r.seidl (rbrc)
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04/21/23 R.Seidl: status of simulation 1
W muon analysis in PHENIXStatus of the background understanding,
signal, smearing and asymmetries
R.Seidl (RBRC)
PHENIX Muon Trigger Upgrade Project
2
MuID trigger (existing)selecting muon momentum > 2GeV/c
MuTR FEE upgrade ( installed)fast selection ofhigh-momentum-tracks
RPC (N installed)provide timing informationand rough position information
μμμμ
MuID MuIDMuTR MuTR
RPC
RPC RPC
absorber
PHENIX status of upgrades for run112009/10/2
New muon trigger system necessary
3PHENIX status of upgrades for run112009/10/2
simulated muons into Muon Arm(2000pb-1, with PYTHIA5.7)
W dominantregion
current trigger (MuID)thresholdσ(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 !
RPCRPC
Upgraded Muon Trigger System
4
digitalizedhit signal
Level-1trigger
PHENIX status of upgrades for run112009/10/2
digitalizedhit signal
digitalizedhit signal
MuTMuTrr
timing informationrough position information
sagitta
Level-1Level-1trigger trigger boardboard
RPC projectRPC project
MuTRG projectMuTRG project
MuTRG installation status
South Arm
Completed installation during this shutdown
North Armalready finished installation
2008 Summer commissioning with run9
500GeV pp data
2009/10/2 PHENIX status of upgrades for run11 5
RPC installation statusRPC 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
04/21/23 R.Seidl: status of simulation 6
RPC3 North: Done (thanks to PHENIX techs and BNL Riggers)!
Muon signal efficiencies and smearing
04/21/23 R.Seidl: status of simulation 7
Wrong charge
Correct charge
Reconstructed Pt
Pse
ud
ora
pid
ity
Momentum smearing matrix
Efficiencies
BackgroundsDominant background:
low Pt hadrons decaying in muon arm
W signal to background 3/1 requires rejection of 1000
Other backgrounds Punch through
hadronsOther decay muonscosmics
04/21/23 R.Seidl: status of simulation 8
Background reduction with better use of current position information Fake high Pt
background reduction by Factor 10 through absorber
At least Factor 100 reduction by tight cuts
Signal to background 3/1
04/21/23 9R.Seidl: status of simulation
K+ 1-2 GeV K+ 2-3 GeV
Run9 “W ” 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
04/21/23 R.Seidl: status of simulation 10
Potential improvements >run11: Forward Vertex detector Slide taken from Xiaorong Wang
Predicted RHICBOS asymmetries
Large sensitivityin m- sample,
Some in m+ sample
For real impact on sea polarization generated fake W data and perform global analysis
04/21/23 R.Seidl: status of simulation 12
Fake data for DSSV impact analysis
04/21/23 R.Seidl: status of simulation 13
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
Forward + Forward -
Backward + Backward -
Forward + Forward -
Backward + Backward -
Backward plots
Luminosity, pol pdf parameterizations, polarization up for discussion
Curves and data for reconstructed Pt (smearing applied to curves as well)
04/21/23 R.Seidl: status of simulation 14
Forward plots
04/21/23 R.Seidl: status of simulation 15
Outlook
PHENIX is well prepared for the Wmuon measurements in the rapidity range 1.2 < || < 2.2(2.4) from run11 and afterwards:Trigger capabilities ready for run 11Additional redundancy after run 11 and Additional background reduction with
FVTX
04/21/23 R.Seidl: status of simulation 16
04/21/23 R.Seidl: status of simulation 17
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)
04/21/23 R.Seidl: status of simulation 18
What do we need for the w analaysis?Signal:
Momentum Smearing, charge reconstruction
EfficienciesPolarized yields
(Rhicbos, Pythia, DSSV?)
(offline) Backgrounds:ContributionsCut optimization
Muon system Internal and relative
alignmentReal position resolutionReconstruction including
new detectores (FVTX, MuTrg, RPC ), new variables
Muon Trigger Efficiencies, turn-on
curveBeam backgrounds
04/21/23 R.Seidl: status of simulation 19
Backward plots
Luminosity, pol pdf parameterizations, polarization up for discussion
Curves and data for reconstructed Pt (smearing applied to curves as well)
04/21/23 R.Seidl: status of simulation 20
Forward plots
04/21/23 R.Seidl: status of simulation 21
Overall reconstruction efficiency and fake rate
Closed symbols: correct charge efficienciesOpen symbols:wrong charge
Cut -1 : no cuts any chargeCut -2: no cuts right chargeCut 0: basic cuts, right chargeCut 5 : tightest cuts
04/21/23 22R.Seidl: status of simulation
Overall effies with cuts:absorber does not affect effies but resolution does
04/21/23 R.Seidl: status of simulation 23
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
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
04/21/23 R.Seidl: status of simulation 24
Real muon backgroundsLarge 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
04/21/23 R.Seidl: status of simulation 25
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
04/21/23 R.Seidl: status of simulation 26
Fake high Pt background: OriginMost 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)
04/21/23 R.Seidl: status of simulation 27
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 importantAdditional timing cuts through RPCs can reduce rate
further (time window and RPC1 before collision hit)Background likely to be ok
04/21/23 R.Seidl: status of simulation 28
“one arm cut” Vertex cut pT cutSingle muon survive cuts
Rate (Hz)
Yes |z|<30 cm, r<25 cm No 59214 0.18
Yes |z|<30 cm, r<5 cm No 15304 0.046
Yes |z|<30 cm, r<25 cm >20 GeV/c, <40 GeV/c 3643 0.011
Yes |z|<30 cm, r<5 cm >20 GeV/c, <40 GeV/c 827 0.0025±0.0001
Describe in detail what is and is not included in A_L simulation resultsData points:
Events from RHICBOS + full detector simulation + reconstruction
1.2 < < 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 < < 2.2 Smearing of the reconstructed momentum (performed accd.
to smearing matrix in finer binning on polarized and unpolarized yields separately)
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