• The path length of the particles crossing the chamber is connected directly to  their momentum. The number of produced hits is then connected to the momentum.
• Two parameters are relevant for the production of the hits:
• • • • • Curvature Radius
        • Range
• The behaviour of both is plotted in the following picture.
• • 
  •  

• a) Electrons with P_t  greater than ~150 MeV/c  and Curvature Radius ~ 25 cm cross the chamber and reach the detector DIRC as can be see in some typical single particle events [Img 1]
• b) Electrons with  P_t  lower than ~ 130 MeV/c then Radius  < 22 cm  can be confined in the chamber and the chamber may be crossed through long paths. Electrons of ~ 1 MeV/c have ranges of ~ 2 m.
• In a) few hits per events are produced (in the average 40 hits, 1 per layer).
• In b) many hits may be produced and  the same cells may be crossed more times. This can be see in the Img 2  , Img 3 , Img  4   showing 1 positron of 50 MeV/c (Radius ~ 8 cm)  and Img 5 , Img 6 where 1 positron of 10 MeV/c ( Radius ~ 1.5 cm) is shown.
• Electrons of ~ 1 MeV/c and Radius ~ 2 mm may be confined in the same cell ( this can be false for stereo layers where wire direction and magnetic field direction is different).
• The most part of electrons of Pt < 1 Mev/c, for example   100 KeV/c with radius ~ 100 microns, will remains in the same cell, considering the low range associated to the momentum.

In conclusion the stop of the particle tracking when only one hit (for P lower than 1 MeV/c)  will be produced  may be a good compromise between requested detail and computer speed.