STAR Pixel Detector Sensors and Readout with status of development and prototyping

L. Greiner 1STAR HFT CD1 Review, BNL, November 2009

STARSTAR

STAR Pixel Detector

Sensors and Readout

with status of development and prototyping


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


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.


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)


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


STARSTARMimostar Analog Output Sensor Prototypes

Pixel

Sensors CDS

ADC Data

sparsification

readout

to DAQ

analogsignals




analog


Disc.

CDS



1


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.


STARSTARPhase-1 Binary Digital Output Sensors

Pixel

Sensors CDS

ADC Data

sparsification

readout

to DAQ

analogsignals




analog


Disc.

CDS



2


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


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


STARSTAR PXL Sensor

Pixel

Sensors CDS

ADC Data

sparsification

readout

to DAQ

analogsignals




analog


Disc.

CDS



3


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)


(N states)


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


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)


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



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



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


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


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


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

http://rnc.lbl.gov/hft/hardware/docs/LVDS/LVDS_test_report_1.pdf


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 %


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.


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.


STARSTAR Backup


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


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.


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


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


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


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


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.


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 %

STAR Pixel Detector Sensors and Readout with status of development and prototyping

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