P.F.Dalpiaz16 june Polarized Antiproton at FAIR The PAX experiment P.F.Dalpiaz P.F.DalpiazFerrara 2 workshop on the QCD structure of the nucleon june 2006 Monte Porzio Catone

P.F.Dalpiaz16 june Transversity

P.F.Dalpiaz16 june The most direct probe Drell-Yan Why it works Elementary LO interaction J. Ralston and D.Soper, 1979 J. Cortes, B. Pire, J. Ralston, 1992 Direct mesurament LO interaction has no initial gluons valence quarks

P.F.Dalpiaz16 june The measurament sea quarks At GSI-FAIR very large asymmetry expected in polarized proton- antiproton scattering valence quarks

P.F.Dalpiaz16 june Polarized Antiprotons Intense beam of never produced

P.F.Dalpiaz16 june How polarize antiproton? Polarized pbar from antilambda decay ( ) Pbar scattering off liquid H 2 target (1995) (Niinikoscki and Rossmanith 1985) Stern-Gerlach separation of a stored beam Very recently :(Th. Walcher et al) polarized electron beam 2006 Theorethical, never tested

P.F.Dalpiaz16 june How polarize antiproton? The Spin Filter Method Experimentally tested in P.L.Csonka,1968, NIM 63 (1968) 247

P.F.Dalpiaz16 june Multiple passage of a stored beam in a Polarized Internal Target (PIT) Principle of spin filter method

P.F.Dalpiaz16 june “parallel spin” scatter more often then ” antiparallel spin,” resulting in a polarized (less intense )beam,after passages in a polarized target Total cross section Low energy scattering An unpolarized beam has an equal population of spin  longitudinal case transverse case

P.F.Dalpiaz16 june Principle of spin filter method Unpolarized anti-p beam Polarized H target Polarized anti-p beam Polarization Staging Signals Timeline

P.F.Dalpiaz16 june The filter

P.F.Dalpiaz16 june gas polarized hydrogen target a short review

P.F.Dalpiaz16 june Atomic Beam Source ABS m j = +1/2 m j = -1/2 m i =-1/2 m i =+1/2 1 |1> |2> |3> |4> ee-ee-p |1> P z+ = |1> + |4> P z- = |2> + |3> P e+ = |1> + |2> P e- = |3> + |4>

P.F.Dalpiaz16 june Hydrogen gas targets: densities , Novosibirsk,Zurig 1998,HERMES 2004,RHIC ,W.Haeberli accumulation cell

P.F.Dalpiaz16 june The storage cell Material:75  m 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.Dalpiaz16 june Performance of Polarized Internal Targets P T =  HERMES H Transverse Field (B=297 mT) HERMES DzDz D zz P T = ± Longitudinal Field (B=335 mT) HERMES: Stored Positrons PINTEX: Stored Protons H Fast reorientation in a weak field (x,y,z) Targets work very reliably (months of stable operation) Polarization Staging Signals Timeline

P.F.Dalpiaz16 june Test experiment on the filter method The TSR experiment with protons 1992

P.F.Dalpiaz16 june Experimental Setup at TSR (1992)

P.F.Dalpiaz16 june m j = +1/2 m j = -1/2 m i =-1/2 m i =+1/2 1 |1> |2> |3> |4> ee-ee-p |1> The FILTEX experiment has runned with state 1 hydrogen ~80% of electronic polarization ~80% of nuclear polarization Transverse target polarization

P.F.Dalpiaz16 june Experimental Setup Results F. Rathmann. et al., PRL 71, 1379 (1993) 1992 Filter Test at TSR with protons, 1992 Filter Test at TSR with protons, T=23 MeV

P.F.Dalpiaz16 june SPIN filtering works! but how?

