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Perspectives for Polarized Antiprotons (PAX: a brief history)

Perspectives for Polarized Antiprotons (PAX: a brief history). Paolo Lenisa Università di Ferrara and INFN 44100 – Ferrara - ITALY. ANKE-PAX Workshop Gatchina, June 25-27 2012. The beginning (2005). We have proposed a method to polarize antiprotons by „ spin-filtering “.

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Perspectives for Polarized Antiprotons (PAX: a brief history)

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  1. Perspectives for Polarized Antiprotons (PAX: a brief history) Paolo Lenisa Università di Ferrara and INFN44100 – Ferrara - ITALY ANKE-PAX Workshop Gatchina, June 25-27 2012 PAX story

  2. The beginning (2005) Wehaveproposed a methodtopolarizeantiprotonsby „spin-filtering“ PAX story

  3. PAX Proposal to FAIR (2005) • 178 Collaborators • 36 institutions (15 EU, 21 NON-EU) High Energy Storage Ring (HESR) for a beam ofantiprotons PAX story

  4. Physics with Polarized 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 TL Measurement of the phase * Hard p-pbar scattering Additional measurement in one of the most intriguing puzzles of HF * Hadron spectroscopy * Low-t pbar-p scattering Spin and isospin dependence of nucleon-antinucleon interaction at low energy PAX story

  5. M invariant Mass of lepton pair Inclusive DIS Semi-inclusive DIS Drell-Yan h1 from Drell-Yan PAX story

  6. Phase I: Fixed target experiments in CSR Physics: EMFF pbar-p elastic pol./unpol. Antiprotons in CSR 0.2 Gev/c<p<2.5 GeV/c polarized internal proton target direction of antiprotons (antiprotons) Independent from HESR running PAX story

  7. Phase II: Asymmetric Proton-Antiproton Collider Physics:Transversity EMFF pbar-p elastic polarized antiprotons in HESR (p=15 GeV/c) polarized protons in CSR (p=3.5 GeV/c) direction of antiprotons direction of protons PAX story

  8. Antiproton Polarizer Ring (APR) Final configuration after spin-filtering studies Target Injection/Extraction Electron Cooler Snake Ion-optics at IP PAX story

  9. Evaluation by QCD-PAC (March 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. Recommendation of the STI of FAIR (Sept. 2005) • The STI 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. PAX story

  10. Luminosity Considerations for Collider Mode “old” “new” L>1031s-1cm-2 Antiprotons in HESR -> protons Bunched beams -> coasting 2006: I milestone for PAX PAX story

  11. Polarized Antiprotons • Intense beam of polarized antiprotons was never produced: • Conventional methods (ABS) not appliable • Polarized antiprotons from antilambda decay • I < 1.5∙105 s-1 (P ≈ 0.35) • Antiproton scattering off liquid H2 target • I < 2∙103 s-1 (P ≈ 0.2) • Little polarization from pbarC scattering exp’ts at LEAR • Stern-Gerlach spin separation in a beam (never tested) Spin filteringis the only succesfully tested technique PAX story

  12. Howtoproducepolarizedantiprotons?Spin-filtering Polarization build-up of a circulating particle beam by interaction with a polarized gas target

  13. 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- PAX story

  14. Two interpretations of FILTEX result (2006) Observedpolarization build-up: dP/dt = ± (1.24 ± 0.06) x 10-2 h-1 P(t)=tanh(t/τ1), 1/τ1=σ1Qdtf σ1 = 72.5 ± 5.8 mb • 1994 Meyer and Horowitz: three distinct effects • Selective removal through scattering beyond θacc=4.4 mrad (σR=83 mb) • Small angle scattering of target prot. into ring acceptance (σS=52 mb) • Spin-transfer from pol. el. of target atoms to stored prot. (σE=-70 mb) • σ1= σR+ σS + σE = 65 mb • 2005 Milstein & Strakhovenko + Nikolaev & Pavlov: only one effect • Only pp elastic scattering contributes • No contribution from other two effects σ1 = 85.6mb PAX story

  15. Spin Filtering: Status in 2006 • Spin Filtering works, but: • Controversial interpretations of FILTEX experiment • Further experimental tests necessary • Which role do electrons play? • How does spin filtering work? •  Tests with protons at COSY • 2. No data to predict polarization from filtering with antiprotons •  Measurements with antiprotons at AD/CERN PAX story

  16. A new idea (2007) Eur. Phys. J. A 34, 447 (2007) PAX story

  17. ep spin flip studies at 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) PAX story

