Post on 19-Dec-2015
LHC
SPS
PS
46 m
22 m
A Toroidal LHC ApparatuS - ATLAS
As large as the CERN main bulding
Inner detector:
Performances:
Rapidity coverage || < 2.5 Reconstruction of isolated leptons pT/ pT ~0.1 pT (TeV)
Track reconstruction efficiency
isolated tracks > 95% within jets > 90%
Low material budget for tracker and ECAL performances Lifetime 10 LHC years (107 s/yr) 3 years at low luminosity (1033 cm-2 s-1) 7 years at high luminosity (1034 cm-2 s-1)
(R)= 16 m(z) = 580 m
(R)= 16 m(R) = 580 m
Barrel
End-cap
•Higgs in SM and in MSSM
•Supersymmetric particles
•B physics (CP violation, ...)
•Exotic physics
Requires a good tracking performance:
Secondary vertices
Impact parameters resolution
Track isolation
Measurement of high momentum particles
Physics requirementsTDR : ”…The guiding principle in optimizing the ATLAS experiment has been maximizing the discovery potential for new physics…”
B-hadrons: c ~ 460 m
Secondary Vertex reconstruction
Daughter impact parameter
Primary vertex : prompt tracks in the event
Secondary vertex:
(R)= 16 m(z) = 580 m
(R)= 16 m(R) = 580 m
Barrel
End-cap
~63 m2 of silicon
~6 million readout channels
~15,000 silicon wafers
~4000 modules
9disks9disk
s
5.6 m
1.04
m
1.53 m
4 barrel layers
Heat spread materials: TPG
Strip lengthPrecise AssemblyLocation
Pitch ~80mStereo ~40 mrad
Mech. StabilityPerm. def. < 5mElastic def. < 50m
>95% Eff.Noise occ. ~510-4
R ~ 19mzR ~580m
No align. Inside module
Op. ThresholdS/N
Vdepletion > 350 VTop = -7oCThermal runaway
21014 neq/cm2 hadron fluence (10 years)
10 Mrad40 MHz bunch frequency100 kHz L1 trigger freq.
3 s T1 latencyTemperature cycles (-15oC <-> 25oC )Low mass: <0.4Xo at outer rad. of SCT
What a module has to stand:
What we require:
Radiation Hardness Radiation Dose = 2 1014 neq/cm2
10 MRadDamage of the surface: - creation of charge carriers in silicon oxide - change of interstrip capacitance -> noise
Damage in the bulk material: - Displacement of Si atoms from lattice sites - Change in effective doping (type inversion) - Deterioration of charge collection efficiency - Increase of depletion voltage ~ 350 V - Increase in leakage current fluence
Before Irradiation
AfterIrradation
Control logic
Data Compression logic
DMILL BiCMOS process
6.6x8.4 mm2
132 cells pipeline 3.3 s latency for L1 Trigger
Readout Chips
Analog Front End
Binary readout: the charge collected by the strips is amplified and then goes through a disciminator. If thecharge is above a certain threshold, commonly 1 fC, the electronics produces a logic-level 1 signal.
180GeV/c pions
Spot Size ~1cm
TestBeam (CERN SPS-H8 beam line)
SCT tracking specifications require
99% efficiency and
noise occupancy below 5.10-4.
Before Irradiation
AfterIrradiation
TRACKING STUDY
Radiation damage to the electronics: • Threshold voltages of MOS transistors changed -> offset spread
• Degraded gain
• Noise increase
50mV/fC
1500ENC
30mV/fC
2000ENCBefore Irradiation After Irradiation
Detectors temperature at –7°C (beneficial annealing)Runaway point > 240 W/mm2 at 0°C
Leakage current
Power dissipation
Temperature
The leakage current is temperature dependend Ileak ~ T2 exp(-Eg/2kT)
Power dissipated7-10 W/moduleTOTAL 30KW
Th
erm
al R
unaw
ay
Thermal Performances
ReferencesTDR:http://atlas.web.cern.ch/Atlas/
/internal/tdr.htmlThermal Performance ATL-INDET-2002-010
Test Beam ATL-INDET-2002-025
Electrical Performance ATL-COM-INDET-2003-008
Mauro DonegàDépartement de Physique Nucleaire
et Corpuscolaire
Université de Genève
Thermal simulations and measurements