491 results on '"Supek, I."'
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102. Measurement of the beam-helicity asymmetry in photoproduction of π0η pairs on carbon, aluminum, and lead
- Author
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Sokhoyan, V., Prakhov, S., Fix, A., Abt, S., Achenbach, P., Adlarson, P., Afzal, F., Aguar-Bartolomé, P., Ahmed, Z., Altangerel, K., Annand, J.R.M., Arends, H.J., Bantawa, K., Bashkanov, M., Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cherepnya, S., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Downie, E.J., Drexler, P., Ferretti Bondy, M.I., Fil'kov, L.V., Gardner, S., Garni, S., Glazier, D.I., Gorodnov, I., Gradl, W., Günther, M., Gurevich, G.M., Heijkenskjöld, L., Hornidge, D., Huber, G.M., Käser, A., Kashevarov, V.L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Livingston, K., Lutterer, S., MacGregor, I.J.D., Macrae, R., Manley, D.M., Martel, P.P., McGeorge, J.C., Middleton, D.G., Miskimen, R., Mornacchi, E., Mullen, C., Mushkarenkov, A., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Otte, P.B., Paudyal, D., Pedroni, P., Powell, A., Rickert, E., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Spieker, K., Steffen, O., Strakovsky, I.I., Strandberg, B., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu.A., Wagner, S., Walford, N.K., Watts, D.P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., and Zachariou, N.
- Published
- 2020
- Full Text
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103. Helicity-dependent cross sections for the photoproduction of π0 pairs from nucleons
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Dieterle, M., Witthauer, L., Fix, A., Abt, S., Achenbach, P., Adlarson, P., Afzal, F., Bartolome, P. Aguar, Ahmed, Z., Annand, J. R. M., Arends, H. J., Bashkanov, M., Beck, R., Biroth, M., Borisov, N., Braghieri, A., Briscoe, W. J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dolzhikov, A. S., Downie, E. J., Drexler, P., Gardner, S., Ghosal, D., Glazier, D. I., Gorodnov, I., Gradl, W., G{ü, M., nther, Gurevich, D., Heijkenskj{ö, L., Hornidge, D., Huber, G. M., K{ä, A., ser, Kashevarov, V. L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I. J. D., Manley, D. M., Martel, P. P., Metag, V., Meyer, W., Middleton, D. G., Miskimen, R., Mornacchi, E., Mullen, C., Mushkarenkov, A., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Otte, P. B., Paudyal, D., Pedroni, P., Polonski, A., Powell, A., Prakhov, S. N., Reicherz, G., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I. I., Strub, T., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N. K., Watts, D. P., Werthmüller, D., Wettig, J., Wolfes, M., and Zana, L. A.
- Subjects
Physics ,Proton ,spin polarization ,neutron ,photodisintegration ,Crystal Ball at MAMI ,Nuclear Theory ,Bremsstrahlung ,General Physics and Astronomy ,Electron ,7. Clean energy ,01 natural sciences ,Resonance (particle physics) ,Helicity ,Nuclear physics ,0103 physical sciences ,Neutron ,010306 general physics ,Nucleon ,Nuclear Experiment ,Crystal Ball - Abstract
The double-polarization observable $E$ and helicity-dependent cross sections $\sigma_{1/2}$, $\sigma_{3/2}$ have been measured for the photoproduction of $\pi^0$ pairs off quasi-free protons and neutrons at the Mainz MAMI accelerator with the Crystal Ball/TAPS setup. A circularly polarized photon beam was produced by bremsstrahlung from longitudinally polarized electrons and impinged on a longitudinally polarized deuterated butanol target. The reaction products were detected with an almost $4\pi$ covering calorimeter. The results reveal for the first time the helicity- and isospin-dependent structure of the $\gamma N\rightarrow N\pi^0\pi^0$ reaction. They are compared to predictions from reaction models in view of nucleon resonance contributions and also to a refit of one model that predicted results for the proton and for the neutron target. The comparison of the prediction and the refit demonstrate the large impact of the new data., Comment: Submitted to Phys. Rev. Lett
- Published
- 2020
104. Signatures of the $d^*(2380)$ hexaquark in d($γ$,$p\vec{n}$)
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Fegan, Stuart, Fix, A., Mullen, C., Neganov, A., Neiser, A., Ostrick, M., Otte, P. B., Paudyal, D., Pedroni, P., Powell, A, Prakhov, S. N., Ron, G., Sarty, A, Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O, Strakovsky, I.I., Strub, T., Supek, I, Thiel, A., Thiel, M, Thomas, A., Usov, Yu A., Wagner, S, Walford, N.K., Werthmüller, Dominik, Wettig, J., Wolfes, M., Zachariou, Nick, and Zana, L A
- Subjects
Nuclear Theory ,Nuclear Experiment - Abstract
We report a measurement of the spin polarisation of the recoiling neutron in deuterium photodisintegration, utilising a new large acceptance polarimeter within the Crystal Ball at MAMI. The measured photon energy range of 300~--~700~MeV provides the first measurement of recoil neutron polarisation at photon energies where the quark substructure of the deuteron plays a role, thereby providing important new constraints on photodisintegration mechanisms. A very high neutron polarisation in a narrow structure centred around $E_{\gamma}\sim$~570~MeV is observed, which is inconsistent with current theoretical predictions employing nucleon resonance degrees of freedom. A Legendre polynomial decomposition suggests this behaviour could be related to the excitation of the $d^*(2380)$ hexaquark.
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- 2020
105. Measurement of the beam-helicity asymmetry in photoproduction of Pairs on Carbon, Aluminum, and Lead
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Sokhoyan, V., Prakhov, S., Fix, A., Abt, S., Achenbach, P., Adlarson, P., Afzal, F., Aguar-Bartolomé, P., Ahmed, Z., Altangerel, K., Annand, J.R.M., Arends, H.J., Bantawa, K., Bashkanov, M., Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cherepnya, S., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Downie, E.J., Drexler, P., Ferretti Bondy, M.I., Fil'kov, L.V., Gardner, S., Garni, S., Glazier, D.I., Gorodnov, I., Gradl, W., Günther, M., Gurevich, G.M., Heijkenskjöld, L., Hornidge, D., Huber, G.M., Käser, A., Kashevarov, V.L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Livingston, K., Lutterer, S., MacGregor, I.J.D., Macrae, R., Manley, D.M., Martel, P.P., McGeorge, J.C., Middleton, D.G., Miskimen, R., Mornacchi, E., Mullen, C., Mushkarenkov, A., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Otte, P.B., Paudyal, D., Pedroni, P., Powell, A., Rickert, E., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Spieker, K., Steffen, O., Strakovsky, I.I., Strandberg, B., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu.A., Wagner, S., Walford, N.K., Watts, D.P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., and Zachariou, N.
- Abstract
The beam-helicity asymmetry was measured, for the first time, in photoproduction of π0η pairs on carbon, aluminum, and lead, with the A2 experimental setup at MAMI. The results are compared to an earlier measurement on a free proton and to the corresponding theoretical calculations. The Mainz model is used to predict the beam-helicity asymmetry for the nuclear targets. The present results indicate that the photoproduction mechanism for π0η pairs on nuclei is similar to photoproduction on a free nucleon. This process is dominated by the D33 partial wave with the ηΔ(1232) intermediate state.
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- 2020
106. The PIBETA spectrometer for studying rare and forbidden decays of muons and pions
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Baranov, V. A., Kalinnikov, V. A., Karpukhin, V. V., Khomutov, N. V., Korenchenko, A. S., Korenchenko, S. M., Kravchuk, N. P., Kuchinskii, N. A., Mzhaviya, D. A., Rozhdestvenskii, A. M., Sidorkin, V. V., Tsamalaidze, Z. B., Sakhelashvili, T., Frlež, E., Počanić, D., Li, W., Minehart, R. C., Smith, L. C., Stephens, W. A., Ziock, K. O. H., Bertl, W., Horisberger, R., Ritt, S., Schnyder, R., Wirtz, H. P., Ritchie, B. G., Supek, I., and Kozlowski, T.
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- 2005
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107. Measurement of the total and differential cross sections for the reaction π − p → ηn with the Crystal Ball detector
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Kozlenko, N. G., Abaev, V. V., Bekrenev, V. S., Kruglov, S. P., Koulbardis, A. A., Lopatin, I. V., Starostin, A. B., Draper, B., Hayden, S., Huddleston, J., Isenhower, D., Robinson, C., Sadler, M., Allgower, C., Cadman, R., Spinka, H., Comfort, J., Craig, K., Ramirez, A., Kycia, T., Clajus, M., Marusic, A., McDonald, S., Nefkens, B. M. K., Phaisangittisakul, N., Prakhov, S., Price, J. W., Tippens, W. B., Peterson, J., Briscoe, W. J., Shafi, A., Strakovsky, I. I., Staudenmaier, H., Manley, D. M., Olmsted, J., Peaslee, D., Knecht, N., Lolos, G., Papandreou, Z., Supek, I., Slaus, I., Gibson, A., Grosnic, D., Koetke, D., Manweiler, R., and Stanislaus, S.
