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L. Greiner 1STAR HFT CD1 Review, BNL, November 2009
STARSTAR
STAR Pixel Detector
Sensors and Readout
with status of development and prototyping
L. Greiner 2STAR HFT CD1 Review, BNL, November 2009
STARSTARPixel Sensor and Electronics Group
LBNLLeo Greiner, Howard Matis
Thorsten Stezelberger, Xiangming Sun, Michal Szelezniak, Chinh Vu,
Howard Wieman
UTAJo Schambach
IPHC StrasburgMarc Winter CMOS group
L. Greiner 3STAR HFT CD1 Review, BNL, November 2009
STARSTARTalk Outline
• Sensor Characteristics.• Sensor and RDO development plan.• Sensor development status.• RDO requirements and design.• Status of RDO prototyping and testing.• Summary.
The primarily focus of this talk is technical.
L. Greiner 4STAR HFT CD1 Review, BNL, November 2009
STARSTARMonolithic Active Pixel Sensors
• Standard commercial CMOS technology • Room temperature operation• Sensor and signal processing are integrated in the same silicon wafer• Signal is created in the low-doped epitaxial layer (typically ~10-15 μm) → MIP
signal is limited to <1000 electrons• Charge collection is mainly through thermal diffusion (~100 ns), reflective
boundaries at p-well and substrate → cluster size is about ~10 pixels (20-30 μm pitch)
• 100% fill-factor • Fast readout• Proven thinning to 50 micron
MAPS pixel cross-section (not to scale)
L. Greiner 5STAR HFT CD1 Review, BNL, November 2009
STARSTARSensor generation and RDO attributes
Pixel
Sensors CDS
ADC Data
sparsification
readout
to DAQ
analogsignals
Complementary detector readout
MimoSTAR sensors 4 ms integration time
PXL final sensors (Ultimate) < 200 μs integration time
analog
digital digital signals
Disc.
CDS
Phase-1 sensors 640 μs integration time
Sensor and RDO Development Path
Develop sensor chips, 3 generation program (WBS 1.2.2.2)
1
2
3
L. Greiner 6STAR HFT CD1 Review, BNL, November 2009
STARSTARMimostar Analog Output Sensor Prototypes
Pixel
Sensors CDS
ADC Data
sparsification
readout
to DAQ
analogsignals
Complementary detector readout
MimoSTAR sensors 4 ms integration time
PXL final sensors (Ultimate) < 200 μs integration time
analog
digital digital signals
Disc.
CDS
Phase-1 sensors 640 μs integration time
Develop sensor chips, 3 generation program (WBS 1.2.2.2)
1
L. Greiner 7STAR HFT CD1 Review, BNL, November 2009
STARSTARMimostar Analog Output Sensor Prototypes
Mimostar-23 Sensor telescope used at STAR for prototype test in 2007 RHIC run.
Description and results are published in:Nuclear Instruments and Methods in Physics Research A 589 (2008) 167–172
• Testing on this generation of sensor is complete. • 3 Sensor telescope used at STAR for prototype test in 2007 RHIC run.• Clean noise environment at STAR.• Interfaces to Trigger and slow controls worked well. • No latch-up events were observed during the run.
L. Greiner 8STAR HFT CD1 Review, BNL, November 2009
STARSTARPhase-1 Binary Digital Output Sensors
Pixel
Sensors CDS
ADC Data
sparsification
readout
to DAQ
analogsignals
Complementary detector readout
MimoSTAR sensors 4 ms integration time
PXL final sensors (Ultimate) < 200 μs integration time
analog
digital digital signals
Disc.
CDS
Phase-1 sensors 640 μs integration time
Develop sensor chips, 3 generation program (WBS 1.2.2.2)
2
L. Greiner 9STAR HFT CD1 Review, BNL, November 2009
STARSTARPhase-1 Precursor Sensor Prototype Performance
120 GeV π- beam test at CERN
• Efficiency > 99%.
• Fake hit rate < 10-4.
• Meets PXL sensor requirements.
CMOS pixel sensor development: a fast readout architecture with integrated zeroSuppression – C. Hu, PIXEL 2008
L. Greiner 10STAR HFT CD1 Review, BNL, November 2009
STARSTARFull Reticle Phase-1 Sensor Status
• Phase-1 prototype sensors have been fabricated• Testing is ongoing. • Functionality tests and yield look very good.• Measured ENC is 15 e-.• Beam test to measure MIP efficiency planned for 2010.
Phase-1 prototype on testing board.
