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Frank Rathmann Forschungszentrum Jülich

http://www.fz-juelich.de/ikp/pax. Spin-physics with Polarized Antiprotons. Frank Rathmann Forschungszentrum Jülich. PAX Collaboration. Spokespersons: Paolo Lenisa lenisa@mail.desy.de Frank Rathmann f.rathmann@fz-juelich.de. Yerevan Physics Institute, Yerevan, Armenia

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Frank Rathmann Forschungszentrum Jülich

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  1. http://www.fz-juelich.de/ikp/pax Spin-physics with Polarized Antiprotons Frank Rathmann Forschungszentrum Jülich

  2. PAX Collaboration Spokespersons: Paolo Lenisa lenisa@mail.desy.de Frank Rathmann f.rathmann@fz-juelich.de Yerevan Physics Institute, Yerevan, Armenia Department of Subatomic and Radiation Physics, University of Gent, Belgium University of Science & Technology of China, Beijing, P.R. China Department of Physics, Beijing, P.R. China Palaiseau, Ecole Polytechnique Centre de Physique Theorique, France High Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia Nuclear Physics Department, Tbilisi State University, Georgia Forschungszentrum Jülich, Institut für Kernphysik Jülich, Germany Institut für Theoretische Physik II, Ruhr Universität Bochum, Germany Helmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany Physikalisches Institut, Universität Erlangen-Nürnberg, Germany Langenbernsodorf, UGS, Gelinde Schulteis and Partner GbR,Germany Department of Mathematics, University of Dublin,Dublin, Ireland Università del Piemonte Orientale and INFN,Alessandria,Italy Dipartimento di Fisica dell’Università and INFN, Cagliari, Italy Università dell’Insubria and INFN,Como,Italy Instituto Nationale di Fisica Nuclelare, Ferrara, Italy

  3. PAX Collaboration Dipartimento di Fisica Teorica, Universita di Torino and INFN, Torino, Italy Instituto Nationale di Fisica Nucleare, Frascati, Italy Andrej Sultan Institute for Nuclear Studies, Dep. of Nuclear Reactions, Warsaw, Poland Petersburg Nuclear Physics Institute, Gatchina, Russia Institute for Theoretical and Experimental Physics, Moscow, Russia Lebedev Physical Institute, Moscow, Russia Physics Department, Moscow Engineering Physics Institute, Moscow, Russia Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Russia Laboratory of Particle Physics, Joint Institute for Nuclear Research, Dubna, Russia Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, Dubna, Russia Budker Institute of Nuclear Physics, Novosibirsk, Russia High Energy Physics Institute, Protvino, Russia Institute of Experimental Physics, Slovak Academy of Science, Kosice Slovakia Department of Radiation Sciences, Nuclear Physics Division, Uppsala University, Uppsala, Sweden Collider Accelerator Department, Brookhaven National Laboratory, Broohhaven USA RIKEN BNL Research Center Brookhaven National Laboratory, Brookhaven, USA University of Wisconsin, Madison, USA Department of Physics, University of Virginia, USA ~180 scientists 35 Institutions (15 EU, 20 Non-EU)

  4. The PAX proposal Jan. 04 LOI submitted 15.06.04 QCD PAC meeting at GSI 18-19.08.04 Workshop on polarized antiprotons at GSI 15.09.04F. Rathmann et al., A Method to polarize stored antiprotons to a high degree (PRL 94, 014801 (2005)) 15.01.05Technical Report submitted 14-16.03.05 QCD-PAC meeting at GSI Polarization enters in the core of FAIR

  5. Outline WHY?Physics Case HOW?Polarized Antiprotons WHAT? Staging Detector and Signal Estimate WHEN? Timeline

  6. Physic Topics • Transversity • Electromagnetic Form Factors • Hard Scattering Effects • SSA in DY, origin of Sivers function • Soft Scattering • Low-t Physics • Total Cross Section • pp interaction Physics Polarization Staging Signals Timeline

