Axel Drees, SUNY Stony Brook

1
PHENIX Physics Agenda and Detector Upgrades

• Overview
• Completion of the PHENIX baseline program
• heavy ion and spin physics program
• completion of PHENIX detector
• running plan for the next 5 years
• Physics beyond the reach of the baseline
  detector
• heavy ion physics program
• spin physics program
• proton-Nucleus Program
• Detector upgrades
• improvements of existing detectors
• concept for additional detector systems
• technical solutions
• cost guesstimate and timelines

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Overview PHENIX Physics Program for the Next
Decade

• first phase
• complete initial heavy ion and spin physics
  program
• complete experimental setup
• enhance detector capabilities
• second phase
• heavy ion physics
• systematic study of high T, r QCD
• address important issues not or only partially
• covered by original detector
• lepton pair continuum below and above the f
• charm and bottom production
• Drell-Yan continuum
• upsilon spectroscopy Y(1S), Y(2S), Y(3S)
• QCD energy loss , g-jet correlations and more
• spin structure of the nucleon
• enhance capabilities, increase kinematical
  acceptance
• W-boson production
• heavy flavor production

3
PHENIX Heavy Ion Program
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PHENIX Core Program
designed to measure penetrating rare probes

• central detector vector mesons w, f, J/y -gt
  ee-
• photons
• high pt pions po, p, p-
• muon arms vector mesons J/y, U -gt mm-
• combined central and muon arms
• charm production DD -gt em
• focus on electromagnetic probes
• well matched to requirements of spin physics
  program

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PHENIX configuration for 2000

• West Arm
• tracking
• DC,PC1
• electron ID
• RICH, EMCal
• photons
• EMCal

• East Arm
• tracking
• DC, PC1, TEC, PC3
• hadron electron ID
• RICH,TEC, TOF,
• EMCal
• photons
• EMCal

• Other Detectors
• vertex centrality
• ZDC, BBC,
• partially equipped systems
• MVD, MuID

initial physics program global
observables identified hadron
spectra inclusive high pt 4 GeV/c
spectra inclusive electrons 3 GeV/c
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Preliminary Physics Results
identified hadrons
inclusive h- and p0
inclusive electrons
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Enhanced Setup for Next Run 2001-2002

• West Arm
• tracking
• DC,PC1, PC2, PC3
• electron ID
• RICH,
• EMCal
• photons
• EMCal

• East Arm
• tracking
• DC, PC1, TEC, PC3
• hadron electron ID
• RICH,TEC, TOF, EMC
• photons
• EMCal

• Other Detectors
• Vertex
• centrality
• ZDC, BBC,
• MVD

• South Arm
• tracking
• MuTr
• muon ID
• MuID

full heavy ion program and major fraction of spin
program vector mesons f and w J/y production
direct photon out to 10 GeV (Au-Au) or 30 GeV
(pp) high pt inclusive out to 10 GeV jet-like
angular correlation
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2003 and Beyond

• additional detector upgrades
• tracking
• east arm PC2
• electron ID
• east arm TRD/TEC

PC2
TRD/TEC

• North Arm
• tracking
• MuTr
• muon ID
• MuID

• DAQ and Trigger
• de-multiplexing
• L2 trigger
• upgraded EVB

high statistics studies with 2 1027 cm-2s-1 Au-Au
and 2 1032 cm-2s-1 pp Au-Au p-p increase pt
range to 20 GeV direct g to 40 GeV precision
J/y and y high mass Drell-Yan pairs first
data on Y bottom production g-jet
correlations W-boson production
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Upgrades of Baseline Setup
significantly enhance detector performance at
moderate effort and cost

• PC2 east 500k
• in beam experience
• redundant (3d) tracking needed to suppress
  no-vertex background
• vital for high pt gt 6 GeV/c and jet-jet
  correlations
• TRD/TEC 700k
• extend electron identification to pt gt 6 GeV

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Other Possible Baseline Upgrades

• DAQ and Trigger partially funded 800k
• increase rate capability as luminosity increases
• includes needs for second phase upgrades
• anode readout for MuTr 3,000k
• issue tracking at highest multiplicities
• need to wait for in beam experience
• TRD/TEC for west arm 1300k
• extended electron identification
• improved momentum resolution

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Proton-Nucleus Physics
has been discussed in length at previous workshop

