R.Seidl (RBRC)

1. W muon analysis in PHENIXStatus of the background understanding, signal, smearing and asymmetries R.Seidl (RBRC) R.Seidl: status of simulation

2. PHENIX Muon Trigger Upgrade Project RPC MuID MuID RPC MuTR MuTR μ RPC absorber RPC (N installed) provide timing information and rough position information MuID trigger (existing) selecting muon momentum > 2GeV/c MuTR FEE upgrade ( installed) fast selection of high-momentum-tracks PHENIX status of upgrades for run11

3. New muon trigger system necessary current trigger (MuID) threshold W dominant region simulated muons into Muon Arm (2000pb-1, with PYTHIA5.7) PHENIX status of upgrades for run11 • σ(tot)=60mb, L=3x1032cm-2s-1 (500GeV) • collision rate = 18MHz • (after luminosity upgrade) • DAQ rate limit < 2kHz (for muon Arm) • Therefore, required rejection ratio • > 9000 • But, MuID-trigger rejection ratio (500GeV) • < 100 • We need momentum dependent trigger !

4. B Upgraded Muon Trigger System RPC RPC project timing information rough position information MuTRG project MuTr Level-1 trigger ADC digitalized hit signal digitalized hit signal digitalized hit signal ADC Level-1 trigger board sagitta ADC PHENIX status of upgrades for run11

5. North Arm MuTRG installation status South Arm Completed installation during this shutdown • already finished installation • 2008 Summer • commissioning with run9 500GeV pp data PHENIX status of upgrades for run11

6. RPC installation status • RPC 3S module and half-octant production ramping up, installation next shutdown Full W trigger ready for run 11 • For further redundancy and offline background reduction: • RPC1 and/or Absorber for run 11 or 12 RPC3 North: Done (thanks to PHENIX techs and BNL Riggers)! R.Seidl: status of simulation

7. Muon signal efficiencies and smearing Momentum smearing matrix Wrong charge Correct charge Efficiencies Pseudorapidity R.Seidl: status of simulation Reconstructed Pt

8. Backgrounds • Dominant background: low Pt hadrons decaying in muon arm • W signal to background 3/1 requires rejection of 1000 • Other backgrounds • Punch through hadrons • Other decay muons • cosmics R.Seidl: status of simulation

9. Background reduction with better use of current position information K+ 1-2 GeV K+ 2-3 GeV • Fake high Pt background reduction by Factor 10 through absorber • At least Factor 100 reduction by tight cuts • Signal to background 3/1 R.Seidl: status of simulation

10. Run9 “W m” analysis • This run still old muon trigger, heavily prescaled • Goals: • confirm background yields at high momentum, • check hadronic cross section in muon arms • Confirm cosmics rate • Sampled muon trigger luminosity : ~0.7 pb-1 • 7 muons each from W decays expected • Analysis is ongoing, framework for longer 500 GeV runs will be set R.Seidl: status of simulation

11. Potential improvements >run11: Forward Vertex detector Slide taken from Xiaorong Wang

12. Predicted RHICBOS asymmetries • Large sensitivity in m- sample, • Some in m+ sample • For real impact on sea polarization generated fake W data and perform global analysis R.Seidl: status of simulation

13. Fake data for DSSV impact analysis Forward m+ Forward m- Forward m+ Forward m- Backward m+ Backward m- Backward m+ Backward m- Fake reconstructed RB asymmetries for 50 and 150 pb-1 recorded as function of eta with 40 and 50 % polarization respectively, Signal to Background ratio fixed to 3/1, no polarization uncertainty R.Seidl: status of simulation

14. Backward plots • Luminosity, polpdf parameterizations, polarization up for discussion • Curves and data for reconstructed Pt (smearing applied to curves as well) R.Seidl: status of simulation

15. Forward plots R.Seidl: status of simulation

16. Outlook • PHENIX is well prepared for the Wmuon measurements in the rapidity range 1.2 < |h| < 2.2(2.4) from run11 and afterwards: • Trigger capabilities ready for run 11 • Additional redundancy after run 11 and • Additional background reduction with FVTX R.Seidl: status of simulation

