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First Workshop on Quark-Hadron Duality and the Transition to pQCD

First Workshop on Quark-Hadron Duality and the Transition to pQCD. 6-8 june Laboratori Nazionali di Frascati. Transversity measurement with polarized antiproton-proton interactions the PAX experiment P.F.Dalpiaz, Ferrara University. transversity. transversity.

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First Workshop on Quark-Hadron Duality and the Transition to pQCD

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  1. First Workshop on Quark-Hadron Duality and the Transition to pQCD 6-8 june Laboratori Nazionali di Frascati Transversity measurement with polarized antiproton-proton interactions the PAX experiment P.F.Dalpiaz, Ferrara University P.F.Dalpiaz

  2. transversity P.F.Dalpiaz

  3. transversity Partonic structure at leading-twist level is characterized by the unpolarized,longitudinally polarized,and transversely polarized parton distribution functions momentum helicity transversity unknown P.F.Dalpiaz

  4. Why transversity has not bean measured? Complete description of quark momentum P and spin S at leading twist chiral-even related to chiral-odd related to P.F.Dalpiaz

  5. P.F.Dalpiaz

  6. must couple to another chiral-odd function. How shell we measure trasversity? – – + Not in inclusive DIS J. Collins, 1993 Indirect measurament Convolution with an unknown fragmentation function P.F.Dalpiaz

  7. first indications collins HERMES, DIS2005 sivers COMPASS, DIS2005 P.F.Dalpiaz

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

  9. The measurament in polarized proton-antiproton scattering sea quarks At GSI-FAIR very large asymmetry expected P.F.Dalpiaz

  10. Similar predictions by Efremov et al., Eur. Phys. J. C35, 207 (2004) from pbar-p Drell-Yan at GSI-FAIR FAIR energies : large valence quarks P.F.Dalpiaz

  11. Asimmetry at GSI-FAIR energies Fixed target polarized p-bar at 22 GeV/c Asimmetric collider p at 3.5GeV/c and p-bar at 15GeV/c Vogelsang et al.,Drago et al P.F.Dalpiaz

  12. small and with much slower evolution than and at small x from p-p Drell-Yan at RICH RICH energies : very small sea quarks Barone, Calarco, Drago Martin, Schäfer, Stratmann, Vogelsang P.F.Dalpiaz

  13. The most direct probe seaquarks sea quarks (RHIC) valence quarks GSI-FAIR P.F.Dalpiaz

  14. "safe region": "safe region": Fermilab E866 800 GeV/c Kinematics for Drell-Yan processes CERN NA51 450 GeV/c QCD corrections might be very large at smaller values of M: yes, for cross-sections, not for ATTK-factor almost spin-independent H. Shimizu, G. Sterman, W. Vogelsang and H. Yokoya, hep-ph/0503270 V. Barone et al., in preparation P.F.Dalpiaz

  15. Polarized antiproton P.F.Dalpiaz

  16. How polarize antiproton? 1985 Krisch,Bogadena Bay 1985 april 18-21, Workshop on Polarized Antiproton source • From Antihyperon Decay • Using a Spin Filter • Stochastic Tecniques • Dynamic Nuclear Polarization • From Spontaneus Syncrotron Radiation emission • From induced Syncrotron Radiation • Polarization of directly produced Antiproton • Repeated Stern-Gerlaqch effect • By Antihydrogen foormation • In a penning trap • … P.F.Dalpiaz

  17. How polarize antiproton? 10 years later, • From Antihyperon Decay Fermilab, 1987 • Using a Spin Filter • Repeated Stern-Gerlach effect P.F.Dalpiaz

  18. The Spin Filter Method P.F.Dalpiaz

  19. pp Elastic Scattering from ZGS 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 P.F.Dalpiaz

  20. The filter P.F.Dalpiaz

  21. Polarized internal target P.F.Dalpiaz

  22. |1> e- p • Atomic Beam Source • NIM A 505, (2003) 633 1 |1> mj = +1/2 mi=+1/2 |2> mi=-1/2 mi=-1/2 |3> mj = -1/2 mi=+1/2 |4> The HERMES target Pz+ = |1> + |4> Pz- = |2> + |3> P.F.Dalpiaz

