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Spin Filtering at COSY and Perspectives for PAX

Spin Filtering at COSY and Perspectives for PAX. September 17, 2012 | Alexander Nass. Our 1st Proposal on Spin Filtering (2005). Polarize antiprotons by „ spin-filtering “. PAX Proposal to FAIR (2005). 178 Collaborators 36 Institutions (15 EU, 21 Non-EU).

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Spin Filtering at COSY and Perspectives for PAX

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  1. Spin Filteringat COSY andPerspectivesfor PAX September 17, 2012 | Alexander Nass

  2. Our 1st Proposal on Spin Filtering (2005) Polarizeantiprotonsby „spin-filtering“ SPIN2012, Dubna, Russia

  3. PAX Proposalto FAIR (2005) 178 Collaborators 36 Institutions (15 EU, 21 Non-EU) High Energy Storage Ring (HESR) for a beam ofantiprotons SPIN2012, Dubna, Russia

  4. Quark structureofthenucleon transversely polarised quarks and nucleons unpolarised quarks and nucleons longitudinally polarised quarks and nucleons Less known Well known Known SPIN2012, Dubna, Russia

  5. PhysicswithPolarized Antiprotons Polarized antiprotons will pave the way to novel double (and single) spin observables: • Proton-spin structure: Complete map of transversity Flavour separation • Electromagnetic Form Factors Independent extraction of moduli of GE-GM in Time-Like region Test of the Rosenbluth separation in Time-Like region Measurement of the phase • Hard p-pbar scattering Additional measurement in one of the most intriguing puzzles of Hadron Physics • Hadron spectroscopy • Low-t pbar-p scattering Spin and isospindependence of nucleon-antinucleoninteractionatlowenergy SPIN2012, Dubna, Russia

  6. Access totransversitythroughDrell-Yan SPIN2012, Dubna, Russia

  7. Phase I: Fixed targetexperiments in CSR pol./unpol. antiprotonsin CSR 0.2 GeV/c<p<2.5 GeV/c polarizedinternalproton target direction of antiprotons (antiprotons) Physics:EMFF pbar-p elastic Independent from HESR running SPIN2012, Dubna, Russia

  8. Phase II: Asymmetric Proton-Antiproton Collider polarizedantiprotons in HESR (p=15 GeV/c) polarizedprotons in CSR (p=3.5 GeV/c) direction of antiprotons direction of protons Physics:Transversity EMFF pbar-p elastic SPIN2012, Dubna, Russia

  9. Antiproton Polarizer Ring (APR) Target Injection/Extraction Finalconfigurationafter spin-filteringstudies Electron Cooler Snake Ion-optics at IP SPIN2012, Dubna, Russia

  10. Evaluation by QCD-PAC (March 2005) Recommendationofthe STI of FAIR (Sept. 2005) … the PAC would like to stress again the uniqueness of the program with polarized anti-protons and polarized protons that could become available at GSI. • The STI (Scientific and Technical Issues) requests R&D work to be continued on the proposed asymmetric collider experiment with both polarized anti-protons and protons: • to demonstrate that the required luminosity for decisive measurements can be reached • ( accomplished) - to demonstrate that a high degree of anti-proton polarisation can be reached • The STI believes that PAX should become part of the FAIR core research program based on its strong scientific merit once the open problems are convincingly solved. SPIN2012, Dubna, Russia

  11. LuminosityConsiderationsforCollider Mode “old” “new” L>1031s-1cm-2 Antiprotons in HESR -> protons Bunched beams -> coasting 2006: I. milestone for PAX SPIN2012, Dubna, Russia

  12. Polarized Antiprotons • Intense beam of polarizedantiprotonswasneverproduced: • Conventionalmethods (ABS) notapplicable • Polarizedantiprotons from anti-lambda decay • I < 1.5∙105 s-1 (P ≈ 0.35) • Antiprotonscattering off liquid H2 target • I < 2∙103 s-1 (P ≈ 0.2) • Small polarization from pbar-C scatteringexperimentsat LEAR • Stern-Gerlach spin separation in a beam (nevertested, theoreticallyunlikely to work) SPIN2012, Dubna, Russia

  13. Productionofpolarization in a stored Beam TwoMethods: Loss versus spinflip For an ensembleofspin ½ particleswithprojections+() and– () SPIN2012, Dubna, Russia

  14. A newidea (2007) Eur. Phys. J. A 34, 447 (2007) SPIN2012, Dubna, Russia

  15. epspinflipstudiesat COSY (2008) • Use protonbeam and co-moving electrons • Turn experiment around: p e → p e into p e → p e • i.e. observe depolarization of a polarized proton beam Velocity mismatch COSYelectron cooler(detuned) SPIN2012, Dubna, Russia

  16. Detuned Cooler Voltage Tdetuned= 50 s Nominal Cooler Voltage Tnominal = 100 s PrincipleoftheDepolarizationMeasurement Eh = 0.001 MeV ΔV = 235 V D2 Target on Ecool on D2 Target off Ecool on/detuned SPIN2012, Dubna, Russia

