09/10/2005NSTAR Graal collaboration1 The Graal collaboration results and prospects Presented by Carlo Schaerf Università di Roma “Tor Vergata” and INFN - Sezione Roma II for the Graal collaboration NSTAR 2005 INTERNATIONAL WORKSHOP ON THE PHYSICS OF EXCITED BARYONS October 2005, Tallahassee, Florida USA

09/10/2005NSTAR Graal collaboration2 Ladon beams in the world Graal: E  = GeV / W= GeV Region of the second and third baryon resonances , K,   ’ thresholds Complementarity of HIGS, LEGS, Graal and LEPS  ’ threshold  threshold K  threshold LEGS/BNL LEPS/SPRING8  (  b)  threshold GRAAL/ESRF HIGS/FEL/Duke E  (GeV)

09/10/2005NSTAR Graal collaboration3 Ladon beams in the world

09/10/2005NSTAR Graal collaboration4 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 12 C using the small NaI crystal ball (7  x 16  ) of the University of Rome "La Sapienza". The experimental points reproduce very well the (1+cos2  ) law expected for a fully polarized beam on a perfect polarization analyser.

09/10/2005NSTAR Graal collaboration5 Graal beam energy

09/10/2005NSTAR Graal collaboration6 Graal beam energy and thresholds

09/10/2005NSTAR Graal collaboration7 Graal beam polarization Absolute value

09/10/2005NSTAR Graal collaboration8 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 Green lineUV line

09/10/2005NSTAR Graal collaboration9 The Graal Apparatus Cross section of the BGO ball 15 x 32=

09/10/2005NSTAR Graal collaboration10 The Graal Experimental Program 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

09/10/2005NSTAR Graal collaboration11 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 2.8 ns corresponding to the distance between successive electron bunches. The timing resolution is ≈ 0.3 ns (FWHM). The level of accidental coincidences in the main peak is less than 0.15%. 2.8 ns ≈ 0,3 ns

09/10/2005NSTAR Graal collaboration12 Two photon spectrum at the  0 mass 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). x 2 ≈ 33 MeV FWHM

09/10/2005NSTAR Graal collaboration13 The azimuthal distribution in  Yields as a function of  for one value of  and E  : a) Vertical polarization; b) Horizontal polarization; c) Sum of a and b; d) The ratio (a-b)/(a+b) The solid line in d presents a fit of the type:

09/10/2005NSTAR Graal collaboration14 Green-UV data comparison  E  =830 MeV E  =865 MeV E  =900 MeV E  =930 MeV E  =965 MeVE  =995 MeV E  =1025 MeVE  =1055 MeV E  =1090 MeV 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.

09/10/2005NSTAR Graal collaboration15  + p  p+  0  Asymmetry Graal o Erevan SAID-FA04 Erevan  + Bonn d  MAID2005 Bonn d  Graal  Bonn2005  N +  N + K  + K  Graal 

09/10/2005NSTAR Graal collaboration16  + p  p+  0 Differential cross section L.E. Graal * Bonn SAID-FA04 MAID2005 Bonn2005

09/10/2005NSTAR Graal collaboration17  + p  p+  0 Differential cross section H.E. SAID-FA04 MAID2005 Bonn2005

09/10/2005NSTAR Graal collaboration18 Preliminary  + p +(n) ->  + p +(n) Quasi-free proton (uv data) Free proton  +p->  +p Said WI00 (free proton) GRAAL data are not included Said FA01 (free proton) GRAAL data up to 1100 MeV are included  + p +(n) ->  + p +(n) Quasi-free proton (green)   for free and quasi-free proton

09/10/2005NSTAR Graal collaboration19 Error bars: only statistical errors  + n +(p)->  0 +n +(p) Said (free neutron) Maid (free neutron) Green Line UV Line Systematic errors <1.5%    for quasi free neutron 1/2 L. E. Preliminary

