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PACE3 Pulse Height Parametrization

Hellenic Society for the Study of High Energy Physics. 200 6 Workshop on Recent Advances in Particle Physics and Cosmology. PACE3 Pulse Height Parametrization. Dr Ioannis Papadopoulos HEP Laboratory Physics Department University of Ioannina GR-45110 Ioannina, Greece pyannis@uoi.gr

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PACE3 Pulse Height Parametrization

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  1. Hellenic Society for the Study of High Energy Physics 2006 Workshop on Recent Advances in Particle Physics and Cosmology PACE3 Pulse Height Parametrization Dr Ioannis Papadopoulos HEP Laboratory Physics Department University of Ioannina GR-45110 Ioannina, Greece pyannis@uoi.gr Ioannina, 14/4/2006

  2. Summary • CMS Preshower • The PACE3 ASIC • PACE3 characterization • Pulse shape data • Pulse parametrization • Pulse height parametrization • Start of pulse estimation • Conclusions – Outlook Ioannina, 14/4/2006

  3. The CMS detector Ioannina, 14/4/2006

  4. CMS Preshower HCAL Endcap ECAL Endcap Preshower Ioannina, 14/4/2006

  5. CMS Preshower Barrel ECAL Preshower Endcap ECAL Ioannina, 14/4/2006

  6. CMS Preshower Barrel ECAL γ / e / π0 Preshower Endcap ECAL Ioannina, 14/4/2006

  7. CMS Preshower absorber absorber γ γ γ • absorber – Si strip sensors – absorber – Si strip sensors sandwich. • provides the “foot” of showers developed in the ECAL • rejects closely spaced γ’s coming from π0 decays • very important for the Zγγ decays Ioannina, 14/4/2006

  8. CMS Preshower 8 “D” supermodules  (×536=) 4288 μmodules (x32=) 137216 channels Ioannina, 14/4/2006

  9. Preshower μmodules • 8 – μmodule ladder Ioannina, 14/4/2006

  10. The PACE3 ASIC • PACE3 is composed of two separate ASICs: • Delta • performs amplification and shaping • operates in two gain modes: • High gain (HG)for calibration purposes usingsingle minimum ionizing particles (MIPs) • Low gain (LG)for normal physics runningwith a wide dynamic range (1 – 400 MIPs) • incorporates an internal calibration circuit • PACE-AM (Analogue Memory) Ioannina, 14/4/2006

  11. PACE3 characterization Ioannina, 14/4/2006

  12. PACE3 characterization • PACE3 chips undergo various tests: • power Ioannina, 14/4/2006

  13. PACE3 characterization • PACE3 chips undergo various tests: • power • digital functionality Ioannina, 14/4/2006

  14. PACE3 characterization • PACE3 chips undergo various tests: • power • digital functionality • linearity Ioannina, 14/4/2006

  15. PACE3 characterization • PACE3 chips undergo various tests: • power • digital functionality • linearity • noise (High gain) Ioannina, 14/4/2006

  16. PACE3 characterization • PACE3 chips undergo various tests: • power • digital functionality • linearity • noise (High gain) • noise (Low gain) Ioannina, 14/4/2006

  17. PACE3 characterization • PACE3 chips undergo various tests: • power • digital functionality • linearity • noise (High gain) • noise (Low gain) • memory uniformity Ioannina, 14/4/2006

  18. PACE3 characterization • PACE3 chips undergo various tests: • power • digital functionality • linearity • noise (High gain) • noise (Low gain) • memory uniformity • timing scan data used in this work Ioannina, 14/4/2006

  19. PACE3 characterization • PACE3 chips undergo various tests: • power • digital functionality • linearity • noise (High gain) • noise (Low gain) • memory uniformity • timing scan data used in this work Ioannina, 14/4/2006

  20. PACE3 pulse parametrization Ioannina, 14/4/2006

  21. PACE3 pulse parametrization Ioannina, 14/4/2006

  22. PACE3 pulse parametrization Ioannina, 14/4/2006

  23. PACE3 pulse parametrization • Assuming for a specific gain thatt0 ,n and ωc are the same for any pulse i • Summing up all pulsesand averaging: • has the same shape as a single pulse • fitting the averaged pulse, we can obtain t0 ,n and ωcwith better statistical errors Ioannina, 14/4/2006

