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