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508 results on '"Supek, I."'

151. Photoproduction of the ωmeson on the proton near threshold

Author

Strakovsky, I. I., Prakhov, S., Azimov, Ya. I., Aguar-Bartolomé, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Costanza, S., Demissie, B. T., Downie, E. J., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Hamilton, D. J., Heid, E., Hornidge, D., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Marinides, Z., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Middleton, D. G., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ortega, H., Ostrick, M., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Starostin, A., Supek, I., Taragin, M. F., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., and Zehr, F.

Subjects
Nuclear Experiment
Abstract

An experimental study of ω 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 γp→ωp differential cross sections are measured from threshold to the incident-photon energy Eγ=1.40 GeV (W=1.87 GeV for the center-of-mass energy) with 15-MeV binning in Eγ and full production-angle coverage. The quality of the present data near threshold gives access to a variety of interesting physics aspects. As an example, an estimation of the ωN scattering length αωp is provided.

Published
2015

152. First measurement of target and beam-target asymmetries in the $��p\to ��^0��p$ reaction

Author

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

Subjects
Nuclear Theory (nucl-th), High Energy Physics - Experiment (hep-ex), Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The first data on target and beam-target asymmetries for the $��p\to��^0��p$ 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 $��3/2^-$ amplitude is confirmed. The data are in particular sensitive to small contributions from other partial waves., 9 pages, 9 figures

Published
2015
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153. [formula omitted] and [formula omitted] photoproduction with fine center-of-mass energy resolution

Author

Jude, T.C., Glazier, D.I., Watts, D.P., Aguar-Bartolomé, P., Akasoy, L.K., Annand, J.R.M., Arends, H.J., Bantawa, K., Beck, R., Bekrenev, V.S., Berghäuser, H., Braghieri, A., Branford, D., Briscoe, W.J., Brudvik, J., Cherepnya, S., Demissie, B.T., Dieterle, M., Downie, E.J., Fil'kov, L.V., Gregor, R., Heid, E., Hornidge, D., Jaegle, I., Jahn, O., Kashevarov, V.L., Keshelashvili, I., Kondratiev, R., Korolija, M., Koulbardis, A.A., Kruglov, S.P., Krusche, B., Lisin, V., Livingston, K., MacGregor, I.J.D., Maghrbi, Y., Manley, D.M., Marinides, Z., Mart, T., Martinez, M., McGeorge, J.C., McNicoll, E.F., Middleton, D.G., Mushkarenkov, A., Nefkens, B.M.K., Nikolaev, A., Nikonov, V.A., Oberle, M., Ostrick, M., Otte, P.B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rostomyan, T., Sarantsev, A.V., Schumann, S., Sikora, M.H., Sober, D.I., Starostin, A., Strakovsky, I., Suarez, I.M., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Werthmüller, D., Witthauer, L., and Zehr, F.

Published
2014
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154. <math altimg='si1.gif' xmlns='http://www.w3.org/1998/Math/MathML'><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><mi>Λ</mi></math> and <math altimg='si2.gif' xmlns='http://www.w3.org/1998/Math/MathML'><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>Σ</mi></mrow><mrow><mn>0</mn></mrow></msup></math> photoproduction with fine center-of-mass energy resolution

Author

Jude, T.C.(School of Physics, University of Edinburgh, Edinburgh, EH9 3JZ, UK), Glazier, D.I.(School of Physics, University of Edinburgh, Edinburgh, EH9 3JZ, UK), Watts, D.P.(School of Physics, University of Edinburgh, Edinburgh, EH9 3JZ, UK), Aguar-Bartolomé, P.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Akasoy, L.K.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Annand, J.R.M.(Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK), Arends, H.J.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Bantawa, K.(Kent State University, Kent, OH, 44242, USA), Beck, R.(Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, Bonn, D-53115, Germany), Bekrenev, V.S.(Petersburg Nuclear Physics Institute, Gatchina, 188300, Russia), Berghäuser, H.(Physikalisches Institut, University of Giessen, Giessen, D-35392, Germany), Braghieri, A.(INFN Sezione di Pavia, Pavia, I-27100, Italy), Branford, D.(School of Physics, University of Edinburgh, Edinburgh, EH9 3JZ, UK), Briscoe, W.J.(The George Washington University, Washington, DC, 20052, USA), Brudvik, J.(The George Washington University, Washington, DC, 20052, USA), Cherepnya, S.(Lebedev Physical Institute, Moscow, 119991, Russia), Demissie, B.T.(The George Washington University, Washington, DC, 20052, USA), Dieterle, M.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland), Downie, E.J.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Fil'kov, L.V.(Lebedev Physical Institute, Moscow, 119991, Russia), Gregor, R.(Physikalisches Institut, University of Giessen, Giessen, D-35392, Germany), Heid, E.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Hornidge, D.(Mount Allison University, Sackville, New Brunswick, E4L3B5, Canada), Jaegle, I.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland), Jahn, O.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Kashevarov, V.L.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Keshelashvili, I.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland), Kondratiev, R.(Institute for Nuclear Research, Moscow, 125047, Russia), Korolija, M.(Rudjer Boskovic Institute, Zagreb, HR-10000, Croatia), Koulbardis, A.A.(Petersburg Nuclear Physics Institute, Gatchina, 188300, Russia), Kruglov, S.P.(Petersburg Nuclear Physics Institute, Gatchina, 188300, Russia), Krusche, B.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland), Lisin, V.(Institute for Nuclear Research, Moscow, 125047, Russia), Livingston, K.(Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK), MacGregor, I.J.D.(Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK), Maghrbi, Y.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland), Manley, D.M.(Kent State University, Kent, OH, 44242, USA), Marinides, Z.(The George Washington University, Washington, DC, 20052, USA), Mart, T.(Departemen Fisika, FMIPA, Universitas Indonesia, Depok, 16424, Indonesia), Martinez, M.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), McGeorge, J.C.(Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK), McNicoll, E.F.(Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK), Middleton, D.G.(Mount Allison University, Sackville, New Brunswick, E4L3B5, Canada), Mushkarenkov, A.(INFN Sezione di Pavia, Pavia, I-27100, Italy), Nefkens, B.M.K.(The George Washington University, Washington, DC, 20052, USA), Nikolaev, A.(Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, Bonn, D-53115, Germany), Nikonov, V.A.(Petersburg Nuclear Physics Institute, Gatchina, 188300, Russia), Oberle, M.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland), Ostrick, M.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Otte, P.B.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Oussena, B.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Pedroni, P.(INFN Sezione di Pavia, Pavia, I-27100, Italy), Pheron, F.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland), Polonski, A.(Institute for Nuclear Research, Moscow, 125047, Russia), Prakhov, S.(The George Washington University, Washington, DC, 20052, USA), Robinson, J.(Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK), Rosner, G.(Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK), Rostomyan, T.(INFN Sezione di Pavia, Pavia, I-27100, Italy), Sarantsev, A.V.(Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, Bonn, D-53115, Germany), Schumann, S.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Sikora, M.H.(School of Physics, University of Edinburgh, Edinburgh, EH9 3JZ, UK), Sober, D.I.(The Catholic University of America, Washington, DC, 20064, USA), Starostin, A.(The George Washington University, Washington, DC, 20052, USA), Strakovsky, I.(The George Washington University, Washington, DC, 20052, USA), Suarez, I.M.(The George Washington University, Washington, DC, 20052, USA), Supek, I.(Rudjer Boskovic Institute, Zagreb, HR-10000, Croatia), Thiel, M.(Physikalisches Institut, University of Giessen, Giessen, D-35392, Germany), Thomas, A.(Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, Bonn, D-53115, Germany), Unverzagt, M.(Institut für Kernphysik, University of Mainz, Mainz, D-55099, Germany), Werthmüller, D.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland), Witthauer, L.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland), and Zehr, F.(Institut für Physik, University of Basel, Basel, CH-4056, Switzerland)

Abstract

Measurements of γp→K+Λ and γp→K+Σ0 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. The new analyses disfavor a strong role for quark–diquark dynamics in the nucleon.

Published
2014

155. New measurement of the rare decay η→π0γγ with the Crystal Ball/TAPS detectors at the Mainz Microtron

Author

Nefkens, B M.K., Prakhov, S., Aguar-Bartolomé, P., Annand, J.R.M., Arends, H.J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R.F.B., Collicott, C., Costanza, S., Danilkin, I.V., Denig, A., Demissie, B., Dieterle, M., Downie, E.J., Drexler, P., Fil'kov, L.V., Fix, A., Garni, S., Glazier, D.I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Jahn, O., Jude, T.C., Kashevarov, V.L., Käser, A., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I.J.D., Maghrbi, Y., Mancel, J., Manley, D.M., McNicoll, E.F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nikolaev, A., Novotny, R., Oberle, M., Ortega, H., Ostrick, M., Ott, P., Otte, P.B., Oussena, B., Pedroni, P., Polonski, A., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M.H., Starostin, A., Strakovsky, I.I., Strub, T., Suarez, I.M., Supek, I., Tarbert, C.M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D.P., Werthmüller, D., and Witthauer, L.