P.F.Dalpiaz16 june Observedpolarization build-up: Observed polarization build-up: Observedcross-section Observed cross-section PIT areal thickness PIT polarization Revolution frequency FILTEX RESULTS

P.F.Dalpiaz 16 june Two interpretations of FILTEX result Meyer and Horowitz: three distinct effects 1.Selective removal through scattering beyond θ acc =4.4 mrad (σ R  =83 mb) 2.Small angle scattering of target prot. into ring acceptance (σ S  =52 mb) 3.Spin-transfer from pol. el. of target atoms to stored prot. (σ E  =-70 mb) σ 1 = σ R  + σ S  + σ E  = 65 mb Milstein & Strakhovenko + Nikolaev & Pavlov: only one effect 1.Selective removal through scattering beyond θ acc =4.4 mrad (σ R  =85.6 mb) No contribution from other two effects (cancellation between scattering and transmission) σ 1 = 85.6 mb

P.F.Dalpiaz16 june Spin-filtering: Present situation Spin filtering works, but: controversial interpretations of TSR result no experimental basis for antiprotons Experimental tests: - Protons ( MeV) (COSY) - Antiprotons (5MeV-3GeV)(AD)

P.F.Dalpiaz16 june How to disentangle hadronic and electromagnetic contributions?

P.F.Dalpiaz16 june … only had - elm. + had. TSR A measurement of  with 10 % precision is needed. Polarization measurement with  P/P = 10% requested. Polarizing cross-section for the two models

P.F.Dalpiaz 16 june How to disentangle had. and elm contributions? 1: Injection of different combination of hyperfine states Inj. statesPePe PzPz InteractionHolding field |1>+1 Elm. + had.Transv. + Long.Weak (20 G) |1>+|4>0+1Only had.Long.Strong. (3kG) |1>+|2>+10Only elm Experiment at AD will require both transverse and longitudinal (weak)field. Different combinations of elm. and hadronic contributions: Strong field can be applied only longitudinally (minimal beam interference) Target polarimetry difficult for pure electron polarization. Null experiment (elm. component = 0) possible in strong holding field

P.F.Dalpiaz 16 june Spin-transfer T (MeV)  elm  (mbarn) Hadronic 2: Use of different energy dependence of the processes Measurement at different energies How to disentangle had. and elm contributions? (Transverse case)

P.F.Dalpiaz 16 june Spin-filtering studies at COSY Goal: deeper understanding spin-filtering mechanism Disentangle between two interpretations of TSR result. Electromagnetic + hadronic contributions (20-120MeV MeV)

P.F.Dalpiaz 16 june Experimental setup Low-beta section Polarized target (HERMES) Detector Snake Commissioning of AD setu-up

P.F.Dalpiaz 16 june  x,y new =0.3 -> increase a factor 30 in density respect ANKE Lower buildup time, higher rates Higher polarization buildup-rate due to higher acceptance Use of HERMES target (in Jülich since March 2006) Low beta section S.C. quadrupole development applicable to AD experiment

P.F.Dalpiaz 16 june Detector concept Reaction: p-p elastic (COSY) p-pbar elastic (AD) Good azimuthal resolution (up/down + left/right asymmetries) Low energy recoil (<8 MeV) Teflon cell requested

P.F.Dalpiaz 16 june Teflon cell (IUCF – 2002)

P.F.Dalpiaz 16 june Detector concept Reaction: p-p elastic (COSY) p-pbar elastic (AD) Good azimuthal resolution (up/down asymmetries) Low energy recoil (<8 MeV) Teflon cell Silicon tracking telescope

P.F.Dalpiaz 16 june The ANKE silicon tracking telescope 3 silicon detector layers ➔ 69 µm silicon ➔ 300/500 µm silicon 128 x 151 segments 51 x 66 mm (≈400 µm pitch) ➔ >5 mm Si(Li) 96 x 96 strip 64 x 64 mm (≈666 µm Pitch) COSY beam cluster beam

P.F.Dalpiaz 16 june Detector concept Reaction: p-p elastic (COSY) p-pbar elastic (AD) Good azimuthal resolution (up/down asymmetries) Low energy recoil (<8 MeV) Teflon cell Silicon tracking telescope Angular resolution on the forward particle for p-pbar AD experiment will require an opening-cell

P.F.Dalpiaz 16 june ANKE vs new interaction point ANKE Cross sections new-IP … elm + had - only had. Lifetimes

