SN0131 : A Helix Track Fitting Program for the Silicon Vertex Tracker SVT in the STAR Experiment
Updated on Sat, 2007-07-14 02:20. Originally created by chajecki on 2007-06-18 19:57.
| Author(s) | : | J. Bielecki |
| Date | : | Apr. 26, 1995 |
| File(s) | : | sn0131.ps.gz |
| Abstract | : | The silicon vertex tracker (SVT) is a detector for low transverse momentum charged particles ranging from .05 to 1 GeV/c in the solenoidal tracker at RHIC experiment (STAR). STAR will be composed of colliding Au-Au beams with an azimuthal shaped detector system around the primary vertex. The major objectives of STAR are to investigate aspects of both soft physics like hadron production at transverse momenta below 1-2 GeV/c and hard physics processes in search of quark gluon plasma (QGP) signatures. The detector system will consist of the SVT (closest to the vertex), time projection chamber (TPC), magnetic field of 0.5 T, electromagnetic calorimeter (EMC), triggering detector system, and data acquisition (DAQ). The SVT constructed of three layers of silicon drift detectors (SDD) and with an acceptance of -1 to +1 in pseudo-rapidity will store three space points for each charged particle traversing all layers. With these space points and the vertex a fit can be performed to reconstruct the track. The tracks are helical due to the magnetic field. Event data and tracking are simulated on a Silicon Graphics Work Station using software packages FRITIOF and GEANT, respectively. This thesis reviews the specific software developed for associating the space points into tracks, fitting the primaries, selecting original tracks out, and determining secondaries and their vertices. Efficiencies for track reconstruction is defined as the number of original tracks reconstructed over the number of original tracks. Overall efficiency is above 95%. Primary fitting is 98%. Secondary retrieving is near 75%, but methods for the reconstruction of secondary vertices is incomplete, because future development on controlling ghost intersections is pending. Origin and momentum resolution are investigated and found to be slightly higher than plots proposed in the conceptual design report. The difference in resolutions are largely caused by multiple Coulomb scattering. |
| Keywords | : | |
| Category | : | Technical |
|