Digital output
Analog output
55Fe spectrum
2 cm x 2 cm
L. Greiner 11STAR HFT CD1 Review, BNL, November 2009
STARSTAR PXL Sensor
Pixel
Sensors CDS
ADC Data
sparsification
readout
to DAQ
analogsignals
Complementary detector readout
MimoSTAR sensors 4 ms integration time
PXL final sensors (Ultimate) < 200 μs integration time
analog
digital digital signals
Disc.
CDS
Phase-1 sensors 640 μs integration time
Develop sensor chips, 3 generation program (WBS 1.2.2.2)
3
L. Greiner 12STAR HFT CD1 Review, BNL, November 2009
STARSTARFull reticle PXL Sensor
S0 S1 S15
N Hits N Hits
-
Col
umn
-0
Col
umn
-63
Col
umn
-0
Col
umn
-63
Col
umn
-63
Col
umn
-0
A/D A/D… A/D A/D A/D A/D
…
…
…
…
…
…
…
…
S0 S1 S16
Memory with M states storage and serial transmission
Col
umn
-0
Col
umn
-63
Col
umn
-0
Col
umn
-63
Col
umn
-63
Col
umn
-0
A/D A/D… A/D A/D A/D A/D
…
…
…
…
…
…
…
…
(N states)
Priority Look-Aheadalgorithm
Selection of 9 states among 17x 9 states for each row
(N states)
Priority Look-Aheadalgorithm
(N states)
Priority Look-Aheadalgorithm
Memory 1
Memory 2
core of the zero suppression
Phase-1SUZE – Zero suppression
(prototype successfully tested 04/2008)
+
• Overall design is in progress and nearly complete.
• 18.4 µm pixels have been chosen for enhanced radiation tolerance.
• Mimosa-26 (smaller prototype sensor) under test in Strasbourg, initial results look good.
Final PXL Sensor
L. Greiner 13STAR HFT CD1 Review, BNL, November 2009
STARSTARRDO Requirements and Design
• Triggered detector system fitting into existing STAR infrastructure (Trigger, DAQ, etc.)
• Deliver full frame events to STAR DAQ for event building at approximately the same rate as the TPC (1 kHz for DAQ1000).
• Have live time characteristics such that the Pixel detector is live whenever the TPC is live.
• Reduce the total data rate of the PXL detector to a manageable level (< TPC rate of ~1MB / event).
• Contain additional functionality for full sensor characterization including production probe testing.
Develop readout electronics (WBS 1.2.2.5)
L. Greiner 14STAR HFT CD1 Review, BNL, November 2009
STARSTARPXL RDO Basic Unit
2m6m
RDO PC100m
• 4 ladders per sector• 1 Mass Termination Board (MTB) per sector• 1 sector per RDO board• 10 RDO boards in the PXL system
Develop readout electronics (WBS 1.2.2.5)
L. Greiner 15STAR HFT CD1 Review, BNL, November 2009
STARSTARFunctional Data Path – One Ladder
buffer
JTAG, CLK, CTL, markers
buffer
LU protected power
Digital hit data
10 sensors
• After power-on and configuration, the sensors are run continuously. • Triggering is handled in the next stage of the RDO.
1 Ladder
Develop readout electronics (WBS 1.2.2.5)
L. Greiner 16STAR HFT CD1 Review, BNL, November 2009
STARSTARFunctional Data Path – Phase-1
• Each received trigger enables an event buffer for one frame.
• The system is dead-time free up to the hardware limit of the number of buffers.
Highly Parallel FPGA based RDO system
AddressCounter(zero-
suppression)
EventBuffer
EventBuffer
EventBuffer
1
2
10
EventBuilder
RDOBuffer
SIU
DAQPC
Disk
160 MHzBinary Data
(4 chains per sensor) * (10 sensors per ladder) *(4 ladders per RDO board) = 160 chains per RDO board
160 independent sensor data chains
One per RDO board
FPGA Block RAM
•40 sensor outputs/ladder
L. Greiner 17STAR HFT CD1 Review, BNL, November 2009
STARSTARFunctional Data Path – PXL Sensor
•20 sensor outputs/ladder
• Each received trigger enables an event buffer for one frame. • Triggered event boundaries are determined by data order.
Highly Parallel FPGA based RDO system
EventBuffer
EventBuffer
EventBuffer
1
2
10
EventBuilder
RDOBuffer
SIU
DAQPC
Disk
160 MHz Address only data
(2 chain per sensor) * (10 sensors per ladder) *(4 ladders per RDO board) = 80 chains per RDO board
80 independent sensor data chains
One per RDO board
• Same hardware with reconfigured firmware
L. Greiner 18STAR HFT CD1 Review, BNL, November 2009
STARSTARParameters and Data Rates
PXL System
• Data rate to storage = 199 MB/sec (1kHz trigger)• 199kB / event• Meets data rate requirement.• Meets data volume requirement.
