star upgrade workshop, yale, jun 15 - 17, 2004 1 people: f. bieser, r. gareus, l. greiner, h. matis,...
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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
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