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Hadronic Multi-particle Final State Measurements with CLAS at Jefferson Lab

Hadronic Multi-particle Final State Measurements with CLAS at Jefferson Lab. Laird Kramer Florida International University Neutrino Scattering, March 2003. Outline. Overview of CLAS Physics Program Description of CLAS Samples of CLAS data and analysis Future nuclear target experiments

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Hadronic Multi-particle Final State Measurements with CLAS at Jefferson Lab

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  1. Hadronic Multi-particle Final State Measurements with CLAS at Jefferson Lab Laird Kramer Florida International University Neutrino Scattering, March 2003

  2. Outline • Overview of CLAS Physics Program • Description of CLAS • Samples of CLAS data and analysis • Future nuclear target experiments • Conclusions

  3. CLAS: the CEBAF Large Acceptance Spectrometer in Hall B at JLAB • International collaboration of 160 scientists • Physics data taking began end of 1997 • 17 major production runs completed • Wide variety of run conditions: • Electron/photon beams, 0.5<E<6 GeV (polarized) • Targets: 1,2H (including polarized), 3,4He, 12C, 56Fe, etc. • 50 PhD theses underway or completed • More info at http://www.jlab.org/Hall-B

  4. CLAS Physics HighlightsBroad program: over 50 experiments • Physics of excited nucleons (N* program) • Neutron electromagnetic form factor • Polarized structure functions • Deep virtual Compton scattering (GPD’s) • Quark/hadron propagation through nuclei • Semi-inclusive deep inelastic scattering • Exotic meson searches • Elementary hyperon photoproduction • Two-nucleon correlations in light nuclei

  5. Charged particle angles 8° - 144° Neutral particle angles 8° - 70° Momentum resolution ~0.5% (charged) Angular resolution ~0.5 mr (charged) Identification of p, p+/p-, K+/K-, e-/e+

  6. Typical Run Conditions • Luminosity of 1034 cm-2s-1 (LH2 target) • 106 hadronic interactions/second • Up to 4000 Hz event rate • Trigger: single electron • Data transfer rate: up to 20 MByte/s (~ 1 TByte/day) • Acquire 10 – 30 billion triggers/year

  7. Physics of Excited NucleonsN* program • Resonance transition form factors • N-D transition • Second resonance region (e.g. S11) • N-D axial form factor • Quark model ‘missing resonances’ • Can find them in unexplored decay channels? • Models have correct degrees of freedom?

  8. Inclusive scattering in the resonance region

  9. CLAS: ep eX, E = 4 GeV N(1680) N(1520) Q2 (GeV2) N(940) D(1232) W (GeV)

  10. CLAS: ep epX, E = 4 GeV W(GeV) w h po Missing Mass (GeV)

  11. Inclusive ep eX, E = 4 GeV 2 hadrons 2 hadrons 2 hadrons 3 hadrons 4 hadrons

  12. cos(q*) F

  13. N-D transition amplitudes

  14. Quark/Hadron Propagation through Nuclei • Space-time properties of hadronization • Mass, size, pT, n, z, Q2, and flavor dependences of hadron formation lengths • Gluon emission • Transverse momentum broadening • Quark-gluon correlations • Quark energy loss • 6 GeV experiment coming in June 2003 • New collaborators welcome • 11 GeV experiment (in 2010-2012?)

  15. Space-time Picture of Hadronization

  16. Nuclear Quark/Hadron Propagation Experimental Method • Use a range of targets, light to heavy • 1H, 2H, 14N, 56Fe, 84Kr, 197Au • DIS kinematics + measure hadrons • Single electron trigger • Nuclear medium modifies fragmentation functions and pT distributions • 6 GeV beam: Q2 ≤ 4 GeV2, n ≤ 5 GeV • 12 GeV beam: Q2 ≤ 9 GeV2, n ≤ 9 GeV • Measure p+,-,0, h, w, h’, f, K +,-,0, p, L, S+,0, X0,-

  17. Recent Data from HERMES at HERA Data: Eur. Phys. J. C20 (2001) 479. Theory: nucl-th/9607036 for gluon bremsstrahlung model, Phys. Rev. Lett. 89 (2002) for twist-4 pQCD model.

  18. Anticipated CLAS Data at 6 GeV

  19. Kinematic Coverage, 12 GeV

  20. Neutral particle detection for fragmentation events at 11 GeV (LEPTO simulation, no vertex cut)

  21. Arie Bodek, Rochester Jorge Morfin, FNAL Ingo Schienbein, DESY Jan Sobczyk, U. Wroclaw Makoto Sakuda, KEK Emmanuel Paschos, U. Dortmund Shri Singh, Aligargh Moslem U. Some Potentially Interested Collaborators Will Brooks, Jlab Maurik Holtrop, UNH David Ireland, Glasgow Mauro Taiuti, INFN Larry Weinstein, ODU Steve Wood, Jlab Laird Kramer, FIU …

  22. Conclusion • CLAS has taken a huge volume of new data including multi-hadron final states • N* and nuclear data likely to be of interest to neutrino community • Collaborative connection likely to be most fruitful – many potential opportunities for collaboration

  23. Hadrons accessible for formation length studies CLAS at 11 GeV

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