line spectrum that is characteristic of sgB[e] stars, while dust mass, composition and disc geometry determined from mid-IR data resemble those of other well known examples such as R126. Extreme historical and ongoing mass loss is inferred from radio observations, while the X-ray properties of Wd1-9 imply the presence of high temperature plasma within the system and are directly comparable to a number of confirmed short-period colliding wind binaries within Wd1. Read More

Beam asymmetries for the reactions gamma p -> p pi0 and gamma p -> n pi+ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged, linearly polarized photon beam with energies from 1.102 to 1.862 GeV. Read More

The primary motivation of the GlueX experiment is to search for and ultimately study the pattern of gluonic excitations in the meson spectrum produced in $\gamma p$ collisions. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons that have both exotic and non-exotic $J^{PC}$, corresponding to $q\bar{q}$ states ($q=u,$ $d,$ or $s$) coupled with a gluonic field. A thorough study of the hybrid spectrum, including the identification of the isovector triplet, with charges 0 and $\pm1$, and both isoscalar members, $|s\bar{s}\ >$ and $|u\bar{u}\ > + |d\bar{d}\ >$, for each predicted hybrid combination of $J^{PC}$, may only be achieved by conducting a systematic amplitude analysis of many different hadronic final states. Read More

2013Mar
Authors: I. Pomerantz1, Y. Ilieva2, R. Gilman3, D. W. Higinbotham4, E. Piasetzky5, S. Strauch6, K. P. Adhikari7, M. Aghasyan8, K. Allada9, M. J. Amaryan10, S. Anefalos Pereira11, M. Anghinolfi12, H. Baghdasaryan13, J. Ball14, N. A. Baltzell15, M. Battaglieri16, V. Batourine17, A. Beck18, S. Beck19, I. Bedlinskiy20, B. L. Berman21, A. S. Biselli22, W. Boeglin23, J. Bono24, C. Bookwalter25, S. Boiarinov26, W. J. Briscoe27, W. K. Brooks28, N. Bubis29, V. Burkert30, A. Camsonne31, M. Canan32, D. S. Carman33, A. Celentano34, S. Chandavar35, G. Charles36, K. Chirapatpimol37, E. Cisbani38, P. L. Cole39, M. Contalbrigo40, V. Crede41, F. Cusanno42, A. D'Angelo43, A. Daniel44, N. Dashyan45, C. W. de Jager46, R. De Vita47, E. De Sanctis48, A. Deur49, C. Djalali50, G. E. Dodge51, D. Doughty52, R. Dupre53, C. Dutta54, H. Egiyan55, A. El Alaoui56, L. El Fassi57, P. Eugenio58, G. Fedotov59, S. Fegan60, J. A. Fleming61, A. Fradi62, F. Garibaldi63, O. Geagla64, N. Gevorgyan65, K. L. Giovanetti66, F. X. Girod67, J. Glister68, J. T. Goetz69, W. Gohn70, E. Golovatch71, R. W. Gothe72, K. A. Griffioen73, B. Guegan74, M. Guidal75, L. Guo76, K. Hafidi77, H. Hakobyan78, N. Harrison79, D. Heddle80, K. Hicks81, D. Ho82, M. Holtrop83, C. E. Hyde84, D. G. Ireland85, B. S. Ishkhanov86, E. L. Isupov87, X. Jiang88, H. S. Jo89, K. Joo90, A. T. Katramatou91, D. Keller92, M. Khandaker93, P. Khetarpal94, E. Khrosinkova95, A. Kim96, W. Kim97, F. J. Klein98, S. Koirala99, A. Kubarovsky100, V. Kubarovsky101, S. V. Kuleshov102, N. D. Kvaltine103, B. Lee104, J. J. LeRose105, S. Lewis106, R. Lindgren107, K. Livingston108, H. Y. Lu109, I. J. D. MacGregor110, Y. Mao111, D. Martinez112, M. Mayer113, E. McCullough114, B. McKinnon115, D. Meekins116, C. A. Meyer117, R. Michaels118, T. Mineeva119, M. Mirazita120, B. Moffit121, V. Mokeev122, R. A. Montgomery123, H. Moutarde124, E. Munevar125, C. Munoz Camacho126, P. Nadel-Turonski127, R. Nasseripour128, C. S. Nepali129, S. Niccolai130, G. Niculescu131, I. Niculescu132, M. Osipenko133, A. I. Ostrovidov134, L. L. Pappalardo135, R. Paremuzyan136, K. Park137, S. Park138, G. G. Petratos139, E. Phelps140, S. Pisano141, O. Pogorelko142, S. Pozdniakov143, S. Procureur144, D. Protopopescu145, A. J. R. Puckett146, X. Qian147, Y. Qiang148, G. Ricco149, D. Rimal150, M. Ripani151, B. G. Ritchie152, I. Rodriguez153, G. Ron154, G. Rosner155, P. Rossi156, F. Sabatie157, A. Saha158, M. S. Saini159, A. J. Sarty160, B. Sawatzky161, N. A. Saylor162, D. Schott163, E. Schulte164, R. A. Schumacher165, E. Seder166, H. Seraydaryan167, R. Shneor168, G. D. Smith169, D. Sokhan170, N. Sparveris171, S. S. Stepanyan172, S. Stepanyan173, P. Stoler174, R. Subedi175, V. Sulkosky176, M. Taiuti177, W. Tang178, C. E. Taylor179, S. Tkachenko180, M. Ungaro181, B. Vernarsky182, M. F. Vineyard183, H. Voskanyan184, E. Voutier185, N. K. Walford186, Y. Wang187, D. P. Watts188, L. B. Weinstein189, D. P. Weygand190, B. Wojtsekhowski191, M. H. Wood192, X. Yan193, H. Yao194, N. Zachariou195, X. Zhan196, J. Zhang197, Z. W. Zhao198, X. Zheng199, I. Zonta200
