1. P.F.Dalpiaz16 june 20061 Polarized Antiproton at FAIR The PAX experiment P.F.Dalpiaz P.F.DalpiazFerrara 2 workshop on the QCD structure of the nucleon 12-16 june 2006 Monte Porzio Catone

2. P.F.Dalpiaz16 june 20062 Transversity

3. P.F.Dalpiaz16 june 20063 The most direct probe Drell-Yan Why it works Elementary LO interaction J. Ralston and D.Soper, 1979 J. Cortes, B. Pire, J. Ralston, 1992 Direct mesurament LO interaction has no initial gluons valence quarks

4. P.F.Dalpiaz16 june 20064 The measurament sea quarks At GSI-FAIR very large asymmetry expected in polarized proton- antiproton scattering valence quarks

5. P.F.Dalpiaz16 june 20065 Polarized Antiprotons Intense beam of never produced

6. P.F.Dalpiaz16 june 20066 How polarize antiproton? Polarized pbar from antilambda decay (1987-90) Pbar scattering off liquid H 2 target (1995) (Niinikoscki and Rossmanith 1985) Stern-Gerlach separation of a stored beam Very recently :(Th. Walcher et al) polarized electron beam 2006 Theorethical, never tested

7. P.F.Dalpiaz16 june 20067 How polarize antiproton? The Spin Filter Method Experimentally tested in 1992 2006 P.L.Csonka,1968, NIM 63 (1968) 247

8. P.F.Dalpiaz16 june 20068 Multiple passage of a stored beam in a Polarized Internal Target (PIT) Principle of spin filter method

9. P.F.Dalpiaz16 june 20069 “parallel spin” scatter more often then ” antiparallel spin,” resulting in a polarized (less intense )beam,after passages in a polarized target Total cross section Low energy scattering An unpolarized beam has an equal population of spin  longitudinal case transverse case

10. P.F.Dalpiaz16 june 200610 Principle of spin filter method Unpolarized anti-p beam Polarized H target Polarized anti-p beam Polarization Staging Signals Timeline

11. P.F.Dalpiaz16 june 200611 The filter

12. P.F.Dalpiaz16 june 200612 gas polarized hydrogen target a short review

13. P.F.Dalpiaz16 june 200613 Atomic Beam Source ABS m j = +1/2 m j = -1/2 m i =-1/2 m i =+1/2 1 |1> |2> |3> |4> ee-ee-p |1> P z+ = |1> + |4> P z- = |2> + |3> P e+ = |1> + |2> P e- = |3> + |4>

14. P.F.Dalpiaz16 june 200614 Hydrogen gas targets: densities 1970 1985, Novosibirsk,Zurig 1998,HERMES 2004,RHIC 1965 - 1984,W.Haeberli accumulation cell

15. P.F.Dalpiaz16 june 200615 The storage cell Material:75  m Al with Drifilm coating Size: length: 400mm, elliptical cross section (21 mm x 8.9 mm) Working temperature: 100 K ( variable 35 K – 300 K)

16. P.F.Dalpiaz16 june 200616 Performance of Polarized Internal Targets P T = 0.795  0.033 HERMES H Transverse Field (B=297 mT) HERMES DzDz D zz P T = 0.845 ± 0.028 Longitudinal Field (B=335 mT) HERMES: Stored Positrons PINTEX: Stored Protons H Fast reorientation in a weak field (x,y,z) Targets work very reliably (months of stable operation) Polarization Staging Signals Timeline

17. P.F.Dalpiaz16 june 200617 Test experiment on the filter method The TSR experiment with protons 1992

18. P.F.Dalpiaz16 june 200618 Experimental Setup at TSR (1992)

19. P.F.Dalpiaz16 june 200619 m j = +1/2 m j = -1/2 m i =-1/2 m i =+1/2 1 |1> |2> |3> |4> ee-ee-p |1> The FILTEX experiment has runned with state 1 hydrogen ~80% of electronic polarization ~80% of nuclear polarization Transverse target polarization

20. P.F.Dalpiaz16 june 200620 Experimental Setup Results F. Rathmann. et al., PRL 71, 1379 (1993) 1992 Filter Test at TSR with protons, 1992 Filter Test at TSR with protons, T=23 MeV

21. P.F.Dalpiaz16 june 200621 SPIN filtering works! but how?

22. P.F.Dalpiaz16 june 200622 Observedpolarization build-up: Observed polarization build-up: Observedcross-section Observed cross-section PIT areal thickness PIT polarization Revolution frequency FILTEX RESULTS

