Event Reconstruction

For the offline and online event reconstruction the same software framework ARTE (Analysis and Reconstruction Tool) [#!Arte!#] is used. This framework contains several packages responsible for cluster finding, pattern recognition, track matching etc.

The algorithm starts with hit preparation and filling the tables HITB, HITC etc.

At the next step standalone reconstruction in subdetectors and track finding starts. For the track finding in the main tracker system the OTR/ITR CATS package is used (see Chapter 4), and for pattern recognition in the Silicon detector a similar algorithm is utilized. The obtained clusters and segments are filled into the corresponding tables i.e. RSEG (reconstructed segments), RCCL (reconstructed ECAL clusters [#!care!#]), RHIT (reconstructed hits).

After the standalone reconstruction is completed for all subdetectors, the information is combined to complete tracks by the package MARPLE [#!marple!#] and stored in the table RTRA (Reconstructed TRAcks). Only tracks produced by matched VDS and ITR/OTR segments are used for this analysis.

For the secondary and primary vertex finding GROVER (Generic Reconstruction Of VERtices) [#!rover!#] package is used. The package also includes a target wire following algorithm for wire position refining. All vertices found are filled into the RVER (Reconstructed VERtex) table.

All tables listed are linked with each other and for example it is possible to find out which hits are used to reconstruct a segment or which hits are used in an ECAL cluster.

The event reconstruction chain is identical for MC and data and differs only in the step of the hit preparation.