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V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

Photoproduction of p o h pairs on the proton. Motivation Data analysis - overview - timing - identification of g p → p o h p reaction - tagging efficiency Results - overview - total cross section - invariant mass spectra - angular distributions Summary.

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V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

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  1. Photoproduction of poh pairs on the proton • Motivation • Data analysis - overview - timing - identification of g p →po h preaction - tagging efficiency • Results - overview - total cross section - invariant mass spectra - angular distributions • Summary V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  2. Motivation GRAAL CB@ELSA Horn et al. arXiv:0711.1138.v1 [nucl-ex] (2007) The systematic error of ±20% is not included J. Ajaka et al. PRL, 100, 052003 (2008) Hatched band: uncertainty of g pD(1700) coupling M. Doring, E. Oset, and D. Strotmann, PR, C73, 045209 (2006) Data near threshold on the both pictures: T. Nakabayashi et al. PR, C74, 035202 (2006) g p→D(1700)D33→ D(1232)P33 h V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  3. Motivation a-f are Born terms, N* is S11(1535), (about 10% of the total cross section) g,f are resonance R in intermediate state A. Fix, M. Ostrick, and L. Tiator. EPJ, (2008) submitted, now is available in ArXiv V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  4. Motivation D(1900)S31 ** D(1920)P33 *** D(1930)D35 *** D(1910)P31 **** D(1700)D33 **** D(1905)F35 **** Canonical CMSfor (pN) Helicity CMSfor (pN) Examples: for J=1/2 resonances distribution over f p(HS) is uniform; for J >1/2 resonances cosQ p depends on the ratio a =A3/2 /A1/2 and it is converx at a=1 Obtaining experimental angular distributions for further theoretical interpretation is main goal of the presented work V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  5. Data analysis: overview • - Beam time periods: 7-21 June 2007 and 10-25 July 2007 • electron beam energy: 1508 MeV • beam current: 12 nA (full target) or 25 nA (empty target) • radiator: 10 mm Cu • diameter of collimator: 4 mm • target: LH2 (4.76 cm) • detectors: CB, PID, TAPS • tagger channels: 1-224 (617-1402 MeV) • for analysis are used channels from 1 upto 147 (932-1402 MeV) • trigger: M2+ and CB energy sum > 350 MeV • Total number of raw events selected to be analyzed • JuneJuly • full target 5.78∙108 (~197 h) 4.62∙108 (~160 h) • empty target 1.37∙107 (~10 h) 8.37∙107 (~60 h) • main criteria for event sorting out: • lost synchronization, wrong scaler readout, detector problems • main analysis cuts: time, invariant mass, missing mass V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  6. Data analysis: timing The best channel (no 202) has FWHM ~ 1ns 1, 27, 167 Ch. 28 212, 217 21, 23, 97 29 28 Tagger TDC hits Tagger-PID time (ns) V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  7. Data analysis: timing FWHM 1.8 ns FWHM 1.4 ns Tagger-PID time (ns) Tagger-CB(photons) time (ns) V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  8. Data analysis: reaction identification g p → po(gg) h(gg) p 4 photons, 3 combinations c2 cut po h cut M(gigj ) (MeV) vs M(gkgl) (MeV) V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  9. Data analysis: reaction identification mp MM cut mpo mh 0.932-1 GeV s = 8.6 MeV s = 23 MeV s = 5 MeV 1.0-1.1 GeV s = 10 MeV s = 8.8 MeV s = 24 MeV 1.1-1.2 GeV s = 15 MeV s = 8.9 MeV s = 24 MeV 1.2-1.3 GeV s = 19 MeV s = 8.9 MeV s = 24 MeV 1.3-1.4 GeV s = 23 MeV s = 9.1 MeV s = 25 MeV MM(g, poh) MM(g, poh) M(gg) M(gg) Blue - full target, black - empty target, green - difference, red - simulation V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  10. Data analysis: reaction identification g p → po(gg) h(3po) p 8 