Atlas SemiConductor Tracker Andrée Robichaud-Véronneau

Journée de réflexion DPNC - Cartigny 2 A Toroidal Lhc ApparatuS The Atlas Detector is divided into several subdetectors Out of them, 2 systems are using silicon sensors technologies: SCT Pixels

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)‏ Andrée Robichaud-VéronneauJournée de réflexion DPNC - Cartigny 3 The SemiConductor Tracker  61 m 2 of Si resulting in 6.2 million readout channels  4088 double-sided modules, coverage  2.5  Modules using optical communication (CLK/COM)‏  Operation temperature : -7 o C (on the Si sensor) using C 3 F 8  Radiation hardness : 2x MeV neutron equivalent ·cm -2 (10 years LHC)‏

Journée de réflexion DPNC - Cartigny 4 From SCT to ID Different assembly phases for the SCT  Assembly of individual barrels in Oxford  Reception testing of the barrels at CERN  4-barrel assembly  EC assembly in NIKHEF and Liverpool  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

5 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-VéronneauJournée de réflexion DPNC - Cartigny

6 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-VéronneauJournée de réflexion DPNC - Cartigny

7 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. Detector Control System Andrée Robichaud-VéronneauJournée de réflexion DPNC - Cartigny

8 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-VéronneauJournée de réflexion DPNC - Cartigny

9 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 25 th EC C was lowered June 18 th 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-VéronneauJournée de réflexion DPNC - Cartigny

10 Challenges ahead Andrée Robichaud-VéronneauJournée de réflexion DPNC - Cartigny 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)‏

11 Next steps Andrée Robichaud-VéronneauJournée de réflexion DPNC - Cartigny 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!

12 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/  performance => Looking forward for the first LHC data! Andrée Robichaud-VéronneauJournée de réflexion DPNC - Cartigny