STAR Run-8 Achievement & Summary Akio Ogawa for the Collaboration RHIC-AGS Users Meeting 29 May 2008 At BNL STAR

2 STAR STAR Run8 Goals Main Physics Goals Gluon saturation in relativistic heavy nuclei Transverse single spin asymmetries of forward  0 (Transverse single spin asymmetries of gamma-jet) (x-dependence of gluon polarization) Non-photonic electron, Upsilon and D-mesons Low energy AuAu test run Detector Upgrades: Commissioning of pp2pp Commissioning of Forward Meson Spectrometer (FMS) Commissioning of DAQ1000 Commissioning of TOF

3 STAR STAR Run8 (Modified) Goals Main Physics Goals Gluon saturation in relativistic heavy nuclei Transverse single spin asymmetries of forward  0 (Transverse single spin asymmetries of gamma-jet) (x-dependence of gluon polarization) Non-photonic electron, Upsilon and D-mesons Low energy AuAu test run Detector Upgrades: Commissioning of pp2pp Commissioning of Forward Meson Spectrometer (FMS) Commissioning of DAQ1000 Commissioning of TOF

4 STAR 1 st part Main Physics Goals Gluon saturation in relativistic heavy nuclei Transverse single spin asymmetries of forward  0 (Transverse single spin asymmetries of gamma-jet) (x-dependence of gluon polarization) Non-photonic electron, Upsilon and D-mesons Low energy AuAu test run Detector Upgrades: Commissioning of pp2pp Commissioning of Forward Meson Spectrometer (FMS) Commissioning of DAQ1000 Commissioning of TOF

5 STAR 2 nd part Main Physics Goals Gluon saturation in relativistic heavy nuclei Transverse single spin asymmetries of forward  0 (Transverse single spin asymmetries of gamma-jet) (x-dependence of gluon polarization) Non-photonic electron, Upsilon and D-mesons Low energy AuAu test run Detector Upgrades: Commissioning of pp2pp Commissioning of Forward Meson Spectrometer (FMS) Commissioning of DAQ1000 Commissioning of TOF

6 STAR STAR Setup 2008 Charged Particle Tracking: Main TPC 1/24 with DAQ1000 Forward TPC (FTPC) Particle ID: MRPC ToF (parts) Calorimetry: Photon Multiplicity Detector (PMD) Barrel EMC Endcap EMC Forward Meson Spectrometer Event Characterization & Trigger: Beam-Beam Counter (BBC) Zero Degree Calorimeter (ZDC) Forward Pion Detectors (FPD)

7 STAR Why is forward rapidity interesting?  Forward scattering probes asymmetric partonic collisions  Mostly scattering of high-x valence quarks (with known & large polarization) 0.25 < x q < 0.7 on low-x gluons < x g < 0.1 N N  qq gg PNPN xqpNxqpN xgpNxgpN   PNPN With heavy nucleus target, gluon density would be even bigger x g ~ few =Au

8 STAR p+p and d+Au   0 +  0 +X correlations with forward  0 Conventional shadowing will change yield, but not angular correlation Coherent effects such as CGC evolution will change the angular correlation Sensitive to x g ~ in pQCD scenario; few x in CGC scenario. BRAHMS STAR PRL 97, Back-to-back correlation

9 STAR Run8 integrated luminosity at STAR Triangles are with final or near-final PMT gains Original goal Reduced goal Diamonds show data taken with a broad range of HV settings Also have ~660M FMS+fast- detector minbias events Final total: 49 nb -1 dAu Slow Luminosity (nb -1 ) dAu 87% of goal CGC reference data Sampled 7.8 pb -1 Integrated Luminosity (nb -1 ) Goal 9 pb -1 pp

10 STAR Forward single-spin asymmetries in STAR  Large transverse single-spin asymmetries at large x F  x F dependence matches Sivers effect expectations qualitatively (but not quantitatively)  p T dependence at fixed x F not consistent with 1/p T expectation of pQCD- based calculations arXiv:hep-ex/

11 STAR Forward single-spin asymmetries Acceptance of FMS and projected RHIC performance will enable… Further reach for inclusive   and heavy mesons Spin-dependent near-side correlations (     )  separation of Sivers and Collins effects Spin-dependent away-side correlations (   -jet)  isolation of Sivers effect Embark on spin-dependent inclusive  and  +jet Projections for 9 pb -1 P=70%

