STAR FTPC Tracking Algorithms - Current Status as of May 3,2001

===> 0. Track Finding  (StFtpcTrackMaker)

    FTPC:
        - the hits belonging to a tracks are found using conformal mapping
        - the list of all "found" hits is saved for the track
        - the number of hits on the track and the maximum number
          of possible hits are saved for the track




===> 1. Detector Track Fitting   (StFtpcTrackMaker)

   FTPC:
       - all "found" hits are fit using a 2 x 2-D track fitter
       - the impact parameter is calculated using the preVertex
       - if the impact parameter is less than "max_Dca" the track
         is flagged as a primary track candidate and the preVertex id
         is saved
       - the momentum fit results are saved for the unconstrained fit
         to the hits




===> 2. Global Track Fitting  (St_dst_Maker/StFtpcGlobalMaker.cxx,
                               pams/global/dst/fill_ftpc_dst.cc)

   FTPC:
       - the fitted ftpc tracks from 1. are copied to the global
         track table (globtrk).
       - r0,phi0,z0 refer to the first hit in the FTPC
       - psi,tanl,invpt,curvature,chisq are from the unconstrained fit
       - covar is not filled
       - x_first,x_last are the first and last hit in the FTPC
       - length is the length within the FTPC
       - impact = the preVertex impact parameter
       - map[0] = 0
         map[1] set bit 31 for FTPC
       - id = global track id number
       - iflag = xyy
         x = 7 for FTPC
         yy in iflag=xyy is set to 01 for the primary track candidates
                         is set to 00 for all other tracks
       - det_id  
                 set to kFtpcWestId for rows 1-10
                 set to kFtpcEastId for rows 11-20
       - method: Finder = FTPC Conformal
                 Fitter = kHelix2StepId
       - pid is not filled
       - n_point         number of hits on track
       - n_max_point     maximum number of hits track can have
       - n_fit_point     number of found hits used in fit
       - icharge
       - id_start_vertex = -(preVertex->id)*10 for primary track candidates
                                               (dca to prevertex < 1.)
                         = 0 (dca to prevertex >= 1.)




===> 2. Primary Track Fitting (St_dst_Maker/StFtpcPrimaryMaker.cxx)

   FTPC:
       - after the primary vertex has been calculated from the TPC-SVT
         tracks, the fitted ftpc tracks from 1. are refit with
         the primary vertex (constrained fit)
         all tracks dca < max_Dca (max_Dca=1.0) are primary tracks
       - r0,phi0,z0 are calculated at the primary vertex
       - psi,tanl,invpt,curvature,chisq are from the constrained fit
       - covar is not filled
       - x_first,x_last are the first and last hit in the FTPC
       - length is the length from the primary vertex to the last hit
         in the FTPC
       - the primary vertex impact parameter is saved
       - map[0] = 1
         map[1] set bit 31 for FTPC
       - id = primary track id  number
       - iflag = xyy
         x = 8 for FTPC + primary vertex
         yy in iflag=xyy is set to 01 for the primary track
       - method: Finder = FTPC Conformal
                 Fitter = kHelix2StepId
       - pid is not filled
       - n_point         number of hits on track 
       - n_max_point     maximum number of hits track can have
       - n_fit_point     number of found hits used in fit
                         the priary vertex is not included in the count
       - icharge
       - id_start_vertex = (Vertex->id)*10 for primary track candidates