STAR RHIC AGS users meeting, May 30, 20081 Star Inner Tracking upgrade F. Videbaek STAR...

STARSTARRHIC AGS users meeting, May 30, 2008RHIC AGS users meeting, May 30, 2008 11

Star Inner TrackingStar Inner Trackingupgradeupgrade

F. VidebaekF. Videbaek

STAR collaborationSTAR collaboration

for the HFT upgrade groupfor the HFT upgrade group

STARSTAR RHIC AGS users meeting, May 30, 2008RHIC AGS users meeting, May 30, 2008 22

OverviewOverview Physics Goals for Heavy Flavour Tracker (HFT)Physics Goals for Heavy Flavour Tracker (HFT) Overview of STAR Overview of STAR Expected Physics Results (Simulations)Expected Physics Results (Simulations) Detector Components for HFTDetector Components for HFT

PixelPixel ISTIST SSDSSD InfrastructureInfrastructure

SummarySummary


Physics GoalsPhysics Goals

New frontier - heavy quark production

- HQ collectivity: test light quark thermalization

- HQ energy loss: explore pQCD in hot/dense medium

Base line reference spectra for the HI program

c and b cross section in pp at 200 and 500 GeV

Method : Topological identification of D’s, c to low pT.


Heavy Flavor Energy LossHeavy Flavor Energy Loss

Surprising results - - challenge our understanding of the energy loss mechanism - force us to RE-think about the collisional energy loss - Requires direct measurements of C- and B-hadrons.

1) Non-photonicelectrons decayedfrom - charm andbeauty hadrons

2) At pT ≥ 6 GeV/c,

RAA(n.e.) ~ RAA(h±)

contradicts naïve pQCD predictions

STAR PRL, 98, 192301 (2007)


u

MeasurementsMeasurements RequirementsRequirements

Heavy IonHeavy Ion

heavy-quark hadron vheavy-quark hadron v22 - -

the heavy-quark collectivitythe heavy-quark collectivity

- Low material budget and high - Low material budget and high

efficiency efficiency minmin ≥ 1% ≥ 1%

- ppTT coverage ≥ 0.5 GeV/c coverage ≥ 0.5 GeV/c

- mid-rapidity mid-rapidity - High counting rateHigh counting rate

heavy-quark hadron Rheavy-quark hadron RAAAA - -

the heavy-quark energy lossthe heavy-quark energy loss

- High pHigh pTT coverage coverage

~ 20 GeV/c~ 20 GeV/c

p+pp+p

energy dependence of the heavy-energy dependence of the heavy-quark productionquark production

- p- pTT coverage down to 0.5 GeV/c coverage down to 0.5 GeV/c

gluon distribution with heavy gluon distribution with heavy quarksquarks

- wide rapidity and p- wide rapidity and pTT coverage coverage


Overview of Layout, conceptsOverview of Layout, concepts Inner high resolution pixels are crucial for Inner high resolution pixels are crucial for

physics goal of direct D0 topological physics goal of direct D0 topological identificationidentification

Relies on TPC-SSD-IST-PIXEL tracking for Relies on TPC-SSD-IST-PIXEL tracking for graded point matching and resolution.graded point matching and resolution.


HFT

TPC

FGT

STAR Detectors: 2 Particle Identification

EMCTOF


Inner Tracking DetectorsInner Tracking Detectors

PXL at 2.5 and 8 cm

20 cm20 cm


Concept of HFT LayersConcept of HFT Layers

Graded Resolution from the Outside – In Resolution()

TPC pointing at the SSD ( 23 cm radius) ~ 1 mm

SSD pointing at IST ( 14 cm radius) ~ 400 m

IST pointing at Pixel-2 ( 8 cm radius) ~ 400 m

Pixel-2 pointing at Pixel-1 (2.5 cm radius) ~ 70 m

pixel-1 pointing at the vertex ~ 40 m

Purpose of intermediate layers to get increasing resolution power with increasing hit-densities, so the high resolution hits in the inner pixel’s can be found, assigned and displaced vertices determined.

SSDSSD

ISTIST

PIXELPIXEL


DCA CutsDCA CutsUses PID from TOF.Uses PID from TOF.

Estimated mass spectra from Estimated mass spectra from 100M central events100M central events


DD00 Reconstruction Efficiency Reconstruction Efficiency

- Central Au+Au collisions: top 10%events. - The thin detector allows measurements down to pT ~ 0.5 GeV/c.

