Segment Finding Efficiencies

 

Two approaches were taken to measure the efficiency of the segment finding algorithm.

1. The number and type of found segments were measured.
2. The correctly found segments were used to determine the number of truth tracks that could be found in an event.

The segment finding analysis has been performed with different fiducial cuts and segment finding algorithm parameters. Unless otherwise stated the following values for the parameters of the algorithm were used,

1. number of hits in a mask, NumMask: ,
2. road width: 1 mm or a cut, and
3. road width change: by a factor of 1.5 if necessary.

This choice of parameter values seems reasonable since five hits are expected in a cell on average [2] and at least three are needed to form a segment. Unless otherwise stated the following fiducial cuts were applied,

1.  GeV/c and
2. .

Fiducial cut 1 selects the most interesting tracks and reduces confusion from low secondary tracks. Fiducial cut 2 is the geometrical acceptance (in the forward direction) for four hits in superlayer three. This geometrical acceptance should alway contain the electron from NC events provided is greater than 100 GeV .

Figure 4 displays the segment finding performance for a NC event. Both signs of the ambiguous drift direction, inefficiencies, and noise hits are shown in figure 4a, while the found segments are shown figure 4b. It can be seen that adequate segments are found to enable the high tracks to be found in this event.

 
Figure 4:   Display for a NC event: a) hits, and b) found segments. A) B)

• Number and Type of Found Segments
• Track Efficiency Using Found Segments