Affiliations: 1The CLAS and Hall-A Collaborations, 2The CLAS and Hall-A Collaborations, 3The CLAS and Hall-A Collaborations, 4The CLAS and Hall-A Collaborations, 5The CLAS and Hall-A Collaborations, 6The CLAS and Hall-A Collaborations, 7The CLAS and Hall-A Collaborations, 8The CLAS and Hall-A Collaborations, 9The CLAS and Hall-A Collaborations, 10The CLAS and Hall-A Collaborations, 11The CLAS and Hall-A Collaborations, 12The CLAS and Hall-A Collaborations, 13The CLAS and Hall-A Collaborations, 14The CLAS and Hall-A Collaborations, 15The CLAS and Hall-A Collaborations, 16The CLAS and Hall-A Collaborations, 17The CLAS and Hall-A Collaborations, 18The CLAS and Hall-A Collaborations, 19The CLAS and Hall-A Collaborations, 20The CLAS and Hall-A Collaborations, 21The CLAS and Hall-A Collaborations, 22The CLAS and Hall-A Collaborations, 23The CLAS and Hall-A Collaborations, 24The CLAS and Hall-A Collaborations, 25The CLAS and Hall-A Collaborations, 26The CLAS and Hall-A Collaborations, 27The CLAS and Hall-A Collaborations, 28The CLAS and Hall-A Collaborations, 29The CLAS and Hall-A Collaborations, 30The CLAS and Hall-A Collaborations, 31The CLAS and Hall-A Collaborations, 32The CLAS and Hall-A Collaborations, 33The CLAS and Hall-A Collaborations, 34The CLAS and Hall-A Collaborations, 35The CLAS and Hall-A Collaborations, 36The CLAS and Hall-A Collaborations, 37The CLAS and Hall-A Collaborations, 38The CLAS and Hall-A Collaborations, 39The CLAS and Hall-A Collaborations, 40The CLAS and Hall-A Collaborations, 41The CLAS and Hall-A Collaborations, 42The CLAS and Hall-A Collaborations, 43The CLAS and Hall-A Collaborations, 44The CLAS and Hall-A Collaborations, 45The CLAS and Hall-A Collaborations, 46The CLAS and Hall-A Collaborations, 47The CLAS and Hall-A Collaborations, 48The CLAS and Hall-A Collaborations, 49The CLAS and Hall-A Collaborations, 50The CLAS and Hall-A Collaborations, 51The CLAS and Hall-A Collaborations, 52The CLAS and Hall-A Collaborations, 53The CLAS and Hall-A Collaborations, 54The CLAS and Hall-A Collaborations, 55The CLAS and Hall-A Collaborations, 56The CLAS and Hall-A Collaborations, 57The CLAS and Hall-A Collaborations, 58The CLAS and Hall-A Collaborations, 59The CLAS and Hall-A Collaborations, 60The CLAS and Hall-A Collaborations, 61The CLAS and Hall-A Collaborations, 62The CLAS and Hall-A Collaborations, 63The CLAS and Hall-A Collaborations, 64The CLAS and Hall-A Collaborations, 65The CLAS and Hall-A Collaborations, 66The CLAS and Hall-A Collaborations, 67The CLAS and Hall-A Collaborations, 68The CLAS and Hall-A Collaborations, 69The CLAS and Hall-A Collaborations, 70The CLAS and Hall-A Collaborations, 71The CLAS and Hall-A Collaborations, 72The CLAS and Hall-A Collaborations, 73The CLAS and Hall-A Collaborations, 74The CLAS and Hall-A Collaborations, 75The CLAS and Hall-A Collaborations, 76The CLAS and Hall-A Collaborations, 77The CLAS and Hall-A Collaborations, 78The CLAS and Hall-A Collaborations, 79The CLAS and Hall-A Collaborations, 80The CLAS and Hall-A Collaborations, 81The CLAS and Hall-A Collaborations, 82The CLAS and Hall-A Collaborations, 83The CLAS and Hall-A Collaborations, 84The CLAS and Hall-A Collaborations, 85The CLAS and Hall-A Collaborations, 86The CLAS and Hall-A Collaborations, 87The CLAS and Hall-A Collaborations, 88The CLAS and Hall-A Collaborations, 89The CLAS and Hall-A Collaborations, 90The CLAS and Hall-A Collaborations, 91The CLAS and Hall-A Collaborations, 92The CLAS and Hall-A Collaborations, 93The CLAS and Hall-A Collaborations, 94The CLAS and Hall-A Collaborations, 95The CLAS and Hall-A Collaborations, 96The CLAS and Hall-A