Probing Hadron Structure with High Energy Proton Beams

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Muon Tracking at PHENIX and other experiments
Rusty Towell of Abilene Christian University for
the collaboration Workshop on Muon
Detection in the CBM experiment GSI
Darmstadt October 16-18, 2006
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Outline

• PHENIX
• detector
• moun arms
• upgrades in progress
• FNAL E866/NuSea
• Other Drell-Yan experiments at lower energy
• FNAL E906
• J-PARC Proposal

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13 Countries 62 Institutions 550
Participants
as of March 2005
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RHIC
2 counter-circulating rings 3.8 km
circumference Any nucleus on any other. Top
energies (each beam) 100 GeV/nucleon Au-Au. 250
GeV polarized p-p.
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RELATIVISTIC HEAVY ION COLLIDER (RHIC)
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PHENIX at RHIC
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PHENIX Muon Arms

• Tracking with 3 stations of cathode strip
  chambers in magnetic field to measure the
  momentum of the muons.
• Muon Indentification with 5 layers of chambers
  and steel.
• Triggering on muons using the Muon Identifier.
• Muon Arms Cover
• 1.2 lt h lt 2.2 (South)
• 1.2 lt h lt 2.4 (North)
• Azimuthal complete
• ptot gt 2 GeV/c
• South Arm installed 2001
• run 2
• North Arm installed 2002
• run 3.

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Muon Tracking Design

• Physics Resolution Required
• Resolve ? from ? ? (? 80 MeV/c2 or 8
  )
• Resolve J/? from ? (? 110 MeV/c2 or 4 )
• Resolve ? from ? ? (? 200 MeV/c2 or 2 )
  
• Cathode Strip Chamber characteristics
• Anode wire and cathode strip spacing 1cm
• Detector gap width 0.6 cm
• Three gaps at stations 1 and 2, two gaps at
  station 3
• Single plane resolution ? 100 ?m ? chamber ? 60
  ?m
• Station 2 chamber thickness ? 0.5 radiation
  length
• Over 20,000 channels to readout in the south arm

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Chamber Construction
Stations 1 and 3 used etched copper skins for
cathode planes.
Station 2 chambers were designed to have a total
thickness ? 0.5 radiation lengths.
Station 2 used etched copper covered mylar
windows for cathode planes to minimize multiple
scattering.
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FEE Overview

• Inside Magnet/no access
• Limited Space
• Power constrain
• Many Channels
• 168 FEMs
• over 20,000 channels

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Station 1 (small ones)
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South Muon MagnetStation 1 Chambers and FEE
Installed
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South Muon Magnet
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Hit distributions in MuTr
North arm
South arm
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Single muon Event vertex
We want to separate the muon contribution from
charm and ?/K decays

• D c? 0.03 cm Decays before absorber
• ? c? 780 cm Most are absorbed, but
  some decay first
  
• K c? 371 cm Most are absorbed, but
  some decay first

magnet
absorber
40 cm
CP
Muon ID
nosecone
Muon tracker
Collisions occurring closer to the absorber will
have fewer ??/k contributions.
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Simulation Study- summation of different
contributions

• We can sum the two contributions together. In
  the summation, we weight each contribution by
  measured pion yield and measured charm production
  cross section.
• Fit the combined event vertex distribution with
  a two-component function, a z dependent component
  and a z independent component, we can separate
  the two contributions.

Counts/8cm
Event vertex ( cm)
Counts /200MeV/c
Transverse momentum ( GeV/c)
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Single muon from PHENIX run3First look at
datavertex
Raw counts
The red line is the expectation from simulation.
Raw counts
Raw data

Muon event vertex distribution (cm)
Rapidity distribution of single muons
Muon event vertex distribution (cm)
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Physics flavor separation of the spindependent
quark and anti-quark distributions
Single Spin Asymmetry
Parity violation of the weak interaction in
combination with control over the proton spin
orientation gives access to the flavor spin
structure in the proton!
Experimental Requirements ? tracking at
high pT ? event selection for muons
difficult due to background muons from
hadron decays and beam backgrounds
(timing resolution!). ? good rejection of
backgrounds in the offline
analysis.
W
Z
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PHENIX Muon Trigger Upgrade