Abstract

A new measurement of the rare, doubly radiative decay η→π0γγ 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, Γ(η→π0γγ), on the two-photon invariant-mass squared, m2(γγ), as well as a new, more precise value for the decay width, Γ(η→π0γγ)=(0.33±0.03tot) eV, are based on analysis of 1.2×103η→π0γγ decays from a total of 6×107η mesons produced in the γp→ηp reaction. The present results for dΓ(η→π0γγ)/dm2(γγ) are in good agreement with previous measurements and recent theoretical calculations for this dependence.

Published
2014

156. Measurement of the H1(γ, p→)π0 reaction using a novel nucleon spin polarimeter

Author

Sikora, M.H., Watts, D.P., Glazier, D.I., Aguar-Bartolome, P., Akasoy, L.K., Annand, J.R.M., Arends, H.J., Bantawa, K., Beck, R., Bekrenev, V.S., Berghauser, H., Braghieri, A., Branford, D., Briscoe, W.J., Brudvik, J., Cherepnya, S., Codling, R.F.B., Demissie, B.T., Downie, E.J., Drexler, P., Fil'kov, L.V., Freehart, B., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Howdle, D.A., Jaegle, I., Jahn, O., Jude, T.C., Kashevarov, V.L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A.A., Kruglov, S.P., Krusche, B., Lisin, V., Livingston, K., MacGregor, I.J.D., Maghrbi, Y., Manley, D.M., Marinides, Z., Martinez, M., McGeorge, J.C., McKinnon, B., McNicoll, E.F., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D.G., Mushkarenkov, A., Nefkens, B.M.K., Nikolaev, A., Novotny, R., Ostrick, M., Otte, P.B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakov, S., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sober, D.I., Starostin, A., Strakovsky, I.I., Suarez, I.M., Supek, I., Thiel, M., Thomas, A., Unversagt, M., Werthmueller, D., Workman, R.L., Zamboni, I., and Zehr, F.

Subjects
Nuclear Theory, Nuclear Experiment, QC
Abstract

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of H1(γ→, p⃗)π0 in the range 0.4

Published
2014

157. Narrow structure in the excitation function of η photoproduction off the neutron

Author

Werthmueller, D., Witthauer, L., Keshelashvili, I., Aguar-Bartolome, P., Ahrens, J., Annand, J.R.M., Arends, H.J., Bantawa, K., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W.J., Brudvik, J., Cherepnya, S., Demissie, B., Dieterle, M., Downie, E.J., Drexler, P., Fil'kov, L.V., Fix, A., Glazier, D.I., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Huber, G.M., Jaegle, I., Jahn, O., Jude, T.C., Kaeser, A., Kashevarov, V.L., Kondratiev, R., Korolija, M., Kruglov, S.P., Krusche, B., Kulbardis, A., Lisin, V., Livingston, K., MacGregor, I.J.D., Maghrbi, Y., Mancell, J., Manley, D.M., Marinides, Z., Martinez, M., McGeorge, J.C., McNicoll, E.F., Metag, V., Middleton, D.G., Mushkarenkov, A., Nefkens, B.M.K., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S.N., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M.H., Sober, D., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Watts, D.P., and Collaboration, A.

Subjects
Nuclear Theory, Nuclear Experiment, QC
Abstract

The photoproduction of η mesons off nucleons bound in H2 and H3e has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the η→2γ and η→3π0 decays and the recoil nucleons were detected with an almost 4π electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of γn→nη. The results from the two measurements are consistent, taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are W=(1670±5) MeV and Γ=(30±15) MeV. For the first time precise results for the angular dependence of this structure have been extracted.

Published
2013

158. Accurate test of chiral dynamics in the ~γp → π\ud 0p reaction

Author

Hornidge, D., Bartolome, P., Annand, J. R. M., Arends, H. J., Beck, R., Bekrenev, V., Berghaeuser, H., Bernstein, A. M., Braghieri, A., Briscoe, W. J., Cherepnya, S., Dieterle, M., Downie, E. J., Drexler, P., Fernandez-Ramirez, C., Filkov, L. V., Glazier, D. I., Barrientos, P., Heid, E., Hilt, M., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Koulbardis, A., Krambrich, D., Kruglov, S., Krusche, B., Laffoley, A. T., Lisin, V., Livingston, K., MacGregor, I.J.D., Mancell, J., Manley, D. M., McNicoll, E.F., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D.G, Moores, K. W., Mushkarenkov, A., Nefkens, B. M. K., Oberle, M., Ostrick, M., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rostomyan, T., Scherer, S., Schumann, S., Sikora, M. H., Starostin, A., Supek, I., Thiel, M., Thomas, A., Tiator, L., Unverzagt, M., Watts, D. P., Werthmueller, D., and Witthauer, L.

Subjects
Nuclear Experiment, QC
Abstract

A precision measurement of the differential cross sections d sigma/d Omega and the linearly polarized photon asymmetry Sigma equivalent to (d alpha(perpendicular to) - d sigma(parallel to))/(d alpha(perpendicular to) + d sigma(parallel to) for the (gamma) over right arrowp -> pi(0) p reaction in the near-threshold region has been performed with a tagged photon beam and almost 4 pi detector at the Mainz Microtron. The Glasgow-Mainz photon tagging facility along with the Crystal Ball/TAPS multiphoton detector system and a cryogenic liquid hydrogen target were used. These data allowed for a precise determination of the energy dependence of the real parts of the S- and all three P-wave amplitudes for the first time and provide the most stringent test to date of the predictions of chiral perturbation theory and its energy region of agreement with experiment.

Published
2013

159. Measurements of 12C(→γ,pp) photon asymmetries for\ud Eγ= 200–450 MeV

Author

Robinson, J., MacGregor, I.J.D., Annand, J.R.M., Aguar-Bartolomé, P., Akasoy, L. K., Arends, H. J., Azimov, Y.I., Bantawa, K., Beck, R., Bekrenev, V.S., Berghäuser, H., Braghieri, A., Branford, D., Briscoe, W.J., Brudvik, J., Cherepnya, S., Codling, R.F.B., Demissie, B.T., Dieterle, M., Downie, E.J., Drexler, P., Fil’kov, L.V., Glazier, D.I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Jahn, O., Jude, T.C., Kashevarov, V.L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A.A., Kruglov, S.P., Krusche, B., Lisin, V., Livingston, K., Manley, D.M., McGeorge, J.C., McNicoll, E.F., Metag, V., Middleton, D.G., Mushkarenkov, A., Nefkens, B.M.K., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Owens, R.O., Otte, P.B., Oussena, B., Pedroni, P., Polonski, A., Prakhov, S., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M.H., Sober, D.I., Starostin, A., Strakovsky, I.I., Suarez, I.M., Supek, I., Tarbert, C.M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D.P., Werthmueller, D., and Witthauer, L.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

The 12C (→γ ,pp) reaction has been studied in the photon energy range 200-450 MeV at the Mainz microtron MAMI-C, where linearly polarised photons were energy-tagged using the Glasgow-Mainz Tagged Photon Spectrometer and protons were detected in the Crystal Ball detector. The photon asymmetry Σ has been measured over a wider Eγ range than previous measurements. The strongest asymmetries were found at low missing energies where direct emission of nucleon pairs is expected. Cuts on the difference in azimuthal angles of the two ejected protons increased the magnitude of the observed asymmetries. At low missing energies the Σ data exhibit a strong angular dependence, similar to deuteron photodisintegration.

