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Forum: Geometry
Date: 04 Sep, 2015
From: <herr_apa>

Hi,

I have a large and complicated geometry described by > 10^5 volumes. I want to simulate the dose absorbed by a set of dust particles moving through the geometry. Everything in the geometry is stationary except for the dust particles, whose position depends on the event number. From what I understand, the proper approach is to describe the particles with a parametrized volume and let ComputeTransformation depend on the event number as explained e