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- 2003
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108. Deuteron photodisintegration by polarized photons in the region of the d⁎(2380)
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Bashkanov, M., Kay, S., Watts, D.P., Mullen, C., Abt, S., Achenbach, P., Adlarson, P., Afzal, F., Ahmed, Z., Akondi, C.S., Annand, J.R.M., Arends, H.J., Beck, R., Biroth, M., Borisov, N., Braghieri, A., Briscoe, W.J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Downie, E.J., Drexler, P., Garni, S., Glazier, D.I., Gorodnov, I., Gradl, W., Günther, M., Gurevich, D., Heijkenskjöld, L., Hornidge, D., Huber, G.M., Käser, A., Kashevarov, V.L., Korolija, M., Krusche, B., Lazarev, A., Livingston, K., Lutterer, S., MacGregor, I.J.D., Macrae, R., Manley, D.M., Martel, P.P., Miskimen, R., Mornacchi, E., Neganov, A., Neiser, A., Ostrick, M., Otte, P.B., Paudyal, D., Pedroni, P., Powell, A., Prakhov, S.N., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I.I., Strub, T., Supek, I., Thiel, A., Thiel, M., Thomas, A., Usov, Yu.A., Wagner, S., Walford, N.K., Werthmüller, D., Wettig, J., Wolfes, M., and Zana, L.A.
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- 2019
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109. Deuteron photodisintegration by polarized photons in the region of the d⁎ (2380)
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Paudyal, D., Pedroni, P., Powell, A, Prakhov, S., Ron, G., Rostomyan, T., Sarty, A. J., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O, Strakovsky, I.I., Strub, T., Supek, I, Thiel, A., Thiel, M, Thomas, A., Usov, Yu A., Wagner, S, Walford, N.K., Werthmüller, Dominik, Wettig, J., Wolfes, M., and Zana, L. A.
- Abstract
We report the first large-acceptance measurement of the beam–spin asymmetry for deuteron photodisintegration (γ→d→pn) in the photon energy range 420
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- 2019
110. Design, commissioning and performance of the PIBETA detector at PSI
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Frlež, E, Počanić, D, Assamagan, K.A, Bagaturia, Yu, Baranov, V.A, Bertl, W, Brönnimann, Ch, Bychkov, M, Crawford, J.F, Daum, M, Flügel, Th, Frosch, R, Horisberger, R, Kalinnikov, V.A, Karpukhin, V.V, Khomutov, N.V, Koglin, J.E, Korenchenko, A.S, Korenchenko, S.M, Kozlowski, T, Krause, B, Kravchuk, N.P, Kuchinsky, N.A, Li, W, Lawrence, D.W, Minehart, R.C, Mzhavia, D, Obermeier, H, Renker, D, Ritchie, B.G, Ritt, S, Sakhelashvili, T, Schnyder, R, Sidorkin, V.V, Slocum, P.L, Smith, L.C, Soić, N, Stephens, W.A, Supek, I, Tsamalaidze, Z, VanDevender, B.A, Wang, Y, Wirtz, H.P, and Ziock, K.O.H
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- 2004
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111. Measurement of the beam-helicity asymmetry I⊙ in the photoproduction of $ \pi^{0}$ $ \pi^{\pm}$ pairs off protons and off neutrons
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Oberle, M., Ahrens, J., Annand, J., Arends, H., Bantawa, K., Bartolome, P., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Branford, D., Briscoe, W., Brudvik, J., Cherepnya, S., Demissie, B., Dieterle, M., Downie, E., Drexler, P., Fil'kov, L., Fix, A., Glazier, D., Heid, E., Hornidge, D., Howdle, D., Huber, G., Jahn, O., Jaegle, I., Jude, T., Käser, A., Kashevarov, V., Keshelashvili, I., Kondratiev, R., Korolija, M., Kruglov, S., Krusche, B., Kulbardis, A., Lisin, V., Livingston, K., MacGregor, I., Maghrbi, Y., Mancell, J., Manley, D., Marinides, Z., Martinez, M., McGeorge, J., McNicoll, E., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D., Mushkarenkov, A., Nefkens, B., Nikolaev, A., Novotny, R., Ostrick, M., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M., Sober, D., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Watts, D., Werthmüller, D., Witthauer, L., Zehr, F., Oberle, M., Ahrens, J., Annand, J., Arends, H., Bantawa, K., Bartolome, P., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Branford, D., Briscoe, W., Brudvik, J., Cherepnya, S., Demissie, B., Dieterle, M., Downie, E., Drexler, P., Fil'kov, L., Fix, A., Glazier, D., Heid, E., Hornidge, D., Howdle, D., Huber, G., Jahn, O., Jaegle, I., Jude, T., Käser, A., Kashevarov, V., Keshelashvili, I., Kondratiev, R., Korolija, M., Kruglov, S., Krusche, B., Kulbardis, A., Lisin, V., Livingston, K., MacGregor, I., Maghrbi, Y., Mancell, J., Manley, D., Marinides, Z., Martinez, M., McGeorge, J., McNicoll, E., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D., Mushkarenkov, A., Nefkens, B., Nikolaev, A., Novotny, R., Ostrick, M., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M., Sober, D., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Watts, D., Werthmüller, D., Witthauer, L., and Zehr, F.
- Abstract
Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of mixed-charge pion pairs in the reactions $ \gamma p\rightarrow n\pi^{0}\pi^{+}$ off free protons and $ \gamma d \rightarrow (p)p\pi^{0}\pi^{-}$ and $ \gamma d\rightarrow (n)n\pi^{0}\pi^{+}$ off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow-Mainz magnetic spectrometer. The charged pions, recoil protons, recoil neutrons, and decay photons from $ \pi^{0}$ mesons were detected in the $ 4\pi$ electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. Using a complete kinematic reconstruction of the final state, excellent agreement was found between the results for free and quasi-free protons, suggesting that the quasi-free neutron results are also a close approximation of the free-neutron asymmetries. A comparison of the results to the predictions of the Two-Pion-MAID reaction model shows that the reaction mechanisms are still not well understood, in particular at low incident photon energies in the second nucleon-resonance region.
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- 2019
112. First measurement of helicity-dependent cross sections in Photoproduction From Quasi-free Nucleons
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Käser, A., Dieterle, M., Witthauer, L., Abt, S., Achenbach, P., Adlarson, P., Afzal, F., Ahmed, Z., Ahrens, J., Annand, J.R.M., Arends, H.J., Bashkanov, M., Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Downie, E.J., Drexler, P., Fix, A., Garni, S., Glazier, D.I., Gorodnov, I., Gradl, W., Günther, M., Gurevich, G.M., Heijkenskjöld, L., Hornidge, D., Huber, G.M., Kashevarov, V.L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A.B., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I.J.D., Manley, D.M., Martel, P.P., Metag, V., Meyer, W., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Neganov, A.B., Neiser, A., Oberle, M., Ostrick, M., Otte, P.B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S.N., Reicherz, G., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I.I., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu.A., Wagner, S., Walford, N.K., Watts, D.P., Werthmüller, D., Wettig, J., Wolfes, M., and Zana, L.
- Abstract
The helicity-dependent cross sections for the photoproduction of π0η pairs have been measured for the first time. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball – TAPS calorimeter. The experiment used a polarized deuterated butanol target and a circularly polarized photon beam. This arrangement allowed the σ1/2 (photon and target spin antiparallel) and σ3/2 (parallel spins) components to be measured for quasi-free production of π0η pairs off protons and neutrons. The main finding is that the two helicity components contribute identically, within uncertainties, for both participant protons and neutrons. The absolute couplings for protons and neutrons are also identical. This means that nucleon resonances contributing to this reaction in the investigated energy range have almost equal electromagnetic helicity couplings, A1/2n,p and A3/2n,p. Identical couplings for protons and neutrons are typical for Δ resonances and identical A1/2 and A3/2 components are only possible for J≥3/2 states, which constrains possible contributions of nucleon resonances.
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- 2018
113. Measurement of the decay <math><mrow><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>→</mo><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><mi>η</mi></mrow></math> at MAMI
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Adlarson, P., Afzal, F., Ahmed, Z., Akondi, C. S., Annand, J. R. M., Arends, H. J., Beck, R., Borisov, N., Braghieri, A., Briscoe, W. J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Downie, E. J., Dieterle, M., Ferretti Bondy, M. I., Gardner, S., Garni, S., Glazier, D. I., Glowa, D., Gradl, W., Gurevich, G., Hamilton, D. J., Hornidge, D., Huber, G. M., Käser, A., Kashevarov, V. L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Linturi, J., Livingston, K., MacGregor, I. J. D., Manley, D. M., Martel, P. P., McGeorge, J. C., Middleton, D. G., Miskimen, R., Mushkarenkov, A., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I. I., Strub, T., Supek, I., Thiel, A., Thiel, M., Tiator, L., Thomas, A., Unverzagt, M., Usov, Y. A., Wagner, S., Watts, D. P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., Workman, R. L., and Zana, L. A.
- Abstract
An experimental study of the η′→π0π0η→6γ decay has been conducted with the best up-to-date statistical accuracy, by measuring η′ mesons produced in the γp→η′p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The results obtained for the standard parametrization of the η′→π0π0η matrix element are consistent with the most recent results for η′→ππη decays, but have smaller uncertainties. The available statistics and experimental resolution allowed, for the first time, an observation of a structure below the π+π− mass threshold, the magnitude and sign of which, checked within the framework of the nonrelativistic effective-field theory, demonstrated good agreement with the cusp that was predicted based on the ππ scattering length combination, a0−a2, extracted from K→3π decays.
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- 2018
114. Quasi-free photoproduction of η -mesons off 3He nuclei
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Witthauer, L., Werthmüller, D., Keshelashvili, I., Aguar-Bartolomé, P., Ahrens, J., Annand, J., Arends, H., Bantawa, K., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W., Brudvik, J., Cherepnya, S., Demissie, B., Dieterle, M., Downie, E., Drexler, P., Fil'kov, L., Fix, A., Glazier, D., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Huber, G., Jaegle, I., Jahn, O., Jude, T., Käser, A., Kashevarov, V., Kondratiev, R., Korolija, M., Kruglov, S., Krusche, B., Kulbardis, A., Lisin, V., Livingston, K., MacGregor, I., Maghrbi, Y., Mancell, J., Manley, D., Marinides, Z., Martinez, M., McGeorge, J., McNicoll, E., Metag, V., Middleton, D., Mushkarenkov, A., Nefkens, B., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rosner, G., Rost, M., Rostomyan, T., Schumann, S., Sikora, M., Sober, D., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., and Watts, D.