  7. QCD Physics at FAIR (CDR): unpolarized Antiprotons in HESR HESR PAX Polarized Antiprotons Central PAX Physics Case: Transversity distribution of the nucleon in Drell-Yan: FAIR as successor of DIS physics • last leading-twist missing piece of the QCD description of the partonic structure of the nucleon • observation of h1q(x,Q2) of the proton for valence quarks (ATT in Drell-Yan >0.2) • transversely polarized proton beam or target () • transversely polarized antiproton beam () Physics Polarization Staging Signals Timeline

  8. Leading Twist Distribution Functions R L L R L R R L quark quark’ 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 proton proton’ R L 1/2 -1/2     -     Probabilistic interpretation in helicity base: + f1(x) q(x) spin averaged (well known) - Dq(x) helicity diff. (known) g1(x) No probabilistic interpretation in the helicity base (off diagonal) h1(x) u = 1/2(uR + uL) u = 1/2(uR - uL) Transversity base dq(x) helicity flip (unknown)

  9. Transversity Properties: • Probes relativistic nature of quarks • No gluon analog for spin-1/2 nucleon • Different evolution than • Sensitive to valence quark polarization Chiral-odd: requires another chiral-odd partner epe’hX ppl+l-X Direct Measurement Indirect Measurement: Convolution of with unknown fragment. fct. Impossible in DIS Physics Polarization Staging Signals Timeline

  10. Polarizedantiproton beam → Polarizedproton target (both transverse) l+ q2=M2 l- q qT p p qL M invariant Mass of lepton pair Transversity in Drell-Yan processes Physics Polarization Staging Signals Timeline

  11. Proton Electromagnetic Formfactors • Measurement of relative phases of magnetic and electric FF in the time-like region • Possible only via SSA in the annihilation pp → e+e- • Double-spin asymmetry • independent GE-Gm separation • test of Rosenbluth separation in the time-like region S. Brodsky et al., Phys. Rev. D69 (2004) Physics Polarization Staging Signals Timeline

  12. Study onset of Perturbative QCD p (GeV/c) • High Energy • small t: Reggeon Exchange • large t: perturbative QCD • Pure Meson Land • Meson exchange • ∆ excitation • NN potential models • Transition Region • Uncharted Territory • Huge Spin-Effects in pp elastic scattering • large t: non-and perturbative QCD Physics Polarization Staging Signals Timeline

  13. pp Elastic Scattering from ZGS/AGS Spin-dependence at large-P (90°cm): Hard scattering takes place only with spins . Similar studies in pp elastic scattering A. Krisch Sci. Am. 257 (1987) “The results challenge the prevailing theory that describes the proton’s structure and forces” Physics Polarization Staging Signals Timeline

  14. Outline WHY? Physics Case HOW?Polarized Antiprotons WHAT? Staging Detector and Signal Estimate WHEN? Timeline

  15. 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 p beam Polarized H target Principle of Spin Filter Method Physics PolarizationStaging Signals Timeline

  16. P beam polarization Q target polarization k || beam direction Polarizedp 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 p beam Principle of Spin Filter Method Polarized H target Physics PolarizationStaging Signals Timeline

  17. 1992 Filter Test at TSR with protons Results Experimental Setup T=23 MeV F. Rathmann. et al., PRL 71, 1379 (1993) For low energy pp scattering: 1<0  tot+<tot- Physics PolarizationStaging Signals Timeline

  18. Experimental Setup at TSR (1992) Physics PolarizationStaging Signals Timeline

  19. 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 Three 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 protons σEM=70 mb (-) Horowitz & Meyer, PRL 72, 3981 (1994) H.O. Meyer, PRE 50, 1485 (1994) Physics PolarizationStaging Signals Timeline

  20. Beam Lifetime Coulomb Loss Total Hadronic ψacc(mrad) 40 10 8 beam lilfetime τbeam (h) 6 30 25 4 20 2 10 10 100 1000 T (MeV) Beam lifetimes in the APR Physics PolarizationStaging Signals Timeline