Published
2013

161. Coherent photoproduction of π0- and η-mesons off 7Li

Author

Maghrbi, Y., Krusche, B., Ahrens, J., Annand, J. R. M., Arends, H. J., Beck, R., Bekrenev, V., Boillat, B., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Downie, E. J., Drexler, P., Fil’kov, L. V., Fix, A., Glazier, D. I., Gregor, R., Heid, E., Hornidge, D., Jaegle, I., Jahn, O., Kashevarov, V. L., Keshelashvili, I., Knezevic, A., Kondratiev, R., Korolija, M., Krambrich, D., Lang, M., Lisin, V., Livingston, K., Lugert, S., MacGregor, I. J. D., Manley, D. M., Martinez, M., McGeorge, J. C., Mekterovic, D., Metag, V., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ostrick, M., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Price, J. W., Rosner, G., Rost, M., Rostomyan, T., Schadmand, S., Schumann, S., Sober, D., Starostin, A., Supek, I., Tarbert, C. M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., and Zehr, F.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

Coherent photoproduction of π0-mesons from threshold (E th ≈ 136 MeV) throughout the Δ-resonance region and of η-mesons close to the production threshold (E th ≈ 570 MeV for η has been measured for 7Li nuclei. The experiment was performed using the tagged-photon beam of the Mainz MAMI accelerator with the Crystal Ball and TAPS detectors combined to give an almost 4π solid-angle electromagnetic calorimeter. The reactions were identified by a combined invariant-mass and missing-energy analysis. A comparison of the pion data to plane-wave impulse modelling tests the nuclear mass form factor. So far coherent η production had been only identified for the lightest nuclear systems (2H and 3He . For 3He a large enhancement of the cross section above plane-wave approximations had been reported, indicating the formation of a quasi-bound state. The present Li data for η production agree with a plane-wave approximation. Contrary to 3He , neither a threshold enhancement of the total cross section nor a deviation of the angular distributions from the expected form factor dependence were observed

Published
2013

162. First measurement of the helicity dependence of 3He photoreactions in the resonance region

Author

Aguar Bartolomé, P., Mushkarenkov, A., Ahrens, J., Annand, J. R. M., Arends, H. J., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Cherepnya, S. N., Costanza, S., Drexler, P., Filʼkov, L. V., Fix, A., Giardina, Giorgio 42, Glazier, D. I., Hamilton, D., Heid, E., Heil, W., Hornidge, D., Howdle, D., Jaegle, I., Jahn, O., Jude, T., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krimmer, J., Krusche, B., Kruglov, S., Kulbardis, A., Lisin, V., Livingston, K., Mancell, J., Middleton, D. G., Macgregor, I. J. D., Manley, D. M., Mcgeorge, J. C., Metag, V., Nefkens, B. M. K., Nikolaev, A., Oberle, M., Ostrick, M., Ortega, H., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Prakhov, S., Polonski, A., Rigamonti, F., Romaniuk, Mariia, Rosner, G., Rostomyan, T., Schumann, S., Sober, D., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Watts, D., and Werthmüller, D.

Published
2013

163. A new determination of the eta transition form factor in the Dalitz decay eta -> e^+ e^- gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

Author

Aguar-Bartolom��, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Bergh��user, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Costanza, S., Denig, A., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Glazier, D. I., Gregor, R., Hamilton, D. J., Heid, E., Hornidge, D., Isaksson, L., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Masjuan, P., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strakovsky, I. I., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthm��ller, D., and Zehr., F.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

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 = (1.95 +/- 0.15_stat +/- 0.10_syst) [1/GeV^2], is in good agreement with recent measurements conducted in eta -> e^+ e^- gamma and eta -> mu^+ mu^- gamma decays, as well as with recent form-factor calculations. The uncertainty obtained in the value of 1/Lambda^2 is lower compared to results from previous measurements of the eta -> e^+ e^- gamma decay., 11 pages, 10 figures, 1 table

Published
2013
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164. Measurement of the g p -> K^0 Sigma^+ reaction with the Crystal Ball/TAPS detectors at the Mainz Microtron

Author

Aguar-Bartolom��, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Bergh��user, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Demissie, B., Dieterle, M., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Glazier, D. I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Isaksson, L., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Mancel, J., Manley, D. M., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Oberle, M., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strakovsky, I. I., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthm��ller, D., Witthauer, L., and Zehr., F.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

The g p -> K^0 Sigma^+ reaction has been measured from threshold to Eg=1.45 GeV (W_cm=1.9 GeV) using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. In the present experiment, this reaction was searched for in the 3pi^0 p final state, by assuming K^0_S -> pi^0 pi^0 and Sigma^+ -> pi^0 p. The experimental results include total and differential cross sections as well as the polarization of the recoil hyperon. The new data significantly improve empirical knowledge about the g p -> K^0 Sigma^+ reaction in the measured energy range. The results are compared to previous measurements and model predictions. It is demonstrated that adding the present g p -> K^0 Sigma^+ results to existing data allowed a better description of this reaction with various models., 12 pages, 10 figures, 4 tables

Published
2013
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166. Accurate Test of Chiral Dynamics in the \boldmath$\vec�� p \rightarrow ��^0p$ Reaction

Author

Hornidge, D., Bartolome, P. Aguar, Annand, J. R. M., Arends, H. J., Beck, R., Bekrenev, V., Berghaeuser, H., Bernstein, A. M., Braghieri, A., Briscoe, W. J., Cherepnya, S., Dieterle, M., Downie, E. J., Drexler, P., Fernandez-Ramirez, C., Filkov, L. V., Glazier, D. I., Barrientos, P. Hall, Heid, E., Hilt, M., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Koulbardis, A., Krambrich, D., Kruglov, S., Krusche, B., Laffoley, A. T., Lisin, V., Livingston, K., MacGregor, I. J. D., Mancell, J., Manley, D. M., McNicoll, E. F., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D. G., Moores, K. W., Mushkarenkov, A., Nefkens, B. M. K., Oberle, M., Ostrick, M., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rostomyan, T., Scherer, S., Schumann, S., Sikora, M. H., Starostin, A., Supek, I., Thiel, M., Thomas, A., Tiator, L., Unverzagt, M., Watts, D. P., Werthmueller, D., and Witthauer, L.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

A precision measurement of the differential cross sections $d��/d��$ and the linearly polarized photon asymmetry $��\equiv (d��_\perp - d��_\parallel) \slash (d��_\perp + d��_\parallel)$ for the $\vec�� p \rightarrow ��^0p$ reaction in the near-threshold region has been performed with a tagged photon beam and almost $4��$ detector at the Mainz Microtron. The Glasgow-Mainz photon tagging facility along with the Crystal Ball/TAPS multi-photon detector system and a cryogenic liquid hydrogen target were used. These data allowed for a precise determination of the energy dependence of the real parts of the $S$- and all three $P$-wave amplitudes for the first time and provide the most stringent test to date of the predictions of Chiral Perturbation Theory and its energy region of agreement with experiment., 5 pages, 2 figures

Published
2012
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167. Determination of the �� mass with the Crystal Ball at MAMI-B

Author

Nikolaev, A., Aguar-Bartolom��, P., Ahrens, J., Annand, J. R. M., Arends, H. J., Beck, R., Bekrenev, V., Boillat, B., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J. W., Cherepnya, S., Codling, R., Dehn, M., Downie, E. J., Fil'kov, L. V., Glazier, D. I., Gregor, R., Heid, E., Hornidge, D., Jahn, O., Jankowiak, A., Kaiser, K. -H., Kashevarov, V. L., Kondratiev, R., Korolija, M., Kotulla, M., Krambrich, D., Krusche, B., Lang, M., Lisin, V., Livingston, K., Ludwig-Mertin, U., Lugert, S., MacGregor, I. J. D., Manley, D. M., Martinez-Fabregate, M., McGeorge, J. C., Mekterovic, D., Metag, V., Nefkens, B. M. K., Novotny, R., Owens, R. O., Pedroni, P., Polonski, A., Prakhov, S. N., Price, J. W., Reiter, A., Rosner, G., Rost, M., Rostomyan, T., Schumann, S., Sober, D., Starostin, A., Supek, I., Tarbert, C. M., Thomas, A., Unverzagt, M., Walcher, Th., Watts, D. P., and Zehr, F.

Subjects
FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

A new precise determination of the �� meson mass is presented. It is based on a measurement of the threshold for the ��p -> p�� reaction using the tagger focal-plane microscope detector at the MAMI-B facility in Mainz. The tagger microscope has a higher energy resolution than the standard tagging spectrometer and, hence, allowed an improvement in the accuracy compared to the previous �� mass measurement at MAMI-B. The result m�� = (547.851 +- 0.031 stat. +- 0.062 syst.) MeV agrees very well with the precise values of the NA48, KLOE and CLEO collaborations and deviates by about 5�� from the smaller, but also very precise value obtained by the GEM collaboration at COSY., Submitted for publication in EPJA

Published
2012
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168. Determination of the eta-transition form factor in the gamma p -< p eta -< p gamma e(+)e(-) reaction

Author

Berghaeuser, H., Metag, V., Starostin, A., Bartolome, P. Aguar, Akasoy, L. K., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Demissie, B. T., Downie, E. J., Drexler, P., Dieterle, M., Fil`kov, L. V., Fix, A., Glazier, D. I., Heid, E., Hornidge, D., Jahn, O., Jude, T. C., Kashevarov, V. L., Knezevic, A., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lemmer, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Martinez-Fabregate, M., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Micanovic, S., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ostrick, M., Owens, R. O., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Prakhov, S. N., Rosner, G., Rostomyan, T., Schumann, S., Sober, D., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmueller, D., Zamboni, I., and Zehr, F.

