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Perspectives for polarized antiprotons

Perspectives for polarized antiprotons. Paolo Lenisa Università di Ferrara and INFN - Italy. MENU 2013 – Rome , September 3 rd 2013. Motivation.

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Perspectives for polarized antiprotons

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  1. Perspectives for polarized antiprotons Paolo Lenisa Università di Ferrara and INFN - Italy MENU 2013– Rome, September 3rd2013 Perspectives for Polarized Antiprotons

  2. Motivation The PAX collaborationproposedtoinvestigateDrellYan processes in scatteringofpolarizedproton- antiprotonbeamsatthe HESR (FAIR). Annihilation ofvalencequarkwithan antivalencequarkallowsdirectaccess to: transversity, …. Requirements: Polarizedprotonbeam Polarizedantiprotonbeam Perspectives for Polarized Antiprotons

  3. A polarized Proton-AntiprotonColliderat FAIR polarizedantiprotons in HESR (p=15 GeV/c) polarizedprotons in CSR (p=3.5 GeV/c) direction of protons direction of anti-protons Perspectives for Polarized Antiprotons

  4. HowtoPolarizeAntiprotons? Spin-1/2 particles 2 states selectiveflip selectiveremoval polarized unpolarized unpolarized polarized • Does not affectintensity • Reduces beam intensity Perspectives for Polarized Antiprotons

  5. Selective-flip: a proposal Eur. Phys. J. A 34, 447 (2007) Perspectives for Polarized Antiprotons

  6. Spin-flip studiesat COSY • 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) Perspectives for Polarized Antiprotons

  7. Detuned Cooler Voltage Tdetuned= 50 s Nominal Cooler Voltage Tnominal = 100 s Measurement cycle Eh = 0.001 MeV ΔV = 235 V D2 Target on Ecool on D2 Target off Ecool on/detuned Perspectives for Polarized Antiprotons

  8. Spin-flip: results 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 σ║ < 3.2 x 107 b σ┴ < 1.7 x 107b 0 110-3 210-3 310-3 |Relative velocityofelectrons in protonrestframe| (c) D.Oellers et al., Physics Letters B 674 (2009) 269 RESULT: Selectiveflip: e+pbarspin-flip cross-sectionistoolow Perspectives for Polarized Antiprotons

  9. HowtoPolarizeAntiprotons? Spin-1/2 particles 2 states selectiveflip selectiveremoval polarized unpolarized unpolarized polarized • Does not affectintensity • Reduces beam intensity Perspectives for Polarized Antiprotons

  10. Spin-filtering Polarization build-up of a circulating particle beam by interaction with a polarized gas target Perspectives for Polarized Antiprotons

  11. Spin-filtering P…beam particlespinorientation Q…targetparticlespinorientation k || beam direction unpolarized p beam polarized target Perspectives for Polarized Antiprotons

  12. Spin-filtering P…beam particlespinorientation Q…targetparticlespinorientation k || beam direction polarized p beam polarized target Perspectives for Polarized Antiprotons

  13. 1992: Filter Test at TSR with protons Spin filteringworksforprotons F. Rathmann. et al., PRL 71, 1379 (1993) 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) Perspectives for Polarized Antiprotons

  14. Measurements at AD (CERN) • Aim: 1st measurement of the spin-dependence of the pbar-p cross section • Method: measurement of polarization build-up by spin-filtering PAX target section Perspectives for Polarized Antiprotons

  15. Spin-dependence of the pbar-p interaction 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). Oct. 2009 SPS Committee: … Taking into account the timeline and constraints of the various projects concerned, the SPSCencourages the PAX Collaboration to first perform their spin filtering measurements at COSY… Perspectives for Polarized Antiprotons

  16. Spin Filteringat COSY Spin filtering with protons for better understanding of the underlying processes and commissioning of the experimental setup • Length: 183.4 m • Injectionenergy: 45 MeV • Electroncoolingforlonglifetimes • upto 600 MeV/c (p) Perspectives for Polarized Antiprotons

  17. Experimental setupat PAX-IT Low-β Quadrupoles ABS Target Chamber Perspectives for Polarized Antiprotons

  18. Low-bsection Beam lifetime : Low-βsection off Low-βsection on Perspectives for Polarized Antiprotons

  19. Atomic Beam Source Perspectives for Polarized Antiprotons

  20. Target chamber SAES getter pump (each 1900 l/s) HiPace 1800 turbo (1200 l/s) Perspectives for Polarized Antiprotons

  21. Beam polarimeter Measurement of asymmetry in pd-elastic scattering 2 Silicon Tracking Telescops left and right of the COSY beam Deuterium Cluster Target () Perspectives for Polarized Antiprotons

  22. Spin-filteringcycle Spin-flipper clustertarg. + STT (beam polarimetry) p COSY ring polarizedtarget Perspectives for Polarized Antiprotons

  23. Spin-filtering: result W. Augustyniaket al., Physi. Lett. B 712 (2012) 64 • Milestonefor the field • Confirms understanding of spin-filtering as a viable method to polarize a stored beam. • Confirms complete control of the systematics of the experiment. Mar. 2012 SPS Committee: … many positive developments have occurred at the AD, leading to an updated program for the coming years ….We consider that PAX is now incompatible with this program. Perspectives for Polarized Antiprotons

  24. Future plans Waiting forapprovalat CERN (orconstructionof FAIR facility) Longitudinal spin-filteringtestat COSY Superconducting 4.7 Tm solenoidordered Longitudinal beam polarimeter in preparation Perspectives for Polarized Antiprotons

  25. Summary Status: Successfullspinfilteringmeasruementat COSY on transversepolarizedtarget. Excellentagreementwiththeoreticalpredictionsforprotons Successfullcommissioningof experimental setupforexperimentswithantiproton • Future plans at COSY • Spin filtering with protons and a longitudinally polarized gas target at COSY at Tp130 MeV ( scattering) • Still pending: • Spin-filteringexperimentsat AD exploringthesystems, , () (transverseand longitudinal polarization) Thankyou! Perspectives for Polarized Antiprotons

  26. Additional Slides Perspectives for Polarized Antiprotons

  27. Spin Filteringwith Longitudinal Polarization • Buildup of longitudinal beam polarization due torepeatedinteractionwith a longitudinallypolarized hydrogen target • Tp 45 - 130 MeV kineticprotonenergy • Detector: Measurement of longitudinal beam polarizationusingelasticscattering • Measurement duringfilteringwith hydrogen targetpossible • Spin correlationcoefficient (~ 0.5) • Nobackground Perspectives for Polarized Antiprotons

  28. Expectedpolarizations after filteringfortwolifetimes transverse longitudinal A D Perspectives for Polarized Antiprotons

  29. Additional calculations… PLB 690 (2010) Projected polarizations Perspectives for Polarized Antiprotons

  30. Stages ofinstallationat 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 Perspectives for Polarized Antiprotons

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