- Subjects
Nuclear Theory ,Nuclear Experiment - Abstract
Quasi-free photoproduction of η-mesons has been measured off nucleons bound in 3He nuclei for incident photon energies from the threshold region up to 1.4 GeV. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with an almost 4π covering electromagnetic calorimeter, combining the TAPS and Crystal Ball detectors. The η-mesons were detected in coincidence with the recoil nucleons. This allowed a comparison of the production cross section off quasi-free protons and quasi-free neutrons and a full kinematic reconstruction of the final state, eliminating effects from nuclear Fermi motion. In the S11(1535) resonance peak, the data agree with the neutron/proton cross section ratio extracted from measurements with deuteron targets. More importantly, the prominent structure observed in photoproduction off quasi-free neutrons bound in the deuteron is also clearly observed. Its parameters (width, strength) are consistent with the expectations from the deuteron results. On an absolute scale the cross sections for both quasi-free protons and neutrons are suppressed with respect to the deuteron target pointing to significant nuclear final-state interaction effects
- Published
- 2018
115. High-statistics measurement of the η → 3π0 decay at MAMI
- Author
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Prakhov, S., Abt, S., Adlarson, P., Afzal, F., Aguar-Bartolome, P., Ahmed, |., Ahrens, J., Annand, J.R.M., Arends, H.J., Bantawa, K., Bashkanov, M., Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cherepnya, S., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Downie, E.J., Drexler, P., Ferretti Bondy, M.I., Fil'kov, L.V., Fix, A., Gardner, S., Garni, S., Glazier, D.I., Gordonov, I., Gradl, W., Gurevich, G.M., Heijkenskjöld, L., Hornidge, D., Huber, G.M., Käser, A., Kashevarov, V.L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I.J.D., Manley, D.M., Martel, P.P., McGeorge, J.C., Middleton, D.G., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Otte, P.B., Paudyal, D., Pedroni, P., Polonski, A., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I.I., Strandberg, B., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N.K., Watts, D.P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., and Zana, L.A.
- Abstract
The largest, at the moment, statistics of 7×106 η→3π0 decay s, based on 6.2×107 η mesons produced in the γp→ηp r eaction, has been accumulated by the A2 Collaboration at the Mainz Microtron, MAMI. It allowed a detailed study of the η→3π0 dynamics beyond its conventional parametrization with just the quadratic slope parameter α and enabled, for the first time, a measurement of the second-order ter m and a better understanding of the cusp structure in the neutral decay. The present data are also compared to recent theoretical calculations that predict a nonlinear dependence along the quadratic distance from the Dalitz-plot center.
- Published
- 2018
116. High-statistics measurement of the η→3π0 decay at the Mainz Microtron
- Author
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Prakhov, S., Abt, S., Achenbach, P., Adlarson, P., Afzal, F., Aguar-Bartolomé, P., Ahmed, Z., Ahrens, J., Annand, J.R.M., Arends, H.J., Bantawa, K., Bashkanov, M., Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cherepnya, S., Cividini, F., Collicott, C., Constanza, S., Denig, A., Dieterle, M., Downie, E.J., Drexler, P., Ferretti Bondy, M.I., Fil'kov, L.V., Fix, A., Gardner, S., Garni, S., Glazier, D.I., Gorodnov, I., Gradl, W., Gurevich, G.M., Hamill, C.B., Heijkenskjöld, L., Horndige, D., Huber, G.M., Käser, A., Kashevarov, V.L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I.J.D., Manley, D.M., Martel, P.P., McGeorge, J.C., Middleton, D.G., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Otte, P.B., Paudyal, D., Pedroni, P., Polonski, A., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Spiekter, K., Steffen, O., Strakovsky, I.I., Strandberg, B., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N.K., Watts, D.P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., and Zana, L.A.
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tagged photon spectrometer ,parameter alpha ,dynamics ,Physics ,High Energy Physics::Experiment ,Nuclear Experiment - Abstract
The largest, at the moment, statistics of 7×106η→3π0 decays, based on 6.2×107η mesons produced in the γp→ηp reaction, has been accumulated by the A2 Collaboration at the Mainz Microtron, MAMI. It allowed a detailed study of the η→3π0 dynamics beyond its conventional parametrization with just the quadratic slope parameter α and enabled, for the first time, a measurement of the second-order term and a better understanding of the cusp structure in the neutral decay. The present data are also compared to recent theoretical calculations that predict a nonlinear dependence along the quadratic distance from the Dalitz-plot center.
- Published
- 2018
117. Experimental study of the $��p\rightarrow K^0��^+$, $��n\rightarrow K^0��$, and $��n\rightarrow K^0 ��^0$ reactions at the Mainz Microtron
- Author
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Akondi, C. S., Bantawa, K., Manley, D. M., Abt, S., Achenbach, P., Afzal, F., Aguar-Bartolom��, P., Ahmed, Z., Annand, J. R. M., Arends, H. J., Bashkanov, M., Beck, R., Biroth, M., Borisov, N., Braghieri, A., Briscoe, W. J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Downie, E. J., Drexler, P., Bondy, M. I. Ferretti, Gardner, S., Glazier, D. I., Gorodnov, I., Gradl, W., G��nther, M., Gurevich, D., Kay, S., Heijkenskj��ld, L., Hornidge, D., Huber, G. M., K��ser, M., Kashevarov, V. L., Korolija, M., Krusche, B., Lazarev, A., Livingston, K., Lutterer, S., McGeorge, J. C., MacGregor, I. J. D., Martel, P. P., Middleton, D. G., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Mullen, C., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Otte, P. B., Oussena, B., Paudyal, D., Pedroni, P., Powell, A., Prakhov, S. N., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I. I., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Walford, N. K., Watts, D. P., Wagner, S., Werthm��ller, D., Wettig, J., Witthauer, L., and Wolfes, M.
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FOS: Physical sciences ,Nuclear Experiment (nucl-ex) ,Nuclear Experiment - Abstract
This work measured $d��/d��$ for neutral kaon photoproduction reactions from threshold up to a c.m.\ energy of 1855MeV, focussing specifically on the $��p\rightarrow K^0��^+$, $��n\rightarrow K^0��$, and $��n\rightarrow K^0 ��^0$ reactions. Our results for $��n\rightarrow K^0 ��^0$ are the first-ever measurements for that reaction. These data will provide insight into the properties of $N^*$ resonances and, in particular, will lead to an improved knowledge about those states that couple only weakly to the $��N$ channel. Integrated cross sections were extracted by fitting the differential cross sections for each reaction as a series of Legendre polynomials and our results are compared with prior experimental results and theoretical predictions., 16 pages, 13 figures, 7 tables
- Published
- 2018
- Full Text
- View/download PDF
118. Measurement of the decay η ′ → π 0 π 0 η at MAMI
- Author
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Adlarson, P., Afzal, F., Cividini, F., Collicott, C., Costanza, S., Denig, A., Downie, E. J., Dieterle, M., Ferretti Bondy, M. I., Gardner, S., Garni, S., Glazier, D. I., Ahmed, Z., Glowa, D., Gradl, W., Gurevich, G., Hamilton, D. J., Hornidge, D., Huber, G. M., Käser, A., Kashevarov, V. L., Kay, S., Keshelashvili, I., Akondi, C. S., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Linturi, J., Livingston, K., MacGregor, I. J. D., Manley, D. M., Martel, P. P., McGeorge, J. C., Annand, J. R. M., Middleton, D. G., Miskimen, R., Mushkarenkov, A., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Arends, H. J., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Beck, R., Spieker, K., Steffen, O., Strakovsky, I. I., Strub, T., Supek, I., Thiel, A., Thiel, M., Tiator, L., Thomas, A., Unverzagt, M., Borisov, N., Usov, Y. A., Wagner, S., Watts, D. P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., Workman, R. L., Zana, L. A., Braghieri, A., and Briscoe, W. J.
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ddc:530 - Abstract
An experimental study of the η′→π0π0η→6γ decay has been conducted with the best up-to-date statistical accuracy, by measuring η′ mesons produced in the γp→η′p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The results obtained for the standard parametrization of the η′→π0π0η matrix element are consistent with the most recent results for η′→ππη decays, but have smaller uncertainties. The available statistics and experimental resolution allowed, for the first time, an observation of a structure below the π+π− mass threshold, the magnitude and sign of which, checked within the framework of the nonrelativistic effective-field theory, demonstrated good agreement with the cusp that was predicted based on the ππ scattering length combination, a0−a2, extracted from K→3π decays.
- Published
- 2018
- Full Text
- View/download PDF
119. Measurement of the decay η′→π0π0η at MAMI
- Author
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Adlarson, P., Afzal, F., Ahmed, Z., Akondi, C.S., Annand, J.R.M., Arends, H.J., Beck, R., Borisov, N., Braghieri, A., Briscoe, W.J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Downie, E.J., Dieterle, M., Ferretti Bondy, M.I., Gardner, S., Garni, S., Glazier, D.I., Glowa, D., Gradl, W., Gurevich, G., Hamilton, D.J., Hornidge, D., Huber, G.M., Käser, A., Kashevarov, V.L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Linturi, J., Livingston, K., MacGregor, I.J.D., Manley, D.M., Martel, P.P., McGeorge, J.C., Middleton, D.G., Miskimen, R., Mushkarenkov, A., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Ott, P., Otte, P.B., Oussena, B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I.I., Strub, T., Supek, I., Thiel, A., Thiel, M., Tiator, L., Thomas, A., Unverzagt, M., Usov, Y.A., Wagner, S., Watts, D.P., Werthmueller, D., Wettig, J., Witthauer, L., Wolfes, M., Workman, R.L., and Zana, L.A.
