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Atlas SemiConductor Tracker. Andrée Robichaud-Véronneau. A Toroidal Lhc ApparatuS. The Atlas Detector is divided into several subdetectors Out of them, 2 systems are using silicon sensors technologies: SCT Pixels.
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Atlas SemiConductor Tracker Andrée Robichaud-Véronneau
A Toroidal Lhc ApparatuS • The Atlas Detector is divided into several subdetectors • Out of them, 2 systems are using silicon sensors technologies: • SCT • Pixels Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 2
The SemiConductor Tracker One central barrel with 4 layers of rectangular modules 2 end-caps containing 9 disks Each disk assembled with max. 3 concentric rows of wedge-shaped modules (Made in Geneva) • 61 m2 of Si resulting in 6.2 million readout channels • 4088 double-sided modules, coverage |h|<2.5 • Modules using optical communication (CLK/COM) • Operation temperature : -7 oC (on the Si sensor) using C3F8 • Radiation hardness : 2x1014 1-MeV neutron equivalent ·cm-2 (10 years LHC) Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 3
From SCT to ID Different assembly phases for the SCT 2004-2005 • Assembly of individual barrels in Oxford • Reception testing of the barrels at CERN • 4-barrel assembly • EC assembly in NIKHEF and Liverpool 2006-2007 • ID Barrel integration (SCT->TRT) • EC reception at CERN • ID Barrel Combined Testing (Cosmics) • ID Barrel Integration in ATLAS • ID EC integration (A and C) • ID EC C Combined Testing (Cosmics) • ID EC integration in ATLAS Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 4
Reception testing • Single barrel tests after reception at CERN • Dec 2004-July 2005 • Were tested: • Cooling uniformity +stability • DAQ & DCS operations • Noise performance • Signal response • Results: • Module condition unchanged compared to module production Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 5
Barrel Cosmics • 450 k events taken from March to June 2006 • ~70 % good tracks • Run at nominal threshold (1 fC) • Allowed for testing of: • Online monitoring • Event Display • Offline reconstruction • Alignment Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 6
Detector Control System • In parallel to the detector assembly, the DCS was developed to provide safe operation of the SCT. • It includes the control and monitoring of: • Power supplies • Environmental conditions (Temp, Humi) • Cooling • A hardware interlock on cooling temperature adds an extra protection to the software controls. • The ID combined test were a good opportunity to test these systems and get experience for the final installation. Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 7
EC C Cosmics ~167 k events taken in December 2006 Scintillators placed to catch horizontal tracks No dependence on trigger rate in physics mode detected No influence from TRT activities Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 8
ID integration in ATLAS • ID Barrel lowered in the Atlas pit in Aug. '06 • Cabling and testing was completed Feb. '07 • EC A was lowered May 25th • EC C was lowered June 18th • The SCT Barrel is now integrated with Atlas central DAQ & DCS SCT ECs are currently being cabled and currently being tested to participate in Atlas commissioning this fall Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 9
Challenges ahead • Evaporative cooling heaters • Used to boil off remaining liquid in coolant between detector and cooling plant • Main source of unreliability of the cooling system • Repositioned outside cryostat • Currently being reworked • Will be re-installed temporarily for cosmics running • Module resistance • Some modules show a high backplane resistance • First on EC C, but also on EC A and Barrel (worst) • Might be linked with presence of humidity (DCS) • Still under investigation (forward biasing solution) Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 10
Next steps • What will keep us busy for the coming months: • Cabling and testing the SCT ECs • Resolving the heaters issue • Run the detector with cooling inside Atlas (M5 in Oct-Nov 07) • Analyse the first SCT data (alignment, performance) Manpower is needed for these important steps! Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 11
Conclusion and Outlook • The SCT is integrated in Atlas • Barrel has already been tested for noise occupancy • Full scale commissioning in 3-4 months • The integration tests were a great success in many aspects • ~99.7 % of barrel channels functional (1 module lost - HV) • Cosmics data taken on surface • Still a lot of work to be done! • Continue development of Barrel DAQ & DCS for the fall • Connect and Test both End-Caps • Integrate the End-Caps with Central Atlas • Work ongoing on the evaporative cooling heaters • Look into the first data to understand e/g performance => Looking forward for the first LHC data! Andrée Robichaud-Véronneau Journée de réflexion DPNC - Cartigny 12