Item Number
Bits/address 20
Integration time (µs) 200
Luminosity (cm-2s-1) 8 × 1027
Hits / frame on Inner sensors (r=2.5 cm) 246
Hits / frame on Outer sensors (r=8.0 cm) 24
Final sensors (Inner ladders) 100
Final sensors (Outer ladders) 300
Event format overhead TBD
Average Pixels / Cluster 2.5
Average Trigger rate 1 kHz
L. Greiner 19STAR HFT CD1 Review, BNL, November 2009
STARSTARLVDS Data Path Testing at 160 MHz
• Data Path Architecture Validated• Measured BER (bit error rate) of < 10-14
2 ns eye patternopening for 1 m 42 AWG cables at 200 MHz
Ladder mock-up with 1-to-4 LVDS fanout buffers
Mass termination board + LU monitoring
42 AWG wires
24 AWG wires
Virtex-5 based RDO system with DDL link to PC
http://rnc.lbl.gov/hft/hardware/docs/LVDS/LVDS_test_report_1.pdf
L. Greiner 20STAR HFT CD1 Review, BNL, November 2009
STARSTARPrototyping Status – Sensor RDO Cables
Cable•4 step development process.•Al traces in low mass region.•Radiation Length ~ 0.073%•Al based cable meets X0 requirement.
Status• Defined signal paths• Schematic entry complete for preliminary FR-4 test version.
http://rnc.lbl.gov/hft/hardware/docs/Phase1/Development_PXL_flex_cable.doc
Develop flex PC readout cable (WBS 1.2.2.3)
Low mass Sensor regionDriver region
Side view (exaggerated vertical scale)
Preliminary Design: Hybrid Copper / Aluminum conductor flex cable
Low mass region calculated X0 for Al conductor = 0.073 %Low mass region calculated X0 for Cu conductor = 0.232 %
L. Greiner 21STAR HFT CD1 Review, BNL, November 2009
STARSTARPrototyping Status – MTB and RDO Boards
Status• Prototype in hand.• Testing in progress.
Status• 3 Prototypes in hand. • Firmware, hardware and software are working for individual sensor testing.
Mass Termination BoardLU protected power regulation boardMass Termination BoardLU protected power regulation board
RDO Board(s)Xilinx VIRTEX-5 development boardMated to a custom readout board.
•Prototype System is in the advanced stages of testing and working well.
L. Greiner 22STAR HFT CD1 Review, BNL, November 2009
STARSTARSummary
• We have a well advanced sensor and RDO development plan with our collaborators at IPHC.
• Analog output sensors have been used successfully in beam at STAR. The noise environment and interfaces to STAR infrastructure seem to be understood.
• First generation digital output sensors (Phase-1) have been fabricated and are currently under test. Initial results look promising.
• The RDO data path architecture has been validated and the prototype RDO system hardware has been produced.
• Prototype RDO firmware and software have been developed and the testing of individual sensors works well.
• We will now extend the firmware and software to reading out 10 sensor ladders.
L. Greiner 23STAR HFT CD1 Review, BNL, November 2009
STARSTAR Backup
L. Greiner 24STAR HFT CD1 Review, BNL, November 2009
STARSTARPixel Detector Characteristics
• Two concentric layers at 2.5 & 8 cm radii• 10 sensors/ladder, 4 ladders/module (arm), 10 modules/detector.• MAPS Pixel technology• Sensor spatial resolution < 10 μm • Coverage 2π in φ and |η|<1• Over 400 M pixels on ~0.16 m2 of Silicon• 0.37 % radiation length/layer • MCS limited resolution • Thinned silicon sensors (50 μm thickness)• Air cooled• Sensor power dissipation ~170 mW/cm2
• Quick extraction and detector replacement• Mechanical stability and insertion reproducibility within a 20 μm
window• Integration time <200 μs (L=8×1027)• Radiation environment at the level of up to 300k rad/year and 1011 -
1012/cm2 Neq /year
L. Greiner 25STAR HFT CD1 Review, BNL, November 2009
STARSTARSensor / RDO Overall Detector Requirements
• Radiation length of cable + sensor = ~ 0.15 %• Integration time of sensors must keep pile up
manageable. (~250 - 350 hits / sensor)• Thermal profile limited by airflow cooling at ~ 170 mW /
cm2
• Survive radiation environment at the level (projected) of 300k rad/year and 1011 - 1012/cm2 Neq /year.
