Physics with the Physics with the PHENIX Muon Trigger PHENIX Muon Trigger

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Brett Fadem, Muhlenberg Brett Fadem, Muhlenberg College for the PHENIX College for the PHENIX

CollaborationCollaboration

DNP Meeting, October12, 2007DNP Meeting, October12, 2007

Overview of TalkOverview of Talk

► OverviewOverview► The proton spin puzzle.The proton spin puzzle.► Current knowledge of sea quark Current knowledge of sea quark

polarizations.polarizations.► Probing proton spin structure with W’s.Probing proton spin structure with W’s.► BackgroundsBackgrounds

Trigger rejection of hadron decaysTrigger rejection of hadron decays High PHigh PTT ghosts ghosts

► ConclusionConclusion

The Proton Spin PuzzleThe Proton Spin Puzzle

1 1

2 2

quark spin

gluon spin

orbital angular mom.

1

2G ZL

0.3 1

0

( )1 1

2 2 zq

x qd Gq L

Spin of proton:

Let x quark

proton

p

p

W physics and the muon trigger upgrade

Current Current Knowledge of Knowledge of

Quark Quark PolarizationsPolarizations

PRD 71:012003,2005

Results of HERMES spin-flavor decomposition using a leading order analysis of inclusive and semi-inclusive deep-inelastic electron scattering.

x uChallenges:

–Large errors–Uncertainties due to low Q2

–“Hadron tagging” relies on fragmentation functions

x u

x d

x d

x s

Tagging quarks with WTagging quarks with W± ±

The RHIC Spin ProgramThe RHIC Spin Program

0,+,- Production

Heavy Flavors

Prompt Photon

Gluon Polarization Flavor Decomposition Transverse single/doublespin physics

W physics

Longitudinal single spin physics

Transversity:Sivers vs. Collins effects

& physics of higher twists;Pion interf. Fragmentation

Transverse single spin physicsPhenix-Local Polarimetry

For illustration: Leading For illustration: Leading order single spin order single spin

asymmetriesasymmetries in W production in W production

► Unpolarized W Unpolarized W

production:production:

► Polarized part:Polarized part:

► Measure moun count rates: Measure moun count rates:

► Count rate difference: Count rate difference:

( ) ( ) ( ) ( )a b b aN W d x u x d x u x

( ) ( ) ( ) ( )a b b aN W d x u x d x u x

( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )a b b a a b b aN d x u x d x u x d x u x d x u x

( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )a b b a a b b aN d x u x d x u x d x u x d x u x

NN

NNA

)()()()(

)()()()(

abba

babaWL

xuxdxuxd

xuxdxuxdA

In this LO schemeIn this LO scheme

►Parity violating decay selects the Parity violating decay selects the quark flavorquark flavor

►ForwardForward/backward region selects /backward region selects valencevalence/sea quark helicity /sea quark helicity contribution contribution

Advantages of W ProbesAdvantages of W Probes► No fragmentation functions are used in the No fragmentation functions are used in the

analysisanalysis► Good statisticsGood statistics► QQ22 is set by the W mass. is set by the W mass.► Rigorous theory framework based on NLO Rigorous theory framework based on NLO

pQCD and soft gluon resummation.pQCD and soft gluon resummation.

Projected PHENIX errors

Projected luminosity::

– ∫Ldt=950pb-1, P=0.7 at √s=500 GeV

W

Z

20 GeVTp

Physics BackgroundsPhysics Backgrounds

The W dominates for

• PT cut removes heavy flavor background

• Z background contributes 10-15 %.

Motivation for Trigger Motivation for Trigger UpgradeUpgrade

• Background from hadron decays from π’s, k’s into μ’s occur at 30 kHz level using the present level 1 trigger.

• Build dedicated trigger muon spectrometer to reject the low momentum decay background and keep the high momentum W signal.

• Use CMS RPC technology.

PHENIX muon trigger upgrade

RPC1(a+b)

RPC2 RPC3

r=3.40m

MuTr

(I) Three dedicated trigger RPC stations (CMS design):

RPC1(a,b): ~180 segments in , 2 in θ

RPC2: ~360 segments in , 2 in θ

RPC3: ~360 segments in , 2 inθ

(Trigger only – offline segmentation higher)

NSF (Funded)

JSPS (Funded)

(II) MuTr front end electronics

Upgrade to allow LL1 information

RPC TechnologyRPC Technology

► HH.00012 : Design and R&D for the HH.00012 : Design and R&D for the PHENIX Muon Trigger RPCsPHENIX Muon Trigger RPCs Session HH: Instrumentation IISession HH: Instrumentation II Young Jin Kim, UIUC, for the PHENIX CollaborationYoung Jin Kim, UIUC, for the PHENIX Collaboration 11:12 AM–11:24 AM, Saturday, October 1311:12 AM–11:24 AM, Saturday, October 13

► HH.00013 : Cosmic Ray Test Stand for HH.00013 : Cosmic Ray Test Stand for the PHENIX Muon Trigger RPCsthe PHENIX Muon Trigger RPCs Session HH: Instrumentation IISession HH: Instrumentation II Beau Meredith, Graduate student at UIUC/PHENIXBeau Meredith, Graduate student at UIUC/PHENIX 11:24 AM–11:32 AM, Saturday, October 1311:24 AM–11:32 AM, Saturday, October 13

Expected Performance of Expected Performance of TriggerTrigger

►The 30 kHz background from hadron The 30 kHz background from hadron decays will be reduced to about 1 kHz.decays will be reduced to about 1 kHz. The DAQ will be able to handle about 9 The DAQ will be able to handle about 9

kHz.kHz.

