2/11/200521st winter's workshop at brekenridge 1 phenix muon trigger upgrade for the study of...
TRANSCRIPT
2/11/2005 21st Winter's Workshop at Brekenridge
1
PHENIX Muon Trigger Upgrade for the Study of Quark Contribution to Proton Spin Structure
Wei Xie (Riken-BNL Research Center)
for PHENIX Collaboration
2/11/2005 21st Winter's Workshop at Brekenridge
2
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)
2/11/2005 21st Winter's Workshop at Brekenridge
3
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
2/11/2005 21st Winter's Workshop at Brekenridge
4
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
2/11/2005 21st Winter's Workshop at Brekenridge
5
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
2/11/2005 21st Winter's Workshop at Brekenridge
6
Expected PHENIX Measurement
Annu. Rev. Nucl. Part. Sci.2000.50:525-75
a.u
.
2/11/2005 21st Winter's Workshop at Brekenridge
7
• 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
2/11/2005 21st Winter's Workshop at Brekenridge
8
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
2/11/2005 21st Winter's Workshop at Brekenridge
9
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
2/11/2005 21st Winter's Workshop at Brekenridge
10
-
+
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
2/11/2005 21st Winter's Workshop at Brekenridge
11
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
2/11/2005 21st Winter's Workshop at Brekenridge
12
• 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
2/11/2005 21st Winter's Workshop at Brekenridge
13
•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.
2/11/2005 21st Winter's Workshop at Brekenridge
14
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
2/11/2005 21st Winter's Workshop at Brekenridge
15
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?
2/11/2005 21st Winter's Workshop at Brekenridge
16
backup
2/11/2005 21st Winter's Workshop at Brekenridge
17
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
2/11/2005 21st Winter's Workshop at Brekenridge
18
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
11
Experimental measurement:
2/11/2005 21st Winter's Workshop at Brekenridge
19
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.
2/11/2005 21st Winter's Workshop at Brekenridge
20
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
2/11/2005 21st Winter's Workshop at Brekenridge
21
Past DIS experiment