1 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

People: F. Bieser, R. Gareus, L. Greiner, H. Matis, M. Oldenburg, F. Retiere, H.G. Ritter, K.S., A. Shabetai(IReS), E. Sichtermann, H. Wieman, N. Xu, E. Yamamoto

The Heavy-Flavor Tracker (HFT)

2 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Motivation

Q G P

nucleon boundary irrelevant

nucleus

Heat

J.C. Collins and M.J. Perry, Phys. Rev. Lett. 34 (1975) 1353.

Compress

Quark Gluon Plasma:

Deconfined and thermalized

state of quarks and gluons

Equilibration:

- hadron yields

Partonic Collectivity:

- Spectra of multi-strange

baryons

Thermalization:

- heavy-quark flow

- (thermal photons, di-leptons)

3 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Outline

1) Physics with the Heavy Flavor Tracker (HFT) spectra elliptic flowheavy flavor (c,b) energy lossvector mesons

2) Tracking with ITTF

track resolution tracking efficiency pile-up / ghost tracks

3) Summary

4 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Open Charm is The Future

Quark coalescence works

Partonic Collectivity !

At pt(q) > 1 GeV/c medium

transparent

Need low pt data !

5 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Charm Production

• First direct measurement at RHIC

• Reducing errors– Measure all charm

hadrons

– Cover large momentum range

• What do we learn?– Test pQCD

– Gluon pdf

6 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Open Charm Flow

PHENIX: measure electrons from c, b e + X

Large stat. and syst. errors !

Need direct open charm reconstruction !

7 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Open Charm Yields

• No thermal creation of c or b

quarks; m(c) = 1.1GeV >> T

• c and b quarks interact with

lighter quarks thermal

recombination ?

– Ds+ yield very sensitive !

– J/suppression vs

recombination ?

Pythia

p-p 200 GeV

Au-Au

Thermal*

D+/D0 0.33 0.455

Ds+/D0 0.20 0.393

c+/D0 0.14 0.173

J//D0 0.0003 0.0004

No suppression

F. Retiere

8 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Heavy-Flavor Energy Loss

• Heavy(H) quarks suffer smaller

energy loss than light(L) quarks

– Dead cone effect

– QCD analog Ter-Mikayelian

effect; nucl-th/0305062

• D/ ratio sensitive to color charge

• Differential study of energy loss

Yu.L. Dokshitzer and D.E. Kharzeev. Phys. Lett. B519 (2001) 199.

L = 5fm

L = 2fm

9 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Measure Vector Mesons

Detectors

TPC+TOF 8 M 2 M

TPC+TOF+SVT+HFT

200K 100K

e+e- : leptons do

not re-scatter probe the

medium at early stage

Background: e+e-

HFT discriminates

background !

Zhangbu Xu et al.

10 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Reconstruct Open Charm

• High precision

~3-6 µm hit-resolution

• Low mass - 1 GeV/c

particles - need low

multiple scattering

40 µm 80 µm

160 µm 320 µm

640 µm

H. Matis

11 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

• Two layers

• 24 ladders

• total length: 16cm

• inner radius: 1.5cm

• outer radius: 5.65cm

• new beampipe, 760m Be

• position resolution: 3-10m

• x~250m Si-equivalent

Monte Carlo Calculations

SVT

HFT

beampipe

12 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Dca - Distributions

Au+Au @200GeV

5% central

Track dca –

resolution: ~20 m

small tail due to

multiple scattering

low mass detector !

13 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Tuning the Tracker

Au+Au @200GeV

5% central

optimize efficiency

vs number of ghost

tracks

Best max. search

window : 500microns

consistent with

projections from SVT

pt = 0.5 – 1.0 GeV/c

14 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Efficiency

Au+Au @200GeV

5% central

Heavy-Flavor

Tracker: 40-50%

can we increase

SVT efficiency ?

Does SSD help ?

15 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Pile-Up and Ghost Tracks

Au+Au @200GeV

5% central

+ 40 pile-up events 10x

central occupancy

~2-3% ghost tracks

How does this influence the

D0 invariant mass spectrum ?

5% central

5% central + pileup

16 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Residuals vs z

z (cm)z (cm)

5 m50 m

z R

esid

ual (

mm

)

y R

esid

ual (

mm

) 10 GeV/c

Residuals in x-y plane : < 5 m

Residuals in z plane : < 50 mM. Oldenburg

17 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Open Charm Reco-Performance

Uncertainty in N events: 30%

System N events for 3 D0 signal

N events for 3 D+

s signal

TPC+SVT 12.6 M 500 M (K0s + K+)

TPC+SVT+TOF 2.6 M 100M

TPC+SVT+HFT 100 K50 K (neural net)

80 M (++)

TPC+SVT+HFT+TOF 10 K 5 M (++)

F. Retiere, A. Shabetai

18 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Summary

Heavy-Flavor efficiency 40-50%

Ghost tracks 2-3%, in pile-up

Improve Efficiency: SVT, SSD(?)

Measure spectra and of elliptic flow of

D0, D, D+s,

C Probe thermalization

Use Heavy-Flavor to probe medium

Measure Vector mesons

19 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

y-residuals [mm] and vs z [cm](green = mean, red = width; left = outer layer, right = inner layer)

20 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Significance

A. Shabetai (IReS)

21 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

Single Track Efficiency

22 STAR upgrade workshop, Yale, Jun 15 - 17, 2004

The Heavy Flavor Tracker• Two layers

– 1.6 cm radius

– 4.8 cm radius

• 24 ladders

– 2 cm by 20 cm

– CMOS Sensors

• Precise (<10 m) , thin and low power

– 50 m thick chip + air cooling

• < 0.3% radiation length

• Power budget 100 mW/cm2