Axel Drees, Stony Brook University

1
The Future of Heavy Flavor Measurements with
PHENIX

• Status of heavy flavor measurements with PHENIX
• Open heavy flavor
• Quarkonia
• Upgrades program for PHENIX
• Forward calorimetry NCC
• Precision vertex tracker VTX/FVTX
• Future measurements from PHENIX
• Charm-beauty separation with VTX and FVTX
• Quarkonium spectroscopy with RHIC PHENIX
  upgrades
• Summary and Outlook

2
Key Experimental Probes of Quark Matter

• Rutherford experiment a ? atom discovery of
  nucleus
• SLAC electron scattering e ?
  proton discovery of quarks

QGP
penetrating beam (jets or heavy particles)
absorption or scattering pattern
Nature provides penetrating beams or hard
probes and the QGP in A-A collisions

• Penetrating beams created by parton scattering
  before QGP is formed
• High transverse momentum particles ? jets
• Heavy particles ? open and hidden charm or bottom
  
• Calibrated probes calculable in pQCD
• Probe QGP created in A-A collisions as transient
  state after 1 fm

3
Hard Probes Open Heavy Flavor

• Status
• Calibrated probe?
• pQCD under predicts cross section by factor 2-5
• Charm follows binary scaling
• Strong medium effects
• Significant charm suppression and v2
• Upper bound on viscosity ?
• Bottom potentially suppressed
• Open issues
• Limited agreement with energy loss calculations!
• What is the energy loss mechanism?
• Are there medium effects on b-quarks?

Electrons from c/b hadron decays

Answers require direct observation of charm and
beauty Progress limited by no b-c
separation ? decay vertex with silicon vertex
detectors statistics (B?J/?) ? increase
luminosity
4
Hard Probes Quarkonium
Deconfinement ? Color screening

• Status
• J/y production is suppressed
• Large suppression
• Similar at RHIC and SPS
• Larger at forward rapidity
• Ruled out comover and melting scenarios
• Consistent with melting J/y followed by
  regeneration
• Open issues
• Are quarkonia states screened and regenerated?
• What is the regeneration (hadronisation)
  mechanism?
• Can we extract a screening length from data?
• Recent Lattice QCD developments Quarkonium
  states do not melt at TC

J/y
Answers require quarkconium spectroscopy
Progress limited by statistics (J/?, Y)
? increase luminosity statistical significance
(?) ? mass resolution photon detection
(cC) ? forward calorimeter
5
Future PHENIX Subsystems
Silicon VTX and FVTX
MuTrig Station 1
MuTrig Station 2
Nose Cone Calorimeter
MuTrig Station 3
6
PHENIX Upgrades in the Vertex Region

• VTX, FVTX and NCC add key measurements to RHIC
  program
• Heavy quark characteristics in dense medium
• Charmonium spectroscopy (J/?, ? , ?c and ?)
• Light qurak/gluon energy loss through g-jet
• Gluon spin structure (DG/G) through g-jet and
  c,b quarks
• A-, pT-, x-dependence of the parton structure of
  nuclei

7
PHENIX Forward EM Calorimeter (NCC)

• NCC characteristics (DOE funding FY08)
• 40 cm from interaction point, 20 cm depth
• 2p coverage in azimuth and 0.9 lt h lt 3.0
• W-silicon sampling calorimeter
• 1.4 cm Mollier radius
• 42 X0 and 1.6 labs
• Lateral segmentation 1.5x1.5 cm2
• 3 longitudinal segments
• 2x2 tracking layers with 500 mm strips
• p-g separation for overlapping showers

W-silicon sampling calorimeter
PS tracking layers
Main objective direct photon and p0 measurements
EM1 EM2 HAD
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Direct Observation of Open Charm and Beauty
Direct Observation of Open Charm and Beauty
Detection of decay vertex will allow a clean
identifications of charm and bottom decays
m ct GeV mm D0
1865 125 D 1869 317 B0
5279 464 B 5279 496

• Heavy flavor detection with VTX and FVTX in
  PHENIX
• Beauty and low pT charm via displaced e and/or m
  -2.7lthlt-1.2 , hlt0.35 , 2.7lthlt1.2
• Beauty through displaced J/? ? ee (mm)
  -2.7lthlt-1.2 , hlt0.35 , 2.7lthlt1.2
• High pT charm through D ? ? K hlt0.35

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PHENIX Silicon Vertex Tracking Upgrades

• VTX silicon VerTeX barrel tracker
• ongoing construction funded by RIKEN and DOE
• 2 inner hybrid pixel layers,
• Pixel sensor 50mm x 425mm,
• ALICE1LHCB chip
• 2 outer layers strip sensors,
• single sided crossed strip design (BNL),
• (80mm x 3cm), SVX4 readout chip
• FVTX Forward silicon VerTeX tracker
• DOE Cost Schedule review next week,
• begin of construction FY08
• 2 endcaps with 4 disks each
• pixel pad structure (75mm x 2.8 to 11.2 mm)
• FPHX readout chip, next generation FPIX

