1. Detector of particle tracking

   

   The ATCS simulation detector has 6 volumes (7, 8, 9, 12, 13, 14, 16, 17, 18). Each volume has 7 layers, and each layer has 2 sublayers. We used the sublayer second of each layer to select hits of the volume. 

2.  Example of a particle track within a detector

   Assuming the track is a set of hits, we supposed a track is a straight line created by some segments. A segment is a line/vector connecting two hits from two layers. 

   The figure below shows an example of a track with 4 hits on 4 layers:

Information:

• 4 layers: (p₁, p₂, p₃, p₄)
• Track t = (h_i, h_j, h_k, h_l)
• Coordinate: (x_i, y_i) -> h_i
• 3 segments: 
  • h_i  -> h_j : (h_i, h_j)
  • h_j  -> h_k : (h_j, h_k)
  • h_k  -> h_l : (h_k, h_l)

3. Remarks

   • A good track is close to a straight line -> the angle (β) is created by two segments that should be small (β -> 0).
   • A good segment of a good track when the angle (δ) is small. If δ is a large angle, then the direction of this segment will be going out of layers (out of the volume).