Collaborations, 97The CLAS and Hall-A Collaborations, 98The CLAS and Hall-A Collaborations, 99The CLAS and Hall-A Collaborations, 100The CLAS and Hall-A Collaborations, 101The CLAS and Hall-A Collaborations, 102The CLAS and Hall-A Collaborations, 103The CLAS and Hall-A Collaborations, 104The CLAS and Hall-A Collaborations, 105The CLAS and Hall-A Collaborations, 106The CLAS and Hall-A Collaborations, 107The CLAS and Hall-A Collaborations, 108The CLAS and Hall-A Collaborations, 109The CLAS and Hall-A Collaborations, 110The CLAS and Hall-A Collaborations, 111The CLAS and Hall-A Collaborations, 112The CLAS and Hall-A Collaborations, 113The CLAS and Hall-A Collaborations, 114The CLAS and Hall-A Collaborations, 115The CLAS and Hall-A Collaborations, 116The CLAS and Hall-A Collaborations, 117The CLAS and Hall-A Collaborations, 118The CLAS and Hall-A Collaborations, 119The CLAS and Hall-A Collaborations, 120The CLAS and Hall-A Collaborations, 121The CLAS and Hall-A Collaborations, 122The CLAS and Hall-A Collaborations, 123The CLAS and Hall-A Collaborations, 124The CLAS and Hall-A Collaborations, 125The CLAS and Hall-A Collaborations, 126The CLAS and Hall-A Collaborations, 127The CLAS and Hall-A Collaborations, 128The CLAS and Hall-A Collaborations, 129The CLAS and Hall-A Collaborations, 130The CLAS and Hall-A Collaborations, 131The CLAS and Hall-A Collaborations, 132The CLAS and Hall-A Collaborations, 133The CLAS and Hall-A Collaborations, 134The CLAS and Hall-A Collaborations, 135The CLAS and Hall-A Collaborations, 136The CLAS and Hall-A Collaborations, 137The CLAS and Hall-A Collaborations, 138The CLAS and Hall-A Collaborations, 139The CLAS and Hall-A Collaborations, 140The CLAS and Hall-A Collaborations, 141The CLAS and Hall-A Collaborations, 142The CLAS and Hall-A Collaborations, 143The CLAS and Hall-A Collaborations, 144The CLAS and Hall-A Collaborations, 145The CLAS and Hall-A Collaborations, 146The CLAS and Hall-A Collaborations, 147The CLAS and Hall-A Collaborations, 148The CLAS and Hall-A Collaborations, 149The CLAS and Hall-A Collaborations, 150The CLAS and Hall-A Collaborations, 151The CLAS and Hall-A Collaborations, 152The CLAS and Hall-A Collaborations, 153The CLAS and Hall-A Collaborations, 154The CLAS and Hall-A Collaborations, 155The CLAS and Hall-A Collaborations, 156The CLAS and Hall-A Collaborations, 157The CLAS and Hall-A Collaborations, 158The CLAS and Hall-A Collaborations, 159The CLAS and Hall-A Collaborations, 160The CLAS and Hall-A Collaborations, 161The CLAS and Hall-A Collaborations, 162The CLAS and Hall-A Collaborations, 163The CLAS and Hall-A Collaborations, 164The CLAS and Hall-A Collaborations, 165The CLAS and Hall-A Collaborations, 166The CLAS and Hall-A Collaborations, 167The CLAS and Hall-A Collaborations, 168The CLAS and Hall-A Collaborations, 169The CLAS and Hall-A Collaborations, 170The CLAS and Hall-A Collaborations, 171The CLAS and Hall-A Collaborations, 172The CLAS and Hall-A Collaborations, 173The CLAS and Hall-A Collaborations, 174The CLAS and Hall-A Collaborations, 175The CLAS and Hall-A Collaborations, 176The CLAS and Hall-A Collaborations, 177The CLAS and Hall-A Collaborations, 178The CLAS and Hall-A Collaborations, 179The CLAS and Hall-A Collaborations, 180The CLAS and Hall-A Collaborations, 181The CLAS and Hall-A Collaborations, 182The CLAS and Hall-A Collaborations, 183The CLAS and Hall-A Collaborations, 184The CLAS and Hall-A Collaborations, 185The CLAS and Hall-A Collaborations, 186The CLAS and Hall-A Collaborations, 187The CLAS and Hall-A Collaborations, 188The CLAS and Hall-A Collaborations, 189The CLAS and Hall-A Collaborations, 190The CLAS and Hall-A Collaborations, 191The CLAS and Hall-A Collaborations, 192The CLAS and Hall-A Collaborations, 193The CLAS and Hall-A Collaborations, 194The CLAS and Hall-A Collaborations, 195The CLAS and Hall-A Collaborations, 196The CLAS and Hall-A Collaborations, 197The CLAS and Hall-A Collaborations, 198The CLAS and Hall-A Collaborations, 199The CLAS and Hall-A Collaborations, 200The CLAS and Hall-A Collaborations

