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TRACKING

Leaders:Jorge Barreto, Vitor Oguri,
Carley Martins and Gilvan Alves

Slides presented by Sérgio Novaes at the September 2001  Collaboration Meeting (.ps)

Summary of the Tasks:

Construct a C++ algorithm that is capable of obtain the physical parameters at the IP position from the measured transversal positions (X,Y) at each pot location.  It must be also capable of find a good track reconstruction at a multihit environment. The algorithm reads fiber numbers and converts it in segments, whose geometrical (X,Y) positions are chosen as track positions at each station.


 
 
Milestones Deadlines
Track Reconstruction (Single Hits) 20/04/2001
Track Reconstruction (Multi Hits) 30/05/2001
Track Reconstruction (Vertex Displacement - proton arm) 15/07/2001
Track Reconstruction (Vertex Displacement - pbar arm) 30/10/2001

Track Reconstruction (Single Hits)

A first version algorithm is already constructed that allows to find the xi- and t-resolutions,
for single hits, at the Interaction Point (IP), defined at Z = 0, for all stations down the proton
and pbar arms. A technical note is underway, describing the reconstruct method and given
the resolutions results. (20/04/2001)

Track Reconstruction (Multi Hits)

07/05/2001 - During real data acquisition, multihit events would probably be very present,
due to beam halo particles, cross talks, and multiple interaction. In order to be able to analyze
correctly these events, the algorithm is being modified to incorporate multihit data in fiber
numbers input. A first version should be ready by the end of May.

09/20/2001 - We have implemented multihit environment in our tracking algorithm. The
code is able to identify correctly events that are true tracks from spurious events, if the
fibers in each station don't present a very closed neighborhood between true and spurious
events. If they do have such a pattern, then the code finds the true and some others
spurious tracks in the reconstruction. Solutions to solve this problem are being developed
(clusters, etc.). This version of the algorithm is included in the D0 Reco (Sep./2001).

Track Reconstruction (Vertex Displacement)

07/05/2001 - Vertex displacements are expected to occur at RunII, as indeed preliminary
results have shown. A Z vertex displacement of +/- 1 meter was observed in these preliminary
data. The track algorithm must be able to include a Z vertex displacement correction during
the reconstruction, in order to obtain the physical parameters (xi,t) at the correct vertex location.
We expect to have a complete study of this matter by middle July, and complete tables given xi-
and t-corrections as a function of the z vertex displacement should be constructed.

09/15/2001 - This study, mainly done by Jose Montanha and Jorge Barreto, is now completed
for the proton arm.  A simple relationship is found relating the expected xi- and t-resolutions
as a function of the z-vertex displacement, when reconstructed at Z = 0. After a few more
checkings, the same study will be done for the pbar arm (quads and dips).

Send all comments and suggestions to barreto@if.ufrj.br