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Outline The idea behind the code Code structure and its usage Test on a magnet run Plan

Minuit Alignment Code. Jianchun Wang 02/14/00. Outline The idea behind the code Code structure and its usage Test on a magnet run Plan. Motivation. Existing hand alignment too slow difficult to deal with correlated parameters Minuit alignment

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Outline The idea behind the code Code structure and its usage Test on a magnet run Plan

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  1. Minuit Alignment Code Jianchun Wang 02/14/00 Outline • The idea behind the code • Code structure and its usage • Test on a magnet run • Plan Jianchun (JC) Wang

  2. Motivation Existing hand alignment • too slow • difficult to deal with correlated parameters Minuit alignment • work on saved tracks (avoid unnecessary calculation) • correlated parameters can be fitted together • can be automated Jianchun (JC) Wang

  3. Code structure • First stage: output track for later fitting user(‘event’)  mn_write_track • Subsequent stages: read in track and fit user(‘endrun’)  mn_prepare_fit  mn_read_track  mn_fit_geo  mn_geo_copy  mn_geo_chi2  mn_geo_copy  mn_derived_geom  mn_fit_tracks Jianchun (JC) Wang

  4. Output Tracks • Only one track in the event • At least two good Y hits • Number of Planes with hits is kept • Local position and sigma are kept • Chi2 of Kalman fit is also kept for comparison ( y slope floating, all y information in the fit) • Output file name “track_out.dat” Jianchun (JC) Wang

  5. Preparation for the fit • Links of geometry planes to Kalman planes created only once to save time • Tracks input from file “track_in.dat” • All track properties stored with a format suitable for Kalman fitting • Planes can be dropped at this stage Jianchun (JC) Wang

  6. Minuit fitting • Parameters for fit • Provided by “mn_skip.dat”, changeable during run • Manipulate parameters interactively in Minuit • Parameter transfer • New geometry parameters in monitor format (mn_geometry.dat) • Geometry parameter  Minuit parameter • Function of the fit • Chi2 of Kalman fit averaged over n.o.f and ntrack Jianchun (JC) Wang

  7. 2 of Kalman fitting • Magnet run 7236 (15o) • 20K events • 10K tracks selected • Hand alignment before create track file • MINUIT fit use only simple fit with part of parameters • 2 is not normalized to n.o.f Jianchun (JC) Wang

  8. Resolution of FPIX1 • FPIX1 pspray at 15o • The resolution is not changed (~11m) • For rough comparison only (magnetic field effects) Jianchun (JC) Wang

  9. Residual of FPIX0 • FPIX0 pstop rotated and placed in magnetic field (~ 17.5 A) • Only two pixel clusters shown, and the improvement is only due to a bug fixed in eta correction • For comparison only Jianchun (JC) Wang

  10. What is next ? • MC test to have objective evaluation (Rob has running MC) • Input & output control • Create procedure of the fitting • Make it more automatic • Align all runs ( how to share the work, and CPU availability) Jianchun (JC) Wang

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