• there are no p-A data at ?s 200 GeV
• has been essential in understanding non-exotic
  multi-body effects
• Strangeness enhancements
• J/Y production/absorption
• Gluon shadowing

example Drell Yan pair acceptance and statistical
errors for 2x 15 weeks pp and pd running
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Possible Run Plan
assume 22 weeks/year heavy ions and 10
weeks/year polarized protons

• Year-2 (2001-2002)
• AuAu, crude p-p comparison run
• first look at J/Y production, high pT
• first polarized proton run
• Year-3 (2003)
• High luminosity AuAu (60) of HI time
• High luminosity light ions (40) of HI time
• Detailed examination of AB scaling of J/Y yield
• DG/G production run with polarized proton
• first p-A measurements
• Year-4 (2004)
• p-d/p-p comparisons
• baseline data for rare processes
• W-boson production with polarized protons
• Drell-Yan study in p-A
• Year-5 (2005)

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Beyond the PHENIX Baseline Program
profit from investments made, exploit further
possibilities to measure rare processes
electromagnetic radiation and hard scattering

• Heavy Ion Physics
• shift of focus from establishing the existence of
  QGP and first studies of its properties
• to systematic study of QCD high T, r
• focus on key measurements not or only partially
  addressed by original PHENIX setup
• pair continuum below and above the f
• charm and bottom production
• Drell-Yan continuum
• upsilon spectroscopy, Y(1S), Y(2S), and Y(S3)
• QCD energy loss via g -jet angular correlations

for these measurements the PHENIX central and
muon spectrometer are essential but not
sufficient !
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Continuum Lepton-Pair Physics
resonances addressed by original
PHENIX setup
pair continuum not yet accessible at RHIC

• large excess of continuum radiation observed in
  heavy ion collisions at CERN
• has been attributed to melting of resonance's,
  dropping masses
• ??? look at vector mesons ?, ?
• however, recent theoretical discussion focuses
  again on thermal radiation
• anomalous lepton pair production in pp collisions
  not excluded
• excluded only within 15-30 systematic errors at
  low energies
• completely open at higher energies!

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Electron Pairs at Low Mass

• in p-Be collisions well described by neutral
  meson decays within 15-30
• systematic errors
• Dalitz decays ??????ee-
• ?? ???ee-
• ?? ? ???ee-
• vector mesons r?? ?ee-
• w?? ?ee-
• f?? ?ee-

anomalous lepton pairs at ?s 200 GeV??

• enhanced ee- production in Pb-Au collisions
• at CERN SPS
• threshold near 2mp
• different spectral shape
• no r resonance structure

0.25 lt m lt 0.75 GeV D/S 2.6 ? 0.5 ? 0.6
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Radiation from Hot and Dense Matter

• pp-annihilation contribution
• pp resonance structure r-meson
• formfactor described by vacuum values
• mr 770 MeV
• Gr 150 MeV
• characteristic shape
• not observed in data
• solution
• modification of
• meson properties in
• dense matter

data seem to require modification of meson
properties
related to chiral symmetry restoration
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More Recent Calculations

• data stimulated more than 100 theoretical paper
• origin of continuum radiation not yet clarified
• recent new development

thermal radiation from QGP
(Schneider Weise)
a lot of interesting physics in lepton pair
continuum
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Experimental Challenge

• huge combinatorial pair background due to
  copiously produced photon conversion and Dalitz
  decays

photon conversion ??? e e - Dalitz
decays po ?? ? e e -
false combinatorial pair
In PHENIX combinatorial background factor gt
1000 larger than signal Note resonances f and
w can be measured due to excellent mass
resolution
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Dalitz and Conversion Rejection

• mass of virtual photon small ? small pair opening
  angle
• need tracking at low momentum
• and sensitivity to opening angle

central arm 200 MeV momentum cut off
70 of pairs one track gt 200 MeV 2nd track lt
200 MeV can not be reconstructed in
central arms
possible mode of operation
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Direct Radiation vs Open Charm

• NA50 ?? -pairs at intermediate masses (1 lt m lt 3
  GeV)

M.C. Abreu et al, Nucl.Phys A661 (99) 538c
R.Rapp E.Shuryak, Phys.Lett B473 (2000) 13
thermal radiation (Ti 220 MeV)
or open-charm enhanced by factor 3-4
Question can PHENIX baseline pin down charm
x-section accurate enough?
via inclusive e,m and ee, mm, em pairs
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Precision Vertex Tracking to Detect Charm