  21. statistical error of a double polarization observable (ATT) Measuring time t to achieve a certain error δATT ~ FOM = P2·I (N ~ I) I/I0 Optimimum time for Polarization Buildup given by maximum of FOM(t) tfilter = 2·τbeam 0.8 Beam Polarization 0.6 0.4 0.2 0 2 6 4 t/τbeam Polarization Buildup: Optimum Buildup Time Physics PolarizationStaging Signals Timeline

  22. Ψacc=50 mrad EM only 0.4 40 30 0.3 20 Beam Polarization P(2·τbeam) 0.2 10 0.1 5 0 1 10 100 T (MeV) Filter Test: T = 23 MeV Ψacc= 4.4 mrad Beam Polarization(Electromagnetic Interaction) Buildup in HESR (800 MeV) Physics PolarizationStaging Signals Timeline

  23. P P 0.20 0.20 0.15 0.15 0.10 0.10 0.05 0.05 Model A: T. Hippchen et al., Phys. Rev. C 44, 1323 (1991) Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995) T (MeV) 100 200 50 150 T (MeV) 100 250 200 50 150 Beam Polarization (Hadronic Interaction) • Experimental Tests required: • EM effect needs protons only (COSY) • Final Design of APR: Filter test with p at AD (CERN) Physics PolarizationStaging Signals Timeline

  24. Polarized Internal Target Physics PolarizationStaging Signals Timeline

  25. 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) Physics PolarizationStaging Signals Timeline

  26. B World-First: Antiproton Polarizer Ring (APR) Injection Siberian Snake APR e-Cooler e-Cooler Internal Experiment Extraction 150 m ABS Polarizer Target F. Rathmann et al., PRL 94, 014801 (2005) Very Large Acceptance APR Small Beam Waist at Targetβ=0.2 m High Flux ABSq=1.5·1017 s-1  Dense TargetT=100 K, longitudinal Q (300 mT) beam tube db=ψacc·β·2dt=dt(ψacc), lb=40 cm (=2·β) feeding tube df=1 cm, lf=15 cm

  27. Outline WHY? Physics Case HOW? Polarized Antiprotons WHAT? Staging Detector and signal estimate WHEN? Timeline

  28. 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 Physics Polarization Staging Signals Timeline

  29. The FAIR project at GSI SIS100/300 50 MeV Proton Linac HESR: High Energy Storage Ring: PANDA and PAX CR-Complex FLAIR: (Facility for very Low energy Anti-protons and fully stripped Ions) NESR Physics Polarization Staging Signals Timeline

  30. The Antiproton Facility HESR (High Energy Storage Ring) • Length 442 m • Bρ = 50 Tm • N = 5 x 1010 antiprotons High luminosity mode • Luminosity = 2 x 1032 cm-2s-1 • Δp/p ~ 10-4 (stochastic-cooling) High resolution mode • Δp/p ~ 10-5 (8 MV HE e-cooling) • Luminosity = 1031 cm-2s-1 SIS100/300 HESR Super FRS Antiproton Production Target CR Gas Target and Pellet Target: cooling power determines thickness NESR Beam Cooling: e- and/or stochastic 2MV prototype e-cooling at COSY • Antiproton production similar to CERN • Production rate107/sec at ~30 GeV/c • T = 1.5 - 15 GeV/c(22 GeV) Physics Polarization Staging Signals Timeline

  31. PAX Accelerator Setup Antiproton Polarizer Ring (APR) + Cooler Storage Ring (CSR, COSY-like): 3.5 GeV/c + HESR: 15 GeV/c  Asymmetric Double-Polarized Antiproton-Proton Collider HESR Physics Polarization Staging Signals Timeline

  32. Phase I: PAX at CSR Physics: Electromagnetic Form Factors pp elastic scattering Experiment: polarized/unpolarized p on polarized target Independent of HESR experiments HESR Physics Polarization Staging Signals Timeline