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Physics ,High Energy Physics::Experiment ,Nuclear Experiment ,matrix-element ,mass ,microtron ,3-Pi(0) ,cusps ,ratio - Abstract
An experimental study of the eta' -> pi(0)pi(0)eta -> 6 gamma decay has been conducted with the best up-to-date statistical accuracy, by measuring. 0 mesons produced in the gamma p -> eta'p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The results obtained for the standard parametrization of the eta' -> pi(0)pi(0)eta matrix element are consistent with the most recent results for eta' -> pi pi eta decays, but have smaller uncertainties. The available statistics and experimental resolution allowed, for the first time, an observation of a structure below the pi(+)pi(-) thorn p-mass threshold, the magnitude and sign of which, checked within the framework of the nonrelativistic effective-field theory, demonstrated good agreement with the cusp that was predicted based on the pi pi scattering length combination, a(0)-a(2), extracted from K -> 3 pi decays.
- Published
- 2018
120. Study of the $��p\to ��^0��p$ reaction with the A2 setup at MAMI
- Author
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Sokhoyan, V., Prakhov, S., Fix, A., Abt, S., Achenbach, P., Adlarson, P., Afzal, F., Aguar-Bartolom��, P., Ahmed, Z., Ahrens, J., Annand, J. R. M., Arends, H. J., Bantawa, K., Bashkanov, M., Beck, R., Biroth, M., Borisov, N. S., Braghieri, A., Briscoe, W. J., Cherepnya, S., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Downie, E. J., Drexler, P., Bondy, M. I. Ferretti, Fil'kov, L. V., Gardner, S., Garni, S., Glazier, D. I., Glowa, D., Gorodnov, I., Gradl, W., G��nther, M., Gurevich, G. M., Hamill, C. B., Heijkenskj��ld, L., Hornidge, D., Huber, G. M., Jude, T. C., K��ser, A., Kashevarov, V. L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Linturi, J., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I. J. D., Macrae, R., Manley, D. M., Martel, P. P., McGeorge, J. C., McNicoll, E. F., Middleton, D. G., Miskimen, R., Mornacchi, E., Mullen, C., Mushkarenkov, A., Neganov, A., Neiser, A., Nikolaev, A., Oberle, M., Ostrick, M., Ott, P., Otte, P. B., Paudyal, D., Pedroni, P., Polonski, A., Rajabi, A., Robinson, J., Ron, G., Rosner, G., Rostomyan, T., Sarty, A., Sfienti, C., Sikora, M. H., Spieker, K., Steffen, O., Strakovsky, I. I., Strandberg, B., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N. K., Watts, D. P., Werthm��ller, D., Wettig, J., Witthauer, L., Wolfes, M., and Zana, L. A.
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FOS: Physical sciences ,Nuclear Experiment (nucl-ex) ,Nuclear Experiment - Abstract
The data available from the A2 Collaboration at MAMI were analyzed to select the $��p\to ��^0��p$ reaction on an event-by-event basis, which allows for partial-wave analyses of three-body final states to obtain more reliable results, compared to fits to measured distributions. These data provide the world's best statistical accuracy in the energy range from threshold to $E_��=1.45$ GeV, allowing a finer energy binning in the measurement of all observables needed for understanding the reaction dynamics. The results obtained for the measured observables are compared to existing models, and the impact from the new data is checked by the fit with the revised Mainz model., 15 pages, 18 figures
- Published
- 2018
- Full Text
- View/download PDF
121. Experimental study of the γ p → π 0 η p reaction with the A2 setup at the Mainz Microtron
- Author
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Sokhoyan, V., Prakhov, S., Annand, J. R. M., Arends, H. J., Bantawa, K., Bashkanov, M., Beck, R., Biroth, M., Borisov, N. S., Braghieri, A., Briscoe, W. J., Cherepnya, S., Fix, A., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Downie, E. J., Drexler, P., Ferretti Bondy, M. I., Fil'kov, L. V., Gardner, S., Abt, S., Garni, S., Glazier, D. I., Gorodnov, I., Gradl, W., Günther, M., Gurevich, G. M., Hamill, C. B., Heijkenskjöld, L., Hornidge, D., Huber, G. M., Achenbach, P., Käser, A., Kashevarov, V. L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Lisin, V., Livingston, K., Adlarson, P., Lutterer, S., MacGregor, I. J. D., Manley, D. M., Martel, P. P., McGeorge, J. C., Middleton, D. G., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Neganov, A., Afzal, F., Neiser, A., Oberle, M., Ostrick, M., Otte, P. B., Paudyal, D., Pedroni, P., Polonski, A., Ron, G., Rostomyan, T., Sarty, A., Aguar-Bartolomé, P., Sfienti, C., Spieker, K., Steffen, O., Strakovsky, I. I., Strandberg, B., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Ahmed, Z., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N. K., Watts, D. P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., Zana, L. A., and Ahrens, J.
- Subjects
ddc:530 ,Nuclear Experiment - Abstract
The data available from the A2 Collaboration at MAMI were analyzed to select the γp→π0ηp reaction on an event-by-event basis, which allows for partial-wave analyses of three-body final states to obtain more reliable results, compared to fits to measured distributions. These data provide the world's best statistical accuracy in the energy range from threshold to Eγ=1.45 GeV, allowing a finer energy binning in the measurement of all observables needed for understanding the reaction dynamics. The results obtained for the measured observables are compared to existing models, and the impact from the new data is checked by the fit with the revised Mainz model.
- Published
- 2018
- Full Text
- View/download PDF
122. Experimental study of the $ \gamma p \rightarrow K^{0}\Sigma^{+}$, $ \gamma n \rightarrow K^{0} \Lambda$, and $ \gamma n \rightarrow K^{0} \Sigma^{0}$ reactions at the Mainz Microtron
- Author
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Akondi, C. S., primary, Bantawa, K., additional, Manley, D. M., additional, Abt, S., additional, Achenbach, P., additional, Afzal, F., additional, Aguar-Bartolomé, P., additional, Ahmed, Z., additional, Annand, J. R. M., additional, Arends, H. J., additional, Bashkanov, M., additional, Beck, R., additional, Biroth, M., additional, Borisov, N., additional, Braghieri, A., additional, Briscoe, W. J., additional, Cividini, F., additional, Collicott, C., additional, Costanza, S., additional, Denig, A., additional, Dieterle, M., additional, Downie, E. J., additional, Drexler, P., additional, Ferretti Bondy, M. I., additional, Gardner, S., additional, Glazier, D. I., additional, Gorodnov, I., additional, Gradl, W., additional, Günther, M., additional, Gurevich, D., additional, Kay, S., additional, Heijkenskjöld, L., additional, Hornidge, D., additional, Huber, G. M., additional, Käser, M., additional, Kashevarov, V. L., additional, Korolija, M., additional, Krusche, B., additional, Lazarev, A., additional, Livingston, K., additional, Lutterer, S., additional, McGeorge, J. C., additional, MacGregor, I. J. D., additional, Martel, P. P., additional, Middleton, D. G., additional, Miskimen, R., additional, Mornacchi, E., additional, Mushkarenkov, A., additional, Mullen, C., additional, Neganov, A., additional, Neiser, A., additional, Oberle, M., additional, Ostrick, M., additional, Otte, P. B., additional, Oussena, B., additional, Paudyal, D., additional, Pedroni, P., additional, Powell, A., additional, Prakhov, S. N., additional, Ron, G., additional, Rostomyan, T., additional, Sarty, A., additional, Sfienti, C., additional, Sokhoyan, V., additional, Spieker, K., additional, Steffen, O., additional, Strakovsky, I. I., additional, Strub, Th., additional, Supek, I., additional, Thiel, A., additional, Thiel, M., additional, Thomas, A., additional, Unverzagt, M., additional, Usov, Yu. A., additional, Walford, N. K., additional, Watts, D. P., additional, Wagner, S., additional, Werthmüller, D., additional, Wettig, J., additional, Witthauer, L., additional, and Wolfes, M., additional
- Published
- 2019
- Full Text
- View/download PDF
123. Threshold π 0 photoproduction on transverse polarised protons at MAMI
- Author
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Schumann, S., Otte, P.B., Akondi, C.S., Annand, J.R.M., Arends, H.-J., Beck, R., Bernstein, A.M., Borisov, N., Braghieri, A., Briscoe, W.J., Cherepnya, S., Collicott, C., Costanza, S., Downie, E.J., Dieterle, M., Fernández-Ramírez, C., Fix, A., Fil'kov, L.V., Garni, S., Glazier, D.I., Gradl, W., Gurevich, G., Hall-Barrientos, P., 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.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., Oussena, B., Paudyal, D., Pedroni, P., Polonski, A., Polyanski, V.V., Prakhov, S., Reicherz, G., Rostomyan, T., Sarty, A., Sikora, M.H., Sokhoyan, V., 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.