VTX barrel hlt1.2
FVTX endcaps 1.2lthlt2.7 mini strips
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PHENIX Barrel VerTeX Detector

• VTX characteristics
• 2 inner pixel layers (50x425 mm2) to measure DCA
• radial position at 2.5 and 5 cm with 1.2
  X/X0
• 2 out strip-pixel (80x1000 mm2) for p measurement
  and tracking
• at 10 and 14 cm with 3. X/X0
• DCA resolution given mostly by inner layer
• Sufficient single hit resolution (15 mm)

• hlt1.2
• 2p
• z ? 10 cm

11
PHENIX Forward VerTeX Detector

• FVTX characteristics
• Cover both muon arms with 4 pixelpad
  layers/endcap
• 2p coverage in azimuth and 1.2 lt h lt 2.4
• 3 space points / track
• DCA resolution lt 200 µm at 5 GeV
• Maximum Radiation Length lt 2.4
• Fully integrated mechanical design with VTX

12
Heavy flavor detection with the VTX
3ltpTlt4 GeV/c
s 40mm

• Results of simulation of AuAu collision.
• After a ?2 cut, D0 decays clearly separated from
  bulk of hadrons

13
Expected RAA(c?e) and RAA(b?e) with VTX
PHENIX VXT 2 nb-1
RHIC II increases statistics by factor gt10
Decisive measurement of RAA for both c and b
14
Expected v2(b?e) and v2(c?e) with VTX
RHIC II increases statistics by factor gt10
Decisive measurement of v2 for both c and b
15
Tracking and DCA Resolution with the FVTX

• General performance
• 3 or more planes hit per track
• Central AuAu occupancy lt 2.8
• Good matching between FVTX and muon tracker
• Sufficient DCA resolution (lt200 mm) to separate
  prompt, heavy quark, and p-K decays.

16
D/B Monte Carlo Simulations with FVTX
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Heavy Ion RAA with FVTX

• Mechanisms for heavy/light quark suppression
  poorly understood
• Clear distinction among models, e.g. I.Vitevs
  radiative, collisional and dissociative energy
  loss predictions

18
Heavy Ion RAA with FVTX (II)
Statistical separation of charm and bottom with
DCA cuts
19
Future Quarkonium Spectroscopy with PHENIX

• RHIC II luminosity upgrade
• Electron cooling and stochastic cooling
• Increase integrated luminosity 2 nb-1 to 20 nb-1
  per run
• ? precision measurements of RAA and v2 for
  J/?
• FVTX Track muons to primary vertex,
• reject decay background (K?mn)
• Improved mass resolution
  clean and significant ?
• Background Rejection ? Upsilon at mid rapidity
• Rapidity dependence J/?, ?, and ?
• FVTX Detected displaced vertex for charm and
  beauty decays
• Precise charm and beauty reference
• NCC add photon measurement at forward rapidity
• Measurement of ?C ?J/? ? possible

20
Examples of Quarkonium Spectroscopy at RHIC II
J/? measurements will reach high precision
21
Charmonium Spectroscopy with the FVTX

• Remove p-K decays
• Background rejection factor 4
• Improve mass resolution
• 170 MeV ? 100 MeV

p-p
Measurement of ? in central Au-Au collisions
Au-Au
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Charmonium spectroscopy with the NCC
Central CuCu collisions
subtracted spectrum
?1-1.5
S/B 10

• J/? in muon arm, g in NCC
• Conditional acceptance 58 if J/? detected
• Determine invariant mass and subtract
  combinatorial background
• Proof of principle MC simulation
• pp should work, CuCu probable
• Full MC simulation in progress

subtracted spectrum
?1.5-2
S/B2
mµµ?-mµµ (GeV/c2)
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Quarkonium Spectroscopy with Forward Upgrades
Reference model based on consecutive melting
without regeneration (Note This results in small
?, ?C yields, other models like regeneration
model will give similar yields for
J/?, ?, ?C !)
?(1S)
RHIC 2 nb-1 With NCC/FVTX
RHIC 2 nb-1 W/O NCC/FVTX
RHIC 20 nb-1 With NCC/FVTX
?(2S)
J??
?c
?
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Timeline of PHENIX upgrades
2012
2010
2014
2008
RHIC
electron cooling RHIC II
Inner pixel layers
Displaced vertex at mid rapidity
VTX
Large acceptance tracking Dhlt1.2
Outer strip layers
Displaced vertex at forward y
FVTX
Forward photon detection
NCC
Construction
Physics
25
Summary and Outlook

• Study of heavy flavor production provides key
  information to understand the properties of quark
  matter
• Strong medium effects seem to exist at RHIC
  energies
• PHENIX devised a comprehensive upgrades program
  to address these issues
• First silicon vertex detector layers may start
  producing results by run 10 (Fall 2010)
• Expect completion of upgrades by 2011/12