r.seidl (rbrc)

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



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


RPC3 North: Done (thanks to PHENIX techs and BNL Riggers)!

Muon signal efficiencies and smearing


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


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


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


Fake data for DSSV impact analysis


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)


Forward plots


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


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)


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


Backward plots

Luminosity, pol pdf parameterizations, polarization up for discussion

Curves and data for reconstructed Pt (smearing applied to curves as well)


Forward plots


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


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


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


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


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)


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


“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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