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Progress and status of the SSD

Progress and status of the SSD. Jörg Reinnarth - SUBATECH STAR Collaboration Meeting Warschaw, Poland August 2005. What is the SSD. SSD. SVT. SSD = Silicon Strip Detector Proposed and designed to enhance the STAR tracking capabilities in the central region

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Progress and status of the SSD

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  1. Progress and status of the SSD Jörg Reinnarth - SUBATECH STAR Collaboration Meeting Warschaw, Poland August 2005

  2. What is the SSD SSD SVT • SSD = Silicon Strip Detector • Proposed and designed to enhance the STAR tracking capabilities in the central region • Improve reconstruction efficiency short-lived particles such as Λ and Ω • 20 ladders x 16 modules = 320 modules • Double-sided silicon, 20m in r, 700m in z, -1< η< 1 TPC

  3. SSD one year ago • One year ago… • All 20 ladders installed at STAR • Ladders were tested • Noise problems reduced • Complete MC-Geometry done • SSD added to online histogramms • Since Jan 2005 SSD in the run + =

  4. SSD in Run ‘05

  5. SSD in Run ‘05 • During Cu+Cu runs SSD worked very well • 74 millionCu+Cu200 TPC events; 57 million with TPC+SSD • 77% of all TPC events include the SSD; 67% SSD+SVT • 90% of the SSD were working properly (2 ladder off) • 93% of all CuCu62 TPC events include SSD; 90% SSD+SVT • Then in pp problems started to occur: • First: Low voltage problems on power supply side • Next: While working the SSD slowed down whole system • Air compressor was frequently infault • Finally:Major CAEN problem, no high voltage • Since middle of June the SSD is no longer in the runs • 41 million p+p events with SSD; 24% of all p+p TPC events

  6. SSD hits with SVT and TPC pp CuCu200 CuCu62 CuCu200 MinBias CuCu62 MinBias pp MinBias pp CuCu200 CuCu200 HighTower ppProduction

  7. Pedestal & noise in Run ‘05 Cu+Cu 62 p+p Cu+Cu 200 CuCu200 Noise higher than in Run `04 Finer study to be done Cu+Cu 200 Cu+Cu 62 p+p

  8. Software progress

  9. Data analysis with SSD Soon future Still needed: Alignment Tracking real data PointMaker Ready, ntuple & histo outputs MySQL database connection DbMaker DaqMaker StSsdUtil No more direct connection Simulation chain Code completed Simulated data exist Tracking Works, first tests, tuning on simulated data alignment needed Alignment Histos and fits created Simulated data help align Calibration Pedestal, noise, gain done Dead strip list needed T O D A Y T O D A Y PointMaker Incorrect Clusterfinding No MySQL database connection DbMaker DaqMaker StSsdUtil direct database connection Simulation chain Old and incomplete code Tracking Never used, Code not usable Tracking not tuned Alignment Data behave strange Calibration No gain calib., no mapping F E B 0 5 F E B 0 5

  10. Progressin detail+Resultsobtained so far

  11. SSD chip calibration • Calibration needed for: • particle identification (dE/dx) • cluster matching H L X X • Cluster matching • Package algorithm works • 70% cluster (1 or 2 strips) • 80% of case: package 1-n • 20% ambiguos hits • Cluster matching works • but: needs calibration X X X X X H L

  12. SSD (Landau distribution for real data) Max = 0.78 Max = 0.9 Different individual Landau distributions Overall gain calibration needed

  13. Calibration through pulser runs 4 Channel per ladder pulsed Pulser not working

  14. SSD calibration

  15. SSD (ITTF tracking with SSD)

  16. SSD Alignment • Alignment needed to get correct SSD position • Installation and ladder exchange move the ladder and wafer from their measured positions • Alignment software is ready • Technique: Plot residuals in x, y against , z, etc. (e.g. Residual in x: Local x track position on wafer – local x hit position = Δx) → Residual in x, y expected to be distributed around zero → SSD shift in one direction: residual → sinus distribution → Rotation: x-residual constantly shifted Alignment needed for tracking Δx Δy

  17. SSD Alignment φ Δx φ Global alignment after correction

  18. Ladder alignment through simulation Δx Δx z z MC with Δy = 0.2 → Slope Real data: No slope but Δx shift → Shift ladder with Δx = 0.043 Negative slope → Shift ladder with Δy = -0.5 Δx z

  19. Different data sets, same parameters Primary tracks: field data Primary tracks: reversed field Global tracks: no field Not consistent data !

  20. Alignment not completely from scratch dX dY

  21. SSD Outlook • Alignment has to be finished • Calibration table will be implemented • Tracking will be persued When SSD alignment and calibration is complete: • Request for the SSD in the next production • Tracking efficiency will be determined • Impact on the detection efficiency will be evaluated

  22. SSD for upcoming runs • In August/September ´05 a team will be at BNL • Low voltage problems • High voltage problems (exchange CAEN) • Ladder 8 (permanent high voltage problem) • Ladder 7 pedestal setting problem (board?) • Overall noise has to be reduced (like run ´04) • SSD will be opened at the EAST plattform

  23. Alignment problem • Did global alignment • Do ladder by ladder alignment • Plot and fit histogramms and compare to simulated behavior • Correct shifts and rotations like predicted from simulated data This does not work. Data do not behave like predicted

  24. SSD (Number of clusters) P side N side

  25. SSD pedestal & noise distribution Pedestal per Chip Mean noise per chip /128! /128!

  26. Simulate the alignment Δx Δx φ z Move whole barrel Δy = 0.2 φ Δx Δx z φ

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