• physics interest in charm and bottom production
• charm and bottom decays compete with thermal pair
  radiation
• charm can be produced thermally ? charm
  enhancement
• probably not at CERN, but maybe at RHIC energies
• best reference for J/y and Y production
• once charm and bottom are known
• ? access to Drell Yan continuum
• displaced vertex distinguishes prompt electrons
  (thermal) form decay electrons (charm and bottom)
  

m ct ? eX GeV mm
D0 1865 125 6.75 D 1869 317
17.2 B0 5279 464 5.3 B
5279 496 5.2
easy to achieve gt20 mm tracking resolution
issue multiple scattering in first detector
layer
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Measurement of Displaced Vertex

• toy detector model 2x 2p silicon pixel tracking
  layers
• standard detectors with 50x425 mm2
• a) R 2.5 cm srf 15 mm
• X/Xo 1 s 115 mm
• b) R 10 cm ditto
• PYTHIA simulation of D mesons for ?s 200 GeV

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Study for Decay Electron Detection
displacement to vertex in x-y projection

• decay electrons
• retrieve decay length
• with multiple scattering
• with detector resolution
• prompt electrons
• (same electrons but
• tracked to decay vertex)
• point back to vertex
• within 100 mm
• what works for Ds

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Upsilon Spectroscopy

• original PHENIX capability
• luminosity upgrade to 8 1026 cm-2s-1 or 8 1027
  cm-2s-1
• muon spectrometer accumulates 16000 Y per 22
  weeks
• central spectrometer accumulates 2000 Y per 22
  weeks
• improved momentum resolution in central
  spectrometer
• (shown later in this talk)

north muon arm sm 190 MeV south muon arm sm
240 MeV 22 week of Au-Au at 2 1026 cm-2s-1
total of 400 Y decays ( 1/10 in central arms)
CDF data 1000 Y
PHENIX comparable to CDF 2000 Y sm 40 MeV
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Jet-Quenching and QCD Energy Loss
Suppose we find indications for jet quenching at
RHIC next step gain detailed understanding of
QCD energy loss systematic studies of many
questions

• How accurate can we measure dE/dx ?
• How does dE/dx depend on x?
• How does dE/dx depend on pt?
• Do gluons lose more energy than quarks?
• What is the flavor dependence of dE/dx?
• Is there dE/dx in cold matter?
• experimental tools (rare processes)
• g - jet correlations
• jet - jet correlation
• flavor tagged jets
• tagged gluon jets ( K / p comparison)
• centrality and A dependence
• p-A and p-p comparision

upgraded PHENIX detector well suited to address
these issues requires highest possible luminosity
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Spin Physics Program
Recall spin crisis of nucleon was discovered by
extending kinematical coverage of original EMC
measurement

• Increase kinematic coverage and measure
• W boson production
• isolation cuts on leptons
• central arm tracking Df 2p, D?? 1
• muon arms forward calorimeter
• heavy flavor production
• precision vertex tracking to tag decay electrons
• jet production
• large acceptance tracking momentum measurement
• gluon distribution function
• g - jet angular correlations
• transversity and spin effect in fragmentation
• enhanced tracking acceptance
• Detector upgrade requirements
• Df 2p, D?? 1 precision vertex tracking
• forward calorimetry

detector requirements similar to those from heavy
ion program
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Lepton Isolation Cuts

• Isolation cut
• count activity around lepton
• distance of lepton from jet axis
• significantly enhances
• heavy flavor tagging
• W ? l ?
• Drell Yan process

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Jet Reconstruction with Charged Particles Only

• Kt Jet algorithm (hep-ex/0005012)
• DR sE/E
• only charged particles 0.08 30
• ????? ? 1 0.1 30
• detector resolution (20) 0.1 36

jet reconstruction with 40 sE/E feasible
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Detector Requirements
enhanced spin and heavy ion physics program
addressed by one multi-detector detector
system vertex spectrometer around beam pipe

