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Spin Physics With PHENIX

Spin Physics With PHENIX. Douglas E. Fields University of New Mexico/Riken-BNL Research Center. Outline. PHENIX Overview Status as of Run3 and Run4 data analysis Run5 achievements Expected Run5 results Future plans Summary. Detector Overview. Multi-purpose experiment:

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Spin Physics With PHENIX

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  1. Spin Physics With PHENIX Douglas E. Fields University of New Mexico/Riken-BNL Research Center Douglas Fields for the PHENIX collaboration

  2. Outline • PHENIX Overview • Status as of Run3 and Run4 data analysis • Run5 achievements • Expected Run5 results • Future plans • Summary Douglas Fields for the PHENIX collaboration

  3. Douglas Fields for the PHENIX collaboration

  4. Detector Overview • Multi-purpose experiment: • Central Spectrometer • Electrons • Photons • Hadrons • Forward Spectrometer • Muons • Very Forward Detectors • Triggering • Centrality • Polarimetry Douglas Fields for the PHENIX collaboration

  5. Central Arm Spectrometers • West Arm • tracking: • DC,PC1, PC2, PC3 • electron ID: • RICH, • EMCal • photons: • EMCal • PID • Aerogel • East Arm • tracking: • DC, PC1, TEC, PC3 • electron & hadron ID: • RICH,TEC/TRD, • TOF, EMCal • photons: • EMCal • PID • TOF Douglas Fields for the PHENIX collaboration

  6. Forward Arm Spectrometers • Muon Tracking • Radial field magnets • 3 stations of cathode strip chambers • 100mm resolution/plane = 60mm resolution/station • J/Y mass resolution = 160MeV • Muon Identification • 5 layers of Irocci tubes • x-y planes between steel absorber • p/m rejection ~ 10-4 • Zero-Degree Calorimeters • hadron calorimeter • neutron sensitive • Beam-Beam Counters • QuartzCherenkov radiators • 3.0 < || < 3.9 • Multiplicity-Vertex Detector • Silicon strip Douglas Fields for the PHENIX collaboration

  7. Spin Physics Overview • Physics • Signal • Single transverse-spin asymmetry • neutron • 0 • charged hadron • single muon from  decay • transversity • Gluon polarization • jet production/direct photons • open heavy flavor • J/ • Flavor decomposed quark polarization • W± • PHENIX can see • neutrons in ZDC/SMD • gg in EMCal • charged hadron (BBC/Central ) • single muons in Muon Arms • AT, ATT Drell-Yan di-muons • leading high pt in central arms • e, m, e, , and D→pK • ee, mm in Central & Muon Arms • high pTm± in Muon Arms Douglas Fields for the PHENIX collaboration

  8. Spin Physics Overview • Physics • Signal • Orbital Angular Momentum • Left-right asymmetry in single transverse polarization • Di-jet kT difference in double-longitudinal polarization • PHENIX can see • leading high ptπ0with correlated h± in central arms Douglas Fields for the PHENIX collaboration

  9. How Do We Measure… = Gluon polarization from DIS from pQCD Douglas Fields for the PHENIX collaboration

  10. Status of Run3 and Run4 Analysis • Unpolarized cross-sections • Measured un-polarized cross section at s=200 GeV well described by NLO pQCD • non-identified charged hadrons,  also measured Douglas Fields for the PHENIX collaboration

  11. Longitudinal Polarization • Double spin asymmetry in π0 production Confidence Levels Douglas Fields for the PHENIX collaboration

  12. Transverse Polarization • Single spin asymmetry in π0and h± production • Run02: 0.15 pb-1 and 15 % polarization • Run05: 0.16 pb-1 and 50% polarization • ~9X better statistical significance Douglas Fields for the PHENIX collaboration

  13. Blue Yellow Blue Yellow Forward Neutron AN • Spin Rotator Magnets enable longitudinal collisions in IRs • PHENIX discovered at low pT and high xF an analyzing power in neutron production in pp collisions at 100 GeV • ZDC + Shower Max Detector PL/P > 0.99 blue & yellow ～1800cm PHENIX Collision Point 10cm (±2mrad) Blue beam Yellow beam Douglas Fields for the PHENIX collaboration