23. P.F.Dalpiaz 16 june 2006 23 Two interpretations of FILTEX result 1994. Meyer and Horowitz: three distinct effects 1.Selective removal through scattering beyond θ acc =4.4 mrad (σ R  =83 mb) 2.Small angle scattering of target prot. into ring acceptance (σ S  =52 mb) 3.Spin-transfer from pol. el. of target atoms to stored prot. (σ E  =-70 mb) σ 1 = σ R  + σ S  + σ E  = 65 mb 2005. Milstein & Strakhovenko + Nikolaev & Pavlov: only one effect 1.Selective removal through scattering beyond θ acc =4.4 mrad (σ R  =85.6 mb) No contribution from other two effects (cancellation between scattering and transmission) σ 1 = 85.6 mb

24. P.F.Dalpiaz16 june 200624 Spin-filtering: Present situation Spin filtering works, but: controversial interpretations of TSR result no experimental basis for antiprotons Experimental tests: - Protons (40-800 MeV) (COSY) - Antiprotons (5MeV-3GeV)(AD)

25. P.F.Dalpiaz16 june 200625 How to disentangle hadronic and electromagnetic contributions?

26. P.F.Dalpiaz16 june 200626 … only had - elm. + had. TSR A measurement of  with 10 % precision is needed. Polarization measurement with  P/P = 10% requested. Polarizing cross-section for the two models

27. P.F.Dalpiaz 16 june 2006 27 How to disentangle had. and elm contributions? 1: Injection of different combination of hyperfine states Inj. statesPePe PzPz InteractionHolding field |1>+1 Elm. + had.Transv. + Long.Weak (20 G) |1>+|4>0+1Only had.Long.Strong. (3kG) |1>+|2>+10Only elm Experiment at AD will require both transverse and longitudinal (weak)field. Different combinations of elm. and hadronic contributions: Strong field can be applied only longitudinally (minimal beam interference) Target polarimetry difficult for pure electron polarization. Null experiment (elm. component = 0) possible in strong holding field

28. P.F.Dalpiaz 16 june 2006 28 Spin-transfer 101001000T (MeV)  elm  (mbarn) 100 10 1 Hadronic 2: Use of different energy dependence of the processes Measurement at different energies How to disentangle had. and elm contributions? (Transverse case)

29. P.F.Dalpiaz 16 june 2006 29 Spin-filtering studies at COSY Goal: deeper understanding spin-filtering mechanism Disentangle between two interpretations of TSR result. Electromagnetic + hadronic contributions (20-120MeV 175-2880 MeV)

30. P.F.Dalpiaz 16 june 2006 30 Experimental setup Low-beta section Polarized target (HERMES) Detector Snake Commissioning of AD setu-up

31. P.F.Dalpiaz 16 june 2006 31  x,y new =0.3 -> increase a factor 30 in density respect ANKE Lower buildup time, higher rates Higher polarization buildup-rate due to higher acceptance Use of HERMES target (in Jülich since March 2006) Low beta section S.C. quadrupole development applicable to AD experiment

32. P.F.Dalpiaz 16 june 2006 32 Detector concept Reaction: p-p elastic (COSY) p-pbar elastic (AD) Good azimuthal resolution (up/down + left/right asymmetries) Low energy recoil (<8 MeV) Teflon cell requested

33. P.F.Dalpiaz 16 june 2006 33 Teflon cell (IUCF – 2002)

34. P.F.Dalpiaz 16 june 2006 34 Detector concept Reaction: p-p elastic (COSY) p-pbar elastic (AD) Good azimuthal resolution (up/down asymmetries) Low energy recoil (<8 MeV) Teflon cell Silicon tracking telescope

35. P.F.Dalpiaz 16 june 2006 35 The ANKE silicon tracking telescope 3 silicon detector layers ➔ 69 µm silicon ➔ 300/500 µm silicon 128 x 151 segments 51 x 66 mm (≈400 µm pitch) ➔ >5 mm Si(Li) 96 x 96 strip 64 x 64 mm (≈666 µm Pitch) COSY beam cluster beam

36. P.F.Dalpiaz 16 june 2006 36 Detector concept Reaction: p-p elastic (COSY) p-pbar elastic (AD) Good azimuthal resolution (up/down asymmetries) Low energy recoil (<8 MeV) Teflon cell Silicon tracking telescope Angular resolution on the forward particle for p-pbar AD experiment will require an opening-cell

37. P.F.Dalpiaz 16 june 2006 37 ANKE vs new interaction point Acceptance @ ANKE Cross sections Acceptance @ new-IP … elm + had - only had. Lifetimes

38. P.F.Dalpiaz 16 june 2006 38 PITFilter. timePolar.Total rateMeas. Time (  P/P=10%) ANKE2  = 16 h1.2 %7.5x10 2 s -1 44 min 5  = 42 h3.5 %5x10 s -1 26 min New IP2  = 5 h16 %2.2x10 4 s -1 1 s 5  = 13 h42 %1.5x10 3 s -1 < 1 s ANKE vs new interaction point Polarization T=40 MeV N inj =1.5x10 10 New IP ANKE