Subjects
High Energy Physics::Experiment, Nuclear Experiment
Abstract

The Dalitz decay eta -> gamma e(+)e(-) has been measured using the combined Crystal Ball and TAPS photon detector setup at the electron accelerator MAMI-C. Compared to the most recent transition form-factor measurement in the e(+)e(-) channel, statistics have been improved by one order of magnitude. The e(+)e(-)invariant mass distribution shows a deviation from the QED prediction for a point-like particle, which can be described by a form-factor. Using the usual monopole transition form-factor parameterization, F(m(2)) = (1 - m(2)/Lambda(2))(-1), a value of Lambda(-2) = (1.92 +/- 0.35(stat) +/- 0.13(syst)) GeV(-2) has been determined. This value is in good agreement with a recent measurement of the eta Dalitz decay in the mu(+)mu(-) channel and with recent form-factor calculations. An improved value of the branching ratio BR(eta -> gamma e(+)e(-)) = (6.6 +/- 0.4(stat) +/- 0.4(syst)) . 10(-3) has been determined. (C) 2011 Elsevier B.V. All rights reserved.

Published
2011
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169. Threshold π0 photoproduction on transverse polarised protons at MAMI

Author

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

Published
2015
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170. Study of the gp-->etap reaction with the Crystal Ball detector at the Mainz Microtron(MAMI-C)

Author

McNicoll, E. F., Prakhov, S., Strakovsky, I. I., Aguar-Bartolomepmainz, P., Akasoy, L. K., Annand, J. R. M., Arends, H. J., Arndt, R. A., Azimov, Ya. I., Bantawa, K., Beck, R., Bekrenev, V. S., Berghaeuser, H., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Demissie, B. T., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Freehart, B., Glazier, D. I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Kellie, J. D., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A. A., Kruglov, S. P., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Marinides, Z., Martinez, M., McGeorge, J. C., McKinnon, B., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ostrick, M., Otte, P. B., Oussena, B., Paris, M. W., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Suarez, I. M., Supek, I., Thiel, M., Thomas, A., Tiator, L., Unverzagt, M., Watts, D. P., Werthmueller, D., Workman, R. L., Zamboni, I., and Zehr, F.

Subjects
High Energy Physics - Phenomenology, Nuclear Theory, Nuclear Experiment, High Energy Physics - Experiment
Abstract

The gp-->etap reaction has been measured with the Crystal Ball and TAPS multiphoton spectrometers in the energy range from the production threshold of 707 MeV to 1.4 GeV (1.49 =< W >= 1.87 GeV). Bremsstrahlung photons produced by the 1.5-GeV electron beam of the Mainz Microtron MAMI-C and momentum analyzed by the Glasgow Tagging Spectrometer were used for the eta-meson production. Our accumulation of 3.8 x 10^6 gp-->etap-->3pi0p-->6gp events allows a detailed study of the reaction dynamics. The gp-->etap differential cross sections were determined for 120 energy bins and the full range of the production angles. Our data show a dip near W = 1680 MeV in the total cross section caused by a substantial dip in eta production at forward angles. The data are compared to predictions of previous SAID and MAID partial-wave analyses and to thelatest SAID and MAID fits that have included our data., Comment: 15 pages, 12 figures

Published
2010

171. A new measurement of the neutron detection efficiency for the NaI Crystal Ball detector

Author

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

Published
2015
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172. First measurement of the circular beam asymmetry in the gamma p --> pi0 eta p reaction

Author

Kashevarov, V. L., Fix, A., Aguar-Bartolom��, P., Akasoy, L. K., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Bergh��user, H., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Demissie, B. T., Downie, E. J., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Jaegle, I., Jahn, O., Jude, T. C., Kellie, J. D., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Martinez-Fabregate, M., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ostrick, M., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S. N., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D., Starostin, A., Stakovsky, I. I., Suarez, I. M., Supek, I., Tarbert, C., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthm��ller, D., Zamboni, I., and Zehr., F.

Subjects
Nuclear Theory (nucl-th), High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The circular photon asymmetry for pi0 eta photoproduction on the proton was measured for the first time at the tagged photon facility of the MAMI C accelerator using the Crystal Ball/TAPS photon spectrometer. The experimental results are interpreted within a phenomenological isobar model that confirms the dominant role of the Delta(1700)D33 resonance. The measured asymmetry allows us to identify small contributions from positive-parity resonances via interference terms with the dominant D33 amplitude., 11 pages, 3 figures, submitted to Phys.Lett. B

Published
2010
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173. Measurement of K-p radiative capture to γΛ and γΣ0 for pK- between 514 and 750 MeV/c

Author

Sergey Prakhov, Pieter Vancraeyveld, Phaisangittisakul, N., Bmk, Nefkens, Bekrenev, V., Wj, Briscoe, Lesley De Cruz, Isenhower, D., Knecht, N., Koulbardis, A., Kozlenko, N., Kruglov, S., Lolos, G., Lopatin, I., Marušić, A., Mcdonald, S., Papandreou, Z., Peaslee, D., Jw, Price, Jan Ryckebusch, Sadler, M., Shafi, A., Starostin, A., Hm, Staudenmaier, Ii, Strakovsky, Supek, I., Tim Van Cauteren, Electronics and Informatics, and Physics

Subjects
HYPERON RESONANCES, Kaon photoproduction, Nuclear Theory, CONSISTENT, Physics::Accelerator Physics, Proton, Nuclear Experiment
Abstract

Differential cross sections for K- radiative capture in flight on the proton, leading to the γΛ and γΣ0 final states, have been measured at eight K- momenta between 514 and 750 MeV/c. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated K/π beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Regge-plus-resonance approach. According to this analysis, the γΣ0 final state is dominated by hyperon-resonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the γΛ final state, in contrast, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.

Published
2010

174. Measurement of the transverse target and beam-target asymmetries in $\eta$ meson photoproduction at MAMI

Author

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

Abstract

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

Published
2014
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175. Quasifree photoproduction of $\eta$ mesons off protons and neutrons

Author

A2 Collaboration, Werthmüller, D., Witthauer, L., Keshelashvili, I., Aguar-Bartolomé, P., Ahrens, J., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Costanza, S., Demissie, B., Dieterle, M., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Glazier, D. I., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Huber, G. M., Jaegle, I., Jahn, O., Jude, T. C., Käser, A., Kashevarov, V. L., Kondratiev, R., Korolija, M., Kruglov, S. P., Krusche, B., Kulbardis, A., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Mancell, J., Manley, D. M., Marinides, Z., Martinez, M., McGeorge, J. C., McNicoll, E. F., Metag, V., Middleton, D. G., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S. N., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., A2 Collaboration, Werthmüller, D., Witthauer, L., Keshelashvili, I., Aguar-Bartolomé, P., Ahrens, J., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Costanza, S., Demissie, B., Dieterle, M., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Glazier, D. I., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Huber, G. M., Jaegle, I., Jahn, O., Jude, T. C., Käser, A., Kashevarov, V. L., Kondratiev, R., Korolija, M., Kruglov, S. P., Krusche, B., Kulbardis, A., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Mancell, J., Manley, D. M., Marinides, Z., Martinez, M., McGeorge, J. C., McNicoll, E. F., Metag, V., Middleton, D. G., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S. N., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., and Watts, D. P.

Abstract

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. Decay photons of the neutral decay modes $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0 \rightarrow 6\gamma$ and coincident recoil nucleons were detected in a combined setup of the Crystal Ball and the TAPS calorimeters. The $\eta$-production cross sections were measured in coincidence with recoil protons, recoil neutrons, and in an inclusive mode without a condition on recoil nucleons, which allowed a check of the internal consistency of the data. The effects from nuclear Fermi motion were removed by a kinematic reconstruction of the final-state invariant mass and possible nuclear effects on the quasifree cross section were investigated by a comparison of free and quasifree proton data. The results, which represent a significant improvement in statistical quality compared to previous measurements, agree with the known neutron-to-proton cross-section ratio in the peak of the $S_{11}(1535)$ resonance and confirm a peak in the neutron cross section, which is absent for the proton, at a center-of-mass energy $W = (1670\pm 5)$ MeV with an intrinsic width of $\Gamma\approx 30$ MeV.