- Subjects
Nuclear and High Energy Physics - Published
- 2015
- Full Text
- View/download PDF
124. Helicity-dependent cross sections and double-polarization observable E in η photoproduction\ud from quasifree protons and neutrons
- Author
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Witthauer, L., Dieterle, M., Abt, S., Achenbach, P., Afzal, F., Ahmed, Z., Akondi, C.S., Annand, J.R.M., Arends, H.J., Bashkanov, M., Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cividini, F., Costanza, S., Collicott, C., Denig, A., Downie, E.J., Drexler, P., Ferretti-Bondy, M.I., Gardner, S., Garni, S., Glazier, D.I., Glowa, D., Gradl, W., Günther, M., Gurevich, G.M., Hamilton, D., Hornidge, D., Huber, G.M., Käser, A., Kashevarov, V.L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A.B., Linturi, J.M., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I.J.D., Mancell, J., Manley, D.M., Martel, P.P., Metag, V., Meyer, W., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Neganov, A.B., Neiser, A., Oberle, M., Ostrick, M., Otte, P.B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S.N., Rajabi, A., Reicherz, G., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sikora, M.H., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I.I., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu A., Wagner, S., Walford, N.K., Watts, D.P., Werthmüller, D., Wettig, J., Wolfes, M., and Zana, L.
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Nuclear Theory ,Nuclear Experiment - Abstract
Precise helicity-dependent cross sections and the double-polarization observable E were measured for η\ud photoproduction from quasifree protons and neutrons bound in the deuteron. The η → 2γ and η → 3π0 → 6γ\ud decay modes were used to optimize the statistical quality of the data and to estimate systematic uncertainties. The\ud measurement used the A2 detector setup at the tagged photon beam of the electron accelerator MAMI in Mainz.\ud A longitudinally polarized deuterated butanol target was used in combination with a circularly polarized photon\ud beam from bremsstrahlung of a longitudinally polarized electron beam. The reaction products were detected with\ud the electromagnetic calorimeters Crystal Ball and TAPS, which covered 98% of the full solid angle. The results\ud show that the narrow structure observed earlier in the unpolarized excitation function of η photoproduction off\ud the neutron appears only in reactions with antiparallel photon and nucleon spin (σ1/2). It is absent for reactions\ud with parallel spin orientation (σ3/2) and thus very probably related to partial waves with total spin 1/2. The\ud behavior of the angular distributions of the helicity-dependent cross sections was analyzed by fitting them with Legendre polynomials. The results are in good agreement with a model from the Bonn-Gatchina group, which\ud uses an interference of P11 and S11 partial waves to explain the narrow structure.
- Published
- 2017
125. Measurement of the ω → π 0 e + e − and η → e + e − γ Dalitz decays with the A2 setup at the Mainz Microtron
- Author
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Adlarson, P., Afzal, F., Borisov, N. S., Braghieri, A., Briscoe, W. J., Cherepnya, S., Cividini, F., Collicott, C., Costanza, S., Danilkin, I. V., Denig, A., Dieterle, M., Aguar-Bartolomé, P., Downie, E. J., Drexler, P., Ferretti Bondy, M. I., Fil'kov, L. V., Gardner, S., Garni, S., Glazier, D. I., Glowa, D., Gradl, W., Gurevich, G. M., Ahmed, Z., Hamilton, D. J., Hornidge, D., Huber, G. M., Jude, T. C., Käser, A., Kashevarov, V. L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Annand, J. R. M., Krusche, B., Lazarev, A., Linturi, J., Lisin, V., Livingston, K., MacGregor, I. J. D., Macrae, R., Manley, D. M., Martel, P. P., McGeorge, J. C., Arends, H. J., McNicoll, E. F., Metag, V., Middleton, D. G., Miskimen, R., Mornacchi, E., Mullen, C., Mushkarenkov, A., Neganov, A., Neiser, A., Nikolaev, A., Bantawa, K., Oberle, M., Ostrick, M., Ott, P., Otte, P. B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Robinson, J., Beck, R., Ron, G., Rosner, G., Rostomyan, T., Sfienti, C., Sikora, M. H., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I. I., Strandberg, B., Berghäuser, H., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N., Watts, D. P., Biroth, M., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., and Zana, L. A.
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ddc:530 - Abstract
The Dalitz decays η→e+e−γ and ω→π0e+e− have been measured in the γp→ηp and γp→ωp reactions, respectively, with the A2 tagged-photon facility at the Mainz Microtron. The value obtained for the slope parameter of the electromagnetic transition form factor of η, Λ−2η=(1.97±0.11tot)GeV−2, is in good agreement with previous measurements of the η→e+e−γ and η→μ+μ−γ decays. The uncertainty obtained in the value of Λ−2η is lower than in previous results based on the η→e+e−γ decay. The value obtained for the ω slope parameter, Λ−2ωπ0=(1.99±0.21tot)GeV−2, is somewhat lower than previous measurements based on ω→π0μ+μ−, but the results for the ω transition form factor are in better agreement with theoretical calculations, compared to earlier experiments.
- Published
- 2017
- Full Text
- View/download PDF
126. Measurement of the ω→π0e+e− and η→e+e−γ Dalitz decays with the A2 setup at the Mainz Microtron
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Adlarson, P., Afzal, F., Aguar-Bartolome, P., Ahmed, Z., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Berghaeuser, H., Biroth, M., Borisov, N. S., Braghieri, A., Briscoe, W. J., Cherepnya, S., Cividini, F., Collicott, C., Costanza, S., Danilkin, I. V., Denig, A., Dieterle, M., Downie, E. J., Drexler, P., Bondy, M. I. Ferretti, Fil`kov, L. V., Gardner, S., Garni, S., Glazier, D. I., Glowa, D., Gradl, W., Gurevich, G. M., Hamilton, D. J., Hornidge, D., Huber, G. M., Jude, T. C., Kaeser, A., Kashevarov, V. L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A., Linturi, J., Lisin, V., Livingston, K., MacGregor, I. J. D., Macrae, R., Manley, D. M., Martel, P. P., McGeorge, J. C., McNicoll, E. F., Metag, V., Middleton, D. G., Miskimen, R., Mornacchi, E., Mullen, C., Mushkarenkov, A., Neganov, A., Neiser, A., Nikolaev, A., Oberle, M., Ostrick, M., Ott, P., Otte, P. B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Robinson, J., Ron, G., Rosner, G., Rostomyan, T., Sfienti, C., Sikora, M. H., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I. I., Strandberg, B., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N., Watts, D. P., Werthmueller, D., Wettig, J., Witthauer, L., Wolfes, M., and Zana, L. A.
- Abstract
The Dalitz decays η→e+e−γ and ω→π0e+e− have been measured in the γp→ηp and γp→ωp reactions, respectively, with the A2 tagged-photon facility at the Mainz Microtron. The value obtained for the slope parameter of the electromagnetic transition form factor of η, Λ−2η=(1.97±0.11tot)GeV−2, is in good agreement with previous measurements of the η→e+e−γ and η→μ+μ−γ decays. The uncertainty obtained in the value of Λ−2η is lower than in previous results based on the η→e+e−γ decay. The value obtained for the ω slope parameter, Λ−2ωπ0=(1.99±0.21tot)GeV−2, is somewhat lower than previous measurements based on ω→π0μ+μ−, but the results for the ω transition form factor are in better agreement with theoretical calculations, compared to earlier experiments.
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- 2017
- Full Text
- View/download PDF
127. Study of η and η' Photoproduction at MAMI
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Kashevarov, V.L., Ott, P., Prakhov, S., Adlarson, P., Afzal, F., Ahmed, Z., Akondi, C.S., Annand, J.R.M., Arends, H.J., Beck, R., Braghieri, A., Briscoe, W.J., Cividini, F., Codling, R., Collicott, C., Costanza, S., Denig, A., Downie, E.J., Dieterle, M., Ferretti Bondy, M.I., Filkov, L.V., Fix, A., Gardner, S., Garni, S., Glazier, D.I., Glowa, D., Gradl, W., Gurevich, G., Hamilton, D.J., Hornidge, D., Howdle, D., Huber, G.M., Käser, A., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Linturi, J., Lisin, V., Livingston, K., MacGregor, I.J.D., MacRae, R., Mancell, J., Manley, D.M., Martel, P.P., McGeorge, J.C., McNicol, E., Middleton, D.G., Miskimen, R., Mornacchi, E., Mullen, C., Mushkarenkov, A., Neiser, A., Oberle, M., Ostrick, M., Otte, P.B., Oussena, B., Paudyal, D., Pedroni, P., Polyanski, V.V., Rajabi, A., Reicherz, G., Robinson, J., Rosner, G., Rostomyan, T., Sarty, A., Schott, D.M., Schumann, S., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strandberg, B., Strakovsky, I.I., Strub, Th., Supek, I., Taragin, M.F., Thiel, A., Thiel, M., Tiator, L., Thomas, A., Unverzagt, M., Wagner, S., Watts, D.P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., Workman, R.L., and Zana, L.
- Subjects
ddc:550 - Abstract
The reactions γp → ηp and γp → η0\ud p are measured from their thresholds up to the center-of-mass\ud energy W ¼ 1.96 GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross\ud sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full\ud production-angle coverage. A strong cusp is observed in the total cross section for η photoproduction at the\ud energies in the vicinity of the η0 threshold, W ¼ 1896 MeV (Eγ ¼ 1447 MeV). Within the framework of a\ud revised ηMAID isobar model, the cusp, in connection with a steep rise of the η0 total cross section from its\ud threshold, can only be explained by a strong coupling of the poorly known Nð1895Þ1=2− state to both ηp\ud and η0\ud p. Including the new high-accuracy results in the ηMAID fit to available η and η0 photoproduction\ud data allows the determination of the Nð1895Þ1=2− properties.