• precision vertex tracking with large acceptance
• Df 2p and Dh ? 1
• 30 mm single track resolution
• reasonable momentum resolution (sp/p 3-4 p)
• electron identification
• p lt 1 GeV for Dalitz rejection
• e / ? 50
• flexible magnetic field configuration
• no field in vertex region for Dalitz rejection
• high field for high pt physics
• high rate capability
• Au-Au L 8 1027 cm-2s-1
• p-p L 2 1032 cm-2s-1

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PHENIX Vertex Spectrometer Scenario A
last nights sketch
central arm acceptance ? 22o ? D? 0.7 ? 20 cm
IR region
magnet coils
micro pad chamber
forward calorimeter
Silicon Pixel
layer 3 15 cm
layer 2 7.5 cm
HBD
layer 1 3 cm
beam axis and vacuum pipe
hadron blind detector
40.4o ? 1 for ? 10 cm IR region
Scenario B replace HBD by TPC (or TEC)
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Vertex Spectrometer

• Silicon Pixel Detectors
• 3 layer system (?) Df 2p and Dh ? 1
• standard pixel devices 50x425 mm2
• contacts with LHC developments for ALICE and NA6i
• possible new collaboration with CERN
• (other options D0 or CMS, ATLAS)
• Hadron-Blind-Detectors
• proximity focusing He-Cherenkov counter
• CsI based photocathode
• GEM based readout
• historical RD by Stony Brook group
• new collaboration at Weizmann Institute on CsI
  GEM
• interest to collaborate with BNL instrumentation
• Micro Pad Chambers
• MWPC with pad readout
• further development of existing PHENIX pad
  chambers
• LUND, Vanderbilt .

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Modified Central Magnet Configuration
add second - inner - coil foreseen in PHENIX
magnet design

• Three field configurations
• new field 0
• original configuration
• - new field reversed polarity
• 0 field along beam axis
• new field same polarity
• factor 1.7 increased Bdl

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Field Integral of New Magnet System

• Two future operation modes of PHENIX
• - field free region out to 50 cm
• sensitive to pair opening angle
• essential for pair continuum measurement
• increase field integral by factor 1.7
• increased momentum resolution
• important for high pt physics

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Momentum Resolution with Inner Tracking

• momentum resolution with new field configuration
• and inner tracking
• - configuration
• similar to original setup
• configuration
• improved by factor 3.5
• silicon tracking only
• ( 3 point estimate)

sp/p 0.03 p sE/E 40 for 20 GeV jet
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Proton-Nucleus Physics Program
Significant fundamental interest beyond AA
comparison run motivation discussed in detail at
previous workshop

• Issues to be addressed
• quark and gluon structure of nucleus
• parton density at small x
• propagation of partons trough nuclei
• hard diffractive processes
• standard tools
• di-leptons from Drell-Yan process
• prompt photons
• g - jet and jet - jet coincidences
• heavy quark production
• similar requirements like heavy ion and spin
  program
• to fully exploit RHICs unique opportunities
• additional equipment to tag forward going baryons
  
• (upgraded ZDCs and Roman Pots)
• extend muon acceptance to forward angles to
  extend x2 coverage below 10-3

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Detector Upgrades for p-A Physics

• Roman Pots and ZDC
• forward muon spectrometer

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Summary Cost Guesstimate
Based on detectors build by PHENIX, experience
with technology, or similar detectors build
elsewhere 30 - 75 contingency, depending on
stage of design and our knowledge of the
technology

• baseline upgrades
• PC2 east 500 k
• TRD east 700 k
• DAQTrigger 800 k
• muon anode electronics 3000 k
• TRD/TEC west 1300 k
• 6300 k
• vertex tracking system
• magnet 700 k
• silicon pixel 12000 k
• HBD (or TPC) 17000 k
• micro Pad chamber 3000 k
• forward calorimeter 2000 k
• 34700 k
• special p-Nucleus upgrades
• ZDC Roman Pots 550 k
• forward muon spect. 3000 k
• 3550 k

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Summary Timeline

• 2001-2002 south muon arm
• all central arm electronics
• Au-Au PC2,PC3 West
• first polarized p-p 70 MVD
• start RD
• 2003 north muon arm
• high-L?Au-Au PC2 east
• high-L light ions TRD/TEC east
• polarized p-p complete MVD
• first p-A continue RD
• 2004 complete RD
• pp/pd comparison Conceptual Design Report
• high-L pol. p-p ZDC roman pots
• forward muon spectrometer
• 2005 upgrade construction