Published
2014
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176. Photoproduction of the $\omega$ meson off the proton near threshold

Author

Strakovsky, I. I., Prakhov, S., Azimov, Y. I., Aguar-Bartolome, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghaeuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Costanza, S., Demissie, B. T., Downie, E. J., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Hamilton, D. J., Heid, E., Hornidge, D., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Marinides, Z., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Middleton, D. G., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ortega, H., Ostrick, M., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Starostin, A., Supek, I., Taragin, M. F., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmueller, D., Zehr, F., Strakovsky, I. I., Prakhov, S., Azimov, Y. I., Aguar-Bartolome, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghaeuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Costanza, S., Demissie, B. T., Downie, E. J., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Hamilton, D. J., Heid, E., Hornidge, D., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Marinides, Z., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Middleton, D. G., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ortega, H., Ostrick, M., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Starostin, A., Supek, I., Taragin, M. F., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmueller, D., and Zehr, F.

Abstract

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 ($W=1.87$ GeV for the center-of-mass energy) with 15-MeV binning in $E_\gamma$ and full production-angle coverage. The quality of the present data near threshold gives access to a variety of interesting physics aspects. As an example, an estimation of the $\omega N$ scattering length $\alpha_{\omega p}$ is provided., Comment: 8 pages, 5 figures. Published version; some typos were fixed

Published
2014
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177. A new measurement of the rare decay eta -> pi^0 gamma gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

Author

Nefkens, B. M. K., Prakhov, S., Aguar-Bartolomé, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Costanza, S., Danilkin, I. V., Denig, A., Demissie, B., Dieterle, M., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Garni, S., Glazier, D. I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Jahn, O., Jude, T. C., Kashevarov, V. L., Käser, A., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Mancel, J., Manley, D. M., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nikolaev, A., Novotny, R., Oberle, M., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Polonski, A., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Starostin, A., Strakovsky, I. I., Strub, T., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., Witthauer., L., Nefkens, B. M. K., Prakhov, S., Aguar-Bartolomé, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Costanza, S., Danilkin, I. V., Denig, A., Demissie, B., Dieterle, M., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Garni, S., Glazier, D. I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Jahn, O., Jude, T. C., Kashevarov, V. L., Käser, A., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Mancel, J., Manley, D. M., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nikolaev, A., Novotny, R., Oberle, M., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Polonski, A., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Starostin, A., Strakovsky, I. I., Strub, T., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., and Witthauer., L.

Abstract

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+/-0.03_tot) eV, are based on analysis of 1.2 x 10^3 eta->pi^0 gamma gamma decays from a total of 6 x 10^7 eta mesons produced in the gamma p -> eta p reaction. The present results for dGamma(eta->pi^0 gamma gamma)/dm^2(gamma gamma) are in good agreement with previous measurements and recent theoretical calculations for this dependence., Comment: 10 pages, 8 figures, 1 table

Published
2014
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178. New results in rare allowed muon and pion decays

Author

Pocanic, D., Munyangabe, E., Bychkov, M., Baranov, V. A., Bertl, W., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Lehman, M. C., Mekterovic, D., Mzhavia, D., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Supek, I., Truoel, P., Tsamalaidze, Z., van der Schaaf, A., Vandevender, B., Velicheva, E. P., Volnykh, V. P., Pocanic, D., Munyangabe, E., Bychkov, M., Baranov, V. A., Bertl, W., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Lehman, M. C., Mekterovic, D., Mzhavia, D., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Supek, I., Truoel, P., Tsamalaidze, Z., van der Schaaf, A., Vandevender, B., Velicheva, E. P., and Volnykh, V. P.

Abstract

Simple dynamics, few available decay channels, and highly controlled radiative and loop corrections, make pion and muon decays a sensitive means of exploring details of the underlying symmetries. We review the current status of the rare decays: pi+ -> e+ nu, pi+ -> e+ nu gamma, pi+ -> pi0 e+ nu, and mu+ -> e+ nu nu-bar gamma. For the latter we report new preliminary values for the branching ratio B(E_gamma >10 MeV, theta_(e-gamma) > 30deg) = 4.365 (9)_stat (42)_syst x 10^{-3}, and the decay parameter eta-bar = 0.006 (17)_stat (18)_syst, both in excellent agreement with standard model predictions. We review recent measurements, particularly by the PIBETA and PEN experiments, and near-term prospects for improvement. These and other similar precise low energy studies complement modern collider results materially., Comment: 5 pages, 2 figures, talk presented at the 9th International Workshop on e+ e- Collisions "From phi to psi 2013", held in Rome, 9-12 Sept 2013

Published
2014
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179. Measurement of $K^- p$ radiative capture to $\gamma \Lambda$ and $\gamma \Sigma^0$ for $p_{K^-}$ between 514 and 750 MeV/$c$

Author

Prakhov, S., Vancraeyveld, P., Phaisangittisakul, N., Nefkens, B. M. K., Bekrenev, V., Briscoe, W. J., De Cruz, L., Isenhower, D., Knecht, N., Koulbardis, A., Kozlenko, N., Kruglov, S., Lolos, G., Lopatin, I., Marušić, A., McDonald, S., Papandreou, Z., Peaslee, D., Price, J. W., Ryckebusch, J., Sadler, M., Shafi, A., Starostin, A., Staudenmaier, H. M., Strakovsky, I. I., Supek, I., and Van Cauteren, T.

Subjects
Physics::Accelerator Physics, Nuclear Experiment, High Energy Physics - Experiment
Abstract

Differential cross sections for $K^-$ radiative capture in flight on the proton, leading to the $\gamma\Lambda$ and $\gamma\Sigma^0$ final states, have been measured at eight $K^-$ momenta between 514 and 750 MeV/$c$. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated $K/\pi$ beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Regge-plus-resonance approach. According to this analysis, the $\gamma\Sigma^0$ final state is dominated by hyperonresonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the $\gamma\Lambda$ final state, on the other hand, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.

Published
2009

180. PEN: a sensitive search for non-(V-A) weak processes

Author

PEN Collaboration, Pocanic, D., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Mekterovic, D., Mzhavia, D., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Shkarovskiy, S. N., Straumann, U., Supek, I., Truoel, P., Tsamalaidze, Z., van der Schaaf, A., Velicheva, E. P., and Volnykh, V. P.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, High Energy Physics - Experiment
Abstract

A new measurement of $B_{\pi e2}$, the $\pi^+ \to e^+\nu(\gamma)$ decay branching ratio, is currently under way at the Paul Scherrer Institute. The present experimental result on $B_{\pi e2}$ constitutes the most accurate test of lepton universality available. The accuracy, however, still lags behind the theoretical precision by over an order of magnitude. Thanks to the large helicity suppression of $\pi_{e2}$ decay, the branching ratio is susceptible to significant contributions from new physics, making this decay a particularly suitable subject of study., Comment: 4 pages, 1 figure, talk given at the 18th International Conference on Particles and Nuclei (PANIC08), held 9 -14 November 2008 in Eilat, Israel; to appear in the Proceedings published by North Holland

Published
2009

181. Differential cross sections of the charge-exchange reaction pi- p --> pi0 n in the momentum range from 103 to 178 MeV/c

Author

Mekterović, D., Supek, I., Abaev, V., Bekrenev, V., Bircher, C., Briscoe, W. J., Cadman, R. V., Clajus, M., Comfort, J. R., Craig, K., Grosnick, D., Isenhover, D., Jerkins, M., Joy, M., Knecht, N., Koetke, D. D., Kozlenko, N., Kulbardis, A., Kruglov, S., Lolos, G., Lopatin, I., Manley, D. M., Manweiler, R., Marušić, A., McDonald, S., Nefkens, B. M. K., Olmsted, J., Papandreou, Z., Peaslee, D., Peterson, J., Phaisangittisakul, N., Prakhov, S. N., Price, J. W., Ramirez, A., Sadler, M. E., Shafi, A., Spinka, H., Stanislaus, S., Starostin, A., Staudenmaier, H. M., Strakovsky, I., Tippens, W. B., and Watson, S.

Subjects
Nuclear Theory, Nuclear Experiment, High Energy Physics - Experiment
Abstract

Measured values of the differential cross sections for pion-nucleon charge exchange, pi- p --> pi0 n, are presented for pi- momenta of 103, 112, 120, 130, 139, 152, and 178 MeV/c. Complete angular distributions were obtained by using the Crystal Ball detector at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Statistical uncertainties of the differential cross sections vary from 3% to 6% in the backward angle region, and from 6% to about 20% in the forward region with the exception of the two most forward angles. The systematic uncertainties are estimated to be about 3% for all momenta., Comment: 18 pages, 12 figures, submitted to Phys. Rev. C

Published
2009

182. Determination of the Dalitz plot parameter α for the decay η → 3 π 0 with the Crystal Ball at MAMI-B

Author

Manley, D., Nefkens, B., Mcgeorge, J., Gregor, R., Mekterovic, D., Aguar-Bartolome, P., Zehr, F., Annand, J., Watts, D., Metag, V., Nikolaev, A., Novotny, R., Owens, R., Pedroni, P., Polonski, A., Prakhov, S., Price, J., Rost, M., Rosner, G., Heidari, E., Hornidge, D., Jahn, O., Kashevarov, V., Kondratiev, R., Glazier, D., FilKov, L., Downie, E., Codling, R., Cherepnya, S., Brudvik, J., Briscoe, W., Branford, D., Korolija, M., Kotulla, M., Walcher, Th., Thomas, A., Tarbert, C., Boillat, B., Filkov, L., Heid, E., Macgregor, I., Braghieri, A., Boillat., B., Bekrenev, V., Beck, R., Supek, I., Starostin, A., Sober, D., Schumann, S., Rostomyan, T., Arends, H., Ahrens, J., Aguar-Bartolomé, P., Unverzagt, M., Krambrich, D., Krusche, B., Lang, M., Lisin, V., Livingston, K., Lugert, S., and Martinez-Fabregate, M.

