Cosmic tests and Performance of the ATLAS Semi-Conductor Tracker

Barrels

Bilge DemirközOxford University

On behalf of the ATLAS SCT Collaboration

Overview• Description of a barrel module• Macro-assembly: Modules Barrels• Data Acquisition System: Calibration mode

– Barrel tests, check for common mode noise– Performance

• 4 Barrels integration “SCT” • SCT + TRT = Inner Detector Barrel• Data Acquisition System: Physics mode• Cosmics!

SCT Barrel ModuleEach side has:• 2 silicon sensors

– Hamamatsu– 768 instrumented strips– Strip pitch = 80µm

• Binary Readout chip: 6 ABCD3T ASICs

– Discriminator– Pipeline– Data compression logic– Readout Buffer

2 sides glued with• 40 mRad stereo angle• TPG baseboard with BeO

ceramic facings– Thermal management– Up to 10W / module at lifetime

dose!12 cm

chan 0

chan 767

40mrad stereo 6cm

ATLAS inner detector

SCT barrels: 4 layers

SCT endcaps: 9 disks

PixelsTRT

Barrel 3 macro-assembly

Hardware Data Flow

ROD BOC

FormattedEvent

MODULE

BPMTTC

SERIALTTCx48

DATA x96

DORIC

VDCDATA

CLK COM

DATA

Electrical Domain

Optical Domain

SBCVME

Configuration& Commands

Histograms& Data

Data Path in ATLAS

TIM

Backplane

TTC

BOC Configuration

ROS

FormattedEvent

SLinkReadout Crate

On Detector

Event Builder

TCP

CTP

Software data flow• Configure and define test • Run… from ROD RawData• FittingService • AnalysisService

– finds optimal settings of the ABCD chip– calculates averages for noise, offsets… – cuts defined for identifying “defects” – publishes TestResults– publishes a subset of the TestResults

(IS)Summaries COOL (database for offline)

Testing and when?• Modules are tested after

– Production (at module assembly sites)– Macro-assembly (at Oxford)– Reception at CERN– Insertion (at CERN)

• Check that module performance does not change at different stages

• Development of “final running” software through all these stages – Also used for endcaps – How to recover errors on modules?

Typical Test Sequence• Basic Tests

– Establish Communication– Optimise Opto settings

• Digital Tests– Verify Communication– Do trigger counters work?

• Analogue Tests– Measure Gain, Offset, Noise– Measure Noise Occupancy– Look for Time Structure– Detect excess noise possibly related to high frequency, synchronous

triggers• Check module supply and sensor currents

The Binary Architecture of the ATLAS SCT dictates that analogue information must be extracted by scanning chip thresholds.

Histogram Data(from ROD)

ChannelFits

CalibrationCurves

Fit

Analyse

Analyse

Channelthresholdcorrections

Channel

DA

C s

ett

ing

Threshold in mV

Thre

shold

in

mV

Example Calibration

Results

<noise occupancy>

= 4 x 10-5

Equivalent Noise Charge (ENC)

Checks for common mode noise

The number of hits per event is summed and histogrammed.

• At higher thresholds, all entries should fall in the 0-3 bin– “Good Chip!”

• Any “spikes” might suggest the presence of common mode– “Bad Chip?”

• One event with between 12 - 15 hits• Vertical scale – Threshold in mV with

reference to 1.0fC – so 20mV is ~1.3fC• Except when coincident with other

known defects, effects such as this were not reproducible.

No significant common mode noise observed!

Good Chip!

Bad Chip?

Plots for Module 20220040200324

Double Trigger Noise

• Verify that the detector readout does not generate noise in subsequent events

• Send two consecutive triggers separated by a controlled time interval

• Scan around 132 bco = pipeline depth

• Pipeline == stores data until trigger (L1A) is received.

# of bcos

6 x10-4

3 x10-5

# o f

bc o

s

Barrel 3 LMT09 z-4Lower side of the module

Light leak!• One opto-package

leaks light onto sensor

• Effect occurs at bin 136

111010nnnnbbbbbbbb

time

chan

nels

2 light leaks on Barrel3:

occupancy of 6 x10-4 on a few channels

very small effect in the large picture…

Optopackages on other barrels fixedbefore macro-assembly No lightleaks found!

Channel Defect StatisticsBarrel Total

ChannelsNot

bondedDead Not

ReachablePart

bonded

Noisy Other Total Defects

3 589824 180 357 384 91 460 11 1483

4 737280 55 245 256 16 242 27 841

5 884736 173 770 256 97 492 30 1818

6 1032192 385 2513 640 197 1936 49 5720

Total 3244032 793 3885 1536 401 3130 117 9862

The Bottom Line: 99.8% working

channels!