  18. Detuned Cooler Voltage Tdetuned= 50 s Nominal Cooler Voltage Tnominal = 100 s Principle of the Depolarization Measurementusing co-moving electrons of the e-cooler (COSY-2008) Eh = 0.001 MeV ΔV = 235 V D2 Target on Ecool on D2 Target off Ecool on/detuned PAX story

  19. ep spin flip cross section at COSY Nominal proton energy in electron rest frame (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 No effect observed: measured cross sections at least 6 orders-of-magnitude smaller than predicted 1013 b |Relative velocity of electrons in proton rest frame| (c) Meanwhile, Mainz group discovered numerical problems in the calculation → two errata. 2008: II milestone for PAX PAX story

  20. Status in 2009: • No contribution from EM interaction to polarization buildup. • Spin-filtering only viable option • Spin-dependence of pbar-p interaction unknown • “Warm” solution for AD lattice PAX at the AD (2009) Siberiansnake Electroncooler PAX target section PAX story

  21. Spin-dependence of the pbar-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). PAX story

  22. Additional calculations… PLB 690 (2010) Cross sections Projected polarizations PAX story

  23. Stages of installation at AD Installation of six magnets for the low-β insertion Phase 1 Installation of the target chamber: Machine acceptance studies. Stacking studies Phase 2 Spin-filtering measurements up to 70 MeV with transverse beam polarization Phase 3 2010 2011 2012 PAX story

  24. The CERN Saga: PAX requests • • Oct. 2009 PAX request to start phase I of installation not interfering with other experiments. • Jan. 2010 PAX informs SPSC of acknowledgement of ERC grant. • • Jan.. 2011 Meeting with Heuer • • Apr. 2011: PAX sends a draft to SPSC Committee with the successful result of commissioning of single elements of experimental apparatus and request to start installation of phase I in Winter 2011 shutdown, to initiate machine studies in 2012 and to avoid conflicts with ELENA installation during 2013 shutdown. • • Mar. 2012 PAX sends to SPSC Committee a draft with the results of spin-filtering studies. PAX story

  25. The CERN Saga: SPSC answer • Oct. 2009 unofficial response from the SPS Committee: … Taking into account the timeline and constraints of the various projects concerned, the SPSC encourages the PAX Collaboration to first perform their spin filtering measurements at COSY, and to report these to the Committee, following which the SPSC will further review the proposal. • Jan. 2010 Valle’s comment to ERC grant communication Congratulation for getting approval of an ERC advanced grant… The comments by many of the referees on the risk and schedule issues of your project confort me in the prudent attitude of the SPSC in respect with the necessary related AD modification … Looking forward to the PAX filtering measurements at COSY to proceed further with your review! • Jan.. 2011 Meeting with Heuer • Apr. 2011: SPSC 101 recommendation: The SPSC received a report by the PAX collaboration describing the progress of their program at COSY The SPSC remains concerned by the impact of PAX on the AD antihydrogenprogramme, the risk factors and manpower requirements for implementing the PAX apparatus at the AD. The Committee considers any installation before the long shutdown to be premature. The Committee is looking forward to the results of the spin filtering measurements. • Mar. 2012 Draft sent to SPSC with final results of August-October 2011 beamtime • Apr. 2012 mail from Vallee. We were pleased to see that you finally succeeded to perform a spin filtering measurement at COSY, showing good control of your apparatus as well as theoretical understanding of spin filtering for protons. However inbetween many positive developments have occured at the AD, leading to an updated program for the coming years which is very constrained on both the scientific and logistic points of view. We consider that PAX is now incompatible with this program. PAX story

  26. PAX gets acknowledgment in the community: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 PAX story

  27. The CERN Saga: PAX requests • • Oct. 2009 PAX request to start phase I of installation not interfering with other experiments. • Jan. 2010 PAX informs SPSC of acknowledgement of ERC grant. • • Jan.. 2011 Meeting with Heuer • • Apr. 2011: PAX sends a draft to SPSC Committee with the successful result of commissioning of single elements of experimental apparatus and request to start installation of phase I in Winter 2011 shutdown, to initiate machine studies in 2012 and to avoid conflicts with ELENA installation during 2013 shutdown. • • Mar. 2012 PAX sends to SPSC Committee a draft with the results of spin-filtering studies. PAX story