12 STAR Collins mechanism: Transversity (quark polarization) * asymmetry in the jet fragmentation Sivers mechanism: Correlation between nucleon spin and parton k T A N and Sivers and Collins effect Phys Rev D41 (1990) 83; 43 (1991) 261Nucl Phys B396 (1993) 161 SPSP k T,q p p SPSP p p SqSq k T, π SqSq Both effects can contribute to inclusive π 0 A N Need to go beyond inclusive π 0 detection to separate them jets and direct photons, or π-π correlation in a jet Asymmetry in hadrons in jets Asymmetry in jet/photon production

13 STAR Sampled 1.6 pb -1 Goal 3.8 pb -1 Integrated FMS FOM P 2 L (nb -1 ) Extend x F and p T range for forward single-spin asymmetries Separation of Collins and Sivers Significant extension, but well short of what we had intended to achieve Study direct photon asymmetries in forward direction Probably not practical with the current limited data set Transversely Polarized p+p FoM (P 2 L) at STAR Using reported CNI values Only 43% of goal, after calibration from jet

14 STAR Run3-5 FPD Inclusive  0 cross sections A N for inclusive  0 production FPD to FMS RUN3 dAu =only one module (South) At deuteron side (west) Inclusive  0 cross sections in dAu and RdA Forward-mid rapidity particle correlations

15 STAR FPD to FMS 47 x more area > Order of magnitude more luminosity Run8 and beyond: FMS FMS will provide full azimuthal coverage for range 2.5    4.0 broad acceptance in x F -p T plane for inclusive , ,,K ,… production in p+p and d(p)+Au broad acceptance for   and     from forward jet pairs to probe low- x gluon density in p+p and d(p)+Au collisions d Au

16 STAR New FMS Calorimeter Lead Glass From FNAL E cells of 5.8cm  5.8cm  60cm Schott F2 lead glass Loaded On a Rental Truck for Trip To BNL Students prepare cells at test Lab at BNL Total number of undergraduate students = 10 Total number of graduate students = 5 Forward Meson Spectrometer (FMS)

17 STAR Forward Meson Spectrometer for Run8 Cockcroft-Walton HV bases with computer control through USB. Designed/built in house for FEU-84. Cockcroft-Walton HV bases with computer control through USB. Designed/built in house for FEU-84. Designed and built at Penn State University Small Cell PSU Type 224 of 476 Small Cell PSU Type 224 of 476 Readout of 1264 channels of FMS provided by QT boards. Each board has 32 analog inputs 12-bit ADC / channel 5-bit TDC / channel Five FPGA for data and trigger Operates at 9.38 MHz and higher harmonics Produces 32 bits for each RHIC crossing for trigger Designed and built at UC Berkeley/SSL QT board First pi0 reconstruction of FMS events in Run8 (Calibration is underway)

18 STAR Calibration is ongoing Adjust gain for each detector by high tower sorted M   1264 M   plots  Run 6 resolution of  (M  )/M  ~10% should be possible. Need multiple iteration through the data since pion and photon energy get spread over several towers.

19 STAR Calorimeter stable at level of ~1%. Minimal run-by-run dependence in mass peak observed Entire Run 8 data set should become quickly available with final calibration. Calibration is ongoing LED system : critical calibration tool MIT (LED optics) UC Berkeley/SSL (flasher boards) Texas / Protovino / BNL (assembly) SULI program (Stony Brook students) / BNL (control electronics)

20 STAR FMS Summary and Future Forward Meson Spectrometer (FMS) is constructed & took data in run8! Low-x physics (Can we see Gluon saturation? CGC?) Separate Sivers from Collins “Jet-like” events, or pi0-pi0 Near and away side jet-pi0 correlations Heavier mesons? Eta, Ks, J/psi… With Future running, Direct Photon + Jet to test “sign change” of Sivers function

21 STAR Heavy Flavor Physics in Run8 1.High-precision non-photonic electron SVT+SSD removed ~ x10 reduction of BG Staged L0 Trigger: d+Au : ~90x statistics (run3) p+p : ~30x statistics 2. ϒ d+Au L2 trigger sampled 35 nb -1 expected yield: ~ 240 (separation of 3 S states unlikely) 3.D 0 d+Au Minimum bias dataset: 46 M events >2x statistics from previous d+Au run3

