At the moment there are three implemented  models to simulate the geometry of the Drift Chamber :

• Fast Cylinder Model  (simple cylindrical fast simulation, the example as implemented by Torre)
• 
   
• Cylinder Model  (cylindrical fast simulation)

• Layer Model  (simulation considering a more detailed DCH structure)

• • The geometry is retrieved from the dbio file dch.db used for bbsim.
  • The inner and outer cylinders, the rear and front endcap are defined for both models (Cylinder and Layer).
  • 
     

    The volume tree is the same declared in bbsim 

   
   
   
   
   

  Defined Volumes
  Volume	Type	Material	R in (cm)	R out (cm)	Z / 2 (cm)
  DCHA	TUBE	Air	23.6	80.9	164.8
  DCHG	TUBE	He-Ibu	23.7	79.9975	138.2
  DCHO	TUBE	Air	79.9975	80.9	140.6
  DCHI	TUBE	Berillium	23.6	23.7	140.6
  DCRP	TUBE	Air	23.6	80.9	140.6
  DCFP	TUBE	Air	23.6	80.9	3.4
  DCO1	TUBE	Aluminium	79.9975	80.0	140.6
  DCO2	TUBE	Carbon-Fiber	80.0	80.15	140.6
  DCO3	TUBE	Air	80.15	80.75	140.6
  DCO4	TUBE	Carbon-Fiber	80.75	80.9	140.6
  DCO5	TUBE	Aluminium	80.9	80.91	140.6
  DCR1	TUBE	Aluminium	23.6	80.9	1.2
  DCR2	TUBE	Aluminium	23.6	23.9	15.0
  DCR3	TUBE	Aluminium	80.5	80.9	15.0
  DCR4	TUBE	Aluminium	23.9	80.5	0.2
  DCR5	TUBE	Aluminium	23.9	80.5	0.7
  DCR6	TUBE	Aluminium	80.0	80.5	5.0
  DCF1	TUBE	Aluminium	23.6	80.9	0.6
  DCF2	TUBE	Aluminium	23.6	46.9	0.6
  DCFA	TUBE	Aluminium	23.6	23.9	2.2
  DCFB	TUBE	Aluminium	79.6	80.9	0.75
  DCFC	TUBE	Aluminium	80.5	80.9	0.15
  DCFD	TUBE	Aluminium	23.9	80.5	0.2
  DCFE	TUBE	Aluminium	23.9	80.5	0.1

     
  • In the layer model 40 sensitive layers are inserted in DCHG.
  • Following a Simone Giani suggestion to reduce execution time in tracking the layers have been defined as:
  • • vertical tree of cylinders with the same internal radius
    • external radius corrisponding to the sense wire of the layer
    • each cylinder contains another cylinder