Slide 1

TPC in Heavy Ion Experiments Jrgen A. Lien, Hgskolen i Bergen and Universitetet i Bergen, Norway for the ALICE Collaboration. Outlook: Presenting some typical TPCs used in Heavy Ion Experiments Fixed target SPS energies: NA49 and CERES/NA45 Collider energies RHIC: STAR LHC: ALICE Slide 2 TPC constituents Drift volume Linear drift (NA49, STAR central TPC, ALICE) Radial drift (NA45, STAR forward TPCs) Readout chambers MWPC Readout electronics Analog charge storage, Switched Capacitor Arrays (SCAs) Fast digitalisation (ALICE) Slide 3 Slide 4 Channels: 182 000 Spatial resolution: 200 m Slide 5 Slide 6 dE/dx as function of momentum for positive particles produced in p+Pb collisions Slide 7 dE/dx distribution at a fixed momentum of 10 GeV/c for central Pb+Pb collisions Slide 8 Slide 9 Operational 1998 Radial drift field Length: 2 m Outer diameter: 2.6 m Gas mixture: Ne(80%)CO 2 (20%) Readout channels: 15360 Slide 10 Slide 11 Slide 12 Main TPC For tracking and PID via dE/dx Collider at RHIC Operational 2000 Length: 4.2 m Outer diameter: 4 m Gas mixture: 10% methane 90 % argon E-field: 135 V/cm Readout channels (pads): 136 608 Covers the pseudorapidity range of -1.8 < || < 1.8 3000 tracks per event Pad size: 2.85 mm x 11.5 mm(inner) Space resolution: ~0.5 mm (along pad rows) Slide 13 Slide 14 Slide 15 Slide 16 STAR Forward TPC: Extend the acceptance of the experiment The 2 FTPCs cover the pseudorapidity range of 2.5 < || < 4.0 on both sides of the experiment. 75 cm in diameter and 120 cm long Radial readout Gas mixture: Ar(50%)CO 2 (50%) 9600 readout pads (1.6 x 20 mm 2 ) Slide 17 Slide 18 25 m aluminized Mylar on Al frame Central Electrode Prototype for tracking and PID via dE/dx - 0.9 < < 0.9 ~ 3 m diameter drift gas 90% Ne - 10%CO 2 Length 5.1 m Outer diameter 5.6 m E-field: 400 V/cm Drift time ~88 s Time Projection Chamber largest ever: 88 m 3, 570 k channels Slide 19 The ALICE TPC becomes real (outer field cage and end plates) Slide 20 Local Controller DDL - INT Slow-Control Interface TTC-RX BOARD CTRL RCU Slow Control (1 Mbit serial link) Detector Link (200 MB / s) (#216) COUNTING ROOM 1 2 25 Each TPC Sector is served by 6 Readout Subsystems Front-end bus (200 MB / sec) Local Slow- Control Serial link ON DETECTOR FEC 128 ch Data Compr. FEC 128 ch FEC 128 ch PASA ADC DIG. Slide 21 Slide 22 Slide 23 Slide 24 THE END Slide 25 Slide 26