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Contalbrigo Marco INFN Ferrara

Transverse spin effects in SIDIS at 11 GeV with transversely polarized target u sing the CLAS12 detector. (A CLAS12 experiment proposal for PAC39). Contalbrigo Marco INFN Ferrara. JLab PAC 39 – Open session June 18, 2012 Newport News. A CLAS12 Proposal For PAC38.

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Contalbrigo Marco INFN Ferrara

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  1. Transverse spin effects in SIDIS at 11 GeV with transversely polarized target using the CLAS12 detector (A CLAS12 experiment proposal for PAC39) Contalbrigo Marco INFN Ferrara JLab PAC 39 – Open session June 18, 2012 Newport News

  2. A CLAS12 Proposal For PAC38 A CLAS12 proposal for PAC38

  3. Physics Motivations

  4. Quantum phase-space distributions of quarks Wpq(x,kT,r) “Mother” Wigner distributions Probability to find a quarkqin a nucleon P with a certain polarization in a position r &momentum k d3r d2kT (FT) TMD PDFs: fpu(x,kT),… GPDs: Hpu(x,x,t), … Semi-inclusive measurements Momentum transfer to quark Direct info about momentum distribution Exclusive Measurements Momentum transfer to target Direct info about spatial distribution x=0,t=0 d2kT May explain SSA PR 12-105 Exclusive Physics: DVCS with Transverse Target PDFs fpu(x),… AN √s = 20 GeV pT< 2 GeV/c May solve proton spin puzzle PR 12-105 SIDIS Physics: di-hadron with Transverse Target xF JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 4

  5. Leading Twist TMDs Number Density Helicity Transversity Quark polarisation E12-06-112 E12-09-008 Boer-Mulders for pions and kaons E12-09-007 Quarknumber and helicities E12-07-107 E12-09-009 Sivers Spin-effects for pions and kaons Nucleon polarisation Worm-gear C12-11-111 This proposal Worm-gear Boer Mulders Pretzelosity CLAS12 has access to all of them through specific azimuthal modulations (f, fS) of the cross-section thanks to the polarized beam and target JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 5

  6. Leading Twist TMDs Number Helicity Transversity: quark polarisation Survives transverse momentum integration (missing leading-twist collinear piece) Differs from helicitydue to relativistic effects and no mix with gluons in the spin-1/2 nucleon Wants multidimensional approach to investigate factorization and transverse momentum dependence Boer-Mulders Density nucleon polarisation Other elements: Worm-gear Interference between wave functions with different angular momenta: contains information about parton orbital angular motion and spin-orbit effects Transversity Sivers Worm-gear FF DF JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 6

  7. The Collins amplitude HERMES Access to transversity and Collins functions • Consistent non-zero signals for pions • Opposite sign for pions reveal Collins features • Puzzle in (low-statistics) kaon signals: • K+amplitudes larger then p+ • K- amplitudes are not in agreement COMPASS JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 7

  8. Transversity Signals Gauss Ansatz NO DATA First extractionsRole of Q2 evolution High-x and tensor charge 1st collinear extraction ! 1stextraction of Transversity! d u d u xh1(x) xh1(x) xh1(x, k ) xh1(x, k ) T T Soffer bound ? Bacchetta et al., PRL 107 (2011) Anselmino et al. Phys. Rev. D 75 (2007) JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 8

  9. The Sivers effect HERMES arXiv:1112.4423 Related to quark orbital angular momentum Non zero signals for p+ and K+ Significant Q2 evolution ? K+ signals larger than p+ arXiv: 1107.4446 ? JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 9

  10. The Sivers effect Sivers effect from SIDIS to Drell-Yan arXiv: 0901.3078 Coverage at large xand relation with Drell-Yan Sign change is a crucial test of TMDs factorization arXiv: 1103.1591 Coverage at large pTand relation with twist-3 collinear approach Sign mismatch between SIDIS and pp SSA ? ? ? Sivers moment from SIDIS T3 correlator from pp JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 10

  11. The Pretzelosity HERMES p COMPASS p Sensitive to the D-wave component and the non spherical shape of the nucleon • Statistical power of existing data is not • enough to observe significant signals • “pretzelosity” still basically unknown! p+proton ? arXiv: 0812.3246 Few % signal expected at Jlab from relativistic covariant model 0.5<pT<0.6 GeV/c JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 11