  23. The storage cell • Material:75 mm 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) P.F.Dalpiaz

  24. Longitudinal Field (B=335 mT) Dz PT = 0.845 ± 0.028 H Fast reorientation in a weak field (x,y,z) Dzz HERMES H PT = 0.795  0.033 HERMES Performance of Polarized Internal Targets HERMES: Stored Positrons PINTEX: Stored Protons Transverse Field (B=297 mT) Targets work very reliably (months of stable operation) P.F.Dalpiaz Polarization Staging Signals Timeline Polarization Staging Signals Timeline

  25. Principle of spin filter method P beam polarization Q target polarization k || beam direction σtot = σ0 + σ·P·Q + σ||·(P·k)(Q·k) For initially equally populated spin states:  (m=+½) and  (m=-½) transverse case: longitudinal case: Unpolarized anti-p beam Polarized H target P.F.Dalpiaz Polarization Staging Signals Timeline

  26. Principle of spin filter method P beam polarization Q target polarization k || beam direction Polarized anti-p beam σtot = σ0 + σ·P·Q + σ||·(P·k)(Q·k) For initially equally populated spin states:  (m=+½) and  (m=-½) transverse case: longitudinal case: Unpolarized anti-p beam Polarized H target P.F.Dalpiaz Polarization Staging Signals Timeline

  27. Principle of spin filter method P beam polarization Q target polarization k || beam direction σtot = σ0 + σ·P·Q + σ||·(P·k)(Q·k) For initially equally populated spin states:  (m=+½) and  (m=-½) transverse case: longitudinal case: For low energy pp scattering: 1<0  tot+<tot- P.F.Dalpiaz Polarization Staging Signals Timeline

  28. The PAX Physics Pogram P.F.Dalpiaz

  29. http://www.fz-juelich.de/ikp/pax Paolo Lenisa Frank Ratman Measure the Transversity via Drell-Yan with PolarizedAntiproton in the FAIR-HESR ring at GSI P.F.Dalpiaz

  30. Transverse Single Spin Asimmetry :QCD “theorem” (Sivers)D-Y =–(Sivers)DIS • Electromagnetic time-like form-factors in double and single spin • Elastic scattering (spin misteries like in pp ?) P.F.Dalpiaz

  31. PAX Physics program (2005-2015) • Demonstrate the feasibility of the method with dedicated test experiments • Design and build the PAX Accelerator Setup • Design and realize the PAX detector P.F.Dalpiaz

  32. Test experiments on the filter method The TSR experiment with protons 1992 P.F.Dalpiaz

  33. Experimental Setup at TSR (1992) P.F.Dalpiaz Polarization Staging Signals Timeline

  34. 1992 Filter Test at TSR with protons Results Experimental Setup T=23 MeV F. Rathmann. et al., PRL 71, 1379 (1993) Low energy pp scattering 1<0  tot+<tot- P.F.Dalpiaz Polarization Staging Signals Timeline

  35. Puzzle from FILTEX Test Observed polarization build-up: dP/dt = ± (1.24 ± 0.06) x 10-2 h-1 ? • Expectedbuild-up: P(t)=tanh(t/τpol), • 1/τpol=σ1Qdtf=2.4x10-2 h-1 •  about factor 2 larger! σ1 = 122 mb (pp phase shifts) Q = 0.83 ± 0.03 dt = (5.6 ± 0.3) x 1013cm-2 f = 1.177 MHz distinct effects: • Selective removal through scattering beyond Ψacc=4.4 mradσR=83 mb • Small angle scattering of target protons into ring acceptanceσS=52 mb • Spin transfer from polarized electrons of the target atoms to the stored protonsσEM=70 mb (-) ??? This measure need to be redone disentangling effects of the electronic polarization from the nucleon polarization in the storage cell P.F.Dalpiaz

