7/6/2005Douglas Fields for the PHENIX collaboration 1 Spin Physics With PHENIX Douglas E. Fields University of New Mexico/Riken-BNL Research Center

7/6/2005Douglas 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

7/6/2005Douglas Fields for the PHENIX collaboration 3

7/6/2005Douglas Fields for the PHENIX collaboration 4 Multi-purpose experiment: Central Spectrometer Electrons Photons Hadrons Forward Spectrometer Muons Very Forward Detectors Triggering Centrality Polarimetry Detector Overview

7/6/2005Douglas Fields for the PHENIX collaboration 5 Central Arm Spectrometers East Arm tracking: – DC, PC1, TEC, PC3 electron & hadron ID: – RICH,TEC/ TRD, – TOF, EMCal photons: – EMCal PID – TOF West Arm tracking: – DC,PC1, PC2, PC3 electron ID: – RICH, – EMCal photons: – EMCal PID – Aerogel

7/6/2005Douglas Fields for the PHENIX collaboration 6 Forward Arm Spectrometers Muon Tracking – Radial field magnets – 3 stations of cathode strip chambers – 100  m resolution/plane = 60  m resolution/station – J/  mass resolution = 160MeV Muon Identification – 5 layers of Irocci tubes – x-y planes between steel absorber –  rejection ~ Zero-Degree Calorimeters – hadron calorimeter – neutron sensitive Beam-Beam Counters – QuartzCherenk ov radiators – 3.0 < |  | < 3.9 Multiplicity- Vertex Detector – Silicon strip

7/6/2005Douglas 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 –  in EMCal – charged hadron (BBC/Central ) – single muons in Muon Arms – A T, A TT Drell-Yan di-muons – leading high p t in central arms – e, , e , , and D →  K – ee,  in Central & Muon Arms – high p T  ± in Muon Arms

7/6/2005Douglas Fields for the PHENIX collaboration 8 Spin Physics Overview Physics – Signal Orbital Angular Momentum – Left-right asymmetry in single transverse polarization – Di-jet k T difference in double-longitudinal polarization PHENIX can see – leading high p t π 0 with correlated h ± in central arms

7/6/2005Douglas Fields for the PHENIX collaboration 9 How Do We Measure… = Gluon polarization from DIS from pQCD

7/6/2005Douglas 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

7/6/2005Douglas Fields for the PHENIX collaboration 11 Longitudinal Polarization Double spin asymmetry in π 0 production Confidence Levels

7/6/2005Douglas Fields for the PHENIX collaboration 12 Transverse Polarization Single spin asymmetry in π 0 and h ± production Run02: 0.15 pb -1 and 15 % polarization Run05: 0.16 pb -1 and 50% polarization ~9X better statistical significance

7/6/2005Douglas Fields for the PHENIX collaboration 13 Forward Neutron A N 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 ～ 1800cm 10cm(±2mrad) PHENIX Collision Point Blue beamYellow beam BlueYellow BlueYellow P L /P > 0.99 blue & yellow

7/6/2005Douglas 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!

7/6/2005Douglas Fields for the PHENIX collaboration 15 RHIC Status as of Run 5 BRAHMS & PP2PP STAR PHENIX AGS LINAC BOOSTER Pol. Proton Source Spin Rotators 20% Snake Siberian Snakes 200 MeV polarimeter Rf Dipoles RHIC pC “CNI” polarimeters PHOBOS RHIC absolute pH polarimeter Siberian Snakes AGS pC “CNI” polarimeter 5% Snake

7/6/2005Douglas 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!

7/6/2005Douglas Fields for the PHENIX collaboration 17 PHENIX Run 5 Integrated L

7/6/2005Douglas Fields for the PHENIX collaboration 18 PHENIX Run 5 Integrated FOM

7/6/2005Douglas Fields for the PHENIX collaboration GeV Transverse Polarization blue : ~33% yellow : ~49% M. Togawa Polarization 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 A N for higher  s

7/6/2005Douglas 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

7/6/2005Douglas Fields for the PHENIX collaboration 21 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 60 MB/s (100 MB/s)

7/6/2005Douglas 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.

