Photoproduction of pi(0)-pairs off protons and off neutrons

Dieterle, M. and Oberle, M. and Ahrens, J. and Annand, J. R. M. and Arends, H. J. and Bantawa, K. and Bartolome, P. A. and Beck, R. and Bekrenev, V. and Berghaeuser, H. and Braghieri, A. and Branford, D. and Briscoe, W. J. and Brudvik, J. and Cherepnya, S. and Costanza, S. and Demissie, B. and Downie, E. J. and Drexler, P. and Fil`kov, L. V. and Fix, A. and Garni, S. and Glazier, D. I. and Hamilton, D. and Heid, E. and Hornidge, D. and Howdle, D. and Huber, G. M. and Jahn, O. and Jude, T. C. and Kaeser, A. and Kashevarov, V. L. and Keshelashvili, I. and Kondratiev, R. and Korolija, M. and Krusche, B. and Lisin, V. and Livingston, K. and MacGregor, I. J. D. and Maghrbi, Y. and Mancell, J. and Manley, D. M. and Marinides, Z. and McGeorge, J. C. and McNicoll, E. and Mekterovic, D. and Metag, V. and Micanovic, S. and Middleton, D. G. and Mushkarenkov, A. and Nikolaev, A. and Novotny, R. and Ostrick, M. and Otte, P. and Oussena, B. and Pedroni, P. and Pheron, F. and Polonski, A. and Prakhov, S. and Robinson, J. and Rostomyan, T. and Schumann, S. and Sikora, M. H. and Sober, D. I. and Starostin, A. and Strub, Th. and Supek, I. and Thiel, M. and Thomas, A. and Unverzagt, M. and Walford, N. K. and Watts, D. P. and Werthmueller, D. and Witthauer, L.. (2015) Photoproduction of pi(0)-pairs off protons and off neutrons. The European physical journal A, 51 (11). p. 142.

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Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of 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 MeV), where both reactions are dominated by the 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 decay for the proton, while the reaction is dominated by a sequential decay via a intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.
Faculties and Departments:05 Faculty of Science > Departement Physik > Former Organization Units Physics > Hadronenphysik (Krusche)
UniBasel Contributors:Krusche, Bernd
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:30 Jun 2016 11:01
Deposited On:09 May 2016 08:58

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