39. P.F.Dalpiaz 16 june 2006 39 Antiproton polarization build-up Test at AD

40. P.F.Dalpiaz16 june 200640 ANKE

41. P.F.Dalpiaz 16 june 2006 41 Commissioning of ANKE PIT Goal: installation of a storage cell with a polarized target in COSY Electron-cooling at injection with storage cell Stochastic cooling at 700 MeV Cooler stacking to increase particles in the ring Propedeutical studies to spin-filtering experiments

42. P.F.Dalpiaz 16 june 2006 42 Storage Cell Setup (coll. Ferrara – FZJ) COSY beam XY-tableFrame with storage cell and aperture Target chamber Feeding tube: l = 120 mm, Ø = 10 mm Extraction tube: l = 230 mm, Ø = 10 mm Beam tube : l = 400 mm, 20x20 mm 2 400mm

43. P.F.Dalpiaz 16 june 2006 43 Storage cell and stochastically cooled beam Cooling off Cooling on T p =831 MeV

44. P.F.Dalpiaz 16 june 2006 44 Target Thickness (from pp → dπ+) Jet Storage Cell MethodJet [atoms/cm 2 ]Storage Cell [atoms/cm 2 ] ABS flux (+ cell geometry)(1.6±0.1)·10 11 (1.9±0.1)·10 13 Rates (pp → dπ+) (1.5±0.1)·10 11 (2.1±0.1)·10 13

45. P.F.Dalpiaz 16 june 2006 45 Cooler Stacking into the Storage Cell 28 stacks followed by 2s electron cooling after 58s acceleration toT p =600 MeV Cooler Stacking allows for higher polarized beam intensities with cell. 2.5·10 10 protons have been injected in the ring

46. P.F.Dalpiaz 16 june 2006 46 Ferrara is building an ion-deflector Next step: Installation of the Lamb-shift polarimeter October 2006

47. P.F.Dalpiaz 16 june 2006 47 Antiproton polarization build-up AD

48. P.F.Dalpiaz 16 june 2006 48 Measurements at AD at CERN (2009-2010) Target Snake E-cooler T:5 MeV÷2.8 GeV N p = 3·10 7 study of spin-filtering in pp scattering Measurement of effective polarization cross-section. Both transverse and longitudinal. Variable ring acceptance. First measurement at all for spin correlations in pp (not pure text experiment!)

49. P.F.Dalpiaz16 june 200649 Timeline Fall 2006 Submission of Technical Proposal for COSY Spring 2007 Submission of Technical Proposal for AD 2006-08Design and construction phase COSY 2008 Spin-filtering studies at COSY Commissioning of AD experiment 2009Installation at AD 2009-2010Spin-filtering studies at AD

50. P.F.Dalpiaz 16 june 2006 50 VERY PRELIMINARY Polarization build-up implemantation at HESR,FAIR

51. P.F.Dalpiaz16 june 200651 PAX ACCELERATOR SETUP EXPERIMENT: Asymmetric collider : s=210GeV 2 polarized antiprotons in HESR (p=15 GeV/c) polarized protons in CSR (p=3.5 GeV/c) Physics: Transversity preliminary! Internal polarized target with 22 GeV/c polarized antiproton beam. s=30GeV2 s=30GeV2 Valence region x>0.5 4<Q 2 <100GeV2 A TT >0.3 L  2x10 30 1000 events by day

52. P.F.Dalpiaz16 june 200652 http://www.fz-juelich.de/ikp/pax

53. P.F.Dalpiaz16 june 200653 THE END

54. P.F.Dalpiaz16 june 200654

55. P.F.Dalpiaz16 june 200655

56. P.F.Dalpiaz16 june 200656

57. P.F.Dalpiaz16 june 200657

58. P.F.Dalpiaz16 june 200658 0.1 0.2 0.3 0.4 Beam Polarization P(2·τ beam ) 10 T (MeV)100 EM only 5 10 30 20 40 Ψ acc =50 mrad 0 1 Filter Test: T = 23 MeV Ψ acc = 4.4 mrad Electron Transfer Polarization Polarization Staging Signals Timeline ?

59. P.F.Dalpiaz16 june 200659 Polarization with hadronic pbar-p interaction Model A: T. Hippchen et al. Phys. Rev. C 44, 1323 (1991) P Kinetic energy (MeV) 10 100 10001 0.05 0.10 0.15 0.20 Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995) P Kinetic energy (MeV) 10 100 10001 0.05 0.10 0.15 0.20

60. P.F.Dalpiaz16 june 200660 pp Elastic Scattering from ZGS Spin- dependence at large-P  90° cm ): Spin- dependence at large-P  (90° cm ): Hard scattering takes place only with spins . D.G. Crabb et al., PRL 41, 1257 (1978) T=10.85 GeV Similar studies in pbar p elastic scattering

61. P.F.Dalpiaz16 june 200661