Optimizations based on these requirements led to the choice of MAPS sensor technology and the sensor development plan and readout design that will be presented.
L. Greiner 26STAR HFT CD1 Review, BNL, November 2009
STARSTARPXL Detector Design
Ladder with 10 MAPS sensors (~ 2×2 cm each)
MAPSRDObuffers/drivers
4-layer kapton cable with aluminium traces
Mechanical support with kinematic mounts
Cabling and cooling infrastructure
Detector extraction at one end of the cone
New beryllium beam pipe (800 µm thick, r = 2.5 cm)
2 layers10 modules4 ladders/module
L. Greiner 27STAR HFT CD1 Review, BNL, November 2009
STARSTARRDO System Design – Physical Layout
1-2 mLow mass twisted pair
6 m - twisted pair
Sensors / Ladders / Sectors(interaction point)
LU Protected Regulators,Mass cable termination
RDO Boards
DAQ PCs(Low Rad Area)
DAQ Room
PowerSupplies
Platform 30 m
100 m - Fiber optic30 mControl
PCs
30 m
L. Greiner 28STAR HFT CD1 Review, BNL, November 2009
STARSTARSensor Generation and RDO Attributes
Mimostar–2 30 µm pixel, 128 x 128 array1.7 ms integration time1 analog outputMimostar–330 µm pixel, 320 x 640 array2.0 ms integration time2 analog outputsPhase–130 µm pixel, 640 x 640 array640 µs integration time, CDS4 binary digital outputsPXL Sensor (Ultimate)18.4 µm pixel, 1024 x 1088 array≤ 200 µs integration time, CDS,zero suppression2 digital outputs (addresses)
Sensor Sensor RDO
50 MHz readout clockJTAG interface, control infrastructureADCs, FPGA CDS & cluster findingzero suppression ≤ 4 sensor simultaneous readout
160 MHz readout clockJTAG interface, control infrastructurezero suppression40 sensor simultaneous readout
160 MHz readout clockJTAG interface, control infrastructure400 sensor simultaneous readout(full system)
DO
NE
PR
OTO
TYP
ED
Gen
1
1
2
3
L. Greiner 29STAR HFT CD1 Review, BNL, November 2009
STARSTARSensor / RDO Services (preliminary)
240 W 180W 300W
1350W (AC)
1100W (AC)
LaddersMTB
Platform(racks)
RDOCrate
DAQ Room
4800 × 42 AWG (TP)160 × 24 AWG (TP)
40 × 0.42” dia. (50 TP cable)20 × 16 AWG
10 × fiber optic cable pair
10 × USB2 × TCD (10 TP)28 × 12 AWG
2m
6m
~100m
PP
~30m
L. Greiner 30STAR HFT CD1 Review, BNL, November 2009
STARSTARRadiation Tolerance Risk Mitigation
• We are putting a program in place to carefully measure the radiation field at STAR. This will improve our current (projected) estimates of the dose received.
• We have reduced the pixel size to the smallest allowed by our design in the AMS 0.35 technology for our final version of the sensor to enhance the tolerance to radiation damage.
• The Pixel detector is designed to be replaceable within a 24 hour timeframe. Replacement of a detector due to sensor damage is a feature and we will have a total of 3 physical Pixel detectors.
• We are currently investigating (with IPHC) different technologies. Graded doping and high resistivity substrate wafers offer the promise of significantly improved collection times and enhanced radiation protection. The results would be available on a timescale to be useful for the final sensor. In addition, IPHC has an active program improving their amplifier designs to be more rad tolerant. Mimosa-22 is expected to reach a tolerance of 1M rad in the next iteration.
L. Greiner 31STAR HFT CD1 Review, BNL, November 2009
STARSTARFlex Cable Development
Low mass Sensor regionDriver region
Side view (exaggerated vertical scale)
Top View
Hybrid Copper / Aluminum conductor flex cable
•2 layer Al conductor cable in low mass region•0.004” (100 um) traces and 0.004” (100 um) spaces•70% fill factor•Conductor thickness in low mass region is 21 um (Cu) or 32 um (Al)•Minimum required conductor trace width 1.325” (33.65 mm) of 46.16 mm available. •Bond wire connection between Al and Cu cable sections.
Low mass region calculated X0 for Cu conductor = 0.232 %Low mass region calculated X0 for Al conductor = 0.073 %