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Position uncertainties


The spatial resolution for hit measurement in the TPC is non-trivial, and so, therefore, are the uncertainties which try to estimate the resolution. Hence, the simple question ``What is the spatial resolution?'' cannot be answered simply. Here, and in 6.3, we describe how hit resolutions are determined in the cluster/hitfinder. See [3,6,7,8,9] for further details.

It is believed that such careful evaluation of spatial uncertainties based hit-by-hit on track characteristics represents an improvement over assignment of uncertainty based on signal width and signal:noise alone (perhaps scaled by some ad hoc factor). It is hoped that a corresponding improvement is thus achieved in the track parameters; verification of this improvement is a task for the future.

The parametrizations employed in the cluster/hitfinder are based on simulations with current (1/96) ``standard'' versions of Geant and TPC slow simulator for STAR. Tuning these packages to better reflect reality may require some changes to TCL. These will be reported in future as needed.

Michael A. Lisa
Tue Feb 6 15:49:35 EST 1996