Construction and quality control of the end-cap Transition Radiation Tracker for the ATLAS experiment Vasiliki A. Mitsou CERN HEP 2003, April, Athens, Greece

18 Apr 2003V. A. Mitsou / CERN2 Outline Introduction: ATLAS detector Transition Radiation Tracker Barrel modules production End-cap wheels production Acceptance tests at CERN Gas tightness Wire tension High voltage Straw straightness (WTS) Status of electronics Concluding remarks

18 Apr 2003V. A. Mitsou / CERN3 ATLAS Inner Detector concept General requirements: Combination of central tracker and TRD features Robust pattern recognition Bunch crossing rate – 40 MHz (25 ns between interactions) Interactions per year Selection level (Higgs) ~ 1:10 13

18 Apr 2003V. A. Mitsou / CERN4 Transition Radiation Tracker (TRT) Length:Total6802 cm Barrel 148 cm End-cap257 cm Outer diameter206 cm Inner diameter cm # straws: Total Barrel End-cap # electronic channels Weight~ 1500 kg Barrel End-caps

18 Apr 2003V. A. Mitsou / CERN5 TRT test-beam performance Threshold: 200 eV Drift-time measurement efficiency within ±2.5 σ: 87% Two thresholds: 0.2 keV and 5.5 keV For 90% electron efficiency, pion rejection

18 Apr 2003V. A. Mitsou / CERN6 Barrel modules construction Production of most of the parts (straws, radiator packs, wire supports, etc) is completed 60 modules are completed so far (~60%) Barrel modules construction is expected to end by July 2003 Module testing is expected to end by August 2004 Module gain mapper now operational

18 Apr 2003V. A. Mitsou / CERN7 Module gain mapping On-line fits, first scan 25 pulse-height spectra are taken along each wire

18 Apr 2003V. A. Mitsou / CERN8 End-cap wheels production status 2 type-A, 4-plane wheels completed at PNPI (St. Petersburg) 2 type-B, 4-plane wheels completed at JINR Dubna All four wheels shipped to CERN – currently under testing 13 (11) wheels partially assembled at PNPI (JINR) – absence of web circuits Type-C wheels (staged detector) not in production yet

18 Apr 2003V. A. Mitsou / CERN9 1. Reception 2. Dimensional checks 3. Check of electrical connections 4. Gas tightness 5. Wire tension 6. HV (CO 2 ) 7. Gas gain uniformity (WTS) 8. HV (Triple mixture) or 16-plane wheel assembly 10. Fluid tightness 11. Final dimensional checks 12. Repairs Building 154 at CERN: Reception Acceptance Tests Assembly Short Term storage Also at assembly sites Acceptance tests at CERN

18 Apr 2003V. A. Mitsou / CERN10 P-regulator Test: measurement of pressure loss inside the straws filled with Ar at 20 mbar overpressure Specification: < 1 mbar/min/bar Time: 1 day INLET Valve P-gauge (room) Exhaust Bubbler (26 cm Isopropyl alcohol) 20 mbar max. Ar cylinder P-gauge (table) RS-232 EXHAUST Valve Interface box PCI MIO16 4-plane wheel T-sensor Table #2 RS-232 PC LABVIEW MainVI.vi P-display Gas tightness setup

18 Apr 2003V. A. Mitsou / CERN11 Gas tightness results Assembly site CERN 20ITPNPA ITPNPA ITJNRB ITJNRB ITPNP Spec: <1 mbar/min/bar

18 Apr 2003V. A. Mitsou / CERN12 Wire tension: method  Method: mechanical resonance induced by a loudspeaker  Frequency scanning: [240,320] Hz  32 channels are scanned simultaneously  Spec: 55 < T < 80 g Slippage < 3 g

18 Apr 2003V. A. Mitsou / CERN13 No systematic wire slippage is observed Discrepancies between tension measured at CERN and assembly sites under investigation Wire tension setup is modified to obtain maximum reliability and efficiency Wire tension: results

18 Apr 2003V. A. Mitsou / CERN14 Test: 1800 V in CO 2 Spec: current < 50 nA The following circuits are checked, at different assembly and acceptance stages: Ground of WEB- high voltage socket Ground of ring - high voltage socket Neighboring high voltage sockets HV socket Ground 1 Flap in a WEB HV Test (I)

18 Apr 2003V. A. Mitsou / CERN15 Current (nA) distribution Wheel 20ITPNPA00001 HV Test (II) 20ITPNPA0001 PNPICERN 00 20ITPNPA0002 PNPICERN 00 20ITJNRB0001 JINRCERN ITJNRA0003 JINRCERN 0 - I > 50 nA

18 Apr 2003V. A. Mitsou / CERN16  6 points of measurements along each straw  Slow control ( T, P, HV, humidity, gas flow)  Monitoring straws  Electronics calibration  Online/Offline analysis  4-plane wheel characterization takes ~20 h at CERN Measurement of gas gain (1% accuracy) to derive eccentricity value per straw Gain variation: Specification: 100% straws with  G/G < 10% (400  m) 95% straws with  G/G < 5% (300  m) Wheel Test Station (WTS)

18 Apr 2003V. A. Mitsou / CERN17 PNPI Wheel #2 20ITPNPA R1 R2 R3 R4 R5 R6 Straw 3407Reference Straw  G/G > 12 % PNPI Wheel #1 20ITPNPA000001, straw 2/285 WTS: gain variation of one straw

18 Apr 2003V. A. Mitsou / CERN18 95% straws  G/G = 5%  300  m 100% straws  G/G = 10%  400  m Readout problems PNPI Wheel #1 20ITPNPA WTS: gain variation in one wheel (I)

18 Apr 2003V. A. Mitsou / CERN19 Wire disconnection (400 μm) 20ITPNPA ITPNPA ITJNRA Wire deviation > 400 μm: WTS: gain variation in one wheel (II)

18 Apr 2003V. A. Mitsou / CERN20 Gain variation (  G/G): Max. error ~ ± 1% RMS < 0.5% WTS results reproducibility

18 Apr 2003V. A. Mitsou / CERN21 Electronics status ASDBLR and DTMROC chips ready to start mass production End-cap FE boards design almost finalized Barrel FE boards: new, more compact design with fewer connections adopted ASDBLR boards DTMROC board

18 Apr 2003V. A. Mitsou / CERN22 Production of TRT barrel models is well under way - 60% of the modules have been constructed so far End-cap wheels of type A & B are being constructed and delivered to CERN since June 2002 Acceptance of first 4-plane wheels assembled at PNPI and JINR is successfully ongoing at CERN No difference between characteristics of wheels (A &B) after assembly and after reception at CERN Concluding remarks