- Essential and unique!


Charm Hadron vCharm Hadron v22

- 200 GeV Au+Au minimum biased collisions (500M events). - Charm collectivity drag/diffusion constants medium properties!


Work is continuing to refine details of the detector Work is continuing to refine details of the detector design/performancedesign/performance

Simulations of the most challenging 3-body decays are encouragingso far

This capability, which will be provided uniquely at RHIC by the HFT, is crucial for determining whether the baryon/meson anomaly extends toheavy quark hadrons


Detector RealizationDetector Realization Briefly discussBriefly discuss

PIXELPIXEL IST (intermediate Silicon Tracker)IST (intermediate Silicon Tracker) SDD (Silicon Strip Detector) - existingSDD (Silicon Strip Detector) - existing InfrastructureInfrastructure


PIXELPIXEL

2 layers of 18x18 m pixels at 2.5 and 8 cm radius, 20 cm longVery low material budget to limit multiple scatteringData reduction and formatting on chipRapid insertion and removalPrecision positioningAir cooling Ongoing APS technology R&D with StrasbourgFor RHIC luminosities needs ‘fast’ detector with better than 200 sec integration time.Efficiencies degrade with ‘pile-up’ within sample time


Active Pixel SensorsActive Pixel Sensors

Properties:

Signal created in low-doped epitaxial layer (typically ~10-15 μm)

Sensor and signal processing integrated in the same silicon wafer

Standard commercial CMOS technology

pixel chips (MAPS) produced by

IReS/LEPSI IPHC (Strasburg)


IPHC Functional Sensor DevelopmentIPHC Functional Sensor Development

Data Processing in RDO and on chip by generation of sensor.

The RDO system design evolves with the sensor generation.

•30 x 30 µm pixels => 18x18 µm•CMOS technology•Full Reticule = 640 x 640 pixel array=> 1024 x 1088 array1024 x 1088 array

Mimostar 2 => full functionality 1/25 reticule, 1.7 µs integration time (1 frame@50 MHz clk), analog output. (in hand and tested)

All sensor families:

Phase-1 and Ultimate sensors => digital output (in development)

SensorPixels

AnalogSignals ADC /

Disc.CDS

DataSparsification

RDOto

DAQ

Mimostar sensors

Phase-1sensors - 640 us integration time

Ultimate sensors - < 200 us integration time

Leo Greiner,LBNL


Some pixel features and specificationsSome pixel features and specificationsPointing resolution (13 19GeV/pc) m

Layers Layer 1 at 2.5 cm radius

Layer 2 at 8 cm radius

Pixel size 18.4 m X 18.4 m

Hit resolution 10 m rms

Position stability 6 m (20 m envelope)

Radiation thickness per layer X/X0 = 0.28%

Number of pixels 436 M

Integration time (affects pileup)

0.2 ms

Radiation tolerance 300 kRad

Rapid installation and replacement to cover rad damage and other detector failure

Installation and reproducible positioning in a shift

criticalanddifficult

(ATLAS Pixels 1.2%)


Pixel support structurePixel support structure

Inner layer

Outer layer

End view

ALICE style carbon support beams (green)

19

2.5 cm radius

8 cm radius

‘D-Tube Duct and Support

Since modified to increase Sensor Clearances

‘D-Tube Duct and Support


Sensor Development StatusSensor Development Status

Mimostar-2Mimostar-2Testing complete – MS-2 Sensor telescope used at STAR for Testing complete – MS-2 Sensor telescope used at STAR for

telescope test in previous run.telescope test in previous run.

Description and results are published in:Description and results are published in:Nuclear Instruments and Methods in Physics Research A 589 (2008) Nuclear Instruments and Methods in Physics Research A 589 (2008)

167–172167–172


Pixel proto in STAR, measured track density at r = 5cm, z = 145cm

4*4 mm

Placed inside STAR during Run-7Placed inside STAR during Run-7Located 150cm (z) 8 cm below beamLocated 150cm (z) 8 cm below beamTrack density low.Track density low.Resolves tracks from collision vs. backgroundResolves tracks from collision vs. background


Bernd Surrow

IST LayoutIST Layout

IST - 3D viewIST - 3D view

Layout:Layout:

r r = 14 cm

~24 ladders12 units (Modules) per ladder

(44cm)

IST IST 1 sensor layer: Silicon-pad type


Bernd Surrow

Technical realizationTechnical realization

IST - Ladder design - OverviewIST - Ladder design - Overview

Ladder: Carbon fiber

base material 12 modules

per ladder

Length: 44cm

Module:Module:

Silicon-pad sensors:

Dimensions: 4cm X 4cm

Pad size structure still being

optimized: 400μm X 1cm

typically

Readout Chip: APV25-S1

3-5 chips per sensor

liquid cooling

Location: APV25-S1 Readout Chips

(Example: PHOBOS Inner Vertex Sensor)

Location: Silicon-pad sensor

42cm


InfrastructureInfrastructure

Integration of Mechanical structures is a critical Integration of Mechanical structures is a critical issue for the project.issue for the project.