We have measured cross sections for the gamma+3He->p+d reaction at photon energies of 0.4 - 1.4 GeV and a center-of-mass angle of 90 deg. Read More

2013Feb
Authors: C. S. Nepali, M. Amaryan, K. P. Adhikari, M. Aghasyan, S. Anefalos Pereira, H. Baghdasaryan, J. Ball, M. Battaglieri, V. Batourine, I. Bedlinskiy, A. S. Biselli, J. Bono, S. Boiarinov, W. J. Briscoe, S. Bültmann, V. D. Burkert, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, P. L. Cole, P. Collins, M. Contalbrigo, V. Crede, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, D. Doughty, R. Dupre, A. El Alaoui, L. El Fassi, G. Fedotov, S. Fegan, R. Fersch, J. A. Fleming, M. Y. Gabrielyan, N. Gevorgyan, K. L. Giovanetti, F. X. Girod, D. I. Glazier, J. T. Goetz, W. Gohn, E. Golovatch, R. W. Gothe, K. A. Griffioen, M. Guidal, N. Guler, K. Hafidi, H. Hakobyan, C. Hanretty, N. Harrison, D. Heddle, K. Hicks, D. Ho, M. Holtrop, C. E. Hyde, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, H. S. Jo, D. Keller, M. Khandaker, P. Khetarpal, A. Kim, W. Kim, A. Klein, F. J. Klein, S. Koirala, V. Kubarovsky, S. E. Kuhn, S. V. Kuleshov, N. D. Kvaltine, H. Y. Lu, I . J . D. MacGregor, N. Markov, M. Mayer, B. McKinnon, T. Mineeva, M. Mirazita, V. Mokeev, R. A. Montgomery, 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, S. Park, E. Pasyuk, E. Phelps, J. J. Phillips, S. Pisano, O. Pogorelko, S. Pozdniakov, J. W. Price, S. Procureur, D. Protopopescu, A. J. R. Puckett, B. A. Raue, D. Rimal, M. Ripani, B. G. Ritchie, G. Rosner, P. Rossi, F. Sabatié, M. S. Saini, C. Salgado, D. Schott, R. A. Schumacher, E. Seder, H. Seraydaryan, Y. G. Sharabian, G. D. Smith, D. I. Sober, D. Sokhan, S. S. Stepanyan, S. Stepanyan, I. I. Strakovsky, S. Strauch, M. Taiuti, W. Tang, C. E. Taylor, Ye Tian, S. Tkachenko, B. Torayev, B. Vernarsky, A. V. Vlassov, H. Voskanyan, E. Voutier, N. K. Walford, D. P. Watts, L. B. Weinstein, D. P. Weygand, N. Zachariou, L. Zana, J. Zhang, Z. W. Zhao, I. Zonta, J. Zhang

Experimental results on the $\Sigma^+(1189)$ hyperon transverse polarization in photoproduction on a hydrogen target using the CLAS detector at Jefferson laboratory are presented. The $\Sigma^+(1189)$ was reconstructed in the exclusive reaction $\gamma+p\rightarrow K^{0}_{S} + \Sigma^+(1189)$ via the $\Sigma^{+} \to p \pi^{0}$ decay mode. The $K^{0}_S$ was reconstructed in the invariant mass of two oppositely charged pions with the $\pi^0$ identified in the missing mass of the detected $p\pi^+\pi^-$ final state. Read More

The primary motivation of the GlueX experiment is to search for and ultimately study the pattern of gluonic excitations in the meson spectrum produced in gamma p collisions. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons that have both exotic and non-exotic JPC, corresponding to q q-bar (q=u, d, or s) states coupled with a gluonic field. A thorough study of the hybrid spectrum, including the identification of the isovector triplet, with charges 0 and +-1, and both isoscalar members, |s s-bar> and |u u-bar> + |d d-bar>, for each predicted hybrid combination of JPC, may only be achieved by conducting a systematic amplitude analysis of many different hadronic final states. Read More

2012Apr
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

The CLAS Collaboration provides a comment on the physics interpretation of the results presented in a paper published by M. Amaryan et al. regarding the possible observation of a narrow structure in the mass spectrum of a photoproduction experiment. Read More

Luminous blue variables (LBVs) are expected to play an important role in massive stellar evolution as well as being the progenitors of some of the most luminous supernovae known. In this paper we provide a multiwavelength study of the population of (candidate) LBVs identified within M33. New spectra provide an observational baseline of >4yr with respect to published data, which is well suited to identifying LBV outbursts. Read More

