1 / 21

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.

teryl
Download Presentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related