1. Eugene Pasyuk Jefferson Lab for the CLAS Collaboration Moscow, September 20-23, 2012 XIII International Seminar on Electromagnetic Interactions of Nuclei

2. ` E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012 2 * Introduction * Experimental tools * Single pion photporoduction * K +  photoproduction * Summary

3. ` 3 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

4. ` * Masses, widths, and coupling constants not well known for many resonances * Most models predict more resonance states than observed N* Constituent quark model Lattice QCD 4 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

5. ` 4 Complex amplitudes: 16 real polarization observables. Complete measurement from 8 carefully chosen observables. πN has large cross section but in KY recoil is self-analysing 4 Complex amplitudes: 16 real polarization observables. Complete measurement from 8 carefully chosen observables. πN has large cross section but in KY recoil is self-analysing I. S. Barker, A. Donnachie, J. K. Storrow, Nucl. Phys. B95 347 (1975). 5 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

6. ` 6 Experiment cross section, spin observables Experiment cross section, spin observables TheoryLQCD, quark models, QCD sum rules QCD sum rules, …TheoryLQCD, quark models, QCD sum rules QCD sum rules, … Reaction Theory dynamical frameworks Reaction Theory dynamical frameworks Amplitude analysis → multipole amplitudes → phase shifts Amplitude analysis → multipole amplitudes → phase shifts σ,dσ/dΩ,Σ,P,T (beam-target) E,F,G,H, (beam-recoil) C x,C z,O x,O z, (target-recoil) L x,L z, T x,T z, Coupled channels: resonance parameter resonance parameterExtraction This session Hiroyuki Kamano E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

7. ` 7

8. ` A B C Injector LINAC Experimental Halls * E: 0.75 –6 GeV * I max : 200μA * Duty Cycle: 100% * δE/E: 2.5x10 -5 * Polarization: ≥85% * Simultaneous distribution to 3 experimental Halls 8 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

9. ` Torus magnet 6 superconducting coils Gas Cherenkov counters e/  separation, 256 PMTs Time-of-flight counters plastic scintillators, 684 photomultipliers Drift chambers 35,000 cells target + start counter target + start counter Electromagnetic calorimeters Lead/scintillator, 1296 photomultipliers 9 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

10. ` Linearly polarized photons: coherent bremsstrahlung on oriented diamond crystal Circularly polarized beam produced by longitudinally polarized electrons 10 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

11. ` 11 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

12. ` HDIce Solid Deuterium-Hydride (HD) – a new class of polarized target * Polarized at very high magnetic field and very low temperature * Transferred to in-beam cryostat * Spin can be moved between H and D with RF transitions * All material can be polarized with almost no background 12 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

13. ` * γp → π 0 p, π + n * γp → ηp * γp → KY (K + Λ, K + Σ 0, K 0 Σ + ) * γp → π + π - p, ωp, ρp, ϕ p * γn → π - p * γn → π + π - n * γn → Σ - K +, ΛK 0 ….. Reactions γp → ηp, ηp, K + Λ provide isospin filter, directly coupled only to N* 13 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

14. ` 14

15. ` CLAS SP07 MAID07 SP08 SN08CLAS SP07 MAID07 SP08 SN08 M. Dugger et al. PRC 79, 065206 (2009) Constrained SAID fit at higher energies. Constrained SAID fit at higher energies. Does not need any new resonances Does not need any new resonances 15 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

16. ` Forum for MAX-IV Ring, Lund, Nov 2011  E=10 MeV 16 preliminary preliminary Michael Dugger, ASU E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

17. ` Forum for MAX-IV Ring, Lund, Nov 2011  E=10 MeV 17 Michael Dugger, ASU preliminary preliminary E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

18. ` Forum for MAX-IV Ring, Lund, Nov 2011  E=10 MeV 18 Michael Dugger, ASU preliminary preliminary E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

19. ` preliminary preliminary S. Strauch, USC 19 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