  24. PACE3 pulse parametrization • Real data: 1ns sampling rate Ioannina, 14/4/2006

  25. PACE3 pulse parametrization • Real data: 1ns sampling rate Ioannina, 14/4/2006

  26. PACE3 pulse parametrization • Real data: 1ns sampling rate Ioannina, 14/4/2006

  27. PACE3 pulse parametrization • Averaged pulse fit (Low gain) Ioannina, 14/4/2006

  28. PACE3 pulse parametrization • Averaged pulse fit (High gain) Ioannina, 14/4/2006

  29. PACE3 pulse parametrization • Averaged pulse fit (High gain) Ioannina, 14/4/2006

  30. PACE3 pulse height parametrization • In CMS: taking three time samples per pulse • Why not take only one sample at the peaking time? • reduce noise (electronic noise, time jitter) • ParametrizationSmax = a S1 + b S2 + c S3 • a, b and c have to be determined • they depend on the times the sampling is done(and of course on the gain mode…) Ioannina, 14/4/2006

  31. PACE3 pulse height parametrization fts=10ns t0=15ns Δt=-5ns 25ns 25ns • PACE3 provides three samples in steps of 25ns • time samples at fts, fts+25ns and fts+50ns • Δt = fts - t0 : time(first sample) – time(start of the pulse, t0) •  parameters a, b and c depend on Δt and the gain mode. Ioannina, 14/4/2006

  32. Pulse height parametrization • Estimation method of the a, b and c parameters: • construction of a χ2function, fcn • fcn minimization using the CERNLIB MINUIT package where, for each pulse i,S1i, S2i and S3i : measured signals at times fts, fts+25ns and fts+50ns respectively,Smaxi : measured maximum signaland σSmaxi is 7 (3) ADC counts for High (Low) gain. Ioannina, 14/4/2006

  33. Pulse height parametrization • fit results for fts=8ns (all High gain data) • Pulse height difference between measured and calculated values Ioannina, 14/4/2006

  34. Pulse height parametrization • fit results for fts=8ns (all Low gain data) • Pulse height difference between measured and calculated values Ioannina, 14/4/2006

  35. Pulse height parametrization • a, b and c fit results as a function of fts • all parameters exhibit a linear dependence with fts • they behave the same for both High and Low gain High gain Low gain Ioannina, 14/4/2006

  36. Start of pulse estimation • n and ωc : • gain specific • estimated fitting the averaged summed pulses • Intensity and pedestal : • selecting pulses of similar height, e.g. with S2(S2-ΔS, S2+ΔS),can be considered as constant for all these pulses • signal : using 3 time samples, setting the fts parameter • t0 : can be estimated constructing a χ2 function, fcn, and minimizing it Ioannina, 14/4/2006

  37. Start of pulse estimation • fit results for High gain data with fts=8ns • selection: S2(3000, 3100) Ioannina, 14/4/2006

  38. Start of pulse estimation • fit results for Low gain data with fts=8ns • selection: S2(3400, 3500) Ioannina, 14/4/2006

  39. Start of pulse estimation • application of the method for data from 150GeV μ-taken during the Preshower beam test at CERN H4 (sep. 2004) Ioannina, 14/4/2006

  40. Conclusions – Outlook • PACE3 pulse height estimation is very important • it is translated to energy deposition affects the energy resolution of the Preshower • The methods described allow • the estimation of the pulse shape parameters for High/Low gain • the estimation of the pulse height parameters for High/Low gainas a function of the sampling synchronization • the determination of the absolute starting time, t0, of the PACE3 pulses, from real datacorrect selection of the pulse height parameters • To do: • acquire more statistics,as PACE3 characterization tests continue at UOI HPLAB • study of systematic errors / sensitivity studiesusing also the data from the Preshower 2004 beam test at CERN • publish … Ioannina, 14/4/2006

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