Despite their importance to a number of astrophysical fields, the lifecycles of very massive stars are still poorly defined. In order to address this shortcoming, we present a detailed quantitative study of the physical properties of four early-B hypergiants (BHGs); Cyg OB2 #12, zeta Sco, HD190603 and BP Cru. These are combined with an analysis of their long-term spectroscopic and photometric behaviour in order to determine their evolutionary status. Read More

2012Jan
Authors: L. El Fassi, L. Zana, K. Hafidi, M. Holtrop, B. Mustapha, W. K. Brooks, H. Hakobyan, X. Zheng, K. P. Adhikari, D. Adikaram, M. Aghasyan, M. J. Amaryan, M. Anghinolfi, J. Arrington, H. Avakian, H. Baghdasaryan, M. Battaglieri, V. Batourine, I. Bedlinskiy, A. S. Biselli, C. Bookwalter, D. Branford, W. J. Briscoe, S. Bultmann, V. D. Burkert, D. S. Carman, A. Celentano, S. Chandavar, P. L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, A. Daniel, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, B. Dey, R. Dickson, C. Djalali, G. E. Dodge, D. Doughty, R. Dupre, H. Egiyan, A. El Alaoui, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, M. Y. Gabrielyan, M. Garcon, N. Gevorgyan, 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, C. Hanretty, D. Heddle, K. Hicks, R. J. Holt, C. E. Hyde, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, S. S. Jawalkar, D. Keller, M. Khandaker, P. Khetarpal, A. Kim, W. Kim, A. Klein, F. J. Klein, V. Kubarovsky, S. E. Kuhn, S. V. Kuleshov, V. Kuznetsov, J. M. Laget, H. Y. Lu, I. J. D. MacGregor, Y. Mao, N. Markov, M. Mayer, J. McAndrew, B. McKinnon, C. A. Meyer, T. Mineeva, M. Mirazita, V. Mokeev, B. Moreno, H. Moutarde, E. Munevar, P. Nadel-Turonski, A. Ni, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A. I. Ostrovidov, L. Pappalardo, R. Paremuzyan, K. Park, S. Park, E. Pasyuk, S. Anefalos Pereira, E. Phelps, S. Pisano, S. Pozdniakov, J. W. Price, S. Procureur, D. Protopopescu, B. A. Raue, P. E. Reimer, G. Ricco, D. Rimal, M. Ripani, B. G. Ritchie, G. Rosner, P. Rossi, F. Sabatie, M. S. Saini, C. Salgado, D. Schott, R. A. Schumacher, H. Seraydaryan, Y. G. Sharabian, E. S. Smith, G. D. Smith, D. I. Sober, D. Sokhan, S. S. Stepanyan, S. Stepanyan, P. Stoler, S. Strauch, M. Taiuti, W. Tang, C. E. Taylor, D. J. Tedeschi, S. Tkachenko, M. Ungaro, B . Vernarsky, M. F. Vineyard, H. Voskanyan, E. Voutier, D. Watts, L. B. Weinstein, D. P. Weygand, M. H. Wood, N. Zachariou, B. Zhao, Z. W. Zhao

We have measured the nuclear transparency of the incoherent diffractive $A(e,e'\rho^0)$ process in $^{12}$C and $^{56}$Fe targets relative to $^2$H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced $\rho^0$'s on a nucleus relative to deuterium, which is sensitive to $\rho A$ interaction, was studied as function of the coherence length ($l_c$), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared ($Q^2$). While the transparency for both $^{12}$C and $^{56}$Fe showed no $l_c$ dependence, a significant $Q^2$ dependence was measured, which is consistent with calculations that included the color transparency effects. Read More