P.F.Dalpiaz 16 june PITFilter. timePolar.Total rateMeas. Time (  P/P=10%) ANKE2  = 16 h1.2 %7.5x10 2 s min 5  = 42 h3.5 %5x10 s min New IP2  = 5 h16 %2.2x10 4 s -1 1 s 5  = 13 h42 %1.5x10 3 s -1 < 1 s ANKE vs new interaction point Polarization T=40 MeV N inj =1.5x10 10 New IP ANKE

P.F.Dalpiaz 16 june Antiproton polarization build-up Test at AD

P.F.Dalpiaz16 june ANKE

P.F.Dalpiaz 16 june Commissioning of ANKE PIT Goal: installation of a storage cell with a polarized target in COSY Electron-cooling at injection with storage cell Stochastic cooling at 700 MeV Cooler stacking to increase particles in the ring Propedeutical studies to spin-filtering experiments

P.F.Dalpiaz 16 june Storage Cell Setup (coll. Ferrara – FZJ) COSY beam XY-tableFrame with storage cell and aperture Target chamber Feeding tube: l = 120 mm, Ø = 10 mm Extraction tube: l = 230 mm, Ø = 10 mm Beam tube : l = 400 mm, 20x20 mm 2 400mm

P.F.Dalpiaz 16 june Storage cell and stochastically cooled beam Cooling off Cooling on T p =831 MeV

P.F.Dalpiaz 16 june Target Thickness (from pp → dπ+) Jet Storage Cell MethodJet [atoms/cm 2 ]Storage Cell [atoms/cm 2 ] ABS flux (+ cell geometry)(1.6±0.1)·10 11 (1.9±0.1)·10 13 Rates (pp → dπ+) (1.5±0.1)·10 11 (2.1±0.1)·10 13

P.F.Dalpiaz 16 june Cooler Stacking into the Storage Cell 28 stacks followed by 2s electron cooling after 58s acceleration toT p =600 MeV Cooler Stacking allows for higher polarized beam intensities with cell. 2.5·10 10 protons have been injected in the ring

P.F.Dalpiaz 16 june Ferrara is building an ion-deflector Next step: Installation of the Lamb-shift polarimeter October 2006

P.F.Dalpiaz 16 june Antiproton polarization build-up AD

P.F.Dalpiaz 16 june Measurements at AD at CERN ( ) Target Snake E-cooler T:5 MeV÷2.8 GeV N p = 3·10 7 study of spin-filtering in pp scattering Measurement of effective polarization cross-section. Both transverse and longitudinal. Variable ring acceptance. First measurement at all for spin correlations in pp (not pure text experiment!)

P.F.Dalpiaz16 june Timeline Fall 2006 Submission of Technical Proposal for COSY Spring 2007 Submission of Technical Proposal for AD Design and construction phase COSY 2008 Spin-filtering studies at COSY Commissioning of AD experiment 2009Installation at AD Spin-filtering studies at AD

P.F.Dalpiaz 16 june VERY PRELIMINARY Polarization build-up implemantation at HESR,FAIR

P.F.Dalpiaz16 june PAX ACCELERATOR SETUP EXPERIMENT: Asymmetric collider : s=210GeV 2 polarized antiprotons in HESR (p=15 GeV/c) polarized protons in CSR (p=3.5 GeV/c) Physics: Transversity preliminary! Internal polarized target with 22 GeV/c polarized antiproton beam. s=30GeV2 s=30GeV2 Valence region x>0.5 4<Q 2 <100GeV2 A TT >0.3 L  2x events by day

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P.F.Dalpiaz16 june THE END

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P.F.Dalpiaz16 june Beam Polarization P(2·τ beam ) 10 T (MeV)100 EM only Ψ acc =50 mrad 0 1 Filter Test: T = 23 MeV Ψ acc = 4.4 mrad Electron Transfer Polarization Polarization Staging Signals Timeline ?

P.F.Dalpiaz16 june Polarization with hadronic pbar-p interaction Model A: T. Hippchen et al. Phys. Rev. C 44, 1323 (1991) P Kinetic energy (MeV) Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995) P Kinetic energy (MeV)

P.F.Dalpiaz16 june pp Elastic Scattering from ZGS Spin- dependence at large-P  90° cm ): 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.Dalpiaz16 june