  14. Run 5 Achievements • RHIC Milestones: • >50% polarization achieved without cold AGS snake! (also commissioned cold snake) • Increased longitudinal polarized statistics by factor of >10! • Accelerated and collided polarized protons to 410GeV! • 110 bunch mode! • Extremely successful! Douglas Fields for the PHENIX collaboration

  15. RHIC Status as of Run 5 RHIC pC “CNI” polarimeters absolute pH polarimeter BRAHMS & PP2PP PHOBOS RHIC Siberian Snakes PHENIX STAR Siberian Snakes Spin Rotators 5% Snake LINAC BOOSTER AGS pC “CNI” polarimeter Pol. Proton Source AGS 200 MeV polarimeter Rf Dipoles 20% Snake Douglas Fields for the PHENIX collaboration

  16. Run 5 Achievements • PHENIX Milestones: • Increased our longitudinal FOM by >200x • Increased our transverse FOM by ~9x • Measured a phi asymmetry at 410GeV • Took scaler data with our new scaler boards. • Transferred data on-the-fly to CCJ for reconstruction. • Extremely successful! Douglas Fields for the PHENIX collaboration

  17. PHENIX Run 5 Integrated L Douglas Fields for the PHENIX collaboration

  18. PHENIX Run 5 Integrated FOM Douglas Fields for the PHENIX collaboration

  19. 410 GeV Transverse Polarization Polarization blue : ~33% yellow : ~49% • Analyzing power of PHENIX Local Polarimeter roughly the same despite doubling of energy • Local Polarimeter can be used at higher s • Demonstrates that RHIC is capable of accelerating to higher s without losing all polarization • Will provide first look at AN for higher s M. Togawa Douglas Fields for the PHENIX collaboration

  20. PHENIX scaler boards -VME based -4 pcs. -25 inputs (24 channels + 1 RHIC-clock) PECL-signals -40 bits deep -80 MB histogram memory -Zero suppression -coarse and vernier delay registers -streaming mode -preparation for high luminosity running Douglas Fields for the PHENIX collaboration

  21. 60 MB/s (100 MB/s) Data Transfer to CCJ • 5+ kHz DAQ Rate • International cooperation with RIKEN for data transfer and production • Central Arm production started on June 16, 2005 • Muon Arm production to follow Douglas Fields for the PHENIX collaboration

  22. Expected Run 5 Results • Run03+Run04 • distinguished between GRSV-max and GRSV-std • Run05 • will distinguish between GRSV-std and G = 0. Douglas Fields for the PHENIX collaboration

  23. Relative Luminosity Measurement For double spin asymmetry measurements, relative luminosity error R works as A systematic uncertainty is checked by consistency between BBC and ZDC counts Scalers ZDC ZDC/BBC for each crossing (run171595) BBC The vertex width fluctuation appears to be small unlike in the past runs. Analysis is on going. Douglas Fields for the PHENIX collaboration

  24. 2 0  h Sivers di-Hadron Analysis Boer and Vogelsang, Phys.Rev.D69:094025,2004, hep-ph/0312320 Douglas Fields for the PHENIX collaboration

  25. Central Collisions Larger Peripheral Collisions Smaller Orbital From Jet kT Un-like Helicity(Positive On Negative Helicity) Like Helicity(Positive on Positive Helicity) Peripheral Collisions Larger Measure jet Integrate over b, left with some residual kT Integrate over b, left with some different residual kT Central Collisions Smaller Douglas Fields for the PHENIX collaboration

  26. Future Plans: q/q via W Nuclear Physics B666(2003)31-55 GS-A,B AL() GRSV valence • At s=500 GeV, high rates from heavy flavor and jets overwhelm existing muon trigger • Requires Muon Trigger Upgrade Douglas Fields for the PHENIX collaboration

  27. W Trigger Upgrade RPC2 Intended RPC Locations • Resistive Plate Chambers technology chosen by PHENIX forward upgrade group • Cheap – wide coverage possible • Can leverage existing RPC R&D from CMS • Timing information to reject backgrounds and track association with correction bunch • 3-dim space point for enhanced pattern recognition • Two small prototypes successfully tested in Run05 • Recently approved NSF-MRI – Full installation expected in Run09 Douglas Fields for the PHENIX collaboration