2012Jan
Authors: Kijun Park, Ralf Gothe, Krishna Adhikari, Dasuni Adikaram-Mudiyanselage, Marco Anghinolfi, Hovhannes Baghdasaryan, Jacques Ball, Marco Battaglieri, Vitaly Baturin, Ivan Bedlinskiy, Robert Bennett, Angela Biselli, Craig Bookwalter, Sergey Boyarinov, Derek Branford, William Briscoe, William Brooks, Volker Burkert, Daniel Carman, Andrea Celentano, Shloka Chandavar, Gabriel Charles, Philip Cole, Marco Contalbrigo, Volker Crede, Annalisa D'Angelo, Aji Daniel, Natalya Dashyan, Raffaella De Vita, Enzo De Sanctis, Alexandre Deur, Chaden Djalali, David Doughty, Raphael Dupre, Ahmed El Alaoui, Lamiaa Elfassi, Paul Eugenio, Gleb Fedotov, Ahmed Fradi, Marianna Gabrielyan, Nerses Gevorgyan, Gerard Gilfoyle, Kevin Giovanetti, Francois-Xavier Girod, John Goetz, Wesley Gohn, Evgeny Golovach, Lewis Graham, Keith Griffioen, Michel Guidal, Lei Guo, Kawtar Hafidi, Hayk Hakobyan, Charles Hanretty, David Heddle, Kenneth Hicks, Maurik Holtrop, Yordanka Ilieva, David Ireland, Boris Ishkhanov, Evgeny Isupov, David Jenkins, Hyon-Suk Jo, Kyungseon Joo, Mahbubul Khandaker, Puneet Khetarpal, Andrey Kim, Wooyoung Kim, Andreas Klein, Franz Klein, A. Kubarovsky, Valery Kubarovsky, Sebastian Kuhn, Sergey Kuleshov, Nicholas Kvaltine, Kenneth Livingston, Haiyun Lu, Ian MacGregor, Nikolai Markov, Michael Mayer, Bryan McKinnon, Mac Mestayer, Curtis Meyer, Taisiya Mineeva, Marco Mirazita, Viktor Mokeev, Herve Moutarde, Edwin Munevar Espitia, Pawel Nadel-Turonski, Rakhsha Nasseripour, Silvia Niccolai, Gabriel Niculescu, Maria-Ioana Niculescu, Mikhail Osipenko, Alexander Ostrovidov, Michael Paolone, Luciano Pappalardo, Rafayel Paremuzyan, Seungkyung Park, Sergio Pereira, Evan Phelps, Silvia Pisano, Oleg Pogorelko, Sergey Pozdnyakov, John Price, Sebastien Procureur, Yelena Prok, Giovanni Ricco, Dipak Rimal, Marco Ripani, Barry Ritchie, Guenther Rosner, Patrizia Rossi, Franck Sabatie, Mukesh Saini, Carlos Salgado, Diane Schott, Reinhard Schumacher, Heghine Seraydaryan, Youri Sharabian, Elton Smith, Gregory Smith, Daniel Sober, Daria Sokhan, Samuel Stepanyan, Stepan Stepanyan, Paul Stoler, Igor Strakovski, Steffen Strauch, Mauro Taiuti, Wei Tang, Charles Taylor, Ye Tian, Svyatoslav Tkachenko, Arjun Trivedi, Maurizio Ungaro, Brian Vernarsky, Alexander Vlasov, Eric Voutier, Daniel Watts, Dennis Weygand, Michael Wood, Nicholas Zachariou, Bo Zhao, Zhiwen Zhao, N. Kalantarians, C. E. Hyde

We report the first extraction of the pion-nucleon multipoles near the production threshold for the $n\pi^+$ channel at relatively high momentum transfer ($Q^2$ up to 4.2 $\rm{GeV^2}$). The dominance of the s-wave transverse multipole ($E_{0+}$), expected in this region, allowed us to access the generalized form factor $G_1$ within the light-cone sum rule (LCSR) framework as well as the axial form factor $G_A$. Read More

NGC346-013 is a peculiar double-lined eclipsing binary in the Small Magellanic Cloud discovered by the VLT-FLAMES survey of massive stars. Spectra obtained with VLT-FLAMES are used to construct a radial velocity curve and photometry obtained with the Faulkes Telescope South is then used to derive orbital parameters, while spectra of the secondary are compared with synthetic spectra from TLUSTY model atmospheres. The orbital period is found to be 4. Read More

There is growing evidence that a treatment of binarity amongst OB stars is essential for a full theory of stellar evolution. However the binary properties of massive stars - frequency, mass ratio and orbital separation - are still poorly constrained. In order to address this shortcoming we have undertaken a multiepoch spectroscopic study of the stellar population of the young massive cluster Westerlund 1. Read More

Recent IR surveys of the Galactic plane have revealed a large number of candidate Luminous Blue Variables. In order to verify these classifications we have been undertaking a long term spectroscopic and photometric monitoring campaign supplemented with tailored non-LTE model atmosphere analysis. Here we present a brief overview of selected aspects of this program, highlighting the prospects for identification, classification and quantitative analysis of LBVs in the near-IR spectral window. Read More

