`` ATLAS inner detector JV Els KoffemanAtlas - Inner Detector1 Tracking in solenoid 2 Tesla field – 3 pixel layers with 50 um x 400 um cells – 4 strip layers with 80 um x 12 cm strips – 36 straw tubes 5 mm x 1 m A. P. Colijn N. Hessey F. Hartjes P. de Jong E. Koffeman P. Werneke W. Liebig P. Ferrari M. Limper C. Magrath E. vd Kraaij, M. Kayl M. Bosma J. Hegeman

` NIKHEF interest ‘SCT ENDCAP A’ 1000 silicon strip modules – Design, production, planning – Connected and tested 1.On arrival 2.After mounting on disk 3.Installation in cylinder 4.Transport to SR1 5.Installation in the cavern 2006 Ship to CERN 2007 Installation 2008 Commissioning JV Els KoffemanAtlas - Inner Detector2

` The events of 2008….. JV Els KoffemanAtlas - Inner Detector3 January Official completion SCT February Start connecting pixel detector March Milestone RUN (M6) April Cooling Plant Failure May June July Beam pipe bake out August Restart and prepare for beam September BEAM October COSMICS November COSMICS December SHUTDOWN

` Concern (I) 2-phase C3F8 cooling: mix of gas and liquid – Cooling loops Heaters located inside the closed inner detector volume. They have failed in the past and some are being operated under unexpected conditions. Loops need power to get started – Cooling plant Incident on April 30 th 2008 After general power failure three compressors overheated/slipped and were seriously damaged Recent analysis has shown unexpected ‘slijtage’ of all compressors: go back to Haug (down time until April 2009) JV Els KoffemanAtlas - Inner Detector4 C1 C3,C4,C5 C6

` Concern (II) VCSEL used instead of LED and are easier to produce. The light is emitted perpendicular to the surface (V = vertical). VCSELs can have ‘slow turn on’ JV Els KoffemanAtlas - Inner Detector5 Optical readout – 4000 modules (each module has two data links and one trigger and control line) – VCSELs suffered from electrostatic damage: only shows up as a strongly reduced lifetime (not known a priori) PIN VCSEL TTC DATA experiment Accessible area DATA PIN VCSEL

` Highlights Combined run of pixels, strips and straws (150 k events with a hit in the B-layer) Tracking with solenoid and toroid on Next slides (focus silicon strips) I.Beam II.Cooling III.Performance IV.Cosmics I.Efficiency II.Validate tracking software III.Alignment JV Els KoffemanAtlas - Inner Detector6

` BEAM Beam on 10 th september Pixels were off SCT barrel was off (HV = 5V) SCT endcap was at HV=20V TRT low voltage, Ar/CO2 Cosmics run Debugging and tuning JV Els KoffemanAtlas - Inner Detector7 Barrel modules in readout99.1% (20 of 2112 removed) Endcap A modules in readout98.7% (13 of 988 removed) Endcap C modules in readout95.3% (10+36 of 988 removed) 98.9% (10 of 952 with loops 1CTR and 9CTR removed from statistics)

`` BEAM JV Els KoffemanAtlas - Inner Detector8

` Cooling Power dissipation can reach 10 W per module so need cooling Run cold to keep the damage from radiation under control – Leakage current ~ exp(T) – Vfd sensitive to annealing Hybrid temperature at lowest (BP) setting (1.2b) is around -8 to -4C JV Els KoffemanAtlas - Inner Detector9 Thesis Erik vd Kraaij Set pressure => control temperature Actual module temperature in endcap

` Performance Noise dominated by strip capacitance Develop fit method Seperate different contributions Sensitive volume grows as √(V bias ) Strip length – Barrel 12 cm strips – Endcap 12, 6, 4 cm long strips – Noise occupancy of 2∙10 -5 has been measured JV Els KoffemanAtlas - Inner Detector10 Bias voltage (V) Noise (electrons) Thesis Caroline Magrath backplane interstrip Strip capacitance

` Cosmics Calibration – Calibration with cosmics awaited (since 2006…) – Different magnetic field configurations (solenoid/toroid) JV Els KoffemanAtlas - Inner Detector11 M. KAYL (ID-week nov’08) Efficiency silicon strip layers front en backside

`` Tracking software validation JV Els KoffemanAtlas - Inner Detector12 expect O(100) random strips hit per event Orange pixels and strips are associated to a track

` Alignment – Procedure is fast – Detector is not moving – Resolution is good σ(d0) = 64/√(2) μm = 45 μm (pT > 2 GeV) Expect σ(d0) = 35 μm (pT > 5 GeV) – BUT NOT FINAL Alignment between subdetectors O(100 μm) Disks are assumed to be rigid Some weak modes missing JV Els KoffemanAtlas - Inner Detector13

` Weak Modes Systematic changes in shape or size not recognized by the standard alignment procedures – curl, size, rotation, egg-shape Reconstruct J/Ψ→μμ events and do a constraint fit to the known mass JV Els KoffemanAtlas - Inner Detector14 Thesis Maaike Limper

` Summary Highlights Beam events recorded 7M cosmics collected 98% modules operational 45 μm d 0 resolution Concerns C3F8 cooling system Optical readout: VCSEL Restart detector operation beginning of May (to some extent independent of LHC schedule) JV Els KoffemanAtlas - Inner Detector15