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, bepress|Physical Sciences and Mathematics|Physics, Photon detector, Dalitz plot, Particle accelerator, n, K and η mesons, Alpha (navigation), law.invention, High Energy Physics - Experiment, law, High Energy Physics::Experiment, Photon beam, Nuclear Experiment, Crystal Ball
Abstract

A precise measurement of the Dalitz plot parameter, alpha, for the eta->3pi^0 decay is presented. The experiment was performed with the Crystal Ball and TAPS large acceptance photon detectors at the tagged photon beam facility of the MAMI-B electron accelerator in Mainz. High statistics of 1.8*10^6 eta->3pi^0 events were obtained, giving the result alpha = -0.032 +/- 0.002(stat) +/- 0.002(syst)., Comment: 9 pages, 6 figures, published in the online-first section of EPJ A, included changes referees asked for, added DOI

Published
2009

183. Measurement of $K^- p$ radiative capture to $����$ and $����^0$ for $p_{K^-}$ between 514 and 750 MeV/$c$

Author

Prakhov, S., Vancraeyveld, P., Phaisangittisakul, N., Nefkens, B. M. K., Bekrenev, V., Briscoe, W. J., De Cruz, L., Isenhower, D., Knecht, N., Koulbardis, A., Kozlenko, N., Kruglov, S., Lolos, G., Lopatin, I., Maru��i��, A., McDonald, S., Papandreou, Z., Peaslee, D., Price, J. W., Ryckebusch, J., Sadler, M., Shafi, A., Starostin, A., Staudenmaier, H. M., Strakovsky, I. I., Supek, I., and Van Cauteren, T.

Subjects
High Energy Physics - Experiment (hep-ex), Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment
Abstract

Differential cross sections for $K^-$ radiative capture in flight on the proton, leading to the $����$ and $����^0$ final states, have been measured at eight $K^-$ momenta between 514 and 750 MeV/$c$. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated $K/��$ beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Regge-plus-resonance approach. According to this analysis, the $����^0$ final state is dominated by hyperonresonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the $����$ final state, on the other hand, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.

Published
2009
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184. Differential cross sections of the charge-exchange reaction pi- p --> pi0 n in the momentum range from 103 to 178 MeV/c

Author

Mekterovi��, D., Supek, I., Abaev, V., Bekrenev, V., Bircher, C., Briscoe, W. J., Cadman, R. V., Clajus, M., Comfort, J. R., Craig, K., Grosnick, D., Isenhover, D., Jerkins, M., Joy, M., Knecht, N., Koetke, D. D., Kozlenko, N., Kulbardis, A., Kruglov, S., Lolos, G., Lopatin, I., Manley, D. M., Manweiler, R., Maru��i��, A., McDonald, S., Nefkens, B. M. K., Olmsted, J., Papandreou, Z., Peaslee, D., Peterson, J., Phaisangittisakul, N., Prakhov, S. N., Price, J. W., Ramirez, A., Sadler, M. E., Shafi, A., Spinka, H., Stanislaus, S., Starostin, A., Staudenmaier, H. M., Strakovsky, I., Tippens, W. B., and Watson, S.

Subjects
High Energy Physics - Experiment (hep-ex), Nuclear Theory, FOS: Physical sciences, Nuclear Experiment
Abstract

Measured values of the differential cross sections for pion-nucleon charge exchange, pi- p --> pi0 n, are presented for pi- momenta of 103, 112, 120, 130, 139, 152, and 178 MeV/c. Complete angular distributions were obtained by using the Crystal Ball detector at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Statistical uncertainties of the differential cross sections vary from 3% to 6% in the backward angle region, and from 6% to about 20% in the forward region with the exception of the two most forward angles. The systematic uncertainties are estimated to be about 3% for all momenta., 18 pages, 12 figures, submitted to Phys. Rev. C

Published
2009
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185. PEN experiment: a precise measurement of the pi+ -> e+ nu decay branching fraction

Author

PEN Collaboration, Pocanic, D., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Mekterovic, D., Mzhavia, D., Palladino, A., Robmann, P., Rozhdestvensky, A. M., Shkarovskiy, S. N., Straumann, U., Supek, I., Truoel, P., Tsamalaidze, Z., van der Schaaf, A., Velicheva, E. P., and Volnykh, V. P.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences
Abstract

A new measurement of $B_{��e2}$, the $��^+ \to e^+��(��)$ decay branching ratio, is currently under way at the Paul Scherrer Institute. The present experimental result on $B_{��e2}$ constitutes the most accurate test of lepton universality available. The accuracy, however, still lags behind the theoretical precision by over an order of magnitude. Because of the large helicity suppression of the $��_{e2}$ decay, its branching ratio is susceptible to significant contributions from new physics, making this decay a particularly suitable subject of study., 4 pages, 3 figures, talk given at the Tenth Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2009), La Jolla/San Diego, CA, 26-31 May 2009; to appear in Proceedings to be published by the American Institute of Physics

Published
2009
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186. Determination of the η-transition form factor in the [formula omitted] reaction

Author

Berghäuser, H., Metag, V., Starostin, A., Bartolomé, P. Aguar, Akasoy, L.K., Annand, J.R.M., Arends, H.J., Bantawa, K., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W.J., Brudvik, J., Cherepnya, S., Demissie, B.T., Downie, E.J., Drexler, P., Dieterle, M., Filʼkov, L.V., Fix, A., Glazier, D.I., Heid, E., Hornidge, D., Jahn, O., Jude, T.C., Kashevarov, V.L., Knezevic, A., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lemmer, B., Lisin, V., Livingston, K., MacGregor, I.J.D., Maghrbi, Y., Manley, D.M., Martinez-Fabregate, M., McGeorge, J.C., McNicoll, E.F., Mekterovic, D., Micanovic, S., Mushkarenkov, A., Nefkens, B.M.K., Nikolaev, A., Novotny, R., Ostrick, M., Owens, R.O., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Prakhov, S.N., Rosner, G., Rostomyan, T., Schumann, S., Sober, D., Suarez, I.M., Supek, I., Tarbert, C.M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D.P., Werthmüller, D., Zamboni, I., and Zehr, F.

Published
2011
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187. Precise Measurement of pi+ -> e+ nu Branching Ratio

Author

Frle��, E., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Mekterovi��, D., Mzhavia, D., Palladino, A., Po��ani��, D., Robmann, P., Rozhdestvensky, A. M., Sidorkin, V. V., Straumann, U., Supek, I., Tru��l, P., van der Schaaf, A., Velicheva, E. P., and Volnykh, V. P.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences
Abstract

The PEN Collaboration is conducting a new measurement of the pi+ -> e+ nu branching ratio at the Paul Scherrer Institute, with the goal uncertainty of delta B/B(pie2)=5E-4 or lower. At present, the combined accuracy of all published pie2 decay measurements lags behind the theoretical calculation by a factor of 40. In this contribution we report on the PEN detector configuration and its performance during two development runs done in 2007 and 2008., pdflatex, 11 pages, 5 figures, to be published in "Progress in High-Energy Physics and Nuclear Safety", NATO Science for Peace Series: B - Physics and Biophysics

Published
2008
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188. Measurement of $��^0 ��$, $\bar{K}^0 n$, and $��^0 ��^0$ production in $K^- p$ interactions for $p_{K^-}$ between 514 and 750 MeV/$c$

Author

Prakhov, S., Nefkens, B. M. K., Bekrenev, V., Briscoe, W. J., Knecht, N., Koulbardis, A., Kozlenko, N., Kruglov, S., Lolos, G., Lopatin, I., Maru��i��, A., McDonald, S., Peaslee, D., Phaisangittisakul, N., Price, J. W., Shafi, A., Starostin, A., Staudenmaier, H. M., Strakovsky, I. I., and Supek, I.