photons, 28 combinations c2 minimization c2 cut M(gg) (MeV) vs M(6g) (MeV) V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  11. Data analysis: tagging efficiency June run July run 11764.dat – black 11881.dat – red 11884.dat – green 11943.dat – blue 11982.dat - yellow 12087.dat – black 12183.dat – red 12251.dat – green 12305.dat – blue (empty) Tagging efficiency Tagger channel Tagger channel V.L. Kashevarov, Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  12. Data analysis: tagging efficiency June run Tagger Efficiency runs ± 5 % July run P2/tagger_scalr(224) ± 5 % Number of scaler readout V.L. Kashevarov, Crystal-Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  13. Results: overview Total number of good events after all cuts, subtraction of random coincidences and empty target contribution: h(3po) h(gg) June run 230.500 75.500 July run 187.700 60.500 July run without TAPS 136.000 21.700 GRAAL 57.400 CB@ELSA (0.93-2.5 GeV) 16.500 For total cross sections are used only July run data (both h decay modes) For angular distributions – June and July data ( h to gg decay mode) V.L. Kashevarov, Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  14. Results: total cross sections g p → po h(gg) p open circles – Tohoku 06 green – CB@ELSA 07 blue – GRAAL 08 black – this work red – this work (without TAPS) July run only Statistical errors only Total cross section (mb) g p → po h(3po) p Total cross section without TAPS are by ~25% lower then GRAAL data Photon energy (GeV) V.L. Kashevarov, Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  15. Results: invariant mass spectra blue: experiment red: g p  h D+(1232) simulation green: g p  po S11(1535) simulation 0.932-1 GeV 1.0-1.1 GeV 1.1-1.2 GeV 1.2-1.3 GeV 1.3-1.4 GeV M(pop) M(h p) M(po h) V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  16. Results: angular distributions Blue points: experiment Red curves: best fit 1.2-1.3 GeV • data are corrected • for the detector • efficiency • integral over each • distribution • equals to 1 1.3-1.4 GeV fp /p(HS) fp /p(CS) cosQp (HS) cosQp (CS) • Photon decay amplitudes for D (1700)  N g : • A3/2 / A1/2 = 1.45 (PDG 0.82±0.2, Arndt-96 1.08±0.25) • Branching fractions for D (1700) decay modes: • (1232) h 2.2 %(no PDG value) S11(1535) p 0.1 % (no PDG value) V.L. Kashevarov, Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  17. Results: invariant mass spectra 1.2-1.3 GeV Blue points: experiment Red curves: theory 1.3-1.4 GeV M(pop) M(h p) M(po h) (GeV) - experimental data are corrected for the detector acceptance - integral over each spectrum equals to 1 V.L. Kashevarov, Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  18. Summary > New experimental data for the total cross section, the angular distributions and the invariant mass spectra have presented; > fit the data to Mainz-Tomsk model have resulted the following parameters of the D(1700)D33 resonance: Things to do: > estimate systematic errors; > evaluate uncertainties of the fit; > verify absolute normalization of the total cross section by obtaining the total cross section ofg p → po po p • relation for helicity photon decay amplitudes: • A3/2 / A1/2 = 1.45 • branching fractions for the decay modes: • (1232) h 2.2 % S11(1535) p 0.1 % V.L. Kashevarov, Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  19. g p → p+ h(gg) n Missing mass cut MM(g, p+h) –mn (MeV) M(gg) (MeV) V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  20. g p → p+ h(3po) n Missing mass cut MM(g, p+h) –mn (MeV) M(3po) (MeV) V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

  21. Results: invariant mass spectra blue: experiment red: g p  h D+(1232) simulation green: g p  po S11(1535) simulation 0.932-1 GeV 1.0-1.1 GeV 1.1-1.2 GeV 1.2-1.3 GeV 1.3-1.4 GeV M(pop) M(h p) M(po h) V.L. Kashevarov. Crystal Ball@MAMI Collaboration Meeting, Dubrovnik, 7-9 April 2008

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