17. Backup R.Seidl: status of simulation

18. So where do the MuTRG upgrades come in? • Triggering: • So far only 1D, in run9 prescaled by factor 30-120: • 10 pb-1 become ~0.1 • W yield in muon arms: a handful • No prescale for MuTRG, • high MuTRG efficiency (not included in plots) • RPC timing: • Cosmics reduction: • Small time window (factor 5) • Early opposite site arm veto (requires RPC1) • Spin crossing information (also important for non W muon arm spin measruements, BBCs will always fire) • even MuTrgFee upgrade samples over several crossings • Wmu track isolation/road quality • RPCs highly efficient, sampling only over one clock tick allows to reject other muon tracks  potential for isolation cuts • Addition RPC3 point for muon Road, Kalman fitter improves signal quality (currently being implemented/studied by Richard Hollis) R.Seidl: status of simulation

19. What do we need for the wm analaysis? • Signal: • Momentum Smearing, charge reconstruction • Efficiencies • Polarized yields (Rhicbos, Pythia, DSSV?) • (offline) Backgrounds: • Contributions • Cut optimization • Muon system • Internal and relative alignment • Real position resolution • Reconstruction including new detectores (FVTX, MuTrg, RPC ), new variables • Muon Trigger • Efficiencies, turn-on curve • Beam backgrounds R.Seidl: status of simulation

20. Backward plots • Luminosity, polpdf parameterizations, polarization up for discussion • Curves and data for reconstructed Pt (smearing applied to curves as well) R.Seidl: status of simulation

21. Forward plots R.Seidl: status of simulation

22. Overall reconstruction efficiency and fake rate Closed symbols: correct charge efficiencies Open symbols: wrong charge Cut -1 : no cuts any charge Cut -2: no cuts right charge Cut 0: basic cuts, right charge Cut 5 : tightest cuts R.Seidl: status of simulation

23. Overall effies with cuts:absorber does not affect effies but resolution does Efficiencies reduced at low Pt with standard cuts (contains a 15 GeV minimal cut) Tightest cuts is severely affecting the signal have to be checked R.Seidl: status of simulation

24. Backgrounds: • Low Pt muons from decays (abundant, reason for Trigger) • High Pt muons: • Fall off relatively fast • High Pt punch-through hadrons: • Sufficiently reduced by absorbers • Fake high Pt muons (mostly low Pt kaons) • Cosmic hight Pt muons • Z background small, possibly nonzero asymmetry, will be included in global analysis R.Seidl: status of simulation

25. Real muon backgrounds • Large amounts of decay muons from light processes as well as heavy flavor dominating at low Pt Triggering required • Yields below W yields above ~15 GeVoffline not a problem R.Seidl: status of simulation

26. High Pt Punch-through hadrons • Get reconstructed at roughly at right momenta • Initial yield terrifying • Absorbers reduce the yield substantially • Some effect of muon cuts R.Seidl: status of simulation

27. Fake high Pt background: Origin • Most hadrons decay in central region or first absorbers • Those surviving basic cuts decay within MuTr volume • Overall and cut decay muons in Muon arms reduced by absorber (no 10cm  35 cm) R.Seidl: status of simulation

28. Cosmics (performed by GSU) • Rate sounds low, but depending on RHIC luminosity this can be a substantial background • Matching cosmics with other side will be important • Additional timing cuts through RPCs can reduce rate further (time window and RPC1 before collision hit) • Background likely to be ok R.Seidl: status of simulation

29. Describe in detail what is and is not included in A_L simulation results • Data points: • Events from RHICBOS + full detector simulation + reconstruction • 1.2 < h < 2.2 both arms combined • Efficiencies of acceptance and reconstruction (70-80%, including charge reconstruction) • Smearing of the reconstructed momentum (through simulation and reconstruction) • Fixed 3 / 1 Signal to background ratio (requires absorber + tighter cuts) • 70 % beam polarization • 300 (1300) pb-1 on tape corresponding roughly to RHIC projections until 2013 (and RHIC-II) • Generated asymmetries • Events RHICBOS, 1.2 < h < 2.2 • Smearing of the reconstructed momentum (performed accd. to smearing matrix in finer binning on polarized and unpolarized yields separately)