2010Nov
Authors: X. Qian, W. Chen, H. Gao, K. Hicks, K. Kramer, J. M. Laget, T. Mibe, Y. Qiang, S. Stepanyan, D. J. Tedeschi, W. Xu, K. P. Adhikari, M. Amaryan, M. Anghinolfi, J. Ball, M. Battaglieri, V. Batourine, I. Bedlinskiy, M. Bellis, A. S. Biselli, C. Bookwalter, D. Branford, W. J. Briscoe, W. K. Brooks, V. D. Burkert, S. L. Careccia, D. S. Carman, P. L. Cole, P. Collins, V. Crede, A. D'Angelo, A. Daniel, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, B. Dey, S. Dhamija, C. Djalali, D. Doughty, R. Dupre, H. Egiyan, A. El Alaoui, P. Eugenio, S. Fegan, M. Y. Gabrielyan, N. Gevorgyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, J. T. Goetz, W. Gohn, R. W. Gothe, L. Graham, K. A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, N. Hassall, M. Holtrop, Y. Ilieva, D. G. Ireland, S. S. Jawalkar, H. S. Jo, K. Joo, D. Keller, M. Khandaker, P. Khetarpal, A. Kim, W. Kim, A. Klein, F. J. Klein, P. Konczykowski, V. Kubarovsky, S. V. Kuleshov, V. Kuznetsov, K. Livingston, D. Martinez, M. Mayer, J. McAndrew, M. E. McCracken, B. McKinnon, C. A. Meyer, K. Mikhailov, T. Mineeva, M. Mirazita, V. Mokeev, B. Moreno, K. Moriya, B. Morrison, H. Moutarde, E. Munevar, P. Nadel-Turonski, A. Ni, S. Niccolai, I. Niculescu, M. R. Niroula, M. Osipenko, A. I. Ostrovidov, R. Paremuzyan, K. Park, S. Park, S. Anefalos Pereira, S. Pisano, O. Pogorelko, S. Pozdniakov, J. W. Price, S. Procureur, D. Protopopescu, G. Ricco, M. Ripani, B. G. Ritchie, G. Rosner, P. Rossi, F. Sabatié, M. S. Saini, C. Salgado, D. Schott, R. A. Schumacher, E. Seder, H. Seraydaryan, Y. G. Sharabian, E. S. Smith, G. D. Smith, D. I. Sober, D. Sokhan, S. S. Stepanyan, P. Stoler, I. I. Strakovsky, S. Strauch, M. Taiuti, C. E. Taylor, S. Tkachenko, M. Ungaro, B . Vernarsky, M. F. Vineyard, E. Voutier, L. B. Weinstein, D. P. Weygand, M. H. Wood, N. Zachariou, L. Zana, J. Zhang, B. Zhao, Z. W. Zhao

We report the first measurement of the differential cross section on $\phi$-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, $K^+$ and $K^-$ near the theoretical production threshold of 1.57 GeV. Read More

We present initial results from a long-baseline radial velocity survey for massive binaries in the cluster Westerlund 1. Four systems are examined: the dust-producing WC binary W239, the double-lined eclipsing binary W13, and the single-lined B0 supergiants W43a and W3003. Finally, the evolutionary implications for the population of massive stars in Westerlund 1 are discussed. Read More

Westerlund 1 is a young, massive Galactic starburst cluster that contains a rich coeval population of Wolf-Rayet stars, hot- and cool-phase transitional supergiants, and a magnetar. We use spectroscopic and photometric observations of the eclipsing double-lined binary W13 to derive dynamical masses for the two components, in order to determine limits for the progenitor masses of the magnetar CXOU J164710.2-455216 and the population of evolved stars in Wd1. Read More

Massive stars exhibit spectroscopic and photometric variability over a wide range of timescales. However the physical mechanisms driving this behaviour remain poorly understood. Westerlund 1 presents an ideal laboratory for studying these processes in a rich, coeval population of post-main sequence stars and we present a pathfinding study aimed at characterising their variability utilising the large body of data that has accumulated since the 1960s. Read More

After leaving the main sequence, massive stars undergo complex evolution, still poorly understood. With a population of 100s OB stars, the starburst cluster Westerlund~1 offers an unparallelled environment to study their evolutionary tracks. We used the VLT/FORS2 to obtain intermediate-resolution spectroscopy over the range 5800-9000A of ~ 100 likely members. Read More

The massive post-Main Sequence star W243 in the galactic starburst cluster Westerlund 1 has undergone a spectral transformation from a B2Ia supergiant devoid of emission features in 1981 to an A-type supergiant with a rich emission-line spectrum by 2002/03. We used VLT/UVES and VLT/FLAMES to obtain high-resolution spectra on six epochs in 2003/04 (UVES) and ten epochs in 2008/09 (FLAMES). These spectra are used alongside other VLT/FLAMES and NTT/EMMI spectra to follow the evolution of W243 from 2002 to 2009. Read More

We characterise the variability in the physical properties of the luminous blue variable AFGL2298 between 1989-2008. In conjunction with published data from 1989-2001, we have undertaken a long term (2001-2008) near-IR spectroscopic and photometric observational campaign for this star and utilise a non-LTE model atmosphere code to interpret these data. We find AFGL2298 to have been highly variable during the two decades covered by the observational datasets. Read More

Multiwavelength observations of the young massive cluster Westerlund 1 have revealed evidence for a large number of OB supergiant and Wolf-Rayet binaries. However, in most cases these findings are based on secondary binary characteristics such as hard X-ray emission and/or non-thermal radio spectra and hence provide little information on binary properties such as mass ratio and orbital period. To overcome this shortcoming we have initiated a long temporal baseline, VLT/FLAMES+GIRAFFE multi-epoch radial velocity survey that will provide the first direct constraints on these parameters. Read More

We aim to characterise the properties of a third massive, red supergiant dominated galactic cluster. To accomplish this we utilised a combination of near/mid-IR photometry and spectroscopy to identify and classify the properties of cluster members, and statistical arguments to determine the mass of the cluster. We found a total of 16 strong candidates for cluster membership, for which formal classification of a subset yields spectral types from K3-M4 Ia and luminosities between log(L/L_sun)~4. Read More