09/10/2005NSTAR Graal collaboration20 Error bars: only statistical errors  + n +(p)->  0 +n +(p) Said (free neutron) Maid (free neutron) Green Line UV Line Systematic errors <1.5%    for quasi free neutron 1/2 H. E. Preliminary

09/10/2005NSTAR Graal collaboration21 Quasi-free proton Quasi-Free neutron Preliminary Comparison of beam asymmetry  for   photo-production on quasi-free proton and quasi-free neutron low energy bins

09/10/2005NSTAR Graal collaboration22 Quasi-free proton Quasi-Free neutron Comparison of beam asymmetry  for   photo-production on quasi-free proton and quasi-free neutron high energy bins Preliminary

09/10/2005NSTAR Graal collaboration23 59 MeV FWHM  Mass (GeV)  Mass after Cuts with simulation after cuts before kinematical cuts  from proton  from neutron  invariant mass

09/10/2005NSTAR Graal collaboration24   +p+(n)->  +p+(n)  +n+(p)->  +n+(p)  Azimuthal Distribution:

09/10/2005NSTAR Graal collaboration25  for the  +p+(n)->  +p+(n) Error bars: only statistical errors Said-BO12 Maid  for quasi free proton: Gr vs UV Green Line UV Line Preliminary

09/10/2005NSTAR Graal collaboration26  cm (deg) Preliminary Said-BO12 (free proton) Maid (free proton)  + p + (n) ->  + p + (n) Quasi-free proton Free proton  + p ->  + p   for free and quasi-free proton

09/10/2005NSTAR Graal collaboration27 Comparison of  of  photoproduction on  +p+(n)->  +p+(n) Quasi-free proton Quasi-Free neutron  +n+(p)->  +n+(p) quasi-free proton and quasi-free neutron Preliminary

09/10/2005NSTAR Graal collaboration28 Summary of results  First results have been obtained on the analysis of the  and  o photoproduction on the quasi-free proton and neutron on a deuteron target: differences in the behaviour start to appear at E  =1 GeV. Results show:  photoproduction: qfp and free proton similar behavior qfn and qfp similar behavior up to 1.2 GeV  o photoproduction: qfp and free proton similar behavior qfn and qfp different behaviour at higher energy bins: NO change of sign for the neutron

09/10/2005NSTAR Graal collaboration29 Asymmetry  in  +p  K+  PreliminaryPreliminary

09/10/2005NSTAR Graal collaboration30 Asymmetry  in  +p  K + +   Preliminary

09/10/2005NSTAR Graal collaboration31  Polarization in  +p  K+  Preliminary

09/10/2005NSTAR Graal collaboration32  Polarization in  +p  K+   Preliminary

09/10/2005NSTAR Graal collaboration33 Invariant mass:  n vs  p. Neutron in Forward Detector Preliminary

09/10/2005NSTAR Graal collaboration34 Invariant  n mass (FD vs BGO) Dashed Line Neutron in the Forward Detector  n Lab < 25° Solid Line Neutron in the BGO  n Lab > 25° Preliminary  n Lab < 25°  n Lab > 25°

09/10/2005NSTAR Graal collaboration35 Vacuum-Assisted Photoionization

09/10/2005NSTAR Graal collaboration36 Green laser line UV laser lines A typical accuracy of 0.03 microstrip (= 9  ) is obtained for the position of a given line, corresponding to 0.2 MeV. Light Speed Anisotropy 1/5 Microstrip channels: 1 channel = 0.3 mm

09/10/2005NSTAR Graal collaboration37 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 = km/s)

09/10/2005NSTAR Graal collaboration38 Light Speed Anisotropy 3/5 0.1 div = 30  m

09/10/2005NSTAR Graal collaboration39 Light Speed Anisotropy 4/ div = 0,3  m

09/10/2005NSTAR Graal collaboration40 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, (2005) Light Speed Anisotropy 5/5