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- 2017
- Full Text
- View/download PDF
128. Determination of the scalar polarizabilities of the proton using beam asymmetry Σ3 in Compton scattering
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Sokhoyan, V., Downie, E. J., Mornacchi, E., McGovern, J. A., Krupina, N., Afzal, F., Ahrens, J., Akondi, C. S., Annand, J. R. M., Arends, H. J., Beck, R., Braghieri, A., Briscoe, W. J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Ferretti, M., Gardner, S., Garni, S., Glazier, D. I., Glowa, D., Gradl, W., Gurevich, G., Hamilton, D., Hornidge, D., Huber, G. M., Käser, A., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lensky, V., Linturi, J., Lisin, V., Livingston, K., MacGregor, I.J.D., Macrae, R., Manley, D. M., Martel, P. P., Middleton, D. G., Miskimen, R., Mushkarenkov, A., Neiser, A., Oberle, M., Ortega Spina, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Rostomyan, T., Sarty, A., Schumann, S., Spieker, K., Steffen, O., Strakovsky, I. I., Strandberg, B., Strub, T., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Wagner, S., Watts, D. P., Wettig, J., Witthauer, L., Werthmüller, D., Wolfes, M., and Zana, L.
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Nuclear Theory ,Physics::Accelerator Physics ,Physics::Atomic Physics ,Nuclear Experiment - Abstract
The scalar dipole polarizabilities, αE1αE1 and βM1βM1 , are fundamental properties related to the internal dynamics of the nucleon. The currently accepted values of the proton polarizabilities were determined by fitting to unpolarized proton Compton scattering cross section data. The measurement of the beam asymmetry Σ3Σ3 in a certain kinematical range provides an alternative approach to the extraction of the scalar polarizabilities. At the Mainz Microtron (MAMI) the beam asymmetry was measured for Compton scattering below pion photoproduction threshold for the first time. The results are compared with model calculations and the influence of the experimental data on the extraction of the scalar polarizabilities is determined.
- Published
- 2017
129. Determination of the scalar polarizabilities of the proton using beam asymmetry Sigma(3) in Compton scattering
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Sokhoyan, V., Downie, E. J., Mornacchi, E., Korolija, M., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Wagner, S., Watts, D. P., Wettig, J., Witthauer, L., Werthmüller, D., Wolfes, M., and Zana, L.
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Nuclear Theory ,TAGGED PHOTON SPECTROMETER ,MAGNETIC POLARIZABILITIES ,NUCLEON POLARIZABILITIES ,POLARIZED PHOTONS ,SPIN 1/2 ,MAINZ ,MAMI ,MICROTRON ,HYDROGEN ,Nuclear Experiment - Abstract
The scalar dipole polarizabilities, alpha(E1) and beta(M1), are fundamental properties related to the internal dynamics of the nucleon. The currently accepted values of the proton polarizabilities were determined by fitting to unpolarized proton Compton scattering cross section data. The measurement of the beam asymmetry Sigma(3) in a certain kinematical range provides an alternative approach to the extraction of the scalar polarizabilities. At the Mainz Microtron (MAMI) the beam asymmetry was measured for Compton scattering below pion photoproduction threshold for the first time. The results are compared with model calculations and the influence of the experimental data on the extraction of the scalar polarizabilities is determined.
- Published
- 2017
130. K+Λ and K+Σ0 photoproduction with fine center-of-mass energy resolution
- Author
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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.
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Nuclear and High Energy Physics - Published
- 2014
- Full Text
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131. First measurement of helicity-dependent cross sections in π0η photoproduction from quasi-free nucleons
- Author
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Käser, A., primary, Dieterle, M., additional, Witthauer, L., additional, Abt, S., additional, Achenbach, P., additional, Adlarson, P., additional, Afzal, F., additional, Ahmed, Z., additional, Ahrens, J., additional, Annand, J.R.M., additional, Arends, H.J., additional, Bashkanov, M., additional, Beck, R., additional, Biroth, M., additional, Borisov, N.S., additional, Braghieri, A., additional, Briscoe, W.J., additional, Cividini, F., additional, Collicott, C., additional, Costanza, S., additional, Denig, A., additional, Downie, E.J., additional, Drexler, P., additional, Fix, A., additional, Garni, S., additional, Glazier, D.I., additional, Gorodnov, I., additional, Gradl, W., additional, Günther, M., additional, Gurevich, G.M., additional, Heijkenskjöld, L., additional, Hornidge, D., additional, Huber, G.M., additional, Kashevarov, V.L., additional, Kay, S., additional, Keshelashvili, I., additional, Kondratiev, R., additional, Korolija, M., additional, Krusche, B., additional, Lazarev, A.B., additional, Lisin, V., additional, Livingston, K., additional, Lutterer, S., additional, MacGregor, I.J.D., additional, Manley, D.M., additional, Martel, P.P., additional, Metag, V., additional, Meyer, W., additional, Miskimen, R., additional, Mornacchi, E., additional, Mushkarenkov, A., additional, Neganov, A.B., additional, Neiser, A., additional, Oberle, M., additional, Ostrick, M., additional, Otte, P.B., additional, Paudyal, D., additional, Pedroni, P., additional, Polonski, A., additional, Prakhov, S.N., additional, Reicherz, G., additional, Ron, G., additional, Rostomyan, T., additional, Sarty, A., additional, Sfienti, C., additional, Sokhoyan, V., additional, Spieker, K., additional, Steffen, O., additional, Strakovsky, I.I., additional, Strub, Th., additional, Supek, I., additional, Thiel, A., additional, Thiel, M., additional, Thomas, A., additional, Unverzagt, M., additional, Usov, Yu.A., additional, Wagner, S., additional, Walford, N.K., additional, Watts, D.P., additional, Werthmüller, D., additional, Wettig, J., additional, Wolfes, M., additional, and Zana, L., additional
- Published
- 2018
- Full Text
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132. First measurement of the helicity dependence of 3He photoreactions in the Δ(1232) resonance region
- Author
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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, G., 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, M., Rosner, G., Rostomyan, T., Schumann, S., Sober, D., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Watts, D., and Werthmüller, D.
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Nuclear and High Energy Physics - Published
- 2013
- Full Text
- View/download PDF
133. Photon asymmetry measurements of γp → π0p for\ud Eγ = 320–650 MeV
- Author
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Gardner, S., Howdle, D., Sikora, M.H., Wunderlich, Y., Abt, S., Achenbach, P., Afzal, F., Aguar-Bartolome, P., Ahmed, Z., Annand, J.R.M., Arends, H.J., Bantawa, K., Bashkanov, M., Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cherepnya, S., Cividini, F., Costanza, S., Collicott, C., Demissie, B.T., Denig, A., Dieterle, M., Downie, E.J., Drexler, P., Ferretti-Bondy, M.I., Filkov, L.V., Glazier, D.I., Garni, S., Gradl, W., Günther, M., Gurevich, G.M., Hall Barrientos, P., Hamilton, D., Heid, E., Hornidge, D., Huber, G.M., Jahn, O., Jude, T.C., Käser, A., Kay, S., Kashevarov, V.L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Linturi, J.M., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I.J.D., Macrae, R., Mancell, J., Manley, D.M., Martel, P.P., McGeorge, J.C., McNicoll, E.F., Middleton, D.G., Miskimen, R., Mullen, C., Mushkarenkov, A., Neganov, A.B., Neiser, A., Nikolaev, A., Oberle, M., Ostrick, M., Owens, R.O., Otte, P.B., Oussena, B., Paudyall, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Robinson, J., Rosner, G., Rostomyan, T., Sarty, A., Schumann, S., Sokhoyan, V., Spieker, K., Steffen, O., Sfienti, C., Strakovsky, I.I., Strandberg, B., Strub, Th., Supek, I., Tarbert, C.M., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu.A., Watts, D.P., Werthümller, D., Wettig, J., Wolfes, M., Witthauer, L., and Zana, L.
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Nuclear Theory ,Nuclear Experiment - Abstract
High-statistics measurements of the photon asymmetry Σ for the γp → π0p reaction have been\ud made in the center-of-mass energy range W = 1214–1450 MeV. The data were measured with the MAMI\ud A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The results significantly\ud improve the existing world data and are shown to be in good agreement with previous measurements, and\ud with the MAID, SAID, and Bonn-Gatchina predictions. We have also combined the photon asymmetry\ud results with recent cross-section measurements from Mainz to calculate the profile functions, Σˇ (= σ0Σ), and perform a moment analysis. Comparison with calculations from the Bonn-Gatchina model shows\ud that the precision of the data is good enough to further constrain the higher partial waves, and there\ud is an indication of interference between the very small F-waves and the N(1520)3/2− and N(1535)1/2−\ud resonances.
- Published
- 2016
134. Insight into the narrow structure in η-photoproduction on the neutron from helicity\ud dependent cross sections
- Author
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Witthauer, L., Dieterle, M., Abt, S., Achenbach, P., Afzal, F, Ahmed, Z., Annand, J.R.M., Arends, H.J., Bashkanov, M, Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cividini, F., Costanza, S., Collicott, C., Denig, A., Downie, E.J., Drexler, P., Ferretti-Bondy, M.I., Gardner, S., Garni, S., Glazier, D.I., Glowa, D., Gradl, W., Günther, M., Gurevich, G.M., Hamilton, D., Hornidge, D., Huber, G.M., Käser, A., Kashevarov, V.L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A.B., Linturi, J.M., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I.J.D., Mancell, J., Manley, D.M., Martel, P.P., Metag, V., Meyer, W., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Neganov, A.B., Neiser, A., Oberle, M., Ostrick, M., Otte, P.B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S.N., Rajabi, A., Reicherz, G., Ron, G, Rostomyan, T., Sarty, A., Sfienti, C., Sikora, M.H., Sokhoyan, V., Spieker, K., Steffen, O., Strakovski, I.I., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N.K., Watts, D.P., Werthmüller, D., Wettig, J., Wolfes, M., and Zana, L.