  12. The Worm-gear function COMPASS p HERMES p Worm-gear function: longitudinally polarized quarks in a transversely polarized nucleon Related to quark orbital motion Statistics not enough to investigate relations supported by many theoretical models: (supported by Lattice QCD and first data) (Wandura-Wilczek type approximation) Jlab Hall-A 3He ? ? From constituent quark model: arXiv: 0903.1271 JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 12

  13. Honour and Duty TMDs are a new class of phenomena providing novel insights into the rich nuclear structure DIS experiments get access to all PDFs and FFs, but in a convoluted way, first generation non-zero resultsprovide promises but also open questions Full coverage of valence region not achieved Limited knowledge on transverse momentum dependences Flavor decomposition often missing Evolution properties to be defined Role of the higher twist to be quantified UniversalityFundamental test of QCD Still incomplete phenomenology is asking for new inputs Crucial: completeness flavor tagging and four-fold differential extraction in all variables (x,z,Q2,PT) to have all dependencies resolved JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 13

  14. Experimental Setup

  15. The CLAS12 Spectrometer FTOF DC R3 R2 R1 Luminosity up to 1035 cm-2 s-1 RICH HD-Ice H and D polarized targets EC Broad kinematic range coverage (current to target fragmentation) HTCC HD-Ice: Transverse Target new concept (common to LOI 11-105) PCAL RICH: Hadron ID for flavor separation (common to SIDIS approved exp.) Solenoid Torus JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 15

  16. Transversely Polarized HD-Ice Target HD-ice ran from Nov/11 to May/12 at Jlab with 15mmØ ×50 mm long HD cells HD-Ice target vsstandard nuclear targets • Advantages: • Minimize nuclear background • small dilution, no attenuation at large pT • Weak holding field (BdL~ 0.1 Tm) • wide acceptance, negligible beam deflection • Disadvantages: • Very long polarizing times (months) • Sensitivity to local heating by charged beams JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 16

  17. Question 1: HD-Ice vs Electron Beam • HD targets used for eHD tests in Feb/12 and Mar/12  H polarization does not appear to suffer radiation damage with 1 nA; D does  heat removal needs improvement – faster raster, larger diameter cell, additional cooling wires, … PLOT ????? Target widerbutnot-longerthan the existingone (5 cm) • Luminosity 5 1033 cm2s-1 (minor impact on projections) • Magnet configuration simplifies (smaller zero-field volume) JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 17

  18. Question 2: Magnet Configuration Solenoid compensation Transverse saddle coil • 2T compensating, 0.5T transversefield • Enhancedversion of the existingNMR magnetsystem inside HD-icecryostat • Free forwardacceptance (up to 35°) • Recoilingprotondetection (>0.4 GeV/c) • No impact on CLAS12 central detector Main Solenoid 70o 60o 50o 35o 5o JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 18

  19. Question 2: Magnet Configuration Drift chamber occupancy 2T longitudinal field for Møller containment Bz • Goodhomogeneity (< 5mT long. field) • Moeller background under control • Workingpointbelowcritical • current of existingSC wires • Dimensioned for standard quench • protection • Static forces one order of magnitude • smaller than G10 epoxy tensile strength JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 19

  20. Question 3: Tracking Resolutions fulfill TDR general specifications JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 20

  21. The RICH Detector DC R3 Mirrors Simulation of n=1.05 aerogel + H8500: ≥ 10 p.e.for direct rings (confirmed by preliminary test-beam results) ≥ 5 p.e. for reflected rings ≥ 500 pion rejection factor @ 99% kaon eff. MA-PMTs Aerogel RICH goal: p/K/p separation of 4-5 s @ 8 GeV/c for a pion rejection factor 1:1000 Pion Contamination JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 21

  22. The RICH Detector About 30 H8500 & 10 R8900 under test Aerogel characterization: - dispersion law - transmittance Realistic prototype under construction for beam test in July 2012 Ongoing R&D with Budker Institute to improve transmittance fiber head + collimator + filters MAPMT – H8500C JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 22

  23. CLAS12 Kinematic Coverage 0.05 < x < 0.6 for Q2>1 GeV2 and W2 > 4 GeV2 Cover valence region at several GeV Q2 Constrain sub-leading twist terms PT > 1 GeV/c Limit given by cross-section 0.3 < z < 0.7 Current fragmentation No exclusivity corner JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 23

