The Future of Heavy Flavor Measurements with PHENIX

Axel Drees, Stony Brook University LBNL, November 1 st , 2007 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

Key Experimental Probes of Quark Matter

Rutherford experiment SLAC electron scattering

a 

e



atom proton discovery of nucleus 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



Heavy particles



jets open and hidden charm or bottom Calibrated probes calculable in pQCD Probe QGP created in A-A collisions as transient state after ~ 1 fm

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Hard Probes: Open Heavy Flavor

Electrons from c/b hadron decays 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?

Answers require direct observation of charm and beauty Progress limited by: no b-c separation



statistics (B



J/



)



decay vertex with silicon vertex detectors increase luminosity

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Hard Probes: Quarkonium

Deconfinement



Color screening Status J/



production is suppressed Large suppression Similar at RHIC and SPS Larger at forward rapidity Ruled out comover and melting scenarios Consistent with melting J/



followed by regeneration J/



Open issues: Are quarkonia states screened and regenerated?

What is the regeneration (hadronisation) mechanism?

Can we extract a screening length from data? Answers require “quarkconium” spectroscopy Quarkonium states do not melt at T C Progress limited by: statistics (J/



, Y) statistical significance (



’) photon detection (

c

C )

  

increase luminosity mass resolution forward calorimeter

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Future PHENIX Subsystems

Silicon VTX and FVTX MuTrig Station 1 MuTrig Station 2 Nose Cone Calorimeter MuTrig Station 3

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PHENIX Upgrades in the Vertex Region

FVTX Si Endcaps Nose Cone Calorimeter VTX Si Barrel VTX, FVTX and NCC add key measurements to RHIC program:

– Heavy quark characteristics in dense medium – Charmonium spectroscopy (J/ 

,



’ ,

c

c and



)

– Light qurak/gluon energy loss through g

-jet

– Gluon spin structure ( D

G/G) through

g

-jet and c,b quarks

– A-, p

T -, x-dependence of the parton structure of nuclei

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PHENIX Forward EM Calorimeter (NCC)

W-silicon sampling calorimeter NCC characteristics (DOE funding FY08) 40 cm from interaction point, 20 cm depth 2

p

coverage in azimuth and 0.9 <

h

< 3.0

W-silicon sampling calorimeter 1.4 cm Mollier radius 42 X 0 and 1.6

l

abs Lateral segmentation 1.5x1.5 cm 2 3 longitudinal segments

  

E E E

23 % /

GeV

1 %

2x2 tracking layers with 500

m

m strips

p-g

separation for overlapping showers PS tracking layers Main objective: direct photon and

p 0

measurements

EM1 EM2 HAD Axel Drees

X e,

m

Detection of decay vertex will allow a clean identifications of charm and bottom decays m GeV c

t m

m D 0 D ± 1865 1869 125 317 B 0 B ± 5279 5279 464 496 Au D K D

p

B J/ Au



X e e Heavy flavor detection with VTX and FVTX in PHENIX:

•

Beauty and low p T charm via displaced e and/or

m

-2.7<

h

<-1.2 ,

• •

Beauty through displaced J/

 

High p T charm through D

 p

K ee (

mm

) -2.7<

h

<-1.2 ,

|h

|<0.35

|h

|<0.35 , 2.7<

h

<1.2

|h

|<0.35 , 2.7<

h

<1.2

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PHENIX Silicon Vertex Tracking Upgrades

VTX: silicon V er T e X barrel tracker ongoing construction funded by RIKEN and DOE 2 inner hybrid pixel layers, Pixel sensor 50

m

m x 425

m

m, ALICE1LHCB chip 2 outer layers strip sensors, single sided crossed strip design (BNL), (80

m

m x 3cm), SVX4 readout chip VTX barrel |

h

|<1.2

FVTX: F orward silicon V er T e X tracker DOE Cost & Schedule review next week, begin of construction FY08 2 endcaps with 4 disks each pixel pad structure (75

m

m x 2.8 to 11.2 mm) FPHX readout chip, next generation FPIX FVTX endcaps 1.2<|

h

|<2.7 mini strips

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PHENIX Barrel

V

er

T

e

X

Detector

X e VTX characteristics 2 inner pixel layers (50x425

m

m 2 ) to measure DCA radial position at 2.5 and 5 cm with ~ 1.2% X/X 0 2 out strip-pixel (80x1000

m

m 2 ) for p measurement and tracking at 10 and 14 cm with ~ 3.% X/X 0 |

h

|< 1.2



|z| ~ 2

p  10

cm

 2 

D beam DCA, distance of closest approach

DCA

   1 2 (

r

2 2

r

2 

r

1  ) 2 2 2

r

1 2   

ms

2 sin

r

1 2 2  

detector



ms



Bdl

~ 0 .

15

Tm

 

p p

~ 10 %

DCA resolution: given mostly by inner layer Sufficient single hit resolution (~15

m

m) Close to beam axis to reduce effect of multiple scattering

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PHENIX F orward V er T e X Detector FVTX characteristics Cover both muon arms with 4 pixelpad layers/endcap 2

p

coverage in azimuth and 1.2 < |

h

| < 2.4

≥ 3 space points / track DCA resolution < 200 µ m at 5 GeV Maximum Radiation Length < 2.4% Fully integrated mechanical design with VTX

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Heavy flavor detection with the VTX

e X



D beam DCA, distance of closest approach

3

~ 40

m

m Results of simulation of Au+Au collision.

After a

c

2 cut, D0 decays clearly separated from bulk of hadrons

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Expected R

AA

(c



e) and R

AA

(b



e) with VTX

PHENIX VXT ~2 nb-1

RHIC II increases statistics by factor >10

Decisive measurement of R AA for both c and b

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Expected v

2

(b



e) and v

2

(c



e) with VTX

PHENIX VXT ~2 nb -1

RHIC II increases statistics by factor >10

Decisive measurement of v 2 for both c and b

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Tracking and DCA Resolution with the FVTX

prompt p  m

General performance 3 or more planes hit per track Central Au+Au occupancy < 2.8% Good matching between FVTX and muon tracker Sufficient DCA resolution (<200

p

-K decays.

m

m) to separate prompt, heavy quark, and

Muon acceptance Momentum (GeV) Axel Drees

D/B Monte Carlo Simulations with FVTX

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Heavy Ion R

AA

with FVTX

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

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Heavy Ion R

AA

with FVTX (II)

Statistical separation of charm and bottom with DCA cuts

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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 R AA and v 2 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

C →J/



γ possible

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Examples of Quarkonium Spectroscopy at RHIC II

J/



measurements will reach high precision

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Charmonium Spectroscopy with the FVTX Remove

p

-K decays Background rejection factor 4 Improve mass resolution: 170 MeV



100 MeV p-p Au-Au Measurement of



‘ in central Au-Au collisions

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Charmonium spectroscopy with the NCC

c

C



J

/   g μ μ Central Cu+Cu collisions η

=1-1.5

subtracted spectrum

γ 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

η

=1.5-2

S/B~2%

subtracted spectrum m

μμγ

-m

μμ

(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

C yields, other models like regeneration model will give similar yields for J/



,



’,

c

C !) RHIC 20 nb -1

c

c

1

S)

2

S) J

 

’

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Timeline of PHENIX upgrades

2008 2010 2012 2014 RHIC electron cooling “RHIC II” VTX Inner pixel layers Outer strip layers Displaced vertex at mid rapidity Large acceptance tracking |

Dh

|<1.2

FVTX Displaced vertex at forward y Forward photon detection NCC Construction Physics

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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

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