LHC SPS PS A Toroidal LHC Apparatu S

LHC SPS PS

A Toroidal LHC Apparatu. S - ATLAS 22 m 46 m As large as the CERN main bulding

Inner detector: Performances: Ø Rapidity coverage | | < 2. 5 Ø Reconstruction of isolated leptons p. T/ p. T ~0. 1 p. T (Te. V) ØTrack reconstruction efficiency isolated tracks > 95% within jets > 90% Ø Low material budget for tracker and ECAL performances Ø 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) s(Rf)= 16 m s(z) = 580 m Barrel s(Rf)= 16 m s(R) = 580 m End-cap

Physics requirements TDR : ”…The guiding principle in optimizing the ATLAS experiment has been maximizing the discovery Requires a good tracking performance: potential for new physics…” Secondary vertices • Higgs in SM and in MSSM • Supersymmetric particles • B physics (CP violation, . . . ) • Exotic physics Impact parameters resolution Track isolation Measurement of high momentum particles Primary vertex : prompt tracks in the event Secondary vertex: s(Rf)= 16 m s(z) = 580 m Barrel s(Rf)= 16 m s(R) = 580 m End-cap B-hadrons: ct ~ 460 m Secondary Vertex reconstruction Daughter impact parameter

1. 04 m 5. 6 m 9 disks ~63 m 2 of silicon ~6 million readout channels ~15, 000 silicon wafers 9 disks 1. 53 m 4 barrel layers ~4000 modules

What a module has to stand: 2 1014 neq/cm 2 hadron fluence (10 years) 10 Mrad 40 MHz bunch frequency 100 k. Hz L 1 trigger freq. 3 s T 1 latency Temperature cycles (-15 o. C <-> 25 o. C ) Low mass: <0. 4 Xo at outer rad. of SCT Mech. Stability Perm. def. < 5 m Elastic def. < 50 m Precise Assembly Location What we require: >95% Eff. Noise occ. ~5 10 -4 R ~ 19 m z. R ~580 m No align. Inside module Op. Threshold S/N Vdepletion > 350 V Top = -7 o. C Thermal runaway Pitch ~80 m Stereo ~40 mrad Strip length Heat spread materials: TPG

Radiation Hardness Radiation Dose = 2 10 14 neq/cm 2 10 MRad Damage 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 After Irradation

Readout Chips Binary readout: the charge collected by the strips is amplified and then goes through a disciminator. If the charge is above a certain threshold, commonly 1 f. C, the electronics produces a logic-level 1 signal. DMILL Bi. CMOS process 6. 6 x 8. 4 mm 2 Analog Front End 132 cells pipeline 3. 3 s latency for L 1 Trigger Data Compression logic Control logic

Test. Beam (CERN SPS-H 8 beam line) 180 Ge. V/c pions Spot Size ~1 cm TRACKING STUDY SCT tracking specifications require 99% efficiency and noise occupancy below 5. 10 -4. Before Irradiation After Irradiation

Radiation damage to the electronics: • Threshold voltages of MOS transistors changed -> offset spread • Degraded gain • Noise increase 50 m. V/f. C 1500 ENC Before Irradiation 30 m. V/f. C 2000 ENC After Irradiation

Thermal Performances Detectors temperature at – 7°C (beneficial annealing) Runaway point > 240 W/mm 2 at 0°C Power dissipated 7 -10 W/module TOTAL 30 KW Thermal Runaway The leakage current is temperature dependend Ileak ~ T 2 exp(-Eg/2 k. T) Leakage current Temperature Power dissipation

Thermal simulations and measurements References TDR: http: //atlas. web. cern. ch/Atlas/ /internal/tdr. html Thermal Performance ATL-INDET-2002 -010 Test Beam ATL-INDET-2002 -025 Electrical Performance ATL-COM-INDET-2003 -008 Mauro Donegà Département de Physique Nucleaire et Corpuscolaire Université de Genève