Subjects
High Energy Physics - Experiment (hep-ex), Nuclear Theory, Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment
Abstract

Differential cross sections and hyperon polarizations have been measured for $\bar{K}^0 n$, $��^0 ��$, and $��^0 ��^0$ production in $K^- p$ interactions at eight $K^-$ momenta between 514 and 750 MeV/$c$. The experiment detected the multiphoton final states with the Crystal Ball spectrometer using a $K^-$ beam from the Alternating Gradient Synchrotron of BNL. The results provide significantly greater precision than the existing data, allowing a detailed reexamination of the excited hyperon states in our energy range.

Published
2008
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189. First measurement of the circular beam asymmetry in the [formula omitted] reaction

Author

Kashevarov, V.L., Fix, A., Aguar-Bartolomé, P., Akasoy, L.K., Annand, J.R.M., Arends, H.J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Branford, D., Briscoe, W.J., Brudvik, J., Cherepnya, S., Codling, R.F.B., Demissie, B.T., Downie, E.J., Drexler, P., Fil'kov, L.V., Glazier, D.I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Jaegle, I., Jahn, O., Jude, T.C., Kellie, J.D., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I.J.D., Maghrbi, Y., Manley, D.M., Martinez-Fabregate, M., McGeorge, J.C., McNicoll, E.F., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D., Mushkarenkov, A., Nefkens, B.M.K., Nikolaev, A., Novotny, R., Ostrick, M., Otte, P.B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S.N., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M.H., Sober, D., Starostin, A., Stakovsky, I.I., Suarez, I.M., Supek, I., Tarbert, C., Thiel, M., Thomas, A., Unverzagt, M., Watts, D.P., Werthmüller, D., Zamboni, I., and Zehr, F.

Published
2010
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191. NEW RESULTS IN RARE ALLOWED MUON AND PION DECAYS

Author

POČANIĆ, D., primary, MUNYANGABE, E., additional, BYCHKOV, M., additional, ALONZI, L. P., additional, BARANOV, V. A., additional, BERTL, W., additional, BYSTRITSKY, Yu. M., additional, FRLEŽ, E., additional, KALINNIKOV, V. A., additional, KHOMUTOV, N. V., additional, KORENCHENKO, A. S., additional, KORENCHENKO, S. M., additional, KOROLIJA, M., additional, KOZLOWSKI, T., additional, KRAVCHUK, N. P., additional, KUCHINSKY, N. A., additional, LEHMAN, M. C., additional, MEKTEROVIĆ, D., additional, MZHAVIA, D., additional, PALLADINO, A., additional, ROBMANN, P., additional, ROZHDESTVENSKY, A. M., additional, SUPEK, I., additional, TRUÖL, P., additional, TSAMALAIDZE, Z., additional, VAN DER SCHAAF, A., additional, VANDEVENDER, B., additional, VELICHEVA, E. P., additional, and VOLNYKH, V. P., additional

Published
2014
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192. A new determination of the eta transition form factor in the Dalitz decay eta -> e^+ e^- gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

Author

Aguar-Bartolomé, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Costanza, S., Denig, A., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Glazier, D. I., Gregor, R., Hamilton, D. J., Heid, E., Hornidge, D., Isaksson, L., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Masjuan, P., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strakovsky, I. I., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., Zehr., F., Aguar-Bartolomé, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Costanza, S., Denig, A., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Glazier, D. I., Gregor, R., Hamilton, D. J., Heid, E., Hornidge, D., Isaksson, L., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Masjuan, P., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strakovsky, I. I., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., and Zehr., F.

Abstract

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 = (1.95 +/- 0.15_stat +/- 0.10_syst) [1/GeV^2], is in good agreement with recent measurements conducted in eta -> e^+ e^- gamma and eta -> mu^+ mu^- gamma decays, as well as with recent form-factor calculations. The uncertainty obtained in the value of 1/Lambda^2 is lower compared to results from previous measurements of the eta -> e^+ e^- gamma decay., Comment: 11 pages, 10 figures, 1 table

Published
2013
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193. Measurement of the g p -> K^0 Sigma^+ reaction with the Crystal Ball/TAPS detectors at the Mainz Microtron

Author

Aguar-Bartolomé, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Demissie, B., Dieterle, M., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Glazier, D. I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Isaksson, L., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Mancel, J., Manley, D. M., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Oberle, M., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strakovsky, I. I., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., Witthauer, L., Zehr., F., Aguar-Bartolomé, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Collicott, C., Demissie, B., Dieterle, M., Downie, E. J., Drexler, P., Fil'kov, L. V., Fix, A., Glazier, D. I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Isaksson, L., Jaegle, I., Jahn, O., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Mancel, J., Manley, D. M., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Oberle, M., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strakovsky, I. I., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., Witthauer, L., and Zehr., F.

Abstract

The g p -> K^0 Sigma^+ reaction has been measured from threshold to Eg=1.45 GeV (W_cm=1.9 GeV) using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. In the present experiment, this reaction was searched for in the 3pi^0 p final state, by assuming K^0_S -> pi^0 pi^0 and Sigma^+ -> pi^0 p. The experimental results include total and differential cross sections as well as the polarization of the recoil hyperon. The new data significantly improve empirical knowledge about the g p -> K^0 Sigma^+ reaction in the measured energy range. The results are compared to previous measurements and model predictions. It is demonstrated that adding the present g p -> K^0 Sigma^+ results to existing data allowed a better description of this reaction with various models., Comment: 12 pages, 10 figures, 4 tables

Published
2013
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194. Narrow Structure in the Excitation Function ofηPhotoproduction off the Neutron

Author

Werthmüller, D., primary, Witthauer, L., additional, Keshelashvili, I., additional, Aguar-Bartolomé, P., additional, Ahrens, J., additional, Annand, J. R. M., additional, Arends, H. J., additional, Bantawa, K., additional, Beck, R., additional, Bekrenev, V., additional, Braghieri, A., additional, Branford, D., additional, Briscoe, W. J., additional, Brudvik, J., additional, Cherepnya, S., additional, Demissie, B., additional, Dieterle, M., additional, Downie, E. J., additional, Drexler, P., additional, Fil’kov, L. V., additional, Fix, A., additional, Glazier, D. I., additional, Hamilton, D., additional, Heid, E., additional, Hornidge, D., additional, Howdle, D., additional, Huber, G. M., additional, Jaegle, I., additional, Jahn, O., additional, Jude, T. C., additional, Käser, A., additional, Kashevarov, V. L., additional, Kondratiev, R., additional, Korolija, M., additional, Kruglov, S. P., additional, Krusche, B., additional, Kulbardis, A., additional, Lisin, V., additional, Livingston, K., additional, MacGregor, I. J. D., additional, Maghrbi, Y., additional, Mancell, J., additional, Manley, D. M., additional, Marinides, Z., additional, Martinez, M., additional, McGeorge, J. C., additional, McNicoll, E. F., additional, Metag, V., additional, Middleton, D. G., additional, Mushkarenkov, A., additional, Nefkens, B. M. K., additional, Nikolaev, A., additional, Novotny, R., additional, Oberle, M., additional, Ostrick, M., additional, Oussena, B., additional, Pedroni, P., additional, Pheron, F., additional, Polonski, A., additional, Prakhov, S. N., additional, Robinson, J., additional, Rosner, G., additional, Rostomyan, T., additional, Schumann, S., additional, Sikora, M. H., additional, Sober, D., additional, Starostin, A., additional, Supek, I., additional, Thiel, M., additional, Thomas, A., additional, Unverzagt, M., additional, and Watts, D. P., additional

Published
2013
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195. Measurement of charge symmetry breaking by the comparison of pi+ d -> pp eta with pi- d -> nn eta

Author

Tippens, W. B., Abaev, V., Leitsch, M. J., Marusic, A., Moriwaki, T., Morrison, T., Nefkens, B. M. K., Peng, J. C., Pile, P. H., Price, J. W., Rigsby, D., Sadler, M. E., Batinic, M., Sawafta, R., Slaus, I., Seyfarth, H., Starostin, A., Supek, I., Sutter, R. J., Svarc, V. L., White, D. B., Bekrenev, V., Briscoe, W. J., Chrien, R. E., Clajus, M., Isenhower, D., Kozienko, N., and Kruglov, S.

Subjects
ddc:530
Published
2001

196. In search of f0 meson: new data on pi0-pi0 production by pi- and K- on Hydrogen

Author

Nefkens, B.M.K., Prakhov, S., Starostin, A., Clajus, M., Marušić, A., McDonald, S., Phaisangittisakul, N., Price, J.W., Tippens, W.B., Isenhower, D., Sadler, M., Allgower, C., Spinka, H., Comfort, J., Craig, K., Ramirez, T., Kycia, T., Petersen, R.J., Briscoe, W.J., Shafi, A., Staudenmaier, H.M., Manley, D.M., Olmested, J., Peaslee, D., Bekrenev, V., Koulbardis, A., Kozlenko, N., Kruglov, S., Lopatin, I., Huber, G.M., Lolos, G.J., Papandreou, Z., Slaus, I., Supek, I., Grosnick, D., Koetke, D., Manweiller, R., Stanislaus, T.D.S., and Nefkens, B.M.K.