7/6/2005Douglas 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 BBC ZDC ZDC/BBC for each crossing (run171595) The vertex width fluctuation appears to be small unlike in the past runs. Analysis is on going.

7/6/2005Douglas Fields for the PHENIX collaboration 24 Sivers di-Hadron Analysis Boer and Vogelsang, Phys.Rev.D69:094025,2004, hep-ph/ 00 22  h

7/6/2005Douglas Fields for the PHENIX collaboration 25 Orbital From Jet k T Like Helicity (Positive on Positive Helicity) Measure jet Central Collisions Smaller Integrate over b, left with some residual k T Peripheral Collisions Larger Un-like Helicity (Positive On Negative Helicity) Peripheral Collisions Smaller Central Collisions Larger Integrate over b, left with some different residual k T

7/6/2005Douglas Fields for the PHENIX collaboration 26 Future Plans:  q/q via W    Nuclear Physics B666(2003)31-55 GS-A,B GRSV valence At  s=500 GeV, high rates from heavy flavor and jets overwhelm existing muon trigger Requires Muon Trigger Upgrade AL()AL()

7/6/2005Douglas Fields for the PHENIX collaboration 27 W  Trigger Upgrade Intended RPC Locations RPC2 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

7/6/2005Douglas Fields for the PHENIX collaboration 28 Silicon Vertex Tracker Mechanical Specifications: 4-layer Cones at forward rapidity: inner radius2.5 cm outer radius18 cm z position (at r = 2.5cm)20, 26, 32, 38 cm mini strips 50 µm x mm total sensor elements~2.0M azimuthal coverage360 deg 4-layer Barrel at central rapidity: layer radius2.5, 5, 10,14 cm layer length24, 24, 30, 36 cm pixels (layers 1+2)10+20 modules, ~3.9 M pixels pixel size50 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 40 cm cm beam pipe radius: 2 cm

7/6/2005Douglas 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!

7/6/2005Douglas Fields for the PHENIX collaboration 30 Backup

7/6/2005Douglas Fields for the PHENIX collaboration 31 π ± A LL Measurement Stratmann Lecture, BNL 1 st Spin School 5-15 GeV  identified by RICH and EMC hadronic shower Not yet possible to determine sign of  g

7/6/2005Douglas Fields for the PHENIX collaboration 32 Jet A LL 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 p T ) 2. How much fraction (Z) do we catch? How much is its ambiguity (  Z)? Compared to pi0: ― More statistics, but Systematic uncertainty in interpretation By K.Nakano One whole arm Theoretical curve is scaled by Z~0.85 to match with our observable.

7/6/2005Douglas Fields for the PHENIX collaboration 33 Run02: 0.15 pb -1 and 15 % polarization h- A N for both charged hadrons and neutral pions consistent with zero at midrapidity. process contribution to  0 More statistics needed to map out p T  x  g/q dependence Run05: 0.16 pb -1 and 50% polarization ~9X better statistical significance

7/6/2005Douglas Fields for the PHENIX collaboration 34 Polarization Direction BLUE (A N = 6.24%) YELLOW (A N = 5.27%) (LR) (TB) (LR) (TB) PHYSICS Period SLSL STST Commisioning Period =A Blue : 10.3%  3.9% Yellow : 21.5%  5.3%

7/6/2005Douglas Fields for the PHENIX collaboration 35 Transverse Spin Asymmetries Neutron asymmetry observed in IP12 while testing a local polarimeter designed to look for  0,  asymmetries: “Left-Right” asymmetry measured for different slices in phi:

7/6/2005Douglas Fields for the PHENIX collaboration 36 Phi Asymmetry 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) Run-02

7/6/2005Douglas Fields for the PHENIX collaboration 37 Local Polarimeter at PHENIX Spin Rotators OFF Blue Yellow Spin Rotators ON, Current Reversed Yellow Blue Yellow Yellow Spin Rotators ON, Almost… Spin Rotators ON, Correct! |P|=30%, P T =0%  P L =30%) |P|=37%, P T =24%  P L =28%) P B =35.5% PB=37% Run-03