Here add the graph From the module paper Showing number of defects On module

Insertion of B3, 20/09/2005Insertion of B3, 20/09/2005

SCT inserted into

the TRT17/02/2006

•Poster by Heinz Pernegger on “SCT Integration and Testing”

Barrel TRT• Proportional counters embedded in radiator

– 4mm diameter straw tube, 30µm wire– 1.4m long wires, readout on both ends – Cosmics: Ar:CO2 = 70:30

• 73 layers of straws ~ 36 hits per track

• Total number of straws: ~ 210176• Noise occupancy = 2% in 75nsec

Final: Xe:CO2:O2 = 70:27:3Drift time accuracy ~140µmMeasured with efficiency 87%

Cosmics setup

• SCT: 504modules12RODs, 1TIM, 1Master LTP

• TRT: 2x6568 chan9RODs, 3 TTCv, 1 Slave LTP

• 3 Scintillators144cmx40cmx2.5cm

• TDC/QDC measurementTrigger time jitter ~ 0.5nsec~ 300MeV cutoff for alignment

studies

View from outside towards Side A

20cm of concrete

TDC/ADC measurementMeasure • time of flight between scintillators • charge deposited by the muonfor event and momentum selection

Measure • Relative time of trigger with respect to system clockfor phase corrections

• TDC, Time resolution ~ 35 psec• ADC, Charge resolution ~100 fC• Decoded online and performed simple time checks• Not yet decoded and used in the offline.

Physics mode of SCT

• Set thresholds to optimal 1fC • Read 3 time bins instead of 1: Expanded mode

– 1 time bin = 25 nsec

• Accept any hit in these three time bins• Latency in components: trigger, TIM, ROD, BOC, cable/fibre

lengths… ~ 30bcos• SCT has a pipeline depth of 132 bcos• Need to delay this signal by the right amount

• TRT: reads every 3.125nsec and 24 time bins (total of 75 nsec).

A module sees cosmics!

• Coincidences between module sides

• And histogram for each module!

• On ROD, histogram while scanning through BOC Tx coarse delays (32bcos)

noise

Coincidences between module sides = cosmics!

Tracks through the top

sector of the SCT and the

TRT

Summary• ATLAS SCT Barrel Integration is complete!

– All 2112 modules tested – 99.8% of 3.2 million channels working

• The Data Acquisition System, SctRodDaq, has been developed– Largest system to date: 1 crate, 14 ROD/BOC pairs, 672 modules– Ongoing work on multi-crate readout– On-ROD monitoring of dataflow – Can “time-in” the readout for physics data taking

• Combined sector test (SCT + TRT) with Cosmics from May 2006

• Offline is looking at the data right now… – Present residuals from tracks (without alignment) are better than the

specified building tolerances.

Next steps• Collect high statistics sample of cosmics muons for

alignment studies

• Offline decoding of the timing (TDC) information– Efficiency estimates– Alignment studies

• Digitization work – Use the online noise and defects lists from the COOL

database in SCT simulation

• Move to the pit in Summer 2006• Endcaps move into the pit Fall 2006

Backup slides

TTCvx

Trigger and Timing

Trigger

LTP TTCvi

L1Ain L1Aout/clocked

BC BC

BC

A-channel

B-channel

OptoLink

TIM

SCT

TRT LTP

Busy

Orbit Orbit

ADCTDC

Corbostart

OR

phase

delayL1Ain

Latency in components: trigger, TIM, ROD, BOC, cable/fibre lengths… ~ 30bcos

NIM

VME

LTP= Local Timing Processor

SCT Sector

• Cooling (3kW of power -- SCT sector only)

• 800,000 channels in the SCT

SCT Module Readout• 1 TX fibre = clock+command for each module• 2 RX/data links • fibre-optic communication

opto-package(DORIC+VDC)

connection to the module

redundant TTCfrom neighboring module

dog-leg

Opto-package

Chip S11

module

Side view of the barrel

SCT databases• DAQ parameters:

– Configuration data (chip settings,…) (frequently updated): 2MB/update

– Average noise, offsets(…) for each chip and lists of defects for each module: ??MB/calibration

• DCS parameters: 100MB/day– Temperatures, currents for each module

• All in COOL by offline identifier• Should be easy to correlate

– Noise versus current

– Figures given for commissioning of full barrel

SctRodDaqFramework

-- simplify!!

Readout: Redundancy• If one side of the module can not be readout from its

master chip due to opto-failure, it can be readout through the other side excepting its own master chip.

M0 S2S1 S3 E5S4

M8 S10S9 S11 E13S12

Link 0

Link 1

Readout: Redundancy• If one side of the module can not be readout from its

master chip due to opto-failure, it can be readout through the other side excepting its own master chip.

M0 S2S1 S3 E5S4

M8 S10S9 S11 E13S12

Link 0

Link 1

Readout: Redundancy• Modified module connects M8 to E13 and allows all

12 chips to be readout. • (similarly for M0 after E5 for Link 0 opto-failure)• Prototype has been made and tested. Will be

available for Barrel 6 construction

M0 S2S1 S3 E5S4

M8 S10S9 S11 E13S12

Link 0

Link 1

Correlated Noise??• Occupancy per event in Noise Occupancy Test• Binomial Distribution

Th

resh

old

ove

r 1

fC

128 channels max

OPE Analysis: LMT21 Z-6

high thresholdT

hre

shol

d o

ver

1fC

Channels