• Three dedicated trigger RPC stations (CMS
  design)
• R1(a,b) 12mm in j, 2 ? pads
• R2 5.4mm in j , 2 ? pads
• R3 6.0mm in j, 2 ? pads
• (Trigger only offline segmentation higher)

R2
R3
R1(ab)
NSF (Funded)
r3.40m
r100-120cm
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Resistive Plate Chambers

• good timing performance comparable to that of
  scintillator ( 1-2 ns)
• space resolution sufficient for muon trigger
  purpose ( cm )
• simple design low cost
• arbitrary readout geometry
• good rate capability (several kHz/cm2)

• RPCs have been used in L3, BaBar, Belle
  experiments.
• All 4 LHC experiments will use RPC for muon
  system.
• STAR and PHENIX used MRPC as TOF

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RPC Tests (UIUC, GSU, Colorado)
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PHENIX ALW/- Sensitivity

• Machine and detector requirements
• ?Ldt800pb-1, P0.7 at vs500 GeV
• Muon trigger upgrade!

2009 to 2012 running at vs500 GeV is projected
to yield ?Ldt 950pb-1
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Other muon tracking experiments
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FNAL E866/NuSea Collaboration
Abilene Christian University Donald Isenhower,
Mike Sadler, Rusty Towell, Josh Bush, Josh
Willis, Derek Wise Argonne National
Laboratory Don Geesaman, Sheldon Kaufman, Naomi
Makins, Bryon Mueller, Paul E. Reimer Fermi
National Accelerator Laboratory Chuck Brown, Bill
Cooper Georgia State University Gus Petitt,
Xiao-chun He, Bill Lee Illinois Institute of
Technology Dan Kaplan Los Alamos National
Laboratory Melynda Brooks, Tom Carey, Gerry
Garvey, Dave Lee, Mike Leitch, Pat McGaughey,
Joel Moss, Brent Park, Jen-Chieh Peng, Andrea
Palounek, Walt Sondheim, Neil Thompson
Louisiana State University Paul Kirk, Ying-Chao
Wang, Zhi-Fu Wang New Mexico State
University Mike Beddo, Ting Chang, Gary
Kyle, Vassilios Papavassiliou, J. Seldon, Jason
Webb Oak Ridge National Laboratory Terry Awes,
Paul Stankus, Glenn Young Texas A M
University Carl Gagliardi, Bob Tribble, Eric
Hawker, Maxim Vasiliev Valparaiso University Don
Koetke, Paul Nord
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Fermilab E866/NuSea Detector
60m x 3m x 3m

• 21012 protons/20 spill
• Momentum analyzing magnet (SM3)
• Beam dump (4.3m Cu)
• Hadronic absorber (13.4 I0-Cu, C, CH2)
• Three tracking stations
• Muon identifier wall 4th tracking

• Forward xF, high mass m-pair spectrometer
• Liquid hydrogen and deuterium targets
• Also used solid W, Be, Fe targets
• Two acceptance defining magnets

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Drell-Yan mm- Production

• Detector acceptance chooses range in xtarget (x2)
  and xbeam (x1)
• xF xbeam xtarget
• For E866 xF peaks where xFgt 0
• high-x valence beam quarks
• Low-x sea target quarks.

Leading Order

• Experiment measures m momenta
• Virtual photon pL and pT

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The Data Sample

• 3 spectrometer magnet settings focused different
  muon pair masses into the detector low,
  intermediate and high

?
J/?
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E866 sea quark distributions

• Select xb gt xt to get first term (detector
  acceptance does this).

• Study ratio of deuterium to hydrogen
• (Actually use full NLO calculation to extract sea
  quark ratio)
• Approx. 360,000 events.