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Nuclear Theory ,Nuclear Experiment - Abstract
The double polarization observable E and the helicity dependent cross sections σ1/2 and σ3/2 were measured for η photoproduction from quasifree protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost 4π detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from η→2γ and η→3π0. The results show that the narrow structure previously observed in η photoproduction from the neutron is only apparent in σ1/2 and hence, most likely related to a spin-1/2 amplitude. Nucleon resonances that contribute to this partial wave in η production are only N1/2− (S11) and N 1/2+ (P11). Furthermore, the extracted Legendre coefficients of the angular distributions for σ1/2 are in good agreement with recent reaction model predictions assuming a narrow resonance in the P11 wave as the origin of this structure.
- Published
- 2016
135. Insight into the Narrow Structure in eta Photoproduction on the Neutron from Helicity-Dependent Cross Sections
- Author
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Witthauer, L., Dieterle, M., Achenbach, S. Abt P., Afzal, F., Ahmed, Z., Annand, J. R. M., Arends, H. J., Bashkanov, M., Beck, R., Biroth, M., Borisov, N. S., Braghieri, A., Briscoe, W. J., Cividini, F., Costanza, S., Collicott, C., Denig, A., Downie, E. J., Drexler, P., Ferretti-Bondy, M. I., Gardner, S., Garni, S., Glazier, D. I., Glowa, D., Gradl, W., Gunther, M., Gurevich, G. M., Hamilton, D., Hornidge, D., Huber, G. M., Kaser, A., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lazarev, A. B., Linturi, J. M., Lisin, V., Lutterer, S., MacGregor, I. J. D., Mancell, J., Manley, D. M., Martel, P. P., Metag, V., Meyer, W., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Neganov, A. B., Neiser, A., Oberle, M., Ostrick, M., Otte, P. B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S. N., Rajabi, A., Reicherz, G., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sikora, M. H., Sokhoyan, V., Spieker, K., Steffen, O., Strakovski, I. I., Strub, Th., Supek, I., Thiel, A., Thiel, M., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N. K., Watts, D. P., Werthmuller, D., Wettig, J., Wolfes, M., and Zana, L.
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PHOTON ,Nuclear Theory ,RESONANCE ,Nuclear Experiment ,MESONS - Abstract
The double polarization observable E and the helicity dependent cross sections sigma(1/2) and sigma(3/2) were measured for eta photoproduction from quasifree protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost 4 pi detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from eta -> 2 gamma and eta -> 3 pi(0). The results show that the narrow structure previously observed in eta photoproduction from the neutron is only apparent in sigma(1/2) and hence, most likely related to a spin-1/2 amplitude. Nucleon resonances that contribute to this partial wave in eta production are only N1/2(-) (S-11) and N1/2(+) (P-11). Furthermore, the extracted Legendre coefficients of the angular distributions for sigma(1/2) are in good agreement with recent reaction model predictions assuming a narrow resonance in the P-11 wave as the origin of this structure.
- Published
- 2016
- Full Text
- View/download PDF
136. Photoproduction of ηπ pairs off nucleons and deuterons
- Author
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Käser, A., Müller, F., Ahrens, J., Annand, J. R.M., Arends, H. J., Bantawa, K., Bartolome, P. A., Beck, R., Braghieri, A., Briscoe, W. J., Cherepnya, S., Costanza, S., Dieterle, M., Downie, E. J., Drexler, P., Fil’kov, L. V., Fix, A., Garni, S., Glazier, D. I., Hamilton, D., Hornidge, D., Howdle, D., Huber, G. M., Jaegle, I., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J.D., Maghrbi, Y., Mancell, J., Manley, D. M., Marinides, Z., McGeorge, J. C., McNicoll, E., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D. G., Mushkarenkov, A., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Otte, P., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D., Starostin, A., Strub, Th, Supek, I., Thiel, M., Unverzagt, M., Walford, N. K., Watts, D. P., Werthmüller, D., and Witthauer, L.
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Nuclear Theory ,Nuclear Experiment - Abstract
Quasi-free photoproduction of πη-pairs has been investigated from threshold up to incident photon energies of 1.4 GeV, respectively up to photon-nucleon invariant masses up to 1.9 GeV. Total cross sections, angular distributions, invariant-mass distributions of the πη and meson-nucleon pairs, and beamhelicity asymmetries have been measured for the reactions γp → pπ0η, γn → nπ0η, γp → nπ+η, and γn → pπ-n from nucleons bound inside the deuteron. For the γp initial-state data for free protons have also been analyzed. Finally, the total cross sections for quasi-free production of π0η pairs from nucleons bound in 3He nuclei have been investigated in view of final state interaction (FSI) effects. The experiments were performed at the tagged photon beam facility of the Mainz MAMI accelerator using an almost 4π covering electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. The shapes of all differential cross section data and the asymmetries are very similar for protons and neutrons and agree with the conjecture that the reactions are dominated by the sequential Δ*3/2- → ηΔ(1232) → πηN decay chain, mainly with Δ(1700)3/2- and Δ(1940)3/2-. The ratios of the magnitude of the total cross sections also agree with this assumption. However, the absolute magnitudes of the cross sections are reduced by FSI effects with respect to free proton data.
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- 2016
137. T and F asymmetries in pi(0) photoproduction on the proton
- Author
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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. 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. P., McNicoll, E. F., Meyer, W., Middleton, D. G., 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, Th., Supek, I., Tiator, L., Thomas, A., Unverzagt, M., Usov, Yu. A., Watts, D. P., Werthmuller, D., Witthauer, L., and Wolfes, M.
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polarized target asymmetry ,neutral pion-photoproduction ,tagged photon spectrometer ,gamma-p ,mami ,microtron ,taps ,Physics::Accelerator Physics ,Nuclear Experiment - Abstract
The γp→π0p reaction was studied at laboratory photon energies from 425 to 1445 MeV with a transversely polarized target and a longitudinally polarized beam. The beam-target asymmetry F was measured for the first time and new high precision data for the target asymmetry T were obtained. The experiment was performed at the photon tagging facility of the Mainz Microtron (MAMI) using the Crystal Ball and TAPS photon spectrometers. The polarized cross sections were expanded in terms of associated Legendre functions and compared to recent predictions from several partial-wave analyses. The impact of the new data on our understanding of the underlying partial-wave amplitudes and baryon resonance contributions is discussed.
- Published
- 2016
138. Photon asymmetry measurements of $\overrightarrow�� \mathrm{p} \rightarrow ��^{0} \mathrm{p}$ for E$_��$=320$-$650 MeV
- Author
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Gardner, S., Howdle, D., Sikora, M. H., Wunderlich, Y., Abt, S., Achenbach, P., Afzal, F., Aguar-Bartolome, P., Ahmed, Z., Annand, J. R. M., Arends, H. J., Bantawa, K., Bashkanov, M., Beck, R., Biroth, M., Borisov, N. S., Braghieri, A., Briscoe, W. J., Cherepnya, S., Cividini, F., Costanza, S., Collicott, C., Demissie, B. T., Denig, A., Dieterle, M., Downie, E. J., Drexler, P., Ferretti-Bondy, M. I., Filkov, L. V., Glazier, D. I., Garni, S., Gradl, W., G��nther, M., Gurevich, G. M., Hamilton, D., Heid, E., Hornidge, D., Huber, G. M., Jahn, O., Jude, T. C., K��ser, A., Kay, S., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Linturi, J. M., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I. J. D., Macrae, R., Mancell, J., Manley, D. M., Martel, P. P., McGeorge, J. C., McNicoll, E. F., Middleton, D. G., Miskimen, R., Mullen, C., Mushkarenkov, A., Neganov, A. B., Neiser, A., Nikolaev, A., Oberle, M., Ostrick, M., Owens, R. O., Otte, P. B., Oussena, B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Robinson, J., Rosner, G., Rostomyan, T., Sarty, A., Schumann, S., Sokhoyan, V., Spieker, K., Steffen, O., Sfienti, C., Strakovsky, I. I., Strandberg, B., Strub, Th., Supek, I., Tarbert, C. M., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Watts, D. P., Werthm��ller, D., Wettig, J., Wolfes, M., Witthauer, L., and Zana, L.
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FOS: Physical sciences ,Nuclear Experiment (nucl-ex) ,Nuclear Experiment - Abstract
High statistics measurements of the photon asymmetry $\mathrm��$ for the $\overrightarrow��$p$\rightarrow��^{0}$p reaction have been made in the center of mass energy range W=1214-1450 MeV. The data were measured with the MAMI A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The results significantly improve the existing world data and are shown to be in good agreement with previous measurements, and with the MAID, SAID, and Bonn-Gatchina predictions. We have also combined the photon asymmetry results with recent cross-section measurements from Mainz to calculate the profile functions, $\check{\mathrm��}$ (= $��_{0}\mathrm��$), and perform a moment analysis. Comparison with calculations from the Bonn-Gatchina model shows that the precision of the data is good enough to further constrain the higher partial waves, and there is an indication of interference between the very small $F$-waves and the $N(1520) 3/2^{-}$ and $N(1535) 1/2^{-}$ resonances.
