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BTeV Beam Test Results

VERTEX 2000 Sep 10 - 15 , 2000 Homestead, Michigan. BTeV Beam Test Results. Jianchun Wang Syracuse University Representing J.A. Appel, J.N. Butler, G. Cardoso, H. Cheung, G. Chiodini, D.C. Christian, E.E. Gottschalk, B.K. Hall, J. Hoff, P. A. Kasper,

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BTeV Beam Test Results

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  1. VERTEX 2000 Sep 10 - 15 , 2000 Homestead, Michigan BTeV Beam Test Results Jianchun Wang Syracuse University Representing J.A. Appel, J.N. Butler, G. Cardoso, H. Cheung, G. Chiodini, D.C. Christian, E.E. Gottschalk, B.K. Hall, J. Hoff, P. A. Kasper, R. Kutschke, S.W.Kwan, A. Mekkaoui, R. Yarema, and S. Zimmermann Fermi National Accelerator Laboratory C. Newsom - University of Iowa A. Colautti, D. Menasce, and S. Sala - INFN(Milan) R. Coluccia and M. Di Corato - Universita’ di Milano M.Artuso and J.C. Wang – Syracuse University

  2. The BTeV Detector Pixel Vertex Detector Dipole Magnet Magnet Coil Beam Pipe Forward tracking RICH PbWO4 EM calorimeter Muon Toroid Jianchun (JC) Wang

  3. 0.5 cm The BTeV Pixel Detector • Function: • Deliver clean, precise space points to detached vertex trigger • Provide vertex information for offline analysis • Pixel sensor • Eliminate ambiguity problems with high track density (essential to the detached vertex trigger) • Radiation hard, low noise • Easy pattern recognition • Pixels size: 50mm  400 mm (total 3  107 channels) 31 2-plane pixel stations Jianchun (JC) Wang

  4. Goals of Beam Test • Gain operational experience, look for potential problems and sensitivities • Study the spatial resolution dependence on track incident angle, digitization accuracy, bias voltage and threshold • Determine validity of our sensor simulations • Compare different detector technologies (p-stop, p-spray) Jianchun (JC) Wang

  5. Beam Test Telescope SSD SPD SSD • Beam: 227 GeV p • Tracking: 6 plane SSD in two boxes • SPD box provides different incident angle: 0, 5, 10, 15, 20, 30 degree • 4 SPD tested with ATLAS sensor prototypes  227 GeV X-Y-X X-Y-X Jianchun (JC) Wang

  6. Silicon Pixel Detector • Readout Chip • FPIX0: 6412 cells, 8-bit external ADC • FPIX1: 16018 cells, 2-bit internal FADC • Pixel sensor (n+np+) • ST1-CiS p-stop (FPIX0) • ST2-CiS p-spray (FPIX0) • ST1-Seiko p-stop (FPIX1) • ST2-Seiko p-spray (FPIX1) Jianchun (JC) Wang

  7. Analog Buffer FPIX0 Inner Board 8 bit ADC Front End Electronics • FPIX0: analog output, with external 8-bit ADC • FPIX1: digital output, with internal 2-bit FADC See David Christian’s talk Jianchun (JC) Wang

  8. Pulser Calibration FPIX0 bump-bonded to ST1 CiS p-stop sensor • Threshold: 2500 e Noise: 106 e • External ADC introduce noise: Total: 400 e Qnoise,ADC=400±96e- Dynamics £1.5MIP Qth=2500±400e- Qnoise=106±13e- Jianchun (JC) Wang

  9. X-ray Source Calibration • Absolute Calibration • Discriminator threshold • Amplifier noise • ADC scale Jianchun (JC) Wang

  10. FPIX0 p-stop Less than 0.7% with Q < 15 ke Saturation bump for CS=1 Pulse Height Charge Collection Peak: 24.7 ke FWHM: 10 ke Jianchun (JC) Wang

  11. Charge Collection FPIX0 p-spray Qmp = 18300 e Charge loss not intrinsic to the p-spray technology, but a feature of this particular sensor – “punch-through biasing”, and floating atoll Jianchun (JC) Wang

  12. Track e- E MC Simulation • Energy deposition by charged track along its path length (spread of the electron cloud due to diffusion) • Drift inE corresponding to doping and bias voltage applied • E  B (our sensors will be in dipole field of 1.6 T) • Realistic parameters of the front end electronics (noise,threshold, digitization accuracy) The interplay of these factors has been studied with a Monte Carlo simulation including: Jianchun (JC) Wang

  13. Charge Sharing Relative Fraction of Cluster Size FPIX0 CiS p-stop Qth = 2500 e- Vbias= -140V Vbias= -85V Delta ray emission results in larger cluster size Jianchun (JC) Wang

  14. h h Position Reconstruction • Error of predicted track position ~ 2mm - 2.5mm,Not subtracted from measured resolution • Charge weighting and s-curve correction used for clusters with 2 or more pixels Jianchun (JC) Wang

  15. Charge Sharing Non-Gaussian residual distribution for 1-pixel cluster • Resolution fit needs to consider the special shape • For small incident angle tracks, the fraction of 1-pixel clusters is proportional to spatial resolution Jianchun (JC) Wang

  16. FPIX0 p-stop FPIX1 p-stop Resolution vs angle • No track projection error subtracted from the measurement • Resolution distribution agrees with simulation • Binary resolution degraded from 8-bit ADC Jianchun (JC) Wang

  17. Resolution Oscillation Simulation Resolution oscillation in binary mode due to change of dominant cluster size Binary Readout Jianchun (JC) Wang

  18. Comparison of Different Detector • Most of difference due to the different readout thresholds • The charge losses in FPIX0 p-spray degrades the spatial resolution • BTeV requirement: better than 9 mm Jianchun (JC) Wang

  19. Digitization Accuracy • “2 bit” ADC is degraded from 8-bit ADC • Resolution of 2-bit ADC is slightly worse than 8-bit • FPIX2 will use 3-bit FADC FPIX0 p-stop Jianchun (JC) Wang

  20. Resolution vs Bias Voltage For 0° track, lower Vbiasmore diffusion  less fraction of Npixel=1 better resolution Jianchun (JC) Wang

  21. Resolution vs Threshold FPIX0 p-stop Large readout threshold degrades the spatial resolution Jianchun (JC) Wang

  22. Occupancy Test • 2.2 mm thick diamond target used • Handle occupancy much larger than expected at BTeV ( ~ factor of 10 ) Interaction vertex in diamond target Interaction vertex in pixel plane Jianchun (JC) Wang

  23. Summary • Large data sample to gain operational experience with pixel silicon detectors (~ 3M events) • The FPIX type front end electronics performs well • Resolution has little sensitivity to the bias voltage, but sensitive to readout threshold • Good resolution at all angles, meets 9mm requirement, and 3-bit ADC is a good choice for FPIX2 • Excellent tracking capability, can easily handle the BTeV multiplicity by 50mm400mm pixels • Monte Carlo simulation describe well the real feature Jianchun (JC) Wang

  24. Charge Sharing Relative Fraction of Cluster (row) Size FPIX0 CiS p-stop Qth = 2500 e- Vbias= -140V Vbias= -85V Delta ray emission results in larger cluster size Jianchun (JC) Wang

  25. Charge Sharing Relative Fraction of Cluster (row) Size FPIX1 Seiko p-stop Qth = 3780 e- Vbias= -75V Vbias= -45V Delta ray emission results in larger cluster size Jianchun (JC) Wang

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