Quasifree photoproduction of mesons off protons and neutrons

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

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43 Citations (Scopus)

Abstract

Differential and total cross sections for the quasifree reactions p-p and n- n have been determined at the MAMI-C electron accelerator by using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy tagged with the Glasgow photon tagger. Decay photons of the neutral decay modes -2 and -3Ï€0-6 and coincident recoil nucleons were detected in a combined setup of the Crystal Ball and the TAPS calorimeters. The -production cross sections were measured in coincidence with recoil protons, recoil neutrons, and in an inclusive mode without a condition on recoil nucleons, which allowed a check of the internal consistency of the data. The effects from nuclear Fermi motion were removed by a kinematic reconstruction of the final-state invariant mass and possible nuclear effects on the quasifree cross section were investigated by a comparison of free and quasifree-proton data. The results, which represent a significant improvement in statistical quality compared to previous measurements, agree with the known neutron-to-proton cross-section ratio in the peak of the S11(1535) resonance and confirm a peak in the neutron cross section, which is absent for the proton, at a center-of-mass energy W=(1670±5) MeV with an intrinsic width of 30 MeV.

Original languageEnglish
Article number015205
JournalPhysical Review C - Nuclear Physics
Volume90
Issue number1
DOIs
Publication statusPublished - 25 Jul 2014

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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    Werthmüller, D., Witthauer, L., Keshelashvili, I., Aguar-Bartolomé, P., Ahrens, J., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Costanza, S., Demissie, B., Dieterle, M., Downie, E. J., ... Watts, D. P. (2014). Quasifree photoproduction of mesons off protons and neutrons. Physical Review C - Nuclear Physics, 90(1), [015205]. https://doi.org/10.1103/PhysRevC.90.015205