Photoproduction of -pairs off protons and off neutrons

M. Dieterle, M. Oberle, J. Ahrens, J. R.M. Annand, H. J. Arends, K. Bantawa, P. A. Bartolome, R. Beck, V. Bekrenev, H. Berghäuser, A. Braghieri, D. Branford, W. J. Briscoe, J. Brudvik, S. Cherepnya, S. Costanza, B. Demissie, E. J. Downie, P. Drexler, L. V. Fil’kov & 31 others A. Fix, S. Garni, D. I. Glazier, D. Hamilton, E. Heid, D. Hornidge, D. Howdle, G. M. Huber, O. Jahn, T. C. Jude, A. Käser, V. L. Kashevarov, I. Keshelashvili, R. Kondratiev, M. Korolija, B. Krusche, V. Lisin, K. Livingston, I. J.D. MacGregor, Y. Maghrbi, J. Mancell, D. M. Manley, Z. Marinides, J. C. McGeorge, E. McNicoll, D. Mekterovic, V. Metag, S. Micanovic, D. G. Middleton, A. Mushkarenkov, The A2 Collaboration

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $ \pi^{0}\pi^{0}$ 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 $ \approx 1550$ MeV), where both reactions are dominated by the $ N(1520)3/2^{-} \rightarrow \Delta(1232)3/2^{+}\pi$ 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^{\star}\rightarrow N\sigma$ decay for the proton, while the reaction is dominated by a sequential decay via a $ \Delta\pi$ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.

Original languageEnglish
Article number142
JournalEuropean Physical Journal A
Volume51
Issue number11
DOIs
Publication statusPublished - 1 Nov 2015

Fingerprint

photoproduction
mass distribution
neutrons
protons
decay
accelerators
angular distribution
cross sections
photon beams
radiators
nucleons
bremsstrahlung
marking
deuterons
balls
foils
pions
electron beams
spectrometers
stars

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

Dieterle, M., Oberle, M., Ahrens, J., Annand, J. R. M., Arends, H. J., Bantawa, K., ... The A2 Collaboration (2015). Photoproduction of -pairs off protons and off neutrons. European Physical Journal A, 51(11), [142]. https://doi.org/10.1140/epja/i2015-15142-8

Photoproduction of -pairs off protons and off neutrons. / 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.; The A2 Collaboration.

In: European Physical Journal A, Vol. 51, No. 11, 142, 01.11.2015.

Research output: Contribution to journalArticle

Dieterle, M, Oberle, M, Ahrens, J, Annand, JRM, Arends, HJ, Bantawa, K, Bartolome, PA, Beck, R, Bekrenev, V, Berghäuser, H, Braghieri, A, Branford, D, Briscoe, WJ, Brudvik, J, Cherepnya, S, Costanza, S, Demissie, B, Downie, EJ, Drexler, P, Fil’kov, LV, Fix, A, Garni, S, Glazier, DI, Hamilton, D, Heid, E, Hornidge, D, Howdle, D, Huber, GM, Jahn, O, Jude, TC, Käser, A, Kashevarov, VL, Keshelashvili, I, Kondratiev, R, Korolija, M, Krusche, B, Lisin, V, Livingston, K, MacGregor, IJD, Maghrbi, Y, Mancell, J, Manley, DM, Marinides, Z, McGeorge, JC, McNicoll, E, Mekterovic, D, Metag, V, Micanovic, S, Middleton, DG, Mushkarenkov, A & The A2 Collaboration 2015, 'Photoproduction of -pairs off protons and off neutrons', European Physical Journal A, vol. 51, no. 11, 142. https://doi.org/10.1140/epja/i2015-15142-8
Dieterle M, Oberle M, Ahrens J, Annand JRM, Arends HJ, Bantawa K et al. Photoproduction of -pairs off protons and off neutrons. European Physical Journal A. 2015 Nov 1;51(11). 142. https://doi.org/10.1140/epja/i2015-15142-8
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. ; The A2 Collaboration. / Photoproduction of -pairs off protons and off neutrons. In: European Physical Journal A. 2015 ; Vol. 51, No. 11.
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abstract = "Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $ \pi^{0}\pi^{0}$ 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 $ \approx 1550$ MeV), where both reactions are dominated by the $ N(1520)3/2^{-} \rightarrow \Delta(1232)3/2^{+}\pi$ 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^{\star}\rightarrow N\sigma$ decay for the proton, while the reaction is dominated by a sequential decay via a $ \Delta\pi$ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.",
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T1 - Photoproduction of -pairs off protons and off neutrons

AU - Dieterle, M.

AU - Oberle, M.

AU - Ahrens, J.

AU - Annand, J. R.M.

AU - Arends, H. J.

AU - Bantawa, K.

AU - Bartolome, P. A.

AU - Beck, R.

AU - Bekrenev, V.

AU - Berghäuser, H.

AU - Braghieri, A.

AU - Branford, D.

AU - Briscoe, W. J.

AU - Brudvik, J.

AU - Cherepnya, S.

AU - Costanza, S.

AU - Demissie, B.

AU - Downie, E. J.

AU - Drexler, P.

AU - Fil’kov, L. V.

AU - Fix, A.

AU - Garni, S.

AU - Glazier, D. I.

AU - Hamilton, D.

AU - Heid, E.

AU - Hornidge, D.

AU - Howdle, D.

AU - Huber, G. M.

AU - Jahn, O.

AU - Jude, T. C.

AU - Käser, A.

AU - Kashevarov, V. L.

AU - Keshelashvili, I.

AU - Kondratiev, R.

AU - Korolija, M.

AU - Krusche, B.

AU - Lisin, V.

AU - Livingston, K.

AU - MacGregor, I. J.D.

AU - Maghrbi, Y.

AU - Mancell, J.

AU - Manley, D. M.

AU - Marinides, Z.

AU - McGeorge, J. C.

AU - McNicoll, E.

AU - Mekterovic, D.

AU - Metag, V.

AU - Micanovic, S.

AU - Middleton, D. G.

AU - Mushkarenkov, A.

AU - The A2 Collaboration

PY - 2015/11/1

Y1 - 2015/11/1

N2 - Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $ \pi^{0}\pi^{0}$ 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 $ \approx 1550$ MeV), where both reactions are dominated by the $ N(1520)3/2^{-} \rightarrow \Delta(1232)3/2^{+}\pi$ 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^{\star}\rightarrow N\sigma$ decay for the proton, while the reaction is dominated by a sequential decay via a $ \Delta\pi$ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.

AB - Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $ \pi^{0}\pi^{0}$ 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 $ \approx 1550$ MeV), where both reactions are dominated by the $ N(1520)3/2^{-} \rightarrow \Delta(1232)3/2^{+}\pi$ 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^{\star}\rightarrow N\sigma$ decay for the proton, while the reaction is dominated by a sequential decay via a $ \Delta\pi$ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.

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