- Published
- 2016
- Full Text
- View/download PDF
139. T and F asymmetries in π0 photoproduction on the proton
- Author
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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., Hall Barrientos, P., 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.P., McNicoll, E.F., Meyer, W., Middleton, D.G., 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, Th., Supek, I., Tiator, L., Thomas, A., Unverzagt, M., Usov, Yu.A., Watts, D.P., Werthmüller, D., Witthauer, L., Wolfes, M., and Ortega Spina, Henry G. Universidad de la República (Uruguay). Facultad de Ciencias. Instituto de Física
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Photoproduction ,Physics::Accelerator Physics ,Nuclear Experiment ,Resonance ,Η photoproduction ,QC - Abstract
The γp→π0p reaction was studied at laboratory photon energies from 425 to 1445 MeV with a transversely polarized target and a longitudinally polarized beam. The beam-target asymmetry F was measured for the first time and new high precision data for the target asymmetry T were obtained. The experiment was performed at the photon tagging facility of the Mainz Microtron (MAMI) using the Crystal Ball and TAPS photon spectrometers. The polarized cross sections were expanded in terms of associated Legendre functions and compared to recent predictions from several partial-wave analyses. The impact of the new data on our understanding of the underlying partial-wave amplitudes and baryon resonance contributions is discussed.
- Published
- 2016
140. Wirklichkeit und Freiheit im Lichte von Heisenbergs Revolution
- Author
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Supek, I. and Dürr, Herausgeber H. P., editor
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- 1971
- Full Text
- View/download PDF
141. The isospin structure of photoproduction of πη pairs from the nucleon in the threshold region
- Author
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Käser, A., Ahrens, J., Annand, J.R.M., Arends, H.J., Bantawa, K., Bartolome, P.A., Beck, R., Bekrenev, V., Berghäuser, H., 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., Jahn, O., Jaegle, I., Jude, T.C., Kashevarov, V.L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kruglov, S.P., Krusche, B., Lisin, V., Livingston, K., MacGregor, I.J.D., Maghrbi, Y., Mancell, J., Manley, D.M., Marinides, Z., McGeorge, J.C., McNicoll, E., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D.G., Mushkarenkov, A., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Otte, P., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S.N., Robinson, J., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M.H., Sober, D.I., Starostin, A., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Watts, D.P., Werthmüller, D., and Witthauer, L.
- Published
- 2015
- Full Text
- View/download PDF
142. First measurement of the polarization observable E and helicity-dependent cross sections in single π0 photoproduction from quasi-free nucleons
- Author
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Dieterle, M., primary, Witthauer, L., additional, Cividini, F., additional, Abt, S., additional, Achenbach, P., additional, Adlarson, P., additional, Afzal, F., additional, Ahmed, Z., additional, Akondi, C.S., additional, Annand, J.R.M., additional, Arends, H.J., additional, Bashkanov, M., additional, Beck, R., additional, Biroth, M., additional, Borisov, N.S., additional, Braghieri, A., additional, Briscoe, W.J., additional, Costanza, S., additional, Collicott, C., additional, Denig, A., additional, Downie, E.J., additional, Drexler, P., additional, Ferretti-Bondy, M.I., additional, Gardner, S., additional, Garni, S., additional, Glazier, D.I., additional, Glowa, D., additional, Gradl, W., additional, Günther, M., additional, Gurevich, G.M., additional, Hamilton, D., additional, Hornidge, D., additional, Huber, G.M., additional, Käser, A., additional, Kashevarov, V.L., additional, Kay, S., additional, Keshelashvili, I., additional, Kondratiev, R., additional, Korolija, M., additional, Krusche, B., additional, Lazarev, A.B., additional, Linturi, J.M., additional, Lisin, V., additional, Livingston, K., additional, Lutterer, S., additional, MacGregor, I.J.D., additional, Mancell, J., additional, Manley, D.M., additional, Martel, P.P., additional, Metag, V., additional, Meyer, W., additional, Miskimen, R., additional, Mornacchi, E., additional, Mushkarenkov, A., additional, Neganov, A.B., additional, Neiser, A., additional, Oberle, M., additional, Ostrick, M., additional, Otte, P.B., additional, Paudyal, D., additional, Pedroni, P., additional, Polonski, A., additional, Prakhov, S.N., additional, Rajabi, A., additional, Reicherz, G., additional, Ron, G., additional, Rostomyan, T., additional, Sarty, A., additional, Sfienti, C., additional, Sikora, M.H., additional, Sokhoyan, V., additional, Spieker, K., additional, Steffen, O., additional, Strakovsky, I.I., additional, Strub, Th., additional, Supek, I., additional, Thiel, A., additional, Thiel, M., additional, Thomas, A., additional, Unverzagt, M., additional, Usov, Yu.A., additional, Wagner, S., additional, Walford, N.K., additional, Watts, D.P., additional, Werthmüller, D., additional, Wettig, J., additional, Wolfes, M., additional, and Zana, L., additional
- Published
- 2017
- Full Text
- View/download PDF
143. PEN: a low energy test of lepton universality
- Author
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Pocanic, Dinko, primary, Alonzi, L.P., additional, Baranov, V., additional, Bertl, W., additional, Bychkov, M., additional, Bystritsky, Yu.M., additional, Frlez, E., additional, Glaser, C.J., 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, Mzhavia, D., additional, Palladino, A., additional, Robmann, P., additional, Rozhdestvensky, A.M., additional, Supek, I., additional, Truoel, P., additional, Van der Schaaf, Andries, additional, Velicheva, E.P., additional, Vitz, M.G., additional, and Volnykh, V.P., additional
- Published
- 2017
- Full Text
- View/download PDF
144. Photoproduction of π0-pairs off protons and off neutrons
- Author
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Dieterle, M., Oberle, M., Ahrens, J., Annand, J. R. M>, Arends, H. J., Bantawa, K., Bartolome, P. A., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Costanza, S., Demissie, B., Downie, E. J., Drexler, P., Fil’kov, L. V., Fix, A., Garni, S., Glazier, D. I., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Huber, G. M., Jahn, O., Jude, T. C., Käser, A., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Mancell, J., Manley, D. M., Marinides, Z., McGeorge, J. C., McNicoll, E., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D. G., Mushkarenkov, A., Nikolaev, A., Novotny, R., Ostrick, M., Otte, P., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strub, Th., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Walford, N. K., Watts, D. P., Werthmüller, D., and Witthauer, L.
- Subjects
Nuclear Theory ,Nuclear Experiment - Abstract
Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of π0π0 pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final-state invariant masses up to ≈1550 MeV), where both reactions are dominated by the N(1520)3/2−→Δ(1232)3/2+π decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an N⋆→Nσ decay for the proton, while the reaction is dominated by a sequential decay via a Δπ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.
- Published
- 2015
145. Measurement of π0 photoproduction on the proton at MAMI C
- Author
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Adlarson, P., Afzal, F., Akondi, C. S., Annand, J. R. M., Arends, H. J., Azimov, Ya. I., Beck, R., Borisov, N., Braghieri, A., Briscoe, W. J., Cherepnya, S., Cividini, F., Collicott, C., Costanza, S., Denig, A., Downie, E. J., Dieterle, M., Ferretti Bondy, M. I., Fil'kov, L. V., Fix, A., Gardner, S., Garni, S., Glazier, D. I., Glowa, D., Gradl, W., Gurevich, G., Hamilton, D. J., Hornidge, D., Huber, G. M., Käser, A., Kashevarov, V. L., Kay, S., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Kulikov, V. V., Lazarev, A., Linturi, J., Lisin, V., Livingston, K., MacGregor, I. J. D., Manley, D. M., Martel, P. P., Martemianov, M., McGeorge, J. C., Meyer, W., Middleton, D. G., Miskimen, R., Mushkarenkov, A., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Paudyal, D., Pedroni, P., Polonski, A., Polyanski, V. V., Prakhov, S., Rajabi, A., Reicherz, G., Ron, G., Rostomyan, T., Sarty, A., Schott, D. M., Schumann, S., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I. I., Strub, Th., Supek, I., Taragin, M. F., Thiel, A., Thiel, M., Tiator, L., Thomas, A., Unverzagt, M., Usov, Yu. A., Wagner, S., Watts, D. P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., Workman, R. L., and Zana, L. A.
- Subjects
Nuclear Experiment - Abstract
Differential cross sections for the γp→π0p reaction have been measured with the A2 tagged-photon facilities at the Mainz Microtron, MAMI C, up to the center-of-mass energy W=1.9GeV. The new results, obtained with a fine energy and angular binning, increase the existing quantity of π0 photoproduction data by ∼47%. Owing to the unprecedented statistical accuracy and the full angular coverage, the results are sensitive to high partial-wave amplitudes. This is demonstrated by the decomposition of the differential cross sections in terms of Legendre polynomials and by further comparison to model predictions. A new solution of the SAID partial-wave analysis obtained after adding the new data into the fit is presented.
- Published
- 2015
146. First measurement of target and beam-target asymmetries in the γp→π0ηp reaction
- Author
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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., Hall Barrientos, P., 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. P., McNicoll, E. F., Meyer, W., Middleton, D. G., 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, Th., Supek, I., Tiator, L., Thomas, A., Unverzagt, M., Usov, Yu. A., Watts, D. P., Werthmüller, D., Witthauer, L., and Wolfes, M.
- Subjects
Physics::Accelerator Physics ,Nuclear Experiment - Abstract
The first data on target and beam-target asymmetries for the γp→π0ηp 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 Δ3/2− amplitude is confirmed. The data are in particular sensitive to small contributions from other partial waves.
- Published
- 2015
147. Photoproduction of the ωmeson on the proton near threshold
- Author
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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
148. First measurement of target and beam-target asymmetries in the $��p\to ��^0��p$ reaction
- Author
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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
- Full Text
- View/download PDF
149. [formula omitted] and [formula omitted] photoproduction with fine center-of-mass energy resolution
- Author
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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
- Full Text
- View/download PDF
150. <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
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