22 STAR  Largest Background source on inclusive electrons so far: Conversion electrons from SVT+SSD material  SVT/SSD removed (Run8) Radiation length reduced ~1/10  Compare the e/h ratio to run3 corresponding results, we find inclusive electrons decrease to ~ 0.10  Less material decreases relative error by factor ~10 NP Electrons in STAR: Inclusive/Background Compare the e/h ratio to run III corresponding results, we find inclusive electrons decrease to Removal of SVT+SSD : Impact on Heavy Flavor Electron hadron ratio run8/run3 Charm production via NPE(EMC), D 0, TOF (e and muon) are all consistent Next crucial check: NPE with reduced material by order of magnitude

23 STAR MinBias usable Events High Tower Integrated Luminosity Goal = 30 Mevts Goal = 30 nb -1 Recorded 46 Mevts 153 % of goal Sampled 36 pb % of goal 92% have Vz  50 cm MinBias Vertex (Z) Distribution d+Au & pp integrated luminosity at STAR dAu pp “slow” Luminosity (nb -1 ) Goal 4.5 pb -1 Sampled 3.1 pb -1 69% of goal pp

24 STAR Low Energy (9 GeV) Test Run Find Collisions Gain understanding of triggering issues Determine Luminosity Luminosities ~ 1 to 3 x cm -2 s -1 Collisions rates =  x L = (6 b)(1.5 x ) = ~.9 Hz Our present understanding of our trigger efficiency, and Angelika’s luminosity, agree very well (~ 20%)!

25 STAR √s NN =9 GeV: Preliminary Analysis STAR preliminary Uncorrected p ⊥ spectra STAR preliminary Raw multiplicity PID (dE/dx only) STAR preliminary Note: Plots should be taken only as illustrative of data quality and analysis capability George Stephans’s Talk on Friday

26 STAR Laser event (plus pileup) DAQ1000 commissioning One sector of the TPC (1/24) instrumented with DAQ1000 electronics Commissioned/integrated and took part of physics data taking by early run8 Routine operation at 250 Hz with TOF triggered events Speed test: operated at 1 kHz with only 5-7% dead time (<<100 us/event) On schedule to full implementation for run9 Replace full TPC readout chain to record full delivered luminosity Dead-time ~ 0 Data taking speed ~x10 Preliminary calibration shows dE/dx resolution and noise better than old electronics.

27 STAR Multi-gap Resistive Plate Chamber Time-of-Flight Joint project between USA & China In detector research 1 tray in some of runs trays in run 8 behind DAQ1000 ~75% in run 9 100% in run 10 (Q2,FY09) -0.9<  <0.9, 0<  <2  23,000 ch (120 trays) Total TOF triggered events 76M for physics and calibration in p+p Provide crucial information for pileup rejection Preliminary calibration : 81ps (goal <100ps) TOF+TPX from run8: Non-photonic electron at low p T with low material 25x statistics for PID spectra in p+p >10x S/B ratio of Resonances (  ) in p+p Posters by Zebo Tang and Jin Fu e

28 STAR  Roman pots installed east and west downstream of STAR (thanks, C-AD!)  pp2pp data acquisition integrated into STAR trigger and DAQ systems  Inserted Roman pots into the beam pipe during last 2 hours of p+p run  Observed pp2pp detector rates as expected  No impact on background levels in STAR mid-rapidity detectors  Physics in Run 9 For the future: STAR

29 STAR SystemTriggerGoalAcquired d+AuFMS60/nb (reduced 30/nb)49/pb d+AuBEMC HT30/nb36/pb d+AuMinBias30M events46M events p+pFMS9/pb7.8/pb p+pFMSP 2 L = 3.8/pbP 2 L = 1.6/pb p+pBEMC HT4.5/pb3.1/pb p+pMinBiasFew k events (76M Events with TOF+TPX) STAR Run8 Goals & Luminosity

30 STAR STAR Run8 Summary Main Physics Goals Gluon saturation in relativistic heavy nuclei Transverse single spin asymmetries of forward  0 (Transverse single spin asymmetries of gamma-jet) (x-dependence of gluon polarization) Non-photonic electron, Upsilon and D-mesons Low energy AuAu test run Detector Upgrades: Commissioning of pp2pp Commissioning of FMS Commissioning of DAQ1000 All 3 used for Physics Commissioning of TOF Short run didn’t allow us to complete some of original goals “Short” run8 was successful Exciting physics will be coming out