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Number of contributors to a cluster pattern

An idea of the task of the cluster/hitfinder is given by looking at the typical number of tracks contributing to a clustr pattern. The slow simulator associates with every occupied pixel the Monte Carlo track ID of one of the tracks that contributed to that pixel. This information is stored in the TPMCPIX table. Then, by counting the number of different track ID's associated with pixels in a cluster pattern, one gets an idea of how many hits a perfect hitfinder may find in the cluster pattern. A distribution of this quantity for clusters found in the inner sector (row# 13) and outer sector (row# 13) is shown in Figure 15. It is seen that single-hit clusters are the most common, but that there is a good deal of overlap as well, especially in the inner rows.

Figure 15: Distributions of the number of different Monte Carlo track ID's associated with pixels of clusters found on the inner and outer sectors from a simulated Au-Au event.

Evaluation of resolution and hitfinding efficiency is based on comparisons of reconstructed hits on a padrow with Monte Carlo padrow crossings. In reality, the current simulation chain gives several (5-9) Monte Carlo ``hits'' for each track crossing a padrow. In our evaluations that follow, we use the Monte Carlo hit that is closest to the center of the padrow as the padrow crossing.

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