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The ATLAS SemiConductor Tracker
commissioning at SR1
Ryuichi Takashima（Kyoto Univ. of Education）
For the Atlas SCT collaboration
SR1
APS and JPS joint conference
October 30, 2006
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A Toroidal LHC ApparatuS (ATLAS)
Muon Spectrometer(<2.7)
MDT/CSC, RPC/TGC
air-core toroidal magnet
Bdl = 2~6Tm (4~8Tm)
Inner Tracking (<2.5)
Pixel, Silicon Strip, TRT
2T solenoid magnet
good e/ id, t/b-tag
Calorimeter (<4.9)
Liq.Ar EM/HAD/FCAL, Tile HAD
good e/ id, energy, ETmiss
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SCT Barrel 4 layers, 2112 modules
Binary read out via opt fiber, work independently
1492mm
SCT Endcap A,C 9 disks, 1976 modules
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The SCT Barrel module
•Survive through direct
irradiation by primary proton beam
Operational until 4X1014protons/cm2 .
•deep submicron technology gives
the radhard feature to the ABCD3T chip.
Strip pitch:80mm
Stereo Angle:40mrad
•remarkable precision < 5 mm
by exquisite construction
procedure.
•Channel by channel
adjustment of threshold to give
uniform response to signal.
•Two readout links can bypass
through a dead chip.
•Chips generates ~6W.
Elaborate thermal
property design needed.
•Carbon has good
thermal conductivity.
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Goals of SR1 Commissioning
• Detector Operation & Commissioning of System:
• Gain experience with detector operation
• Test combined detector supply systems
• Development of standalone & combined monitoring tools
• Commission and test combined readout and trigger
• Commission offline SW chain with real data
• The detector performance aspects:
• TRT performance with SCT inserted and powered
• Test 4 SCT barrels together and operation with TRT
• Checks of grounding for SCT and TRT
• Test synchronous operation and check for X-talk and noise
• Collect cosmics for efficiency, alignment & tracking studies
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Assembly at Oxford
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Barrel 3 insertion into Barrel 4,5,6 and thermal enclosure
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Barrel SCT insertion into barrel TRT
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Individual test at SR1 for barrel 3 through 5
defective channels 0.3%
expected electron number
for 285mm Si ~20000=3.2fC
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Detector Tests
• Detector performance checks
– Standalone calibration tests on SCT and TRT after insertion
– Noise studies on SCT and TRT before installation in the pit
• Physics-mode running with common readout and trigger for SCT and
TRT
• Synchronous readout of 4 SCT barrels and SCT+TRT
• Noise on SCT from TRT + Noise on TRT from SCT
• Test with heater system
• Feedback of readout cycle to FE noise
– Studies with cosmics currently ongoing
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Track Reconstruction
First look at efficiencies in SCT and TRT
Residuals
Detector alignment and test/tuning of different alignment
methods
• Analysis of data is on-going, so please consider the
following slides as preliminary results
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Cosmics
• First cosmics very helpful in commissioning the
online and offline SW chain
– Combined DAQ, DCS and LTP trigger + TOF of Scintillator
– Configuration, data handling, mapping, BS converter,
monitoring and event display
– Software frame work is different. Offline uses Athena. Online
uses Scram.
– Data base shifted to COOL which interfaces to Oracle,
MySQL and sqlite.
• Preliminary results from the cosmic data taking and
analysis ….(talk by Y. Nagai)
– Run at nominal thresholds (1fC SCT)
– Collected 0.5M cosmic triggers
• ~70% with good tracks
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Barrel Configuration in SR1 Test
View from outside
towards Side A
• SCT:
– 468 of 2112 modules ~
1/4 of SCT barrel
– Keep detector dry
using dry air to thermal
enclosure
– Readout using 12
ROD +1 TIM+1LTP
• TRT
– 2x ~6600 Channels ~
1/8 of TRT barrel
– Readout in 9 ROD
• Note: usually no
electronics on bottom
-Z sector
• 3 scintillators for trigger
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Alignment using Cosmic tracks
Residual without alignment
red dots: space poits, orange dots: cluster hits
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Robust pattern
recognition even
in tripled noise
condition.
Noise counts
tripled in expand
mode on the ROD
and hit mode on
the chip.
Very few fake
space points
V pattern of SPs in
pseudo-f- plane
gives track
params.
Minimize the sum
of residulals on
the surface of
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wafers.
Noise Occupancy at SR1 compatible with production
Noise Occupancy at 1fC threshold
1fC Noise run at SR1(Offline Monitor)
<NO> = 4.5 x 10-5
Module production
(NO specs: < 5 x 10-4)
run3065
side0
side1
Barrel 3
4.87
4.94
Barrel 4
4.36
4.91
Barrel 5
4.26
4.89
Barrel 6
4.90
4.75
x 10-5
Chip NO. No trigger rate dependence
run3065,black,500Hz
run3066,red,5kHz
run3067,blue,50kHz
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•Noise runs changing threshold
•Equivalent Noise Charge
is very sensitive to
the threshold setting.
Number of chips
•ENC can be derived
fitting a plot of occupancy vs
threshold using error function.
•Offline value matched with
production.
•~ 1600 e- ENC at 30C
hybrid temperature
•reduces at final operation
temperature by ~ 5e-/C * 30C
ENC = 1605 electrons
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Quiet, Stable, Respond properly
Noise run of 1.0 fC threshold
Typical Cosmic-ray run
Cut Nhit < 200
Perfect Gaussian!
Nhit (Number of hits /event)
Nhit (Number of hits /event)
Longest 30kHz noise run of 10M
event observed no spike
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Summary
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SCT and TRT barrel tested for 3 months in SR1 with 1/4 of SCT and
1/8 of TRT connected
– Gained a lot of experience on detector operation
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Noise studies
– Have not observed any cross talk between SCT and TRT
– Noise on SCT well below specs
– No evidence of significant noise increase in SCT with all 4 barrels together
and inside TRT during tests
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Cosmic runs
– Tracked cosmics through both barrels!
– First efficiency and noise-hit studies confirm expected detector performance
– Alignment work is going on.
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Threshold can be checked by noise. But no experience of extra noise.
Cosmic trigger at the PIT expected to be ~0.03Hz. So SR1 cosmic data
are very important.
2 chips out of 5832 was not functional.
Learned much SCT jargon.
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