  28. The CERN Saga • Oct. 2009 unofficial response from the SPS Committee: … Taking into account the timeline and constraints of the various projects concerned, the SPSC encourages the PAX Collaboration to first perform their spin filtering measurements at COSY, and to report these to the Committee, following which the SPSC will further review the proposal. • Jan. 2010 Valle’s comment to ERC grant communication Congratulation for getting approval of an ERC advanced grant… The comments by many of the referees on the risk and schedule issues of your project confort me in the prudent attitude of the SPSC in respect with the necessary related AD modification … Looking forward to the PAX filtering measurements at COSY to proceed further with your review! • Jan.. 2011 Meeting with Heuer • Apr. 2011: SPSC 101 recommendation: The SPSC received a report by the PAX collaboration describing the progress of their program at COSY The SPSC remains concerned by the impact of PAX on the AD antihydrogenprogramme, the risk factors and manpower requirements for implementing the PAX apparatus at the AD. The Committee considers any installation before the long shutdown to be premature. The Committee is looking forward to the results of the spin filtering measurements. • Mar. 2012 Draft sent to SPSC with final results of August-October 2011 beamtime • Apr. 2012 mail from Vallee. We were pleased to see that you finally succeeded to perform a spin filtering measurement at COSY, showing good control of your apparatus as well as theoretical understanding of spin filtering for protons. However inbetween many positive developments have occured at the AD, leading to an updated program for the coming years which is very constrained on both the scientific and logistic points of view. We consider that PAX is now incompatible with this program. PAX story

  29. Spin-filtering at 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 PAX story

  30. p D2 Commissioning (2008-2011): • 2008-11: Installation and commissioning of the HERMES pol. target ABS • 2008-11: Installation and commissioning of the ANKE beam polarimeter Breit-Rabi polarimeter PAX story

  31. Commissioning (2008-2011): • 2009-10: Installation and commissioning of the low-β section • 2010-11: Studies of beam-lifetime limitations (t: 300 s  8000 s) PAX story

  32. The CERN Saga: PAX requests • • Oct. 2009 PAX request to start phase I of installation not interfering with other experiments. • Jan. 2010 PAX informs SPSC of acknowledgement of ERC grant. • • Jan.. 2011 Meeting with Heuer • • Apr. 2011: PAX sends a draft to SPSC Committee with the successful result of commissioning of single elements of experimental apparatus and request to start installation of phase I in Winter 2011 shutdown, to initiate machine studies in 2012 and to avoid conflicts with ELENA installation during 2013 shutdown. • • Mar. 2012 PAX sends to SPSC Committee a draft with the results of spin-filtering studies. PAX story

  33. The CERN Saga • Oct. 2009 unofficial response from the SPS Committee: … Taking into account the timeline and constraints of the various projects concerned, the SPSC encourages the PAX Collaboration to first perform their spin filtering measurements at COSY, and to report these to the Committee, following which the SPSC will further review the proposal. • Jan. 2010 Valle’s comment to ERC grant communication Congratulation for getting approval of an ERC advanced grant… The comments by many of the referees on the risk and schedule issues of your project confort me in the prudent attitude of the SPSC in respect with the necessary related AD modification … Looking forward to the PAX filtering measurements at COSY to proceed further with your review! • Jan.. 2011 Meeting with Heuer • Apr. 2011: SPSC 101 recommendation: The SPSC received a report by the PAX collaboration describing the progress of their program at COSY The SPSC remains concerned by the impact of PAX on the AD antihydrogenprogramme, the risk factors and manpower requirements for implementing the PAX apparatus at the AD. The Committee considers any installation before the long shutdown to be premature. The Committee is looking forward to the results of the spin filtering measurements. • Mar. 2012 Draft sent to SPSC with final results of August-October 2011 beamtime • Apr. 2012 mail from Vallee. We were pleased to see that you finally succeeded to perform a spin filtering measurement at COSY, showing good control of your apparatus as well as theoretical understanding of spin filtering for protons. However inbetween many positive developments have occured at the AD, leading to an updated program for the coming years which is very constrained on both the scientific and logistic points of view. We consider that PAX is now incompatible with this program. PAX story

  34. Spin-filteringat COSY (2011) cluster targ. + STT (beam polarimetry) Spin-flipper COSY ring p 2011: III milestone for PAX polarized target (more about in Dieter’s talk) PAX story

  35. The CERN Saga: PAX requests • • Oct. 2009 PAX request to start phase I of installation not interfering with other experiments. • Jan. 2010 PAX informs SPSC of acknowledgement of ERC grant. • • Jan.. 2011 Meeting with Heuer • • Apr. 2011: PAX sends a draft to SPSC Committee with the successful result of commissioning of single elements of experimental apparatus and request to start installation of phase I in Winter 2011 shutdown, to initiate machine studies in 2012 and to avoid conflicts with ELENA installation during 2013 shutdown. • • Mar. 2012 PAX sends to SPSC Committee a draft with the results of spin-filtering studies. PAX story

