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None Wrong Copy ID of replicated/parametrised volumes 

Forum: Geometry
Date: 15 Jan, 2015
From: valentina <valentina>

Dear All,

I need to build a set of pixellated layers (a Gamma-ray tracker). More precisely, about 2000x2000 pixels in about 100 layers.

I tried to use both the (i) replicated and the (ii) parametrised volumes for the pixels, while the 100 layers are physically built in a loop.
The replica volume IDs (the pixels) start from 0 for each layer, while the layer volume ID is assigned in the G4PVPlacement().

My problem is that the copy ID of the replica/parametrised volumes for the secondaries is wrong, while the position seems to be correct (the physical track is correct).
The problem occurs both with replica and parametrised volumes, which are built in a complete different way.

Could the problem arise from the loop?

Thank you very much for any suggestion.
Cheers,
Valentina

Example:
When simulating a muon (for example), the volume IDs are all correct until Geant4 starts to track its secondaries. At this point, when the particle crosses the vertical layers, sometimes the copy ID of the replica (the pixels) is repeated, i.e. the pixel ID is the same of the crossed pixel of the previous layer. The effect is the creation of fake vertical tracks (see image).

Code (SiTopDetector_phys is the layer mother volume created in the loop):
i) Replica:
//Creation of Silicon pixels
PixelTop_sol = new G4Box("sPixelTop", Pixel_side/2., Pixel_side/2., SiDetector_t/2.);
PixelTop_log = new G4LogicalVolume(PixelTop_sol, SiPixel_mat,"lPixelTop",0,0,0);

//Creation of Silicon strips
PixelTopLine_sol = new G4Box("sPixelTopLine", Pixel_side/2., Tray_side/2., SiDetector_t/2.);
PixelTopLine_log = new G4LogicalVolume(PixelTopLine_sol, SiDetector_mat,"lPixelTopLine",0,0,0);

PixelTop_phys = new G4PVReplica( "pPixelPos",PixelTop_log,PixelTopLine_log, kYAxis, Pixel_NY, Pixel_side, 0);
PixelTopLine_phys = new G4PVReplica( "pPixelPosTopLine",PixelTopLine_log,SiTopDetector_log, kXAxis, Pixel_NX, Pixel_side, 0);

for (G4int nt = 0; nt < N_layers; nt++)
{

SiTopDetector_phys = new G4PVPlacement(0,SiUpperModulePos,SiTopDetector_log,"pSiTopDetector",World_log,false,copyM + 9*10000);

}

ii) Parametrised:

SiTopParamDetector_sol = new G4Box("sSiTopParamDetector", Pixel_side/2., Pixel_side/2., SiDetector_t/2.);
SiTopParamDetector_log = new G4LogicalVolume(SiTopParamDetector_sol, SiPixel_mat,"lSiTopParamDetector",0,0,0);

//Pixel physical volumes
pixelParam = new GeometryST_TrackerParameterisation( Pixel_N,
                              Pixel_NX,
               startX,
                               startY,
                               Pixel_side );
 SiTopParamDetector_phys = new G4PVParameterised("pixelPhysical",SiTopParamDetector_log,SiTopDetector_log,kUndefined,Pixel_N,pixelParam);


for (G4int nt = 0; nt < N_layers; nt++)
{

 SiTopDetector_phys = new G4PVPlacement(0,SiUpperModulePos,SiTopDetector_log,"pSiTopDetector",World_log,false,copyM + 9*10000);


}

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2015/01/15/05.52-63971-WrongCopyID_tracker.png

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1 Question: Re: Wrong Copy ID of replicated/parametrised volumes   (Gabriele Cosmo - 15 Jan, 2015)
1 None: Re: Wrong Copy ID of replicated/parametrised volumes   (valentina - 15 Jan, 2015)
2 More: Re: Wrong Copy ID of replicated/parametrised volumes   (Gabriele Cosmo - 15 Jan, 2015)
1 None: Re: Wrong Copy ID of replicated/parametrised volumes   (valentina - 15 Jan, 2015)
1 None: Re: Wrong Copy ID of replicated/parametrised volumes   (valentina - 15 Jan, 2015)
2 Feedback: Re: Wrong Copy ID of replicated/parametrised volumes   (Gabriele Cosmo - 15 Jan, 2015)
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