2/11/200521st Winter's Workshop at Brekenridge 1 PHENIX Muon Trigger Upgrade for the Study of Quark...

2/11/2005 21st Winter's Workshop at Brekenridge

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PHENIX Muon Trigger Upgrade for the Study of Quark Contribution to Proton Spin Structure

Wei Xie (Riken-BNL Research Center)

for PHENIX Collaboration


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Proton Spin Structure

Naive parton model: valance quark are responsible for proton spin

QCD: sea quark and gluons. Parton orbital angler momentum also contribute .

Proton spin:

½ = ½ (quark)+ G(gluon) + Lz

q

q

Proton

u u

d

p

f(x) = f(x) – f(x), where f(x) and f(x) are PDF with spin parallel and anti-parallel to the proton spin.

u d s u d s 0 2.

u d s 0 2. (EMC: Spin crisis)


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Current Measurement on Quark and Gluon spin

•SLAC: E80, E130, E142, E143, E154, E155 (1978-2001)

•CERN: EMC, SMC, COMPASS (1988-2004)•DESY: HERMES (1995-2004)

Quark spin : well constrained

Sea Quark spin: large uncertainty

Gluon spin: Unknown


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Spin of Different Flavor of Quarks has been Measured

• Q2 is low

• “Hadron taging” technique relies on knowledge of fragmentation functions

Hermes: Phys.Rev.Lett 92 (2004) 012005


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How PHENIX Measure Quark Spin

W is produced through V-A process, helicity of quark is fixed:

A Wu x

u xLa

a

( )( )

( )

,When Xa>>Xb

,When Xb>>Xa A Wd x

d xL

b

b

( )( )

( )

Excellent ability to measure electron

Excellent ability to measure muon


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Expected PHENIX Measurement

Annu. Rev. Nucl. Part. Sci.2000.50:525-75

a.u

.


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• A trigger is needed to select only interesting events to record.

• W sample: ~104 for the 800pb-1 luminosity. • can’t be pre-scaled!

•collision rates in 500GeV run: ~12MHz,. • trigger rate w/ perfect background shielding: ~24KHz• trigger rate w/o background shielding ~50KHz

•PHENIX bandwidth: 12KHz(or 24KHz with additional $2M)•1-2kHz assigned to W trigger

•need additional rejection of 20-50, i.e. above 10000 rejection faactor

Single Muon Trigger Need Upgrade

RateTrigger

RateCollision factor rejection signalinput total

signal accepted efficiency


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Hodoscope I

CerenkovHodoscope II

Ideas for trigger upgrade Pad Chamber II

MuTr#1

Nosecone calorimeter

Pad Chamber I

MuID road

MuTr#2MuTr#3

PHENIX magnetic field


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Muon road ID ()=angle I – angle II: momentum cut

Option I: pad chamber solution

Enough rejection power with good efficiency for high pT muons

deg <0.7 <1.0 <2.0

rejection 36000 19980 10090


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-

+

Sagitta<=1 strip

Sagitta<=2 strips

Sagitta<=3 strips

Rej 23700 10900 7180

Result from Kazuya Aoki

A birds eye view

Option II: MuTr Solution

eff

icie

ncy

Sagitta<=1 strip

Sagitta<=2 strips

Sagitta<=3 strips

Enough rejection power with good efficiency for high pT muons


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Ongoing R&D Effort

•Measurement of background in central and forward region using scintilliator has been successfully done by RBRC and UIUC.

• Outgoing beam background (attenuated by PHENIX absorber)

• Incoming beam background (un-attenuated)

• Neutron background which is out of time.

3 background components:

ClockForward

Forward&BBCLL1Forward&MUIDS_1D


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• Plan to use CMS RPC technology

Picture of 2 chambers

HV

courtesy of Y. Mao

Gas

•RPC test bench was setup at UIUC.

•RPC prototype test during RUN5 p-p run by UIUC, RBRC and PKU

• A byproduct: Relative-luminosity monitor.

Chamber technology: Good position and time resolution and cheap price


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•R&D on fast readout FEE is ongoing at Kyoto University.

• have built a test MuTr#1 chamber with the help of UMN

• plan to have the final design in 2005 and mass production in 2006.

MuTr test chamber at Kyoto.


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Possible Configuration

• pad chamber solution only

• Downstream hybrid trigger

• rebuilt MuTr electronics i.e. MuTr LL1

• combination of the two method

• nosecone calorimeter (Vasily’s NCC talk)

MuTr#1

Nosecone calorimeter

MuTr#2

MuTr#3MuID


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University of ColoradoUniversity of ColoradoFrank Ellinghaus, Ed Kinney, Jamie Nagle, Joseph Seele, Matt Wysocki

University of California at RiversideUniversity of California at RiversideKen Barish, Stefan Bathe, Tim Hester, Xinhua Li, Astrid Morreale, Richard Seto, Alexander Solin

University of Illinois at Urbana ChampaignUniversity of Illinois at Urbana ChampaignMickey Chiu, Matthias Grosse Perdekamp, Hiro Hiejima, Alexander Linden-Levy, Cody McCain,

Jen-Chieh Peng, Joshua Rubin, Ralf SeidelIowa State UniversityIowa State University

John Lajoie, John Hill, Gary SleegeKyoto UniversityKyoto University

Kazuya Aoki, Ken-ichi Imai, Naohito Saito, Kohei ShojiColumbia UniversityColumbia University

Cheng Yi Chi, William ZajcUniversity of New MexicoUniversity of New Mexico

Doug FieldsRBRCRBRC

Gerry Bunce, Wei XieAbilene Christian UniversityAbilene Christian UniversityRusty Towell, Larry Isenhower

Peking UniversityPeking UniversityYajun Mao, Ran Han, Hongxue Ye, Hongtao Liu

Who is proposing?


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backup


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An Alternative Way to Measure Quark Spin

Nadolsky and Yuan, Nucl. Phys.B 666(2003) 31).

AL(W

+)

AL(W

+an

d W

- )

pT(muon)

pT(muon)

Resummation Method:

first principles calculation by Nadolsky and Yuan at NLO pQCD (Nucl. Phys.B 666(2003) 31).

When there’s no charge sign identification


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Study Spin Structure in Deep Inelastic Scattering

Gluon included in NLO:

F x e f xi ii u d s

121

2( ) ( )

, ,

Un-polarized:

g x e f xi ii u d s

121

2( ) ( )

, ,

polarized:

LO picture:S

Sq Sq

Jz = -1/2

proton

S Sq

forbidden

Jz = -3/2

P e q

P e q

ii u d s

ii u d s

2

2

, ,

, ,

A

q x

q x

g

FAL L

ii u d s

ii u d s

( )

( ), ,

, ,

1

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Experimental measurement:


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Current DIS experiment for G measurement through hadron pair production

Contributions to the asymmetry measurement

A aq

qa

g

gL L L Lq qg

L Lg qq

Relative low Q^2 and need long running time.


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Study Spin Structure in polarized p-p collisionLO:

Many different channel to measure G, e.g. prompt photon production:

Solid theoretical support:

A a qg qg

g

e f

e fa qg q

g

gAL L L L

ii u d s i

ii u d s iL L

( ) ( ), ,

, ,

2

2 1


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Past DIS experiment

2/11/200521st Winter's Workshop at Brekenridge 1 PHENIX Muon Trigger Upgrade for the Study of Quark...

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