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Question Any example (in G4 or from some user out there) for custom G4VSolid subclass? 

Forum: Geometry
Date: 22 Feb, 2017
From: Michael H. Kelsey <Michael H. Kelsey>

I have a situation in my geometry which has managed to kill both visualization and tracking :-) We have a multistage cryostat with detectors and electronics at the center. To get all of the readout and control cables out to room temperature, we will have more than 200 holes and feedthroughs on the lid of the 4K stage (see the attached picture).

I would like to model this detailed structure explicitly, in order to do thermal studies tracking how IR photons get through the holes to the low temperature stages. The obvious (and horribly wrong) solution is to subtract each hole from the cylindrical can of the cryostat. When I do this, both visualization and tracking hang up in a lovely 250-deep calling stack as "DistanceToIn()" calls down through all of the nested boolean solids.

To replace this, I suspect that writing a custom G4VSolid subclass (maybe even a G4Tubs subclass?) is a much better approach. Then the coded in hole positions could be used to determine in vs. out, normals, etc. This was mentioned in a similar posting several years ago (http://hypernews.slac.stanford.edu:5090/HyperNews/geant4/get/geometry/1146/1.html). My question is whether anyone out there has an example of how to properly write a solid subclass, which they would be willing to share. I don't believe any of the G4 examples have one.

  -- Michael Kelsey

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/02/22/13.58-71579-feedthroughs_0.gif

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1 None: Re: Any example (in G4 or from some user out there) for custom G4VSolid subclass?   (John Apostolakis - 23 Feb, 2017)
(_ None: Re: Any example (in G4 or from some user out there) for custom G4VSolid subclass?   (Michael H. Kelsey - 23 Feb, 2017)
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