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W muon analysis in PHENIX Status of the background understanding, signal, smearing and asymmetries. R.Seidl (RBRC). PHENIX Muon Trigger Upgrade Project. RPC. MuID. MuID. RPC. MuTR. MuTR. μ. RPC. absorber. RPC (N installed) provide timing information and rough position information.
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W muon analysis in PHENIXStatus of the background understanding, signal, smearing and asymmetries R.Seidl (RBRC) R.Seidl: status of simulation
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
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 !
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
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
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
Muon signal efficiencies and smearing Momentum smearing matrix Wrong charge Correct charge Efficiencies Pseudorapidity R.Seidl: status of simulation Reconstructed Pt
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
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
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
Potential improvements >run11: Forward Vertex detector Slide taken from Xiaorong Wang
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
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
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
Forward plots R.Seidl: status of simulation
Outlook • PHENIX is well prepared for the Wmuon 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
Backup R.Seidl: status of simulation
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 • Wmu 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
What do we need for the wm 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
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
Forward plots R.Seidl: status of simulation
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
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
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
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 GeVoffline not a problem R.Seidl: status of simulation
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
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
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
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)