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

  • The Crystal Ball at MAMI, TAPS, and A2 Collaborations
  • Y. Maghrbi
  • B. KruscheEmail author
  • J. Ahrens
  • J. R. M. Annand
  • H. J. Arends
  • R. Beck
  • V. Bekrenev
  • B. Boillat
  • A. Braghieri
  • D. Branford
  • W. J. Briscoe
  • J. Brudvik
  • S. Cherepnya
  • R. F. B. Codling
  • E. J. Downie
  • P. Drexler
  • L. V. Fil’kov
  • A. Fix
  • D. I. Glazier
  • R. Gregor
  • E. Heid
  • D. Hornidge
  • I. Jaegle
  • O. Jahn
  • V. L. Kashevarov
  • I. Keshelashvili
  • A. Knezevic
  • R. Kondratiev
  • M. Korolija
  • D. Krambrich
  • M. Lang
  • V. Lisin
  • K. Livingston
  • S. Lugert
  • I. J. D. MacGregor
  • D. M. Manley
  • M. Martinez
  • J. C. McGeorge
  • D. Mekterovic
  • V. Metag
  • B. M. K. Nefkens
  • A. Nikolaev
  • R. Novotny
  • M. Ostrick
  • P. Pedroni
  • F. Pheron
  • A. Polonski
  • S. Prakhov
  • J. W. Price
  • G. Rosner
  • M. Rost
  • T. Rostomyan
  • S. Schadmand
  • S. Schumann
  • D. Sober
  • A. Starostin
  • I. Supek
  • C. M. Tarbert
  • A. Thomas
  • M. Unverzagt
  • D. P. Watts
  • D. Werthmüller
  • F. Zehr
Regular Article - Experimental Physics

Abstract.

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

Keywords

Form Factor Total Cross Section Incident Photon Energy Charge Form Factor Crystal Ball 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© SIF, Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • The Crystal Ball at MAMI, TAPS, and A2 Collaborations
  • Y. Maghrbi
    • 1
  • B. Krusche
    • 1
    Email author
  • J. Ahrens
    • 2
  • J. R. M. Annand
    • 3
  • H. J. Arends
    • 2
  • R. Beck
    • 2
    • 4
  • V. Bekrenev
    • 5
  • B. Boillat
    • 1
  • A. Braghieri
    • 6
  • D. Branford
    • 7
  • W. J. Briscoe
    • 8
  • J. Brudvik
    • 9
  • S. Cherepnya
    • 10
  • R. F. B. Codling
    • 3
  • E. J. Downie
    • 2
    • 3
    • 8
  • P. Drexler
    • 11
  • L. V. Fil’kov
    • 10
  • A. Fix
    • 12
  • D. I. Glazier
    • 7
  • R. Gregor
    • 11
  • E. Heid
    • 2
  • D. Hornidge
    • 13
  • I. Jaegle
    • 1
  • O. Jahn
    • 2
  • V. L. Kashevarov
    • 10
    • 2
  • I. Keshelashvili
    • 1
  • A. Knezevic
    • 14
  • R. Kondratiev
    • 15
  • M. Korolija
    • 14
  • D. Krambrich
    • 2
  • M. Lang
    • 2
    • 4
  • V. Lisin
    • 15
  • K. Livingston
    • 3
  • S. Lugert
    • 11
  • I. J. D. MacGregor
    • 3
  • D. M. Manley
    • 16
  • M. Martinez
    • 2
  • J. C. McGeorge
    • 3
  • D. Mekterovic
    • 14
  • V. Metag
    • 11
  • B. M. K. Nefkens
    • 9
  • A. Nikolaev
    • 2
    • 4
  • R. Novotny
    • 11
  • M. Ostrick
    • 2
  • P. Pedroni
    • 6
  • F. Pheron
    • 1
  • A. Polonski
    • 15
  • S. Prakhov
    • 9
  • J. W. Price
    • 9
  • G. Rosner
    • 3
  • M. Rost
    • 2
  • T. Rostomyan
    • 6
  • S. Schadmand
    • 11
  • S. Schumann
    • 2
    • 4
  • D. Sober
    • 17
  • A. Starostin
    • 9
  • I. Supek
    • 14
  • C. M. Tarbert
    • 7
  • A. Thomas
    • 2
  • M. Unverzagt
    • 2
    • 4
  • D. P. Watts
    • 7
  • D. Werthmüller
    • 1
  • F. Zehr
    • 1
  1. 1.Department of PhysicsUniversity of BaselBaselSwitzerland
  2. 2.Institut für KernphysikUniversity of MainzMainzGermany
  3. 3.School of Physics and AstronomyUniversity of GlasgowGlasgowUK
  4. 4.Helmholtz-Institut für Strahlen- und KernphysikUniversity of BonnBonnGermany
  5. 5.Petersburg Nuclear Physics InstituteGatchinaRussia
  6. 6.INFN, Sezione di PaviaPaviaItaly
  7. 7.School of PhysicsUniversity of EdinburghEdinburghUK
  8. 8.Center for Nuclear StudiesThe George Washington UniversityWashington, DCUSA
  9. 9.University of California Los AngelesLos AngelesUSA
  10. 10.Lebedev Physical InstituteMoscowRussia
  11. 11.II. Physikalisches InstitutUniversity of GiessenGiessenGermany
  12. 12.Laboratory of Mathematical PhysicsTomsk Polytechnic UniversityTomskRussia
  13. 13.Mount Allison UniversitySackvilleCanada
  14. 14.Rudjer Boskovic InstituteZagrebCroatia
  15. 15.Institute for Nuclear ResearchMoscowRussia
  16. 16.Kent State UniversityKentUSA
  17. 17.The Catholic University of AmericaWashington, DCUSA

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