Tracking: very first results 

 Procedure:
- modified Qweak_GEANT : fills with every call of the subfuncion GUSTEP a Ntuple containing
   event_counter, particle_id,E_total,E_kin,x,y,z,px,py,pz,Bx,By,Bz,theta,phi
   [x: vertical plane, y: horizontal plane, z: beam axis, theta: azimutal angel, phi: polar angel]
- At present the Ntuple contains for test purpose only 10.000 events (elastic scattered electrons)
- somehow GEANT calles sometimes GUSTEP twice per tracking step without any change in the tracking parameters
   -> leads to identical Ntuple entries 8-(
- converting the Ntuple into a ROOT tree using h2root
- ROOT: looping through the tree :
     - removing identical entries
     - filling classes/structures to get access to each entry:  
       e.g.   GeantTrack->Track[i]->Node[j]->Get_z()
     - performing a cubic spline fit for x,y,theta,phi versus z :
        ->  DC track parameter x,y,theta,phi as a function of z
    - evaluating DC track parameter for DC2 and DC3 Front/Back with
      more or less arbitrary z positions:
                -> DC2.Front: z=-200 cm , DC2.Back: z=-150 cm
                -> DC3.Front: z= 400 cm , DC3.Back: z= 430 cm

                -> filling 2D histograms, checking for correlations

Single track of an elastic electron

                                      Pic above: Spline fit of a single track




                 

                Pic above: correlation plot of DC2.Front versus DC3.Front (10.000 elastic e-)



        Pic above: correlation plot of DC2.Front versus DC2.Back (10.000 elastic e-)



Pic above: correlation plot of DC3.Front versus DC3.Back (10.000 elastic e-)

3D visualizer for Qweak Geant:

download qweak_view.C and start it as a macro in ROOT:

root> .x qweak_view.C