  33. Phase II: PAX at CSR Physics: Transversity EXPERIMENT: Asymmetric Collider: Polarized Antiprotons in HESR (15 GeV/c) Polarized Protons in CSR (3.5 GeV/c) Second IP with minor interference with PANDA HESR Physics Polarization Staging Signals Timeline

  34. HESR Injection cycle APR space charge limit Factor of 10 loss (2 lifetimes) CSR space charge limit protons 10 bunches of 1010 pbar Physics Polarization Staging Signals Timeline

  35. Outline WHY? Physics Case HOW? Polarized Antiprotons WHAT? Staging Detector and Signal Estimate WHEN? Timeline

  36. Polarizedantiproton beam → polarizedproton target (both transverse) l+ q2=M2 l- q qT p p qL M invariant Mass of lepton pair Transversity in Drell-Yan processes Physics Polarization Staging Signals Timeline

  37. ATT for PAX Kinematic Conditions ATT/aTT > 0.2 Models predict |h1u|>>|h1d| RHIC: τ=x1x2=M2/s~10-3 →Exploration of sea quark content:ATT small (~ 1 %) PAX: M2~10 GeV2, s~200 GeV2 τ=x1x2=M2/s~0.05 →Exploration ofvalence quarks h1q(x,Q2) large • s~200 GeV2 ideal: • Large range in xF • Large asymmetry, (h1u/u)2 ~ ATT xF=x1-x2 Anselmino et al., PLB 594,97 (2004) Efremov et al., EPJ C35, 207 (2004) Physics Polarization Staging Signals Timeline

  38. 2 k events/day collider 22 GeV M (GeV/c2) • M2 = s x1x2 • xF=2QL/√s = x1-x2 Kinematics and cross section • Estimated luminosities: • Fixed target: 2.7x1031 cm-2s-1 • Collider: 1-2 x 1030 cm-2s-1 Physics Polarization Staging Signals Timeline

  39. PAX conceptional Detector Design GEANT simulation (200 mm) Cerenkov (20 mm) Designed for Collider but compatible with fixed target Physics Polarization Staging Signals Timeline

  40. Estimated signal for h1 (Phase II) 1 year of data taking Collider: L=2x1030 cm-2s-1 Fixed target: L=2.7x1031 cm-2s-1 Physics Polarization Staging Signals Timeline

  41. Estimated signal for EMFF (Phase I) Npbar = 1x1011 f=LCSR/bc dt=1x1014cm-2 Q=0.8 (p pol) P=0.3 (pbar pol) e=0.5 Running days to get DO = 0.05 PS170 and E835 PAX could run down to 200 MeV/c with double polarization Physics Polarization Staging Signals Timeline

  42. Estimated Signal for pp elastic (Phase I) Cross section estimation for p=3.6 GeV/c, q=120° BNL E838 N10 Event rate (Dt=0.1 GeV2): 2 hours to get Physics Polarization Staging Signals Timeline

  43. Outline WHY? Physics Case HOW? Polarized Antiprotons WHAT? Staging Detector and signal estimate WHEN? Timeline

  44. Timeline Phase 0: 2005-2012 Polarizer design and construction. Physics: polarizing cross-section measurements (COSY & CERN). Phase I: 2013-2017 APR+CSR @ GSI Physics: EMFF, p-pbar elastic with fixed target. Phase II: 2018 - … HESR+CSR asymmetric collider Physics: h1 Physics Polarization Staging Signals Timeline

  45. Conclusions • Challenging opportunities accessible with polarized p’s • Unique access to a wealth of new fundamental physics observables • Central physics issue: h1q(x,Q2) of the proton in DY processes • Other issues: • Electromagnetic Formfactors • Polarization effects in Hard and Soft Scattering processes • differential cross sections, analyzing powers, spin correlation param. • Staged approach • Filter Tests Experiments with protons (COSY) and antiprotons (CERN) • Projections for double polarization experiments: • Pbeam > 0.20 • L> 1.6 ·1030 cm-2s-1(Collider) • L 2.7 ·1031 cm-2s-1 (fixed target) • Detector concept: • Large acceptance detector with a toroidal magnet

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