Commissioning of the ATLAS Transition Radiation Tracker (TRT) 11 th Topical Seminar on Innovative Particle and Radiation Detector (IPRD08) 3 October 2008 bocci@fnal.gov On behalf of the ATLAS TRT community Beam halo Event in TRT Disclaimer: I will cover only few topics of the TRT commissioning, mainly those related to real data taking p1
The ATLAS Inner Detector p2
The ATLAS Inner Detector The Transition Radiation Tracker (TRT) is a straw based gas detector that serves as the outer tracking chamber and also aids in electron identification (through X-ray identification from the radiation material) p3
The Transition Radiation Tracker (TRT) Robust pattern recognition requires large number of on-track measurements Wires should be far enough to each other to avoid closeby correlations Length of wires should be small Measurement accuracy ~ 150mm Light weight construction (X 0 ~10%) Self supporting system to minimize X 0 Detector must be compact Minimum space for electronics Detecting elements inside the radiator medium to minimize detector size and enhance TRD performance Sensitive elements as transparent as possible to soft X-ray TRT Barrel p4
The Transition Radiation Tracker (TRT) p5
TRT Barrel Layout 3 Layers of modules 32 module per phi sector 72 strawlayers per sector Axial only (no z information) Fanny shape so no radial dead spot About 35 measurement per track p6
TRT Endcap Layout 40 plain wheel (each side) 768 straws placed along the radius 4 strawlayers per wheel About 40 measurement for tracks full crossing p7
TRT Measurements Two thresholds in order to detect TR signal Since full drift time is ~50ns, signal span 3 bunch crossing 25ns 25ns 25ns p8 Time of the first bit converted to distance using a R-t relation The outcomes of the measurement are: Drift Circle Time of Threshold High threshold flag
Timing is Everything!! p9
TRT Timing p10
Data TRT have been commissioned with data for a long time now Combined Test Beam (essential for TR study) Cosmics on surface in 2006 Cosmics in the pit since August 2007 Cosmics with magnetic field already in August 2008 Beam Events Because of the cosmics trigger acceptance, tracks are mainly in the Barrel However a lot of commissioning work in the endcap too (low statistics) Equally important is the tuning of the daily operation of the detector (shifter task, data transfer, feedback between online and offline, etc ) p11
Trigger for Commissioning in the Pit p12
M6 Cosmic Runs Already look at the alignment in the pit Internal movement ~50mm p13
Cosmics Data First Evidence of Module Deformation (deviation from the rigid body approx.) Rotation as a function of z in the TRT (barrel) TWIST! Deformations (kind and magnitude) cannot be foreseen a priori : only data will tell us p14
More Milestone Runs p15
More Milestone Runs p16
More Milestone Runs p17
More Milestone Runs Endcap too! p18
TRT Threshold Setting p19
Mileston Run with Magnetic Field TRT was the only Inner Detector system operational during the solenoid test in August 08 p20
Mileston Run with Magnetic Field TRT was the only Inner Detector system operational during the solenoid test in August 08 Impact on r-t relation calibration p21
Beam Data for Journalists! Black Hole or Dark Matter? p22
Beam Halo p23
Beam Splash Beam splash events: Rough estimate: 10-100 per straw Unique opportunity to time whole the detector at once in one event! This saves may be months of work. p24
Beam Splash Events p25
Beam Splash Events p26
With the full illumination of the detector the timing can be done with 1 event Beam Splash Events COSMIC DIRECTION Timing derived from cosmics clearly seen When accounted for time of flight, timing was within few ns p27
Monitoring Monitoring is an essential component of the detector operation p28
Monitoring with Real Data Testing of all the infrastructure in the real data taking scenario (not trivial) Invaluable feedback on which quantities are most useful and need to be watched closely Adjustment/reshuffling of plots for different level of monitoring (shifter, expert,..) p29
Monitoring with Real Data Testing of all the infrastructure in the real data taking scenario (not trivial) Invaluable feedback on which quantities are most useful and need to be watched closely Adjustment/reshuffling of plots for different level of monitoring (shifter, expert,..) NEXT STEP: TRT MONITOR ON IPOD! p30
Other Aspects of the Commissioning Low Voltage equalization Noise Equalization High rate read out with and w/o 0 suppression Validation of the 0 suppression Validation of mapping (online and offline) Integration of services in monitor system (DCS) Gas Operation (leaking, gas change, etc ) CO2 (straw) and electronics cooling Continuous operation of DAQ, LV, HV, etc Offline reconstruction (see C. Schmitt talk) p31
Conclusions TRT started its commissioning in the pit already in summer 2007 and moved to continuous operation since summer 2008 Several Milestone Runs helped the commissioning of all the aspects of the TRT operation A fairly operation stability already achieved, focusing on data quality and quick online/offline feedback Final gas mixture (Xe) finally in place and started to be commissioned (stability, gas leak, calibration, etc ) Plans are now to take as much cosmics as possible with the full Inner Detector subsystems operational and with nominal magnetic field on p32