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Future Drell-Yan at Lower Beam Energies

• Repeating FNAL E866/NuSea at lower energies has
  its advantages
• Lower energy means a higher cross section

• Primary backgrounds, decay of J/?, scales with s

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Challenges of DY at Lower Beam Energies

• Lower boost implies reconfiguration of detector
• Redesign spectrometer
• Funding to build a new spectrometer
• Increased probability of hadron decay before
  absorber, and
• Greater multiple scattering of muons.
• Both can be minimized with careful design

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FNAL E906 Collaboration
University of Illinois Jen-Chieh Peng Los Alamos
National Laboratory Gerry Garvey, Mike Leitch,
Pat McGaughey, Joel Moss Rutgers University Ron
Gilman, Charles Glashausser, Xiaodong Jaing, Ron
Ransome Texas A M University Carl Gagliardi,
Bob Tribble, Maxim Vasiliev Valparaiso
University Don Koetke
Abilene Christian University Donald Isenhower,
Mike Sadler, Rusty Towell Argonne National
Laboratory John Arrington, Don Geesaman, Roy
Holt, Hal Jackson, Paul E. Reimer, David
Potterveld University of Colorado Ed
Kinney Fermi National Accelerator
Laboratory Chuck Brown Co-Spokespersons
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Lower Beam Energy The E906 Advantage

• E906 will use an extracted, slow-spill 120 GeV
  beam from the Fermilab Main Injector.
• Cross section scales as 1/s
• 7x that of 800 GeV beam

• Backgrounds, primarily from J/? decays scale as
  s
• 7x Luminosity
• 50x statistics!!

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E906 Detector
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GEANT4 SIMULATION FOR E906

• Detector simulations are in progress to determine
  the optimal configuration to minimize background
  hits in the detector with minimal multiple
  scattering of muons.

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Expected Drell-Yan from E906
E906 will extend our knowledge of dbar/ubar to x
0.5
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E906 Schedule ?
Expt. runs
Expt.. Construction
Magnet Design and construction
Expt. Funded
906 Publications
2010
2008
2007
2006
2009

• Approved in 2001
• Schedule no longer driven by Fermilab long range
  plan
• Which was the case for 3 years after we received
  approval
• Fermilab is now willing to run E906 as soon as it
  is ready
• Our schedule is now dependent on funding.
• Request for funding has been submitted to DOE
• E906 should be able to run 2 years after we
  receive funding.
• Current DOE budget projections look extremely
  promising. DOE and FNAL reviews are scheduled
  for Nov, Dec of this year.

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High-Mass Dimuon Production with 50 GeV Protons
Letter of Intent for the J-PARC
Collaboration
Abilene Christian University Argonne National
Laboratory Duke University KEK University of
Illinois at Urbana-Champaign Kyoto
University Los Alamos National Laboratory
Massachusetts Institute of Technology Tokyo
Institute of Technology
Contact persons J.C. Peng and S. Sawada
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Lower Beam Energy 50 GeV _at_ J-PARC

• The 50 GeV Proton Synchroton at J-PARC will yield
  huge increases in statistics.
• Cross section scales as 1/s
• 16x that of 800 GeV beam

• Backgrounds, primarily from J/? decays scale as
  s
• 16x Luminosity
• gt100x statistics!!

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Expected Drell-Yan from J-PARC
J-PARC could extend our knowledge of dbar/ubar
to higher x values
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Schematic View in the Horizontal Plane
15m

• Two vertically bending magnets with PT kick of
  2.5 GeV/c and 0.5 GeV/c
• A tapered copper beam dump and Cu/C absorbers in
  the first magnet
• Tracking is provided by three stations of
  chambers
• Station 4 provides muon identification and
  tracking
• 2 x 1012 50 GeV protons/spill is requested

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Simulation of Detector Acceptance
Expected Drell-Yan counts for a two-month pd run
at 50 GeV

• 2 x 1012 protons/spill
• 50-cm long liquid deuterium target
• Assume 50 percent efficiency
• X2 upto 0.7!!!

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Simulation of Detector Resolutions
Expected resolutions for Drell-Yan events

• Mass resolution
• 160 MeV
• X2 resolution
• 0.024
• X1 resolution
• 0.018
• pT resolution
• 150 MeV

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Thank you for inviting me to this workshop.