20. ` For W< 1.75 GeV all of the models represent the data fairly well. For W> 1.75 GeV none of the models represents the data well. 20 preliminary preliminary E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

21. ` 21 Michael Dugger, ASU E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

22. ` PRELIMINARY cos(   )=-1 to -0.6 cos(   )=-0.6 to -0.2cos(   )=-0.2 to 0.2 cos(   )=0.2 to 0.6 cos(   )=0.6 to 1.0 Jo McAndrew 22 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

23. ` 23 Michael Dugger, ASU E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

24. ` 24 Michael Dugger, ASU E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

25. ` 25

26. ` 26 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

27. ` recoil polarization P excitation function g11: W=1.7 – 2.8 GeV (unpolarized beam & target) M.E. McCracken et al., PRC 81, 025201 (2010) 27 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

28. ` Nikonov et al’.’s refit of Bonn-Gachina multi-coupled- channel isobar model mix includes: S11 wave, P13(1720),P13(1900),P11(1840) Bradford et al Bradford et al. PRC 75, 035205 (2007), 28 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

29. ` preliminary preliminary C. Patterson 29 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

30. ` C. Patterson preliminary preliminary 30 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

31. ` C. Patterson preliminary preliminary 31 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

32. ` C. Patterson preliminary preliminary 32 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

33. ` (PhD L. Casey, CUA) preliminary preliminary 33 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

34. ` (PhD L. Casey, CUA) preliminary preliminary 34 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

35. ` 35

36. ` ✔ - published ✔ - acquired 36 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

37. ` * γp → ηp * γp → η’p * γp → π + π - p ωp, ρp, ϕ p * γn → π - p * γn → π + π - n * γn → Σ - K +, ΛK 0 ….. We have measured cross sections an polarization observables 37 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

38. ` * “compete measurement” in pseudoscalar meson photoproduction is reality * Data collection with proton and deuteron targets is complete * Data are being analyzed 38 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

39. ` 39

40. ` * 1968: 11 events from the ABBHHM bubble chamber experiment * 1976: 7 events from the AHHM streamer chamber experiment * 1998: 250 events from the SAPHIR collaboration (first differential cross sections) * 2006: over 2×10 5 events from the CLAS collaboration * 2009: another few orders of magnitude from CLAS g11 data set 40 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

41. ` * SAID * MAID * NH (K. Nakayama and H. Haberzettl) 41 M. Dagger et al. PRL 96, 062001 (2006) E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

42. ` K. Nakayama and H. Haberzettl, Phys. Rev. C 73, 045211 (2006). Different versions of the model yield similar results for cross section, but quite different predictions for beam asymmetry Predictions for beam asymmetry are quite different 42 M. Dugger et al. PRL 96, 062001 (2006) E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

43. ` 43 S 11 (1535) S 11 (1650) S 11 (2090) P 11 (1710) P 11 (2100) P 13 (1720) P 13 (1900) D 13 (1520) D 13 (1700) D 13 (2080) g η ´NN = 1.91 S 11 (2090) P 11 (2100) P 13 (1900) D 13 (1700) g η ´NN = 0.43 S 11 (2090) P 11 (2100) P 13 (1900) D 13 (1700) D 13 (2080) g η ´NN = 0.25 S 11 (1535) S 11 (1650) S 11 (2090) P 11 (1710) P 11 (2100) P 11 (2400) P 13 (1900) D 13 (1700) D 13 (2080) g η ´NN = 1.33 S 11 (1535) S 11 (2090) P 11 (1710) P 11 (2100) D 13 (1700) D 13 (2080) g η ´NN = 0.002 IIIIIIIVV E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

44. ` M. Williams et al. PRC 80, 045213 (2009) 44 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

45. ` The  appears 100% polarized when created with a fully polarized beam. 45 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

46. ` * Energy and angle averages are consistent with unity. * No model predicted this CLAS result. 46 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012

47. ` 47 E. Pasyuk, EMIN-2012, Moscow, September 20-23 2012