  36. The CERN Saga • Oct. 2009 unofficial response from the SPS Committee: … Taking into account the timeline and constraints of the various projects concerned, the SPSC encourages the PAX Collaboration to first perform their spin filtering measurements at COSY, and to report these to the Committee, following which the SPSC will further review the proposal. • Jan. 2010 Valle’s comment to ERC grant communication Congratulation for getting approval of an ERC advanced grant… The comments by many of the referees on the risk and schedule issues of your project confort me in the prudent attitude of the SPSC in respect with the necessary related AD modification … Looking forward to the PAX filtering measurements at COSY to proceed further with your review! • Jan.. 2011 Meeting with Heuer • Apr. 2011: SPSC 101 recommendation: The SPSC received a report by the PAX collaboration describing the progress of their program at COSY The SPSC remains concerned by the impact of PAX on the AD antihydrogenprogramme, the risk factors and manpower requirements for implementing the PAX apparatus at the AD. The Committee considers any installation before the long shutdown to be premature. The Committee is looking forward to the results of the spin filtering measurements. • Mar. 2012 Draft sent to SPSC with final results of August-October 2011 beamtime • Apr. 2012 mail from Vallee. We were pleased to see that you finally succeeded to perform a spin filtering measurement at COSY, showing good control of your apparatus as well as theoretical understanding of spin filtering for protons. However inbetween many positive developments have occured at the AD, leading to an updated program for the coming years which is very constrained on both the scientific and logistic points of view. We consider that PAX is now incompatible with this program. PAX story

  37. Spin-filtering: status in 2012 • No contribution from EM interaction to polarization buildup. • Only viable solution for “in-situ” polarization is spin-filtering • Complete understanding of the physics spin-filtering mechanism • Spin-dependence of proton antiproton interaction still unkown • New prediction existing Whataboutthephysicscaseforpolarizedantiprotons? PAX story

  38. Status in 2005: The nucleon collinear structure PAX story 38 L.L. Pappalardo - QNP2012 – Palaiseau – April 16-20 2012

  39. FF - + + - Status in 2005: Transversity totally unkown! PAX story 39 L.L. Pappalardo - QNP2012 – Palaiseau – April 16-20 2012

  40. FF 2007 milestone in hadron physics: Transversity first extraction Tensor charge + Anselmino et al. Phys. Rev. D 75 (2007) d u u d xh1(x, k ) xh1(x) xh1(x, k ) xh1(x) T T 1: Quark-diquark model 2: Chiral quark soliton model 3: Lattice QCD 4: QCD sum rules Soffer bound FF FF M. Anselmino et al hep-ph:0812.4366 PAX story 40 L.L. Pappalardo - QNP2012 – Palaiseau – April 16-20 2012

  41. FF 2011: II independent extraction! + • Survives integration over transverse momentum • Collinear factorization (simple product) • DGLAP evolution 2h Semi-Inclusive DIS FF FF PAX story 41 L.L. Pappalardo - QNP2012 – Palaiseau – April 16-20 2012

  42. 2011: II independent extraction! COMPASS 2010 HERMES Phys.Rev.Lett.107:072004,2011 Bacchetta et al., PRL 107 (11) PAX story 42 L.L. Pappalardo - QNP2012 – Palaiseau – April 16-20 2012

  43. worm-gears 2005-2012: A new field has born: The non-collinear structure of the nucleon momentum helicity Boer-Mulders transversity pretzelosity Sivers PAX story 43 L.L. Pappalardo - QNP2012 – Palaiseau – April 16-20 2012

  44. Physicscasefor pol.-pbar: status in 2012 • ATT in DY 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 TMDs • Interest in proton EMFF has developed: • Different SL experiment addressing two-photon contribution • Still no individual determination yet of FF in the TL region • Necessity of a complete space-time description PAX story

  45. PAX betweenpastandfuture… • Pol.-pbar remain a missing and unique tool for hadron physics • Antiproton polarization: • Spin-filtering only viable mechanism • Complete understanding of spin-filtering • Data on spin-dependence of pbar-p interaction needed • Keep the option open… • … but additional horizon in perspective: • besides polarization technology for hadron physics • … also polarization technology for fundamental physics • The bridge to the new hera is the new PAX detector: • Longitudinal spin-filtering • Deuteron-breakup • Time Reversal Invariance • … (EDM) (More about in the talks of Alex, Christian and Yuri…) PAX story

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