Pad Response Function

1
Pad Response Function

• Motivation There was a disagreement between
  calculated (Mathieson Formula) and measured pad
  response functions.
• Induced Signals in all geometries can be
  calculated with the use of the weighting field
  formalism.
• The weighting field can be calcu-lated as the
  field that would bepresent, if the read out
  elec-trode is set on 1V and all otherelectrodes
  are grounded.
• The induced current signal canthen be calculated
  as

2
Pad Response Function

• Simulation is done with GARFIELD
• Mathieson Formula gives smaller value of sigma
• The difference is explained by the fact that one
  cathode plane is made of wires.

3
Drift Time Map for AliRoot

• GARFIELD, Va 1.55kV, Vd-2.1kV, Xe-CO2 85-15.

4
Average Drift Velocity

• Average drift velocity is not homegeneous

5
Average Drift Velocity

• Try to implement this for a correction of the
  beam data

6
Residuals on the Track

• There is definitely some distortion through the
  non-constant average drift velocity

7
Extend Time Bins in Amplification Region
15deg 0.8deg ? 0.66deg 10deg 0.68deg ?
0.6deg 5deg 0.54deg ? 0.54deg 0deg 0.49deg
? 0.36deg