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Heavy flavor physics and Vertex detector

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People involved

RNC GroupHoward WiemanHans-Georg Ritter Fred Bieser (Lead Electronic Engineer)Howard MatisLeo GreinerFabrice RetiereEugene YamamotoKai SchwedaMarkus OldenburgRobin Gareus (Univ. of Heidelberg)

LEPSI/IReS (Strasbourg)Claude Colledani, Michel Pellicioli, Christian Olivetto, Christine Hu, Grzegorz Deptuch Jerome Baudot, Fouad Rami, Wojciech Dulinski, Marc Winter

UCIrvineStuart Kleinfelder + students

LBNL Mechanical EngineeringEric Anderssen (consultation – ATLAS Pixels)Design works

BNL Instrumentation Div (consulting)Ohio State U

Ivan Kotov

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Heavy flavor in ultra-relativistic heavy-ion collisions

Heavy Q pairformation

How many?

c/b quarks in matterThermalization?

Coalescence? Flow?

Heavy flavor hadronsto detectors

Heavy quark energy loss

High pT

LowIntermediate pT

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Measuring yields

Large uncertaintiesIn data

In theory

Way to improveMeasure and identify all charm hadrons

Measure precise spectra

STAR preliminary

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Heavy-quark energy loss

p + p

d + Aup + p

d + Aup + p

d + Au

Heavy quarks radiate less energy than light quarks (prediction)

Yield of charm and beauty (leading) hadrons less suppressed

May be measured by D → X+e- and B → X+e-

Without vertex information systematic error from background substraction

STAR preliminary

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Flow and thermalization

Flow: spectra and v2 Charm thermalization by chemistry

J. Nagle, S. Kelly, M. Gyulassy, S.B. JN, Phys. Lett. B 557, pp 26-32

e-p & e+ e- Thermal

f(c→D0) 0.557 0.483

f(c→D+) 0.232 0.21

f(c→Ds+) 0.101 0.182

f(c→c+) 0.076 0.080

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Measuring heavy flavor with the Vertex detector

GoalsHeavy flavor energy loss

Remove background

Charm flowPrecise D0 spectra

D0 v2

Charm thermalizationYield of D+, Ds

+, c+

(challenging 3 body decays)

Vertex strategySeparate charm and beauty decay product from primary tracks

Typically D0 c = 124 m

Vertex requirement: a very good vertex resolution

Position resolution < 10 m

Thickness < 0.2% of rad length to limit multiple scattering

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STAR Vertex Detector

Two layers1.5 cm radius

4 cm radius

24 ladders2 cm by 20 cm each

< 0.2% X0

~ 100 Mega Pixels

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Charm hadron reconstruction performances

System N events for 3 D0 signal

N events for 3 D+

s signal

In progressTPC+SVT 12.6 M ~500 M (K0

s + K+)

TPC+SVT+TOF 2.6 M ~1,000 M (++)

TPC+SVT+Vertex 100 K ~100 M (++)TPC+SVT+Vertex+TOF

10 K ~1 M (++)

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STAR Vertex Detector

New vertex detector centered in existing SVT, supported one end only

End view showing 3 of 6 ladder modules

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Support: thin stiff ladder concept

Under development

Will be tested for vibration in our wind tunnel

carbon composite (75 m)Young’s modulus 3-4 times steel

aluminum kapton cable(100 m)

silicon chips(50 m)

21.6 mm

254 mm

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Sensors: Active Pixel Sensors

AdvantagesPrecise

Can be thin

Rather fast

Low power

DisadvantagesSmall signal

Not that fast

NewNeed R&D

p-well p-welln-well

p-epi

p-substrate

5-20 m

CMOS electronicAnalog & digital

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Sensors: 2 generations

1st Generation: 5-10 ms readout time

MIMOSTAR1 designed by LEPSI/IRES (Strasbourg)

640*640 pixel of 30*30 m2 pitch

Purely analog

Parallel readout on-chip multiplexed to 2 kind of outputs

1 * 100MHz driver

10 * 10 MHz drivers

2nd Generation: Faster but need more R&D

R&D with UCIrvine and LEPSI/IRES

Improve charge collection and remove need for CDS

Photogate, Active reset, …

Some digital processingUp to cluster-finder?

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Readout

Analog to end of the ladder (~1 m away)Challenge to drive analog signal at 100 MHz over 1m

Piggy back chipADC and memory on a chip bounded to the pixel chip

On-chip processing in 2nd generation

Data reduction at the end of the ladderHardware reduction (zero suppression)

Single board computer

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Budget

FY02-FY04 LBNL LDRD (total 375K$)FY04 RHIC R&D (200 K$ through Brookhaven)

Expected to continue until project is funded

Preparing a strategic LDRD fund request geared towards the development of future tracking apparatus with the Physics Division (Linear Collider)

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The time-scale

Proposal in April 2004

1st ladder prototype this fall (2004)Investigate mechanical support, cabling and some readout issues

Sensor: MIMOSA5 large but slow and “noisy”

2nd ladder prototype next year (fall 2005)Sensor: MIMOSTAR1 (submitted in July)

R.Gareus’s Readout chip (submitted in July)

The real thing starting in 2006Pending funding and success of prototypes

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Summary

A lot of work ahead of us!