Differential cross sections for the reaction $\gamma p \to n \pi^+$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.725 to 2.875 GeV. Read More

A technique is presented for precision measurements of the area densities, density * T, of approximately 5% radiation length carbon and 208Pb targets used in an experiment at Jefferson Laboratory to measure the neutral pion radiative width. The precision obtained in the area density for the carbon target is +/- 0.050%, and that obtained for the lead target through an x-ray attenuation technique is +/- 0. Read More

Differential cross sections for the reaction $\gamma p \to p \pi^0$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.675 to 2.875 GeV. Read More

2005Dec
Affiliations: 1the CLAS Collaboration, 2the CLAS Collaboration, 3the CLAS Collaboration, 4the CLAS Collaboration, 5the CLAS Collaboration

Differential cross sections for the reaction gamma p -> eta-prime p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. Read More

Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare Pi+ -> Pi0 e+ Nu,(pi_beta) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed pi_beta decays to the number of observed Pi+ -> e+ Nu, (pi_{e2}) decays. We find the value of Gamma(Pi+ -> Pi0 e+ Nu)/Gamma(total) = [1. Read More

We have studied radiative pion decays Pi+ -> e+ nu gamma in three broad kinematic regions using the PIBETA detector and a stopped pion beam. Based on Dalitz distributions of 42,209 events we have evaluated absolute Pi -> e nu gamma branching ratios in the three regions. Minimum chi^2 fits to the integral and differential (E(e+),E(gamma)) distributions result in the axial-to-vector weak form factor ratio of gamma = F_A/F_V = 0. Read More

We describe the design, construction and performance of the PIBETA detector built for the precise measurement of the branching ratio of pion beta decay, pi+ -> pi0 e+ nu, at the Paul Scherrer Institute. The central part of the detector is a 240-module spherical pure CsI calorimeter covering 3*pi sr solid angle. The calorimeter is supplemented with an active collimator/beam degrader system, an active segmented plastic target, a pair of low-mass cylindrical wire chambers and a 20-element cylindrical plastic scintillator hodoscope. Read More

We present the results of high-resolution AP3M+SPH simulations of merging clusters of galaxies. We find that the compression and shocking of the core gas during a merger can lead to large increases in bolometric X-ray luminosities and emission-weighted temperatures of clusters. Cooling flows are completely disrupted during equal-mass mergers, with the mass deposition rate dropping to zero as the cores of the clusters collide. Read More

The analysis and results are presented from the complete data set recorded at Palo Verde between September 1998 and July 2000. In the experiment, the $\nuebar$ interaction rate has been measured at a distance of 750 and 890 m from the reactors of the Palo Verde Nuclear Generating Station for a total of 350 days, including 108 days with one of the three reactors off for refueling. Backgrounds were determined by (a) the $swap$ technique based on the difference between signal and background under reversal of the positron and neutron parts of the correlated event and (b) making use of the conventional reactor-on and reactor-off cycles. Read More

2000Jun
Affiliations: 1Palo Verde Collaboration, 2Palo Verde Collaboration, 3Palo Verde Collaboration, 4Palo Verde Collaboration, 5Palo Verde Collaboration, 6Palo Verde Collaboration, 7Palo Verde Collaboration, 8Palo Verde Collaboration, 9Palo Verde Collaboration, 10Palo Verde Collaboration, 11Palo Verde Collaboration, 12Palo Verde Collaboration, 13Palo Verde Collaboration, 14Palo Verde Collaboration, 15Palo Verde Collaboration, 16Palo Verde Collaboration

The yield of neutrons produced by cosmic ray muons at a shallow depth of 32 meters of water equivalent has been measured. The Palo Verde neutrino detector, containing 11.3 tons of Gd loaded liquid scintillator and 3. Read More

We adapt the Smoothed-Particle Hydrodynamics technique to allow a multiphase fluid in which SPH particles of widely differing density may be freely intermixed. Applications include modelling of galaxy formation and cooling flows. Read More

The $\nuebar$ flux and spectrum have been measured at a distance of about 800 m from the reactors of the Palo Verde Nuclear Generating Station using a segmented Gd-loaded liquid scintillator detector. Correlated positron-neutron events from the reaction $\nuebar$p$\to$e^+n were recorded for a period of 200 d including 55 d with one of the three reactors off for refueling. Backgrounds were accounted for by making use of the reactor-on and reactor-off cycles, and also with a novel technique based on the difference between signal and background under reversal of the e^+ and n portions of the events. Read More

We report on the initial results from a measurement of the anti-neutrino flux and spectrum at a distance of about 800 m from the three reactors of the Palo Verde Nuclear Generating Station using a segmented gadolinium-loaded scintillation detector. We find that the anti-neutrino flux agrees with that predicted in the absence of oscillations to better than 5%, excluding at 90% CL $\rm\bar\nu_e - \bar\nu_x$ oscillations with $\Delta m^2 > 1.12\times 10^{-3}$ eV^2 for maximal mixing and $\sin^2{2\theta} > 0. Read More