Issues in the Physics AnalysisIssues in the Physics Analysis

► Charge sign reconstruction required for ACharge sign reconstruction required for AL L WW++ and Aand AL L WW-- determination determination

► Smearing from momentum resolutionsSmearing from momentum resolutions► Hadron decay ghostsHadron decay ghosts

Requires two nuclear interaction lengths of absorberRequires two nuclear interaction lengths of absorber With the absorber, the S/B improves from 1:3 to 3:1.With the absorber, the S/B improves from 1:3 to 3:1. Work in progress: Study of asymmetry extraction Work in progress: Study of asymmetry extraction

including smearing, charge sign reconstruction and including smearing, charge sign reconstruction and high Phigh PTT ghosts. ghosts.

Hadron decays in the MuTR can make tracks appear straighter

High pT track

W-backgrounds:Low pT Hadron Punch Through + Decay

Fake High pT

Solution to the GhostsSolution to the Ghosts

Requires two nuclear interaction lengths Requires two nuclear interaction lengths of absorberof absorber

With the absorber, the S/B improves from With the absorber, the S/B improves from 1:3 to 3:1.1:3 to 3:1.

Work in progress: Study of asymmetry Work in progress: Study of asymmetry extraction including smearing, charge extraction including smearing, charge sign reconstruction and high PT ghosts.sign reconstruction and high PT ghosts.

ConclusionConclusion

►The upgrade to the front-end electronics The upgrade to the front-end electronics of the muon tracker and the addition of of the muon tracker and the addition of a new subsystem based on resistive a new subsystem based on resistive plate chamber (RPC) technology will plate chamber (RPC) technology will allow the measurement of sea-quark allow the measurement of sea-quark contributions to the proton’s spin using contributions to the proton’s spin using the decay of W bosons to muons. This the decay of W bosons to muons. This approach will avoid some of the approach will avoid some of the complications of “hadron tagging”.complications of “hadron tagging”.

Unused SlidesUnused Slides

AcknowledgmentsAcknowledgments

► PHENIX Collaboration and Forward Upgrade PHENIX Collaboration and Forward Upgrade GroupGroup

► Students: Joshua Adams, Amanda Caringi, Students: Joshua Adams, Amanda Caringi, Justine Ide, Phil LichtenwalnerJustine Ide, Phil Lichtenwalner

► Dr. Rusty Towell, Dr. Ralf SeidlDr. Rusty Towell, Dr. Ralf Seidl► ACU Students: Tim, Dan, Dillon, ACU Students: Tim, Dan, Dillon, ► DOE Intermediate Energy Nuclear Physics DOE Intermediate Energy Nuclear Physics

Division at BNLDivision at BNL► UIUC, Faculty, post-docs, and graduate studentsUIUC, Faculty, post-docs, and graduate students► Special Thanks to Matthias PerdekampSpecial Thanks to Matthias Perdekamp

Motivation for W physics: Motivation for W physics: sea polarizationsea polarization

► Parity violating decay selects Parity violating decay selects quark flavor:quark flavor:

► ForwardForward/backward region /backward region selects selects valencevalence/sea quark /sea quark helicity contribution helicity contribution

► High luminosity and high High luminosity and high √s=500 GeV needed√s=500 GeV needed

► Measurement with PHENIX Measurement with PHENIX muon arms:muon arms: Only Only ± ± detected detected

control of backgrounds control of backgrounds importantimportant

High energy muon trigger High energy muon trigger necessarynecessary

W a b a bL

a b a b

u(x )d(x ) d(x )u(x )A

u(x )d(x ) d(x )u(x )

)()(),()( abbaba xdxdxuxuxx

)()(

)()(

ba

baWL

xdxu

xdxuA

Advantages of W as probe:

• Large Scale ( Q2~mW2)

• no Fragmentation functions required

PHENIX PHENIX AALLWW+/-+/- SensitivitySensitivity

Machine and detector requirements::

– ∫Ldt=800pb-1, P=0.7 at √s=500 GeV

– Muon trigger upgrade!

2009 to 2012 running at √s=500 GeVis projected to deliver ∫Ldt ~980pb-1

Projected PHENIX errors

Backgrounds: physics backgrounds such as Z0

pT>20 GeV, NZ/NW~0.15

hadron punch through

not signficant! (GEANT)

hadron punch through + decay (falsely reconstructed high momentum tracks)

muon spectrometer + absorber S/B=3/1 (GEANT)

Unfold Δq,Δq from AL using

experimental information on q(x), G(x), pQCD + resummation techniques: P.M. Nadolsky, C.P. Yuan Nucl.Phys.B666:3-30,2003