  28. beam pipe radius: 2 cm 0 10 20 cm 0 10 20 30 40 cm Mechanical Specifications: 4-layer Cones at forward rapidity: inner radius 2.5 cm outer radius 18 cm z position (at r= 2.5cm) 20, 26, 32, 38 cm mini strips 50 µm x 2.2-13 mm total sensor elements ~2.0M azimuthal coverage 360 deg 4-layer Barrel at central rapidity: layer radius 2.5, 5, 10,14 cm layer length 24, 24, 30, 36 cm pixels (layers 1+2) 10+20 modules, ~3.9 M pixels pixel size 50 µm x 425 µm strip-pixels (layers 3+4) 18+26 modules, ~378 K r/o ch. strip-pixel size 80 µm x 1 mm (3 cm) azimuthal coverage ~320 deg Silicon Vertex Tracker Douglas Fields for the PHENIX collaboration

  29. Summary • RHIC is steadily making progress towards luminosity and polarization goals. • PHENIX has set the baseline for RHIC Spin Physics in previous runs. • Run 5 was a tremendous success! • PHENIX has many pots in the analysis fire - next stop: Waco. • Future is even brighter, with a rich assortment of interesting new physics in the coming years! Douglas Fields for the PHENIX collaboration

  30. Backup Douglas Fields for the PHENIX collaboration

  31. π± ALL Measurement Stratmann Lecture, BNL 1st Spin School • 5-15 GeV  identified by RICH and EMC hadronic shower • Not yet possible to determine sign of g Douglas Fields for the PHENIX collaboration

  32. Jet ALL One whole arm Theoretical curve is scaled by Z~0.85 to match with our observable. By K.Nakano Even with a limited acceptance in PHENIX central arm, we can capture most of a Jet. → Tag one photon, sum all energy in one arm. Question : 1. Are those really jets? (agreement much worse at low pT) 2. How much fraction (Z) do we catch? How much is its ambiguity (DZ)? • Compared to pi0: • More statistics, but Systematic uncertainty in interpretation Douglas Fields for the PHENIX collaboration

  33. process contribution to 0 AN for both charged hadrons and neutral pions consistent with zero at midrapidity. h- More statistics needed to map out pT x  g/q dependence • Run02: 0.15 pb-1 and 15 % polarization • Run05: 0.16 pb-1 and 50% polarization • ~9X better statistical significance Douglas Fields for the PHENIX collaboration

  34. =A ST SL Polarization Direction BLUE (AN = 6.24%) (LR) (LR) YELLOW (AN = 5.27%) Commisioning Period PHYSICS Period (TB) (TB) • Blue : 10.3%  3.9% • Yellow : 21.5%  5.3% Douglas Fields for the PHENIX collaboration

  35. Transverse Spin Asymmetries • Neutron asymmetry observed in IP12 while testing a local polarimeter designed to look for p0, g asymmetries: • “Left-Right” asymmetry measured for different slices in phi: Douglas Fields for the PHENIX collaboration

  36. Phi Asymmetry Run-02 • Successful measurement of forward neutron asymmetry. • Understood (?) in terms of single pion exchange. • Large asymmetry gives good figure of merit for local (PHENIX) polarimetry. Y. Fukao et al., "Proceedings of the 15th International Spin Physics Symposium (SPIN2002) Douglas Fields for the PHENIX collaboration

  37. Local Polarimeter at PHENIX Run-03 Spin Rotators OFF Spin Rotators ON, Current Reversed Yellow Blue Blue Yellow Spin Rotators ON, Correct! Spin Rotators ON, Almost… PB=35.5% PB=37% |P|=30%, PT=0%  PL=30%) |P|=37%, PT=24% PL=28%) Yellow Blue Yellow Blue Douglas Fields for the PHENIX collaboration

  38. L : Distance from Absorber m Absorber p/K Beam Beam Event Vertex PYTHIA+Decay Real Data Normalized Yield Distance from Absorber [cm] Transverse Spin Asymmetries • Charged hadron asymmetry • Measured using BBC • Hadrons in central arms • Decay muons in Muon Arms AN from quark polarization 80 cm Douglas Fields for the PHENIX collaboration

