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
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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
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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.
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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)
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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
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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.
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HFT
TPC
FGT
STAR Detectors: 2 Particle Identification
EMCTOF
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Inner Tracking DetectorsInner Tracking Detectors
PXL at 2.5 and 8 cm
20 cm20 cm
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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
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DCA CutsDCA CutsUses PID from TOF.Uses PID from TOF.
Estimated mass spectra from Estimated mass spectra from 100M central events100M central events
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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!
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Charm Hadron vCharm Hadron v22
- 200 GeV Au+Au minimum biased collisions (500M events). - Charm collectivity drag/diffusion constants medium properties!
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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
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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
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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
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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)
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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
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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%)
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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.
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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
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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.
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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
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