7/6/2005Douglas Fields for the PHENIX collaboration 38 Transverse Spin Asymmetries Charged hadron asymmetry – Measured using BBC – Hadrons in central arms – Decay muons in Muon Arms Normalized Yield PYTHIA+Decay Real Data Distance from Absorber [cm] 80 cm   /K Beam Absorber L : Distance from Absorber Event Vertex A N from quark polarization

7/6/2005Douglas Fields for the PHENIX collaboration 39 Longitudinal Double Spin Asymmetries proton beam  or  gluon photon jet Want to measure inclusive photon production (NLO calculations available). Need higher luminosity. Instead, (for now) measure leading  0 as a jet tag.  G(x) x prompt photon GS95

7/6/2005Douglas Fields for the PHENIX collaboration 40 Longitudinal Double Spin Asymmetries To determine  G, look at A LL : R is the relative luminosity, and can be measured (to some accuracy) at PHENIX. Our Goal:  R/R < 1×10 -3 for each fill   A LL < 2×10 -3 (expected A LL for pions ~ 3×10 T =3 GeV/c)

7/6/2005Douglas 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) = N A (i)/N B (i) – Ratio should be the same for all crossings (constant) if: N A (i) = L * ε and N B (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+A LL P 1 (i)P 2 (i)] C, A LL are the fitting parameters. – Precision of relative luminosity can be estimated by:  C/C – If  2 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.

7/6/2005Douglas 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.

7/6/2005Douglas 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)

7/6/2005Douglas 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  0 cross- section. Agreement with pQCD indicates we can extend A LL analysis to lower p T, important for increasing statistical precision with Run-3 data set. submitted to PRL, hep-ex/

7/6/2005Douglas Fields for the PHENIX collaboration 45 Gluon Polarization Next step: Measure A LL at In Run-02, had 150nb -1 with polarization ~15%. In Run-03, we have ~350nb -1 with polarization ~30% (  A LL goes as P 4 ). Expect that we can make a differentiation with maximal  G:

7/6/2005Douglas Fields for the PHENIX collaboration 46 Gluon Polarization PHENIX can measure J/  → e + e ,     Can also measure open heavy quark decay to single and di-leptons (e ±,  ±, e +  , e    . Future upgrades to detect offset vertex.  G(x) x cc  eX bb  e  X J/  GS95

7/6/2005Douglas Fields for the PHENIX collaboration 47 Open Charm Single muons or electrons e-  coincidence Better:

7/6/2005Douglas Fields for the PHENIX collaboration 48 Spin Physics with VTX Upgrade Jet-axis for photon+jet-axis  constraint on x c  e,  displaced vertex low-x S/B, D  K  high- x b  displaced J/  low/high-x, b  e, displaced vertex  high -x

7/6/2005Douglas Fields for the PHENIX collaboration 49 Flavor Decomposed Quark Polarization At = 500GeV/c 2, PHENIX can measure W ± decay to single, high p t 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*10 32 cm -2 s -1  W in 10 weeks – reduce interaction rate ~12 MHz to few kHz

7/6/2005Douglas 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

7/6/2005Douglas Fields for the PHENIX collaboration 51 Summary PHENIX is well suited to the study of spin physics with a wide variety of probes. Run-02 gave us a baseline for transverse spin asymmetry and cross-sections. So far, in Run-03, we have commissioned with longitudinal polarized protons (successful spin rotators) and are taking data for an A LL measurement using  0. We have studied our relative luminosity systematics and can make an A LL measurement that is statistics limited. We have an upgrade plan that will give us the triggers and vertex information that we need for precise future measurements of  G,  q and new physics at higher luminosity and energy.

7/6/2005Douglas Fields for the PHENIX collaboration 52 Additional Material

7/6/2005Douglas Fields for the PHENIX collaboration 53 Other Topics Transversity structure function g2 in Drell-Yan

7/6/2005Douglas Fields for the PHENIX collaboration 54 Vertical polarization profile (scan with horizontal target) Raw asymmetry (x10 -3 ) L-R asymmetry Count rate (beam size profile) 2mm In BLUE ring at flattop

7/6/2005Douglas Fields for the PHENIX collaboration 55 Current J/  From Run-02 Using like-sign subtraction from lepton pairs: