Commissioning the ATLAS Silicon Microstrip Tracker

1. ATLAS and ID2. SCT3. Commissioning4. Integration5. Latest Runs6. Conclusions

Commissioning the ATLAS Silicon Microstrip Tracker

IPRD08 - Siena

Jose E. GarciaUniversité de Genèvefor the Atlas SCT collaboration

ATLAS Detector2


Jose E. Garcia IPRD08 - Siena

ATLAS is being assembled toexploit the 14TeV pp collisions at the LHC

The Inner Detector forms the heart of the ATLAS experiment. The closest to the interaction point.

• Pixel Detector• Semiconductor Tracker (SCT)• Transition Radiation Detector (TRT)

Semi-Conductor Tracker3


• 61 m2 of silicon with 6.2 million readout channels• 4088 silicon modules arranged to form 4 Barrels and 9+9 Disks• Barrels : 2112 modules with acceptance || < 1.1 to 1.4• Endcaps : 1976 modules with acceptance 1.1 to 1.4 <|| < 2.5

• Space point resolution r ~17m / Z ~ 580 m (23 m strip resolution)

• Radiation hard: tested to 2x1014 1-MeV neutron equivalent /cm2 • Material: 3% X0 per layer ( = 0)


Silicon Modules4


• Back-to-back sensors, glued to highly thermallyconductive substrates for mechanical stability and sensor cooling• 40mrad stereo angle between sensors• 1536 channels (768 on each side)• Optical communication• 5.6W/module (adding ~1W per sensor after 10 years LHC)• Cooled to -25oC to limit sensor radiation damage and -8oC ambient temperature.• up to 500V sensor bias

• 2112 Barrel modules• one module type

• 1976 EndCap modules• 4 module types


Front End Electronics5


• 128 channel ASIC with binary architecture• Radiation-hard DMILL technology• 12 chips per module (6 each side)• glued to hybrid (Cu/polyimide flex circuit)• 40MHz (25ns) clock• 20ns front end shaping time• Redundancy scheme (chips, link, TTC)

DAC

Binary Pipeline (132 deep)

Comparator

PreAmp+Shaper

Threshold Voltage

Edge-Detect circuit

Readout Buffer

Test-Input

t

t

v

“Shaped” input pulse to Comparator

“Logic” output of comparator

• 3 pipeline bins read out, centeredon L1A trigger

Data Compression

Circuit


Assembly Sites6


• 4 Assembly Sites• Oxford - Barrel• Nikhef - EndCap A• Liverpool - EndCap C• SR1 at CERN


Installation Timeline7


2006

Quarter 1

Quarter 2

Quarter 3

Quarter 4

2007

Quarter 1

Quarter 2

Quarter 3

Quarter 4

2008

Quarter 1

Quarter 2

Quarter 3

Quarter 4

Barrel in Pit

EndCaps in Pit

ID sealed

ID operational in Atlas

Cooling Issues• 3 ID compressors failed• 100 kg of C3F8 lost and 900 contaminated• Cooling plant cleaned up and broken parts replaced• Fortunately detector not affected• Measures have been taken to prevent this to happen again

•Test Module connectivity and performance comparing with surface data


Pixels in Pit

Commissioning Tests8


• Electrical Connections• Check LV arrives at modules: VDD, VCC, IPIN, IVCSEL • HV current voltage scan• Check temperature readings

• Optical Connections• P-i-n current checks• Light from fiber data measured at Redaout Driver (ROD) • Check fiber connection and correct module mapping

• Calibration Tests• Digital and Analogue functionality tested• Gain curve, Noisy/Dead channel map• Noise occupancy Tests

• Cosmic Tests• Milestone 6 (M6) :

• Global commissioning run with ATLAS


Combined SCT and TRT track.

Atlas Integration9


• Calibration and configuration changes are being made to improve performance. Some modules were removed from due to readout issues. They will be back in once they are properly adjusted. Approximate numbers:

– Barrel: 99.6% modules

– EndCaps (*): 97.8% modules

(*2 out of 72 cooling loops off, partially recoverable during shutdown)

• Around 97% configuration for stable readout in ATLAS


• Standalone calibration was performed up to the first week of September. From then SCT has been included in the Atlas data taking

– Full Barrel and Endcap ROD readout

– Athena and ROS Level Monitoring

– Data Quality Monitoring

• Since middle of August cooling is back and running stably for the detectors.

• SCT running fully powered since end August

Noise Occupancy10



Barrel Noise Occupancy at 150 V• measured ~4.4 x 10-5

• Outer/middle NO of ~ 5 x10-5

• Inner type modules much lower due to short strip length• Values in agreement to measurements from production, integration and installation.

Broken TX fibre or dead PINClock and control from neighbouringmodule Broken TX fibre or dead PINClock and control from neighbouring

module

Current issue: TTC link11


Some SCT channels generate no pin current (TX). Suspect ESD damage.

RX Ch

TX Ch

ROD BOC

DATA

TTC

Currently affected around 2.5 % of the modules

o Currently we are using redundancy whenever possible (this is not possible where two adjacent modules have zero pin current).

o If a few channels in a specific TX plugin are lost, it will be needed to change them.o Plugins can be replaced at the USA15. Newly manufactured plugins are being tested.


Broken TX fibre or dead PINClock and control from neighboringmodule

Timing In with ATLAS12


• Apply global trigger delay offset on top of the 4088 individual delays,and scan offset to look for increase in number of coincidental hits, increasing the number of space-points and tracks.• Reading 3 bunch crossings (3 x 25 ns clock cycles).

• Scans were done and SCT was timed in using cosmics before first beam and continued after

• LATER (with beam!): When roughly timed in, start fine delay (steps of 280ps) to tune relative bin occupancies and optimise hit efficiency. Fine scan delay scan with different offsets for each module


0 1 X

First Beam (10th Sept)13



SCT EndCaps at 20 V during the first

beam

Many tracks and space-points seen during the circulating

beam

Combined Tracks: SCT + Pixels14



Data taking is ongoing 24/7 with the rest of the sub-systems.

First tracks seen with hits in pixels and SCT combined

The residuals for the SCT barrel show a behaviour similar to the M6 results.

Alignment with Last Cosmics Data15



SCT

Level 1Barrel

EndCap

Level 2Barrel layers

EndCap disks

Level 3Barrel modules

EndCap modules

Hits on tracks for barrel layers

The residuals for the SCT barrel show a behavior similar to the M6 results.

Conclusions16



• SCT running fully powered since beginning of September with 97% configuration for stable readout in ATLAS after the first round of readout adjustments.

• Integrated the full SCT into ATLAS combined partition

• Observed first beam and used beam splashes to get first timing (on endcaps)

• Currently ongoing cosmics runs for:– Timing studies– Alignment– DAQ, DCS and Monitoring tuning up– Improvement on module calibration

Backup Slides17


1. ATLAS and ID2. SCT3. Commissioning4. Integration5. Latest Runs6. Conclusions7. Backup

Timing In18


BOC coarse delayUp to 32 clock cycles

BOC fine delay up to 35ns in 280ps

steps

… x48

ROD

Trig

ROD Crate

FINE

FINE

FINE

FINE

Fibres to modules

Compensate for differentpropagation delays ofC&C from BOC to module(which varies from 380nsto 446ns)

• 4088 individual delaysfrom 0 to 66ns


Optical Communication19



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Commissioning the ATLAS Silicon Microstrip Tracker