  36. |1> e- p 1 |1> mj = +1/2 mi=+1/2 |2> mi=-1/2 mi=-1/2 |3> mj = -1/2 mi=+1/2 |4> The FILTEX experiment has runned with state 1 hydrogen ~80% of electronic polarization ~80% of nuclear polarization P.F.Dalpiaz

  37. Ψacc=50 mrad EM only 0.4 40 30 0.3 20 Beam Polarization P(2·τbeam) 10 0.2 5 0.1 0 1 10 100 T (MeV) Electron Transfer Polarization ? Filter Test: T = 23 MeV Ψacc= 4.4 mrad P.F.Dalpiaz Polarization Staging Signals Timeline

  38. What about the nuclear polarization effect? (wherefrom comes the name of the method) P.F.Dalpiaz

  39. Polarization with hadronic pbar-p interaction Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995) P 0.20 0.20 0.15 0.15 0.10 0.10 0.05 0.05 1 1 10 10 1000 1000 100 100 Kinetic energy (MeV) Model A: T. Hippchen et al. Phys. Rev. C 44, 1323 (1991) P Kinetic energy (MeV) P.F.Dalpiaz

  40. An Antiproton Polarizer Ring (APR) seems a necessary item.It will be optimized after the tests on the building-up of the polarization PAX Accelerator Setup P.F.Dalpiaz Polarization Staging Signals Timeline

  41. Test experiments on the filter method 2005-2008 …. COSY at 40, 70 and 100 MeV ….. • Measurements of σEM,σEM|| eventually using HERMES-like at TP1 • Repeat TSR experiment with target in pure spin states: Hydrogen target (HERMES-like) in a pure electronic/nuclear polarization state on a proton beam. (AD?) • Hydrogen target (HERMES-like)on an antiproton very low energy and cooled antiproton beam P.F.Dalpiaz

  42. PAX program (2005-2015) • Demonstrate the feasibility of the method with dedicated test experiments • Design and build the PAX Accelerator Setup • Design and realize the PAX detector P.F.Dalpiaz

  43. The PAX Accelerator Setup How implement in HESR the possibility to mesure trasversity P.F.Dalpiaz

  44. Facilty for Antiproton and Ion Research (GSI, Darmstadt, Germany) • Proton linac (injector) • 2 synchrotons (30 GeV p) • A number of storage rings •  Parallel beams operation P.F.Dalpiaz

  45. The Antiproton Facility HESR (High Energy Storage Ring) p = 1.5 - 15 GeV/c(22 GeV/c) (Length 442 m Bρ = 50 Tm) PANDA: storage ring (N=5 x 1010 pbar) High luminosity mode (Δp/p ~ 10-4) Luminosity = 2 x 1032 cm-2s-1 High resolution mode (Δp/p ~ 10-5) Luminosity = 1031 cm-2s-1 PAX : synchroton (N=3 x 1011 pbar) Collider mode Luminosity = 2 x 1030 cm-2s-1 SIS100/300 HESR Super FRS Beam Cooling: e- and/or stochastic CR NESR Antiproton Production Target • Antiproton production similar to CERN • Production rate107/sec at 30 GeV P.F.Dalpiaz

  46. PAX ACCELERATOR SETUP STAGE 2 preliminary! Physics: Transversity EXPERIMENT: Asymmetriccollider: s=210GeV2 polarized antiprotons in HESR (p=15 GeV/c) polarized protons in CSR (p=3.5 GeV/c) Internal polarized target with 22 GeV/c polarized antiproton beam. s=30GeV2 P.F.Dalpiaz

  47. Particle Losses * main loss due to recombination (absent for pbar p) P.F.Dalpiaz

  48. Equilibrium Parameters P.F.Dalpiaz

  49. PAX Cycle: Antiproton production rate: R = 3.61010 h-1, APR~ 17 h APR space charge limit Factor of 10 loss (2 lifetimes) CSR space charge limit protons 10 bunches of 1010 pbar P.F.Dalpiaz

  50. PAX ACCELERATOR SETUP STAGE 1 Physics: EMFF pbar-p elastic Experiment: pol./unpol. pbar on internal polarized target Independent from HESR running P.F.Dalpiaz

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