Subjects
chiral fluctuation, f0 meson
Abstract

New data on pi0-pi0 production by pi- and K- on hydrogen are presented providing information on f0 meson

Published
2001

197. Study of the gamma p --> pi0 pi0 p reaction with the Crystal Ball/TAPS at the Mainz

Author

Kashevarov, V. L., Fix, A., Prakhov, S., Aguar-Bartolomé, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Downie, E. J., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Heid, E., Hornidge, D., Isaksson, L., Jaegle, I., Jahn, O., Jude, T. C., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strakovsky, I. I., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., Zehr, F., Kashevarov, V. L., Fix, A., Prakhov, S., Aguar-Bartolomé, P., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Briscoe, W. J., Brudvik, J., Cherepnya, S., Codling, R. F. B., Downie, E. J., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Heid, E., Hornidge, D., Isaksson, L., Jaegle, I., Jahn, O., Jude, T. C., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Mushkarenkov, A., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ortega, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strakovsky, I. I., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Werthmüller, D., and Zehr, F.

Abstract

The gamma p --> pi0 pi0 p reaction has been measured from threshold to 1.4 GeV using the Crystal Ball and TAPS photon spectrometers together with the photon tagging facility at the Mainz Microtron. The experimental results include total and differential cross sections as well as specific angular distributions, which were used to extract partial-wave amplitudes. In particular, the energy region below the D13(1520) resonance was studied., Comment: 12 pages, 13 figures, corrected version, published in PRC

Published
2012
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198. New studies of allowed pion and muon decays

Author

Pocanic, D., Palladino, A., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Lehman, M. C., Mekterovic, D., Munyangabe, E., Mzhavia, D., Robmann, P., Rozhdestvensky, A. M., Shkarovskiy, S. N., Straumann, U., Supek, I., Truöl, P., Tsamalaidze, Z., van der Schaaf, A., Velicheva, E. P., Volnykh, V. P., Pocanic, D., Palladino, A., Alonzi, L. P., Baranov, V. A., Bertl, W., Bychkov, M., Bystritsky, Yu. M., Frlez, E., Kalinnikov, V. A., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Korolija, M., Kozlowski, T., Kravchuk, N. P., Kuchinsky, N. A., Lehman, M. C., Mekterovic, D., Munyangabe, E., Mzhavia, D., Robmann, P., Rozhdestvensky, A. M., Shkarovskiy, S. N., Straumann, U., Supek, I., Truöl, P., Tsamalaidze, Z., van der Schaaf, A., Velicheva, E. P., and Volnykh, V. P.

Abstract

Building on the rare pion and muon decay results of the PIBETA experiment, the PEN collaboration has undertaken a precise measurement of B_{\pi e2} = R^\pi_{e/\mu}, the \pi^+ -> e^+\nu(\gamma) decay branching ratio, at the Paul Scherrer Institute, to reduce the present 40\times experimental precision lag behind theory to ~ 6-7\times. Because of large helicity suppression, R^\pi_{e/\mu} is uniquely sensitive to contributions from non-(V-A) physics, making this decay a particularly suitable subject of study. Even at current precision, the experimental value of B_{\pi e2} provides the most accurate test of lepton universality available. During runs in 2008-10, PEN has accumulated over 2\times 10^7 \pi_{e2} events; a comprehensive maximum-likelihood analysis is currently under way. The new data will also lead to improved precision of the earlier PIBETA results on radiative \pi and \mu decays., Comment: 3 pages, 3 figures, to appear in Proceedings, 11th Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2012), held at St. Petersburg, Florida, 29 May - 3 June 2012

Published
2012
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199. Radiative pi0 photoproduction on protons in the Delta+(1232) region

Author

Schumann, S., Boillat, B., Downie, E. J., Aguar-Bartolomé, P., Ahrens, J., Annand, J. R. M., Arends, H. J., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J. W., Cherepnya, S., Codling, R., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Heid, E., Hornidge, D., Jahn, O., Kashevarov, V. L., Kondratiev, R., Korolija, M., Kotulla, M., Krambrich, D., Krusche, B., Lang, M., Lisin, V., Livingston, K., Lugert, S., MacGregor, I. J. D., Manley, D. M., Martinez-Fabregate, M., McGeorge, J. C., Mekterovic, D., Metag, V., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ostrick, M., Owens, R. O., Pedroni, P., Polonski, A., Prakhov, S. N., Price, J. W., Rosner, G., Rost, M., Rostomyan, T., Sober, D., Starostin, A., Supek, I., Tarbert, C. M., Thomas, A., Unverzagt, M., Walcher, Th., Watts, D. P., Zehr, F., Schumann, S., Boillat, B., Downie, E. J., Aguar-Bartolomé, P., Ahrens, J., Annand, J. R. M., Arends, H. J., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J. W., Cherepnya, S., Codling, R., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Heid, E., Hornidge, D., Jahn, O., Kashevarov, V. L., Kondratiev, R., Korolija, M., Kotulla, M., Krambrich, D., Krusche, B., Lang, M., Lisin, V., Livingston, K., Lugert, S., MacGregor, I. J. D., Manley, D. M., Martinez-Fabregate, M., McGeorge, J. C., Mekterovic, D., Metag, V., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ostrick, M., Owens, R. O., Pedroni, P., Polonski, A., Prakhov, S. N., Price, J. W., Rosner, G., Rost, M., Rostomyan, T., Sober, D., Starostin, A., Supek, I., Tarbert, C. M., Thomas, A., Unverzagt, M., Walcher, Th., Watts, D. P., and Zehr, F.

Abstract

The reaction gamma p -> p pi0 gamma' has been measured with the Crystal Ball / TAPS detectors using the energy-tagged photon beam at the electron accelerator facility MAMI-B. Energy and angular differential cross sections for the emitted photon gamma' and angular differential cross sections for the pi0 have been determined with high statistics in the energy range of the Delta+(1232) resonance. Cross sections and the ratio of the cross section to the non-radiative process gamma p -> p pi0 are compared to theoretical reaction models, having the anomalous magnetic moment kappa_Delta+ as free parameter. As the shape of the experimental distributions is not reproduced in detail by the model calculations, currently no extraction of kappa_Delta+ is feasible., Comment: 14 pages, 19 figures

Published
2010
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200. Photoproduction of pi^0 eta on protons and the Delta(1700)D_{33} resonance

Author

Kashevarov, V. L., Fix, A., Aguar-Bartolome, P., Akasoy, L. K., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghauser, H., Boillat, B., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Downie, E. J., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Heid, E., Hornidge, D., Jahn, O., Jude, T. C., Knezevic, A., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Martinez-Fabregate, M., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Micanovic, S., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ostrick, M., Owens, R. O., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Prakhov, S. N., Rosner, G., Rostomyan, T., Schumann, S., Sober, D., Starostin, A., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Zamboni, I., Zehr, F., Kashevarov, V. L., Fix, A., Aguar-Bartolome, P., Akasoy, L. K., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Berghauser, H., Boillat, B., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Downie, E. J., Drexler, P., Fil'kov, L. V., Glazier, D. I., Gregor, R., Heid, E., Hornidge, D., Jahn, O., Jude, T. C., Knezevic, A., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A., Kruglov, S., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Manley, D. M., Martinez-Fabregate, M., McGeorge, J. C., McNicoll, E. F., Mekterovic, D., Metag, V., Micanovic, S., Nefkens, B. M. K., Nikolaev, A., Novotny, R., Ostrick, M., Owens, R. O., Pedroni, P., Pheron, F., Polonski, A., Robinson, J., Prakhov, S. N., Rosner, G., Rostomyan, T., Schumann, S., Sober, D., Starostin, A., Suarez, I. M., Supek, I., Tarbert, C. M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D. P., Zamboni, I., and Zehr, F.

Abstract

Total and differential cross sections for the reaction gamma p -> pi^o eta p have been measured with the Crystal Ball/TAPS detector using the tagged photon facility at the MAMI C accelerator in Mainz. In the energy range E_gamma=0.95-1.4 GeV the reaction is dominated by the excitation and sequential decay of the Delta(1700)D33 resonance. Angular distributions measured with high statistics allow us to determine the ratio of hadronic decay widths \Gamma_{\eta \Delta}/\Gamma_{\pi S11} and the ratio of the helicity amplitudes A_{3/2}/A_{1/2} for this resonance., Comment: 9 pages, 11 figures

Published
2009
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