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FTPC calibration status & plans for Y03 Joern Putschke for the STAR FTPC group

FTPC calibration status & plans for Y03 Joern Putschke for the STAR FTPC group. STAR Calibration Meeting 2002 November 7, 2002. Overview. The Forward-TPC layout Laser Calibration “TimeStep problem” DCA distribution ToDo list & Plans before Y03 physics run

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FTPC calibration status & plans for Y03 Joern Putschke for the STAR FTPC group

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  1. FTPC calibration status & plans for Y03 Joern Putschke for the STAR FTPC group STAR Calibration Meeting 2002 November 7, 2002

  2. Overview • The Forward-TPC layout • Laser Calibration • “TimeStep problem” • DCA distribution • ToDo list & Plans before Y03 physics run • Online tool & calibration runs in Y03 STAR Calibration Meeting

  3. The Forward-TPC layout • 2 FTPCs • 2.5 < || < 4.0 • 6 azimuthal sectors (~60 deg.) with 5*2 rows in z- direction • electron drift ~1/r and  to magnetic field STAR Calibration Meeting

  4. Radial drift / space point reconstruction vD(r) and D(r) have to be known with high accuracy  using MAGBOLTZcalculations How to check ? STAR Calibration Meeting

  5. Residuals of the inclined laser tracks Momentum resolution r  Laser residuals & momentum resolution  momentum resolution and residuals reach design goals (for laser tracks) ! STAR Calibration Meeting

  6. Deflection angle Comparsion of the measured deflection angle vs. raidus and MAGBOLTZ calculations • differences between different laser calibration sets in the azimuthal direction due to mirror movement in laser system • tool to compare different MAGBOLTZ versions calculations STAR Calibration Meeting

  7. Residuals of different intensity laser tracks charge (cluster geometry) dependence of residuals explains the poor space point resolution in Y02 (factor of 2) because of low gas gain (for safety reasons due to earlier problems with contaminated gas) ! STAR Calibration Meeting

  8. ReversedFullField Run 311 FullField Run 313 west west east east zvertex,FTPC-zvertex,TPC [cm] zvertex,FTPC-zvertex,TPC [cm] Vertex reconstruction of minBias data tool to adjust drift velocity (and t0) with physics data possible explainations: drift velocity change, wrong B-field distortion corrections (bug in geant magnetic field table ?)  but effect could not be explained at current calibration level ! STAR Calibration Meeting

  9. “TimeStep problem” AuAu central (timeStep) AuAu minBias (radialStep)  azimuthal dependence of the TimeStep/inner radius of reconstructed hits ! pp minbias (radialStep) No idea … (maybe a new one, thanks Dave) STAR Calibration Meeting

  10. east west DCA distribution(ReversedFullField Run313) STAR Calibration Meeting

  11. ToDo list also in TPC ??? (heard about …) There are a lot of tasks more …  need help from outside FTPC group (small group) !!! STAR Calibration Meeting

  12. Plans before Y03 physics run • Pulser runs • check exchanged FE cards • gain correction • Laser Calibration (as soon as possible) • gain scan  residuals (azimuthal reproducibilty of laser tracks) • zero field laser  look at timeStep problem • zero field laser and drift velocity mointor fix drift velocity and MAGBOLTZ • B-field scan  check ExB corrections • laser during data runs spacecharge • Data calibration runs • gain scan  cluster shapes and residuals • B-field scan  solve vertex-z position puzzle • zero field run, laser and drift velocity mointor fix drift velocity and MAGBOLTZ STAR Calibration Meeting

  13. Online tool & calibration runs in Y03 • online tools • use event pool and FTPC clf & tracker (not ready yet) • laser calibration online tool possible with L3 ? • integration into L3 (DAQ 100) need separate hitfindingmodule - maybe not for dAu (has to be checked) • calibrations runs • daily laser runs to check drift velocity and ExB • zero field physic runs • combination zero field physic and laser runs as often as possible STAR Calibration Meeting

  14. The STAR FTPC group • Volker Eckhardt • Maria Mora Corral • Markus Oldenburg • Joern Putschke • Janet Seyboth • Peter Seyboth • Frank Simon STAR Calibration Meeting

  15. transform to STAR coordinate system compare FTPC and TPC vertex pos. Vertex reconstruction a tool to check our drift velocity with real data STAR Calibration Meeting

  16. Reconstruction quality Residuals  Cluster geometry (on track) Residuals r Why are the residuals a factor of 2 larger than expected ? STAR Calibration Meeting

  17. Laser shift STAR Calibration Meeting

  18. r  padwidth timewidth Residuals of different intensity laser tracks Residuals selection of a low intensity laser track (black) with cluster geometry similar to physics data to compare with the high intensity laser track (red)  factor of 2 visible STAR Calibration Meeting

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