The W program at PHENIX

1. The W program at PHENIX Workshop on Parity Violating Spin Asymmetries BNL, April 26-27th R. Seidl (University of Illinois and RBRC) for the PHENIX Collaboration

2. Motivation for W physics I: sea polarization • Parity violating decay selects quark flavor: • Forward/backward region selects valence/sea quark helicity contribution • High luminosity and high √s=500 GeV needed • Only m± detected  control of backgrounds important • High energy muon trigger necessary • Advantages of W as probe: • Large Scale ( ~mW) • no Fragmentation functions required R.Seidl:The W physics program at PHENIX

3. Motivation for W physics II: asymmetric (unpolarized) sea? • Asymmetry between d(x) and u(x) seen at E866, HERMES and NA51 • Test asymmetry in W production w/o possible nuclear effects • Also high-x behavior of u(x)/d(x) can be tested R.Seidl:The W physics program at PHENIX

4. The PHENIX Detector • Philosophy (initial design): • High rate capability & granularity • Good mass resolution & particle ID • Sacrifice acceptance • p0/g/h detection • Electromagnetic Calorimeter • p+/p- • Drift Chamber • Ring Imaging Čerenkov Counter • Heavy quarks • Muon Id/Muon Tracker • Relative Luminosity • Beam Beam Counter (BBC) • Zero Degree Calorimeter(ZDC) • Local Polarimetry - ZDC R.Seidl:The W physics program at PHENIX

5. Necessity of muon trigger upgrade • Hadronic decays dominate muon rates • W dominate only above 20-25 GeV • DAQ cannot take full rate @500GeV • Current muon trigger momentum “blind” • Need for a momentum sensitive muon trigger • Add Resistive Plate Counters(RPCs) • Add fast readout electronics for Muon tracker R.Seidl:The W physics program at PHENIX

6. RPC2 RPC3 • Three dedicated trigger RPC stations (CMS design): • RPC1(a,b): ~180 segments inj, 2 in θ • RPC2: ~360 segments in j, 2 in θ • RPC3: ~360 segments in j, 2 inθ • (Trigger only – offline segmentation higher) RPC1(a+b) NSF (Funded) r=3.40m MuTr • MuTr front end electronics • Upgrade to allow LL1 information JSPS (Funded) PHENIX muon trigger upgrade R.Seidl:The W physics program at PHENIX

7. Resistive Plate Counters -HV GND GND -HV Challenges: • Equip large areas (RPC2 ~22 m2) • Limited space (smallest ~30cm) • Varying rates from pp to Heavy Ion  Bakkelite RPCs: • Modules can cover larger area • Lower resistivity than glass  higher rate capability • Thickness of a module only ~3cm Readout Collaborative effort between groups in Korea, China, several American universities and BNL R.Seidl:The W physics program at PHENIX

8. Limited space for installation • RPC2 R.Seidl:The W physics program at PHENIX

9. Sideview of PHENIX with RPCs RPC3 South RPC2 South RPC2 North RPC3 North R.Seidl:The W physics program at PHENIX

10. New MuTRG Front End Electronics(FEE) MuTRG-TX MuTRG-AD MuTr Chamber Current FEE R.Seidl:The W physics program at PHENIX

11. Offline backgrounds in W analysis • Cosmic muons • Reliable rates not available • First tests suggest a small rate • Muons from Z/g decays • Z have small x-section • Z sensitive to quark helicities • Fake high PT muons from low PT hadron decays R.Seidl:The W physics program at PHENIX

12. How to address fake high PT hadrons I: Absorber • At early stage (2009-2010) additional absorber instead of RPC1 to reduce rate • Maybe already install Tungsten instead of Cu in the nosecone ( needed for Nose Cone Calorimeter ) R.Seidl:The W physics program at PHENIX

13. How to address fake high PT hadronsII:The PHENIX NoseCone Calorimeter (NCC) Electromagnetic Preshower and Shower-Max Hadronic • g+e identification • g – p0 separation • e/m isolation • jet identification • dE/dx • e/g/jet triggers Fake hadron reduction NCC R.Seidl:The W physics program at PHENIX

14. How to address fake high PT hadrons III:The forward Vertex detector • Baseline: • 4 layers • Vertical planes • 75 m radial pitch, 7.5° phi segmentation (2 – 13 mm) • Maximize z and r extent to give good resolution and ≥3 hits/track as much as possible • 2*600K channels • Scope • Recently favorably reviewed for FY08 start • Bootstrapped by LANL LDRD funds to construct one octant prototype • Submitted proposal to DOE for FY08 funding start • New Idea on hadron suppression for W physics: • Average dE/dx in 3 planes can distinguish low energetic hadrons and high energetic muons R.Seidl:The W physics program at PHENIX

15. PHENIX ALW+/-Sensitivity Expected Sensitivity with W measurement • Machine and detector requirements: • ∫Ldt=800pb-1, P=0.7 at √s=500 GeV • Muon trigger upgrade! 2009 to 2012 running at √s=500 GeV is projected to deliver ∫Ldt ~980pb-1 R.Seidl:The W physics program at PHENIX

16. vs HERMES • SIDIS: • large x-coverage • uncertainties from • Fragmentation functions • W-physics: • limited x-coverage • High Q2 theoretically • clean • No FF-info needed R.Seidl:The W physics program at PHENIX

17. Upgrade Schedule R&D Phase Construction Phase Ready for Data R.Seidl:The W physics program at PHENIX

18. Physics Timeline see Spin report to DOE http://spin.riken.bnl.gov/rsc/ L= 1x1031cm-2s-1 6x1031cm-2s-1 1.6x1032cm-2s-1 P= 0.5 0.6 0.7 …………………………………… √s= ……………………….. 200 GeV …………………......... 500 GeV| 2005 2006 2007 2008 2009 …. 2012 (RHIC II) 10 pb-1 …………………………………… 275pb-1 …….. 980pb-1 @ 200GeV @ 500GeV Inclusive hadrons + Jets ~ 25% Transverse Physics Charm Physics direct photons bottom physics W-physics ALL(hadrons, Jets) ALL(charm) ALL(γ) AL(W) R.Seidl:The W physics program at PHENIX

19. Outlook: strange polarization with RHICII luminosities P1 • At high luminosities possibility to tag strangeness: • Detect muon from W decay (Muon Trigger) • Detect displaced vertex of D meson decay (VTX and FVTX detectors) • Charge of m selects strange/antistrange • More in Yokoya-san’s talk P2 R.Seidl:The W physics program at PHENIX

20. Summary • Muon Trigger upgrade funded and progressing well • First Test Octant of FEE upgrade will be ready for RUN8 • First new muon Trigger available for run 10 • Additional upgrades will improve offline W analysis R.Seidl:The W physics program at PHENIX