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Yoshikazu Nagai , Kazuhiko Hara (Univ. of Tsukuba)

The Detector Performance Study for the Barrel Section of the ATLAS Semiconductor Tracker (SCT) with Cosmic Rays. Yoshikazu Nagai , Kazuhiko Hara (Univ. of Tsukuba) Yoshiki Yamashita, Ryuichi Takashima （ Kyoto Univ. of Education ） Satoru Mima, Reisaburo Tanaka （ Okayama Univ. ）

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Yoshikazu Nagai , Kazuhiko Hara (Univ. of Tsukuba)

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  1. The Detector Performance Study for the Barrel Section of the ATLAS Semiconductor Tracker (SCT) with Cosmic Rays Yoshikazu Nagai, Kazuhiko Hara (Univ. of Tsukuba) Yoshiki Yamashita, Ryuichi Takashima （Kyoto Univ. of Education） Satoru Mima, Reisaburo Tanaka （Okayama Univ.） Taka Kondo （KEK）

  2. Contents • Introduction Large Hadron Collider (LHC) & ATLAS ID Barrel Combined Cosmic Ray Test • SCT Analysis Track reconstruction SCT Module Efficiencies High Resistance Modules • Summary and Plans

  3. First collision will be in November 2007 with . The collisions with will be in April 2008. LHC（Large Hadron Collider) @ CERN MONT BLANC Lac Léman Geneva Air Port LHCb CMS ATLAS 8.5km ALICE Large Hadron Collider (LHC) LHC is a proton-proton collider which is under construction @ CERN. • physics motivations • Higgs physics • Physics beyond the SM • Supersymmetry • Extra dimension etc … • Many other physics …

  4. LAr HEC LAr EM Magnet systems Tile HD LAr HEC 23m 42m Muon Systems AToroidal LHC ApparatuS (ATLAS) • Inner Detector • Pixel : the pixel detector • SCT : the semiconductor tracker • TRT : the transition radiation tracker • Calorimeter • Muon Systems • Magnet systems Overall weight : 8000 Tons Tracker : Calorimeter :

  5. S1 layer 3 layer 1 layer 0 layer 2 S2 S3 trigger: or No magnetic field 12 modules ID Barrel Combined Cosmic Ray Test TRT Top SCT Bottom Link1 Link0 # of Modules =468 (Top=252, Bottom=216) (layer 0,1,2,3) = (84/108/144/132)

  6. ID Barrel Combined Cosmic Ray Test First combined test of ID with realistic geometry Goals of combined cosmic ray test • Test SCT 4 barrels with operating TRT • Check detector efficiency, noise level, alignment study, tracking study • Develop monitoring tools for SCT/TRT • etc …

  7. track candidate Spacepoint definition Track Reconstruction • Event Info SCT + TRT Combined Run # of Events : 110K SCT • Track Reconstruction (with no alignment) Tracks are reconstructed in ATHENA (ATLAS software) flame work. • Spacepoint is formed by finding the intersection of the strips on the front and back side of a module • Track candidates are built by fitting these spacepoints with straight-line (pattern finding procedure)

  8. Track Reconstruction 1 module muon track if track has chi^2 / ndof < 40, it is accepted !! (Here, tracks are roughly cut) strip fired remove hit if refitted track fills : chi^2 / ndof < 10 & Hits in Top sector >4 & Hits in Bottom sector > 4 this track is used for efficiency caluculation SCT Hit difinition if track candidates are found • Track candidates are fitted by hits (single or a few strips) (fitting procedure) • For accepted tracks • remove one layer hits (e.g. remove hits in layer 0) • refit the track

  9. Efficiency Caluculation strip fired 1.5mm Hit Observed !! black : real data red : sim data predicted hit position chi^2 / ndof • extrapolate the refitted track to the layer surface which hits removed = predicted hit position • search hits from the predicted hit position within 1.5mm = observed hit or not real data mm sim data mm • Efficiency Eff = # of observed hit / # of predicted hit

  10. SCT Module Efficiencies real data shows ~ 99% Efficiency sim data shows ~ 95% Efficiency real data layer 0 Link1 layer 3 Link0 layer 0 Link0 layer 1 Link0 layer 1 Link1 layer 2 Link0 layer 2 Link1 layer 3 Link1 sim data Both sim & real data show low Efficiency in Layer 3 What are the inefficiency sources ?? layer 0 Link1 layer 3 Link0 layer 0 Link0 layer 1 Link0 layer 1 Link1 layer 2 Link0 layer 2 Link1 layer 3 Link1

  11. SCT Module Efficiencies real data layer 3 Link 0 layer 3 Link 1 cable swap layer 3 Link 0 sim data layer 3 Link 1 some bottom sector modules shows low Efficiency !!

  12. Layer 3 Module Efficiencies top vs bottom top RMS :0.0332 Mean :0.9808 bottom RMS :0.0842 Mean :0.9627 normalize real data Efficiency / 0.5% Efficiency / 0.5% top RMS :0.0311 Mean :0.9719 bottom RMS :0.0488 Mean :0.8852 normalize sim data Efficiency / 0.5% Efficiency / 0.5%

  13. High resistance modules • High resistance in HV bias line are found in ID barrel cosmic test Statistics Out of 468 SCT barrel modules for ID barrel cosmic test 46 Modules have R>40k 28 Modules have R>40k after 100-10A cycle. 4 Modules have R>100k after 100-10A cycle. normal SCT modules should have R = 35 ~ 40k resistance through the bias voltage circuit

  14. 46 Modules have R>40k High resistance modules Resistance (kOhm)

  15. High resistance modules Red Line : R>40kOhmmodules (46modules) RMS : 0.0973 Mean : 0.9656 Black Line : R<40kOhm modules RMS : 0.0252 Mean : 0.9861 Efficiency / 0.5%

  16. Summary • module efficiency for layer 0,1,2 show ~ 99% with cosmic ray. • module efficiency for layer 3 show ~ 98.2%, a bit lower than other layers. • layer 3 top sector efficiency is a bit higher than bottom sector. • modules with high resistance show the possibility of efficiency degradation. Plans • check what the layer 3 module inefficiency sources are • check high resistance modules are really a little bit of inefficient

  17. back up

  18. Module Efficiencies top vs bottom top RMS :0.02142 Mean :0.986349 bottom RMS :0.0482003 Mean :0.982505 normalize real data Efficiency / 0.5% Efficiency / 0.5% top RMS :0.027498 Mean :0.970437 bottom RMS :0.0503772 Mean :0.900905 normalize sim data Efficiency / 0.5% Efficiency / 0.5%

  19. Residual ly0 sim data real data

  20. Residual ly1 real data sim data

  21. Residual ly2 real data sim data

  22. Residual ly3 sim data real data

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