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Question Hole in a conical section 

Forum: Geometry
Date: 23 Nov, 2009
From: Estela Suarez <Estela Suarez>


in my Geant4 simulation I have a shielding in the shape of a conical section, where I need to open a hole so that the detector passes trough it (staying half outside, half inside the conical section).

I think that the easiest way to do that is to define a second conical section as a small part of the first conical section, and subtract it from it.

So, if my mother conical section is: G4Cons("coneA",Rmin1A,Rmin1A+thickness,Rmin2A,Rmin2A+thickness,zA,phiA,DphiA)

I can define the small section (a kind of square window of side zB) as G4Cons("coneB",Rmin1B,Rmin1B+thickness,Rmin2B,Rmin2B+thickness,zB,phiB,DphiB)

And finally I make the subtraction using G4SubtractionSolid *sub = new G4SubtractionSolid("sub", coneA, coneB);

Now, when I visualize the result, I see that the "edges" of the voxels that define both volumes are not exactly at the same place (I checked that by inserting in the hole a volume equal to coneB). Is this only a visualization problem? When I put my detector in the hole and fire it with many particles I don't get any segmentation violation, which I think would be the case if I would have volumes superimposed. Nevertheless I would like to be sure that the procedure is in principle correct.

And last question: to be sure that no parts from the coneA are remaining in the window region, I was thinking on defining a larger thickness for coneB. Is it possible to subtract a volume from a mother volume, where the subtracted part is larger in some dimensions than the mother? Would that bring any problems when installing my detector in the produced hole?

Thanks for your attention, Estela.

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1 None: Re: Hole in a conical section   (John Allison - 24 Nov, 2009)
1 None: Re: Hole in a conical section   (John Apostolakis - 25 Nov, 2009)
1 Question: Re: Hole in a conical section   (Estela Suarez - 25 Nov, 2009)
2 Question: Re: Hole in a conical section   (Estela Suarez - 25 Nov, 2009)
2 More: Re: Hole in a conical section   (Gabriele Cosmo - 25 Nov, 2009)
1 Ok: Re: Hole in a conical section   (Estela Suarez - 25 Nov, 2009)
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