  39. GS95 prompt photon DG(x) x Longitudinal Double Spin Asymmetries proton beam jet gluon  or  • Want to measure inclusive photon production (NLO calculations available). • Need higher luminosity. • Instead, (for now) measure leading p0 as a jet tag. photon  or  proton beam Douglas Fields for the PHENIX collaboration

  40. Longitudinal Double Spin Asymmetries • To determine DG, look at ALL: • R is the relative luminosity, and can be measured (to some accuracy) at PHENIX. • Our Goal: dR/R < 1×10-3 for each fill dALL < 2×10-3(expected ALL for pions ~ 3×10-3 @PT=3 GeV/c) Douglas Fields for the PHENIX collaboration

  41. Relative Luminosity • In order to investigate our ability to measure the relative (++ vs. +-) luminosity: • look at ratio of 2 detector scalers crossing-by-crossing: • a(i) = NA(i)/NB(i) • Ratio should be the same for all crossings (constant) if: • NA(i) = L * ε and NB(i) = L * ε • B is always the counts from the beam-beam counter (BBCLL1), A is one of the other scalers. • Fit this by the expected pattern: • a(i) = C[1+ALLP1(i)P2(i)] • C, ALL are the fitting parameters. • Precision of relative luminosity can be estimated by: • dC/C • If c2 of the fitting is bad, look for other factors in N(i). Ratio of Zero-Degree Counter scalars to Beam-Beam Counter scalers, sorted by bunch crossing and fit to a constant. Douglas Fields for the PHENIX collaboration

  42. Correction factors • What other factors could play a role in the determination of the scaler rate besides the luminosity? • Vertex width • Vertex width also measured crossing by crossing. • Look for a correlation of the scalers ratio with the vertex width: • Good correlation • Can correct ratio for this factor. Douglas Fields for the PHENIX collaboration

  43. Limit on Relative Luminosity Measurement • After correction for (measured) vertex width, the ratio of counts in the two detectors is consistent with constant up to our level of statistics • This means that if we apply correction for this the precision on R goes from:0.11%  0.06% (syst. limited) (stat. limited) Douglas Fields for the PHENIX collaboration

  44. Gluon Polarization • Next step: Measure cross-section as a test for perturbative QCD at • In Run-02, precise measure of p0 cross-section. • Agreement with pQCD indicates we can extend ALL analysis to lower pT, important for increasing statistical precision with Run-3 data set. submitted to PRL, hep-ex/0304038 Douglas Fields for the PHENIX collaboration

  45. Gluon Polarization • Next step: Measure ALL at • In Run-02, had 150nb-1 with polarization ~15%. • In Run-03, we have ~350nb-1 with polarization ~30% (dALL goes as P4). • Expect that we can make a differentiation with maximal DG: Douglas Fields for the PHENIX collaboration

  46. DG(x) x Gluon Polarization • PHENIX can measure J/Y→ e+e-, m+m- • Can also measure open heavy quark decay to single and di-leptons (e±, m±, e+m-, e-m+). • Future upgrades to detect offset vertex. GS95 cceX bbeX J/ Douglas Fields for the PHENIX collaboration

  47. Open Charm • Single muons or electrons • e-m coincidence • Better: Douglas Fields for the PHENIX collaboration

  48. Spin Physics with VTX Upgrade • Jet-axis for photon+jet-axis  constraint on x • ce, m displaced vertex low-x S/B, DKp high-x • bdisplaced J/y low/high-x, be, displaced vertexhigh -x Douglas Fields for the PHENIX collaboration

  49. Flavor Decomposed Quark Polarization • At = 500GeV/c2, PHENIX can measure W± decay to single, high pt muons. • W-production sensitive to polarized anti-quark and quark distributions • interpretation of asymmetry theoretically well established • insensitive to fragmentation functions • insensitive to higher twist • Experimental challenge • acceptance for W   X • 1 nb cross-section at 500 GeV • at 2*1032 cm-2s-1  10000 W in 10 weeks • reduce interaction rate ~12 MHz to few kHz Douglas Fields for the PHENIX collaboration

  50. Muon Cherenkov Trigger Upgrade • Possible solutions for an enhanced muon trigger: • forward hodoscopes • anode readout • cherenkov detector • nosecone calorimeter Douglas Fields for the PHENIX collaboration

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