Till now the templates used in track reconstruction were generated in a grid ptot (1 \% ptot) theta (0.2 degree). This grid was good for negative pions with the particle momenta of about 500 MeV/c. I did some studies of the necessary grid for both negative and positive pions and also other momenta: 200 MeV/c, 500 MeV/c and 1000 MeV/c.
Single templates for several momentum and theta values were generated.
Then the particles with close momenta were simulated and the chi2
for the appropriate template were calculated. The plots of accepted
tracks and their probabilities are shown in the following pictures:
pi -, 200 MeV/c, theta=60
pi +, 200 MeV/c, theta=60
pi -, 500 MeV/c, theta=50
pi +, 500 MeV/c, theta=50
pi -, 1 GeV/c, theta=50
pi +, 1 GeV/c, theta=50
First scatter plot on each figure shows the arrea, where the tracks were accepted.
On the second scatter plot the central area is shown.
Third and fourth plots show the probability values - on the last we can
see the black area for accepted tracks and small dots depicting the probablility
for "rejected" track candidates.
The results show a regular dependence: the lower is the momentum the larger is the area in which the tracks are accepted. However there are some irregularities, which cause large differencies between acceptance regions for the same momenta. We can not thus make the grid too coarse, without potential loss of the paticles, which will fit between the accepatnce areas of neighbour templates.