1 / 40

The Graal collaboration

NSTAR 2005 INTERNATIONAL WORKSHOP ON THE PHYSICS OF EXCITED BARYONS 12 - 15 October 2005, Tallahassee, Florida USA. The Graal collaboration. results and prospects Presented by Carlo Schaerf Universit à di Roma “Tor Vergata” and INFN - Sezione Roma II for the Graal collaboration.

dermot
Download Presentation

The Graal collaboration

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. NSTAR 2005 INTERNATIONAL WORKSHOP ON THE PHYSICS OF EXCITED BARYONS 12 - 15 October 2005, Tallahassee, Florida USA The Graal collaboration results and prospects Presented by Carlo Schaerf Università di Roma “Tor Vergata” and INFN - Sezione Roma II for the Graal collaboration NSTAR2005 - Graal collaboration

  2. GRAAL/ESRF LEGS/BNL LEPS/SPRING8 Graal: Eg = 0.6-1.5 GeV / W=1.4-1.9 GeV Region of the second and third baryon resonances h, K, w,h’ thresholds Complementarity of HIGS, LEGS, Graal and LEPS s (mb) Eg(GeV) h’ threshold threshold KL threshold HIGS/FEL/Duke h threshold Ladon beams in the world NSTAR2005 - Graal collaboration

  3. Ladon beams in the world NSTAR2005 - Graal collaboration

  4. Ladon beam polarization The first verification of the polarization of Ladon beams was performed at Frascati with the elastic scattering of the Ladon gamma-ray beam on the 15.1 MeV level of 12C using the small NaI crystal ball (7q x 16f ) of the University of Rome "La Sapienza". The experimental points reproduce very well the (1+cos2f) law expected for a fully polarized beam on a perfect polarization analyser. NSTAR2005 - Graal collaboration

  5. Graal beam energy NSTAR2005 - Graal collaboration

  6. Graal beam energy and thresholds NSTAR2005 - Graal collaboration

  7. Graal beam polarization Absolute value NSTAR2005 - Graal collaboration

  8. Green line UV line Graal beam polarization Theoretical linear polarization of the -ray beam for two laser lines:  =514 nm (green line) and  =351 nm (UV line). The threshold energy of the tagging system is also shown NSTAR2005 - Graal collaboration

  9. Cross section of the BGO ball 15 x 32=480 0 31 1 30 2 29 3 28 4 27 5 26 6 25 7 24 8 23 9 22 10 21 11 20 12 19 13 18 14 17 15 16 The Graal Apparatus NSTAR2005 - Graal collaboration

  10. We have enough data Results have been published and more are coming Preliminary results are available but we want more data We need more data and more efforts on the analysis The Graal Experimental Program NSTAR2005 - Graal collaboration

  11. ≈ 0,3 ns 2.8 ns Time Of Flight resolution Typical experimental Time Of Flight spectrum for the thin monitor versus the tagging counters. The distance between two adjacent peaks is 2.8ns corresponding to the distance between successive electron bunches. The timing resolution is ≈ 0.3ns (FWHM). The level of accidental coincidences in the main peak is less than 0.15%. NSTAR2005 - Graal collaboration

  12. x 2 2  invariant mass spectrum around the 0 mass. Data (closed circles), before and after all kinematical cuts are applied, are compared with the simulation (solid line). The experimental width of the peak is ≈ 33 MeV (FWHM). Two photon spectrum at the 0 mass ≈ 33 MeV FWHM NSTAR2005 - Graal collaboration

  13. Yields as a function of  for one value of  and E: Vertical polarization; Horizontal polarization; Sum of a and b; The ratio (a-b)/(a+b) The solid line in d presents a fit of the type: The azimuthal distribution in  NSTAR2005 - Graal collaboration

  14. S Eg=900 MeV Eg=865 MeV Eg=830 MeV Eg=965 MeV Eg=995 MeV Eg=930 MeV Eg=1025 MeV Eg=1055 MeV Eg=1090 MeV Green-UVdata comparison Comparison of the data obtained with the Green laser line and the UV. The different laser lines produce -ray spectra with different intensities and polarizations. NSTAR2005 - Graal collaboration

  15. • Graal o Erevan SAID-FA04 Erevan  + Bonn d MAID2005 Bonn dGraal  Bonn2005 N + N + K + KGraal   + p  p+ 0  Asymmetry NSTAR2005 - Graal collaboration

  16. SAID-FA04 MAID2005 Bonn2005  + p  p+ 0 Differential cross section L.E. • Graal * Bonn NSTAR2005 - Graal collaboration

  17. SAID-FA04 MAID2005 Bonn2005  + p  p+ 0 Differential cross section H.E. NSTAR2005 - Graal collaboration

  18. p°S for free and quasi-free proton Quasi-free proton (uv data) g+ p +(n) -> p°+ p +(n) Quasi-free proton (green) g + p +(n) -> p°+ p +(n) Free proton g+p-> p°+p Said WI00 (free proton) GRAAL data are not included Said FA01 (free proton) GRAAL data up to 1100 MeV are included Preliminary NSTAR2005 - Graal collaboration

