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

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
Proton Spin Structure
Naive parton model valance quark are responsible
for proton spin
?f(x) f?(x) f?(x), where f?(x) and f?(x) are
PDF with spin parallel and anti-parallel to the
proton spin.
(EMC Spin crisis)
QCD sea quark and gluons. Parton orbital angler
momentum also contribute .
Proton spin ½ ½ ??(quark) ?G(gluon) Lz
3
Current Measurement on Quark and Gluon spin
Quark spin well constrained Sea Quark
spin large uncertainty Gluon spin Unknown

• SLAC E80, E130, E142, E143, E154, E155
  (1978-2001)
• CERN EMC, SMC, COMPASS (1988-2004)
• DESY HERMES (1995-2004)

4
Spin of Different Flavor of Quarks has been
Measured

• Q2 is low
• Hadron taging technique relies on knowledge of
  fragmentation functions

5
How PHENIX Measure Quark Spin
W is produced through V-A process, helicity of
quark is fixed
6
Expected PHENIX Measurement
a.u.
Annu. Rev. Nucl. Part. Sci.2000.50525-75
7
Single Muon Trigger Need Upgrade

• A trigger is needed to select only interesting
  events to record.
• W sample 104 for the 800pb-1 luminosity.
• cant 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

8
Pad Chamber II
Ideas for trigger upgrade
MuTr3
MuTr2
MuTr1
MuID road
Pad Chamber I
Nosecone calorimeter
Hodoscope I
PHENIX magnetic field
Hodoscope II
Cerenkov
9
Option I pad chamber solution
?(?)angle I angle II momentum cut
Enough rejection power with good efficiency for
high pT muons
10
Option II MuTr Solution
m
m-
A birds eye view
Result from Kazuya Aoki
Enough rejection power with good efficiency for
high pT muons
11
Ongoing RD Effort

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

3 background components

• Incoming beam background (un-attenuated)

• Outgoing beam background (attenuated by PHENIX
  absorber)

• Neutron background which is out of time.

12
Chamber technology Good position and time
resolution and cheap price

• Plan to use CMS RPC technology

• 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.

13

• RD on fast readout FEE is ongoing at Kyoto
  University.
• have built a test MuTr1 chamber with the help
  of UMN
• plan to have the final design in 2005 and mass
  production in 2006.

MuTr test chamber at Kyoto.
14
Possible Configuration
MuID
MuTr3
MuTr2
MuTr1
Nosecone calorimeter

• pad chamber solution only
• Downstream hybrid trigger
• rebuilt MuTr electronics i.e. MuTr LL1
• combination of the two method
• nosecone calorimeter (Vasilys NCC talk)

15
Who is proposing?

• University of Colorado
• Frank Ellinghaus, Ed Kinney, Jamie Nagle, Joseph
  Seele, Matt Wysocki
• University of California at Riverside
• Ken Barish, Stefan Bathe, Tim Hester, Xinhua Li,
  Astrid Morreale, Richard Seto, Alexander Solin
• University of Illinois at Urbana Champaign
• Mickey Chiu, Matthias Grosse Perdekamp, Hiro
  Hiejima, Alexander Linden-Levy, Cody McCain,
• Jen-Chieh Peng, Joshua Rubin, Ralf Seidel
• Iowa State University
• John Lajoie, John Hill, Gary Sleege
• Kyoto University
• Kazuya Aoki, Ken-ichi Imai, Naohito Saito, Kohei
  Shoji
• Columbia University
• Cheng Yi Chi, William Zajc
• University of New Mexico
• Doug Fields
• RBRC
• Gerry Bunce, Wei Xie
• Abilene Christian University
• Rusty Towell, Larry Isenhower

16
backup
17
An Alternative Way to Measure Quark Spin
Resummation Method first principles calculation
by Nadolsky and Yuan at NLO pQCD (Nucl. Phys.B
666(2003) 31).
AL(W)
pT(muon)
AL(Wand W-)
When theres no charge sign identification
pT(muon)
18
Study Spin Structure in Deep Inelastic Scattering
LO picture
Experimental measurement
19
Current DIS experiment for ?G measurement through
hadron pair production
Contributions to the asymmetry measurement
Relative low Q2 and need long running time.
20
Study Spin Structure in polarized p-p collision
Many different channel to measure ?G, e.g. prompt
photon production
Solid theoretical support
21
Past DIS experiment