Replacement of existing beam pipe -> r ~2cm.Replacement of existing beam pipe -> r ~2cm. Support of thin and light weight structures. Support of thin and light weight structures.

Recall the total radiation length is aimed at Recall the total radiation length is aimed at <=3%.<=3%.

Ease in replacement of pixel ladders in case of Ease in replacement of pixel ladders in case of failures, and effect of radiation.failures, and effect of radiation.

Support for PIXEL, IST, SSD and FGTSupport for PIXEL, IST, SSD and FGT


Conceptual Inner Part of STARConceptual Inner Part of STAR

Intricate layout for 3 HFT trackers + beam pipe + FGT.Intricate layout for 3 HFT trackers + beam pipe + FGT.

25

SSDIST

IFCWSC

New Cone Structures inside of Inner Field Cage

ISCPixel

East Cone


ISC fits inside and is supported by the cone

ISC supports IST on outsideISC ISC supports pixel and beam pipe inside

Inner Support Cylinder (ISC)Inner Support Cylinder (ISC)

26

SSD Supported on outside

SSD Services out both sides

IST Services out East side on ISC


Follower guided insertion Follower guided insertion operationoperation

Open Closed

27

Clears Beam Pipe overLarge Diameter

Clearance for Beam Pipe Supports andKinematic Mounts

Final Motion engages

Kinematic M

ountsArticulationRegion


SSDSSD

The SSD is an integral part of the upgrade. It is The SSD is an integral part of the upgrade. It is an existing detector. It will be upgraded to be an existing detector. It will be upgraded to be compatible with DAQ1000. Redundancy is built compatible with DAQ1000. Redundancy is built with the outer strip layer.with the outer strip layer.


SummarySummary

Physics of the Heavy FlavorPhysics of the Heavy Flavor Tracker at STAR Tracker at STAR

1) Au+Au collisions1) Au+Au collisions (1) Measure heavy-quark hadron v(1) Measure heavy-quark hadron v22, heavy-quark collectivity, to study the medium, heavy-quark collectivity, to study the medium

properties properties e.g.e.g. light-quark thermalization light-quark thermalization (2) Measure heavy-quark energy loss to study pQCD in hot/dense medium (2) Measure heavy-quark energy loss to study pQCD in hot/dense medium e.g. e.g. energy loss mechanism energy loss mechanism (3) (3) Measure di-leptions to study the direct radiation from the hot/dense mediumMeasure di-leptions to study the direct radiation from the hot/dense medium (4) Analyze hadro-chemistry including heavy flavors (4) Analyze hadro-chemistry including heavy flavors

2) p+p collisions2) p+p collisions (1) energy dependence of the heavy-quark production (1) energy dependence of the heavy-quark production

(2) reference spectra for AuAu (2) reference spectra for AuAu


3 year Run Plan when installed3 year Run Plan when installed

11) First run with HFT: 200 GeV Au+Au v2 and RCP with 500M M.B. collisions

2) Second run with HFT: 200 GeV p+p RAA

3) Third run with HFT: 200 GeV Au+Au centrality dependence of v2 and RAA

Charm background and first attempt for electron pair measurements

Sufficient Statistics for c

A technical driven schedule would allow complete detector for Run-12. The real world with budget constraints ??

An engineering run with a few pixel ladders is planned.


Final wordFinal word An HFT upgrade to STAR than will utilize all the An HFT upgrade to STAR than will utilize all the

strengths of STAR (2strengths of STAR (2 coverage, TOF,..) and will provide coverage, TOF,..) and will provide crucial charm and bottom measurements. crucial charm and bottom measurements.

See also Jan Kapitan’s poster at this meetingSee also Jan Kapitan’s poster at this meeting


The EndThe End

STAR RHIC AGS users meeting, May 30, 20081 Star Inner Tracking upgrade F. Videbaek STAR...

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