  19. po S for quasi free neutron 1/2 L. E. Green Line UV Line Said (free neutron) Maid (free neutron) g + n +(p)->p0+n +(p) Preliminary Error bars: only statistical errors Systematic errors <1.5% NSTAR2005 - Graal collaboration

  20. po S for quasi free neutron 1/2 H. E. Green Line UV Line Said (free neutron) Maid (free neutron) g + n +(p)->p0+n +(p) Preliminary Error bars: only statistical errors Systematic errors <1.5% NSTAR2005 - Graal collaboration

  21. quasi-free proton and quasi-free neutron Comparison of beam asymmetry S for po photo-production on low energy bins Quasi-free proton Quasi-Free neutron Preliminary NSTAR2005 - Graal collaboration

  22. quasi-free proton and quasi-free neutron Comparison of beam asymmetry S for po photo-production on high energy bins Quasi-free proton Quasi-Free neutron Preliminary NSTAR2005 - Graal collaboration

  23.  invariant mass before kinematical cuts after cuts 59 MeV FWHM hfrom neutron hfrom proton • Mass after Cuts with simulation hMass (GeV) hMass (GeV) NSTAR2005 - Graal collaboration

  24. hAzimuthal Distribution: g+p+(n)->h+p+(n) g+n+(p)->h+n+(p) fh NSTAR2005 - Graal collaboration

  25. h  for quasi free proton: Gr vs UV Green Line UV Line Maid Said-BO12 S for the g+p+(n)->h+p+(n) Error bars: only statistical errors Preliminary NSTAR2005 - Graal collaboration

  26. h for free and quasi-free proton Quasi-free proton g + p + (n) -> h + p + (n) Free proton g + p -> h + p Said-BO12 (free proton) Maid (free proton) Preliminary qcm (deg) NSTAR2005 - Graal collaboration

  27. quasi-free proton and quasi-free neutron Comparison of S of h photoproduction on Quasi-free proton g+p+(n)->h+p+(n) Quasi-Free neutron g+n+(p)->h+n+(p) Preliminary NSTAR2005 - Graal collaboration

  28. Summary of results • First results have been obtained on the analysis of theh andpo photoproduction on thequasi-freeproton and neutron on a deuteron target: • differences in the behaviour start to appear at E=1 GeV. • Results show: • h photoproduction: qfp and free proton similar behavior • qfn and qfpsimilar behaviorup to 1.2 GeV • po photoproduction: qfp and free proton similar behavior • qfn and qfpdifferent behaviour at higher energy bins: NO change of sign for the neutron NSTAR2005 - Graal collaboration

  29. Asymmetry S in g+p  K+ L Preliminary NSTAR2005 - Graal collaboration

  30. Asymmetry S in g+p  K++ S Preliminary NSTAR2005 - Graal collaboration

  31. L Polarization in g+p  K+ L Preliminary NSTAR2005 - Graal collaboration

  32. S Polarization in g+p  K+ S0 Preliminary NSTAR2005 - Graal collaboration

  33. Invariant mass:  n vs  p. Neutron in Forward Detector Preliminary NSTAR2005 - Graal collaboration

  34. Invariant n mass (FDvsBGO) nLab> 25° Dashed Line Neutron in the Forward Detector nLab< 25° Solid Line Neutron in the BGO nLab> 25° Preliminary nLab< 25° NSTAR2005 - Graal collaboration

  35. Vacuum-Assisted Photoionization NSTAR2005 - Graal collaboration

  36. Green laser line UV laser lines Light Speed Anisotropy 1/5 A typical accuracy of 0.03 microstrip (= 9 ) is obtained for the position of a given line, corresponding to 0.2 MeV. Microstrip channels: 1 channel = 0.3 mm NSTAR2005 - Graal collaboration

  37. Light Speed Anisotropy 2/5 Our “absolute” velocities Rotation of the earth around its axis ≈0.32 km/s (Grenoble) Revolution of the earth around the sun ≈ 30 km/s Velocity of the Solar System in the Galaxy ≈ 215 km/s Velocity of the Local Group of Galaxies ≈ 600 km/s Motion relative to the Last Scattering Surface ≈ 370 km/s (Velocity of light: c = 299 792 km/s) NSTAR2005 - Graal collaboration

  38. Light Speed Anisotropy 3/5 0.1 div = 30 m NSTAR2005 - Graal collaboration

  39. Light Speed Anisotropy 4/5 0.001 div = 0,3 m NSTAR2005 - Graal collaboration

  40. The Graal beam line has been used also for some measurements of more fundamental physics. The most interesting result is a “Probe of the Light Speed Anisotropy With Respect to the Cosmic Microwave Background Radiation Dipole” . This measurement has been made possible by the high stability of the ESRF machine and the very good reproducibility of the Graal gamma-ray spectra. Many years of data have been used to plot the maximum gamma-ray energy as a function of the orientation of the Graal-ESRF interaction region with respect to the absolute direction of the Cosmic Microwave Background Radiation Dipole. Our result sets an upper limit on the anisotropy of the velocity of light of: This limit is two-three orders of magnitude better than the one obtained from measurements involving space probes. Mod. Phys. Lett. A 20, N. 1, 19-28 (2005) Light Speed Anisotropy 5/5 NSTAR2005 - Graal collaboration

More Related