  24. CLAS12 Kinematic Coverage p+ acceptance Electron Large electron scattering angles (> 20o) mandatory to reach high Q2 values Intermediate anguar range (15-25o) mandatory to reach high PT values Electron The CLAS12 forward detector is perfectly suitable for high-Q2 and high-pT measurements since designed to cover up to 40 degrees angles JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 24

  25. Projections

  26. Systematic uncertainty 1÷4 4 1÷3 3÷6 1÷3 2 ~ 5÷8 • Estimates based on: • Current knowledge on HD-Ice target • - Experience from CLAS/HERMES measurements Dominated by uncertainties in transfer losses between cryostats Optimization after tests in fall Reduces with statistics and bin number Benefits from the large acceptance JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 26

  27. Single- and Double-Spin asymmetries • Experiment: CLAS12 with • HD-Ice transversely polarized target • 75 % polarization and 1/3 dilution for Hydrogen @ 1034cm-2s-1 • RICH detector for flavor tagging • pions, kaons and protons ID in the 3-8 GeV/c momentum range equivalent to the cross-section asymmetry for opposite spin states • Analysis: the relevant Fourier amplitudes (Collins, Sivers, etc) are extracted • simultaneously, thanks to their specific azimuthal dependence, by fitting • (ML unbinned in f,fS) the yield (cross-section) asymmetries for opposite spin states JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 27

  28. CLAS12 Projections Large pT important to test perturbativeto non-perturb. transient and for Bessel function analysis Large x important to constrain the tensor charge Sivers asymmetry Collins asymmetry JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 28

  29. Statistical precision Stat. error for a 4D analysis of the p+Sivers asymmetry on proton (x1.5 on D) target 4D analysis is possible The wanted high-Q2 high-pT defines the beam-time request 2D projection (x-pT) of the p+Sivers asymmetry JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 29

  30. The main goals Transverse spin effects in SIDIS at 11 GeVwith transversely polarized target using the CLAS12 detector • Maininterest on transverse-target single and double spin asymmetries; • Access to leading-twist poorlyknown or unmeasured TMD PDFs • which provide3-dimensional picture of the nucleon in momentumspace • (nucleontomography); • * SSA Transversity, Sivers, Pretzelosityfunctions; • * DSA Worm-gearfunction; • Multi dimensionalanalysis in x, Q2, z, pTthanks to large-acceptance and high-luminosity; • * disentanglepartondistribution from fragmentationfunctions(x vs z); • * isolate sub-leading-twist effectsfrom 1/Qdependence; • * investigate transversedegrees of freedomand perturbative to • non-perturbative QCD transient from pTdependence; • Together with alreadyapprovedexperiments with unpolarized and longitudinallypolarized • targets, complete the mapping of the TMD tableat CLAS12. JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 30

  31. Beam time request • The proposedexperimentrequires: • 11 GeV (highlypolarized) electron beam • CLAS12 detector equipped with: • - HD-Icetransverselypolarized target • - Suitablemagneticsystem (compensation + saddle coil) • - RICH (pion/kaonseparationwithin 3-8 GeV/c) FTOF DC R3 R2 R1 RICH HD-Ice EC HTCC In order to reach the desired statistical precision at high-x (valence region) and high pTfor both pion and kaons, and to allow a fully differentyal analysis in x,Q2,z,pT we ask the PAC to award 110 days of beam time (including 10 days for calibrations, empty target runs, supportive tests, etc.) PCAL Solenoid Torus JLab PAC 39, 18th June 2012, Newport News Contalbrigo M. 31

  32. • HD targets condensed, polarized and aged to the Frozen-Spin state in HDice Lab (TestLab annex) • transferred as solid, polarized HD between cryostats; moved to Hall B • In-Beam Cryostat (IBC) operates in Hall at 50 mK, 0.9 tesla • g14 ran from Nov/11 to May/12 with 15mm Ø ×50mm long HD cells • γ-beam lifetimes ~ years with 108 γ/s HDice operations during g14 / E06-101 • HD targets used for eHD tests in Feb/12 and Mar/12  H polarization does not appear to suffer radiation damage with 1 nA; D does  heat removal needs improvement – faster raster, larger diameter cell, additional cooling wires, …

  33. HD polarization during g14/E06-101

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