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 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 Large Hadron Collider (LHC) physics motivations Higgs physics Physics beyond the SM Supersymmetry Extra dimension etc Many other physics ALICE MONT BLANC Lac Lman Geneva Air Port LHCb CMS ATLAS 8.5km LHC Large Hadron CERN First collision will be in November 2007 with. The collisions with will be in April LHC is a proton-proton collider which is under CERN. Inner Detector Pixel : the pixel detector SCT : the semiconductor tracker TRT : the transition radiation tracker Calorimeter Muon Systems Magnet systems A Toroidal LHC ApparatuS (ATLAS) Tile HD LAr EM LAr HEC Muon Systems 42m 23m Magnet systems Overall weight : 8000 Tons Tracker : Calorimeter : ID Barrel Combined Cosmic Ray Test # of Modules =468 (Top=252, Bottom=216) (layer 0,1,2,3) = (84/108/144/132) layer 0 layer 3 layer 1 layer 2 Top Bottom S3 S2 S1 trigger: or No magnetic field 12 modules Link0 Link1 TRT SCT 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 Event Info SCT + TRT Combined Run # of Events : 110K Track Reconstruction 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) SCT Spacepoint definition Track Reconstruction (with no alignment) Tracks are reconstructed in ATHENA (ATLAS software) flame work. track candidate Track Reconstruction if track candidates are found Track candidates are fitted by hits (single or a few strips) (fitting procedure) SCT Hit difinition strip fired if track has chi^2 / ndof < 40, it is accepted !! (Here, tracks are roughly cut) 1 module track For accepted tracks remove one layer hits (e.g. remove hits in layer 0) refit the track 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 muon remove hit Efficiency Caluculation strip fired predicted hit position 1.5mm Hit Observed !! 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 black : real data red : sim data chi^2 / ndof mm Efficiency Eff = # of observed hit / # of predicted hit real data sim data SCT Module Efficiencies real data sim data layer 0 Link1layer 1 Link0layer 0 Link0layer 2 Link0layer 1 Link1layer 2 Link1layer 3 Link0layer 3 Link1 layer 0 Link1layer 1 Link0layer 0 Link0layer 2 Link0layer 1 Link1layer 2 Link1layer 3 Link0layer 3 Link1 real data shows ~ 99% Efficiency sim data shows ~ 95% Efficiency Both sim & real data show low Efficiency in Layer 3 What are the inefficiency sources ?? SCT Module Efficiencies real data sim data layer 3 Link 0 layer 3 Link 1 cable swap some bottom sector modules shows low Efficiency !! top RMS : Mean : bottom RMS : Mean : real data sim data Efficiency / 0.5% normalize top RMS : Mean : bottom RMS : Mean : Layer 3 Module Efficiencies top vs bottom 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 A cycle. 4 Modules have R>100k after A cycle. normal SCT modules should have R = 35 ~ 40k resistance through the bias voltage circuit High resistance modules 46 Modules have R>40k Resistance (kOhm) High resistance modules Efficiency / 0.5% Red Line : R>40kOhm modules (46modules) Black Line : R