  17. epspinflipcrosssectionat COSY Nominal protonenergy in electronrestframe (keV) 0 1 2 3 4107 D.Oellers et al., Physics Letters B 674 (2009) 269 2107 depol (barn) 0 -2107 -4107 0 110-3 210-3 310-3 |Relative velocityofelectrons in protonrestframe| (c) No effect observed: measured cross sections at least 6 orders-of-magnitude smaller than predicted 1013 b Meanwhile, Mainz group discovered numerical problems in the calculation → two errata. 2008: II. milestone for PAX SPIN2012, Dubna, Russia

  18. Productionofpolarization in a stored Beam TwoMethods: Loss versus spinflip For an ensembleofspin ½ particleswithprojections+() and– () SPIN2012, Dubna, Russia

  19. Unpolarized anti-p beam Polarizedtarget Spin Filtering Polarization build-up of a circulating particle beam by interaction with a polarized gas target SPIN2012, Dubna, Russia

  20. Polarizedanti-p beam Unpolarized anti-p beam Spin Filtering Polarization build-up of a circulating particle beam by interaction with a polarized gas target Polarized target SPIN2012, Dubna, Russia

  21. Filter Test at TSR withprotons (FILTEX, 1992) Experimental Setup T=23 MeV F. Rathmann. et al., PRL 71, 1379 (1993) Low energy pp scattering 1<0  tot+<tot- PAX submitted new proposal to find out how well does spin filtering work for antiprotonsMeasurement ofthe Spin-Dependenceofthe pp Interaction atthe AD Ring (CERN-SPSC-2009-012 / SPSC-P-337) SPIN2012, Dubna, Russia

  22. Plan for PAX at AD / CERN (2009) • Status in 2009: • Spin-filtering only viable option • Spin-dependence of pbar-p interaction unknown • “Warm” solution for AD lattice Siberiansnake PAX target section Electroncooler SPIN2012, Dubna, Russia

  23. Spin dependenceofthepbar-p interaction • Measurement of the polarization buildup equivalent to the determination of σ1andσ2 • Once a polarized antiproton beam is available, spin-correlation data can be measured at AD (50-500 MeV) Model A: T. Hippchen et al., Phys. Rev. C 44, 1323 (1991). Model OBEPF:J. Haidenbauer, K. Holinde, A.W. Thomas, Phys. Rev. C 45, 952 (1992). Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995). SPIN2012, Dubna, Russia

  24. Additional calculations PLB 690 (2010) Cross sections Projected polarizations SPIN2012, Dubna, Russia

  25. Stages ofinstallationat AD Installation of six magnets for the low-β insertion Installation of the target chamber: Machine acceptance studies. Stacking studies Spin-filtering measurements up to 70 MeV with transverse beam polarization 2010 2011 2012 SPIN2012, Dubna, Russia

  26. PAX getsacknowledgement in thecommunity: EU-Grants • 2008-2011 – I3HP2 WP25 (PolAntiP) • Depolarization studies • Transverse spin-filtering at COSY • 2012-2014 – I3HP3 WP25 (PolAntiP) • Longitudinal spin-filtering at COSY • 2010-2015 – Advanced Resarch Grant POLPBAR SPIN2012, Dubna, Russia

  27. Spin Filteringat COSY (2008-2011) Main purpose: 1. Commissioning of the experimental setup for CERN/AD 2. Quantitative understanding of the machine parameters WASA e-cooler ANKE PAX SPIN2012, Dubna, Russia

  28. p D2 Commissioning (2008-2011) ABS • 2008-11: Installation andcommissioningofthe HERMES pol. target Breit-Rabi polarimeter • 2008-11: Installation andcommissioningofthe ANKE beam polarimeter SPIN2012, Dubna, Russia

  29. Commissioning (2008-2011) • 2009-10: Installation andcommissioningofthelow-βsection • 2010-11: Studies of beam-lifetimelimitations • (t: 300 s  8000 s) SPIN2012, Dubna, Russia

  30. cluster targ. + STT (beam polarimetry) Spin-flipper Spin Filteringat COSY (2011) COSY ring p polarized target 2011: III. milestone for PAX SPIN2012, Dubna, Russia

  31. Conclusion: Spin Filtering • Antiproton polarization: • Spin filtering only viable mechanism • Complete understanding of spin filtering with p • Data on spin-dependence of pbar-p interaction needed • Polarized antiprotons remain a missing and unique • tool for hadron physics (More about in the talk of G.Ciullo) SPIN2012, Dubna, Russia

  32. Conclusion: Physicscasefor pol. antiprotons • ATT in Drell-Yan production remains the unique direct way to access h1 • pbar-p, pbar-d, p-p, p-d collider remains a unique machine to perform the flavour decomposition of transversity • Interest in Transverse Momentum dependent effect has increased • PAX physics case should be updated with the novel transverse momentum distributions (TMD) • Interest in proton EMFF has developed: • Different Space-Like experiments addressing two-photon contribution • Still no individual determination yet of FF in the Time-Like region • Necessity of a complete space-time description SPIN2012, Dubna, Russia

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