W&M  report 10-13-2004


Progress on Geant4 Simulation

I started to develop the Qweak simulation based on Geant4 including the VDC's exposed to realistic tracks.
Main purpose is to extract/resolve the hits on the VDCs including the position and angle information.
For the finalization/verification of the drift cell geometry and overall chamber size the VDC will be made out
of individual hit sensitive drift cells in order to record the number of drift cells beeing hit , esp. for extreme tracks
close to the VDC frame

So far archived:

-  Event generator  based on the primaries given in the Qweak Geant3 ntuple (q_weak.nt)
-  Simple target container
-  Magnetic field based on the (newest) field map, using the same field interpolation (trilinear)
    - tracking within the field can be handled with different procedures (default Runge-Kutta)
-  Shielding wall with octant openings
-  1 tilted single VDC consisting of two position sensitive planes  located in the U,V wire plane
    -  positions are stored in ROOT histograms

Currently working on:
    - implementaton of individual drift cells with variable cell geometry
    - recording the number of responding drift cells per plane for a track
    - writing all  VDC track related information into a ntuple in order to analyse e.g. for (in)elastic tracks
    - defining collimators (derived from shielding wall class), placing them into postions


Pics of setup : http://dilbert.physics.wm.edu/elog/Software/31   (red: electrons, green: photons, yellow: interaction vertices)
VDC hits      : http://dilbert.physics.wm.edu/elog/Software/35

Snapshot of my Qweak Geant4 code: http://dilbert.physics.wm.edu/qweak/Simulation/Geant4/


Here you can see a current snapshot of the setup:
     - blue shielding wall with enlarged octant openings
     - tilted single VDC (yellow: overall alu frame, white current active area)
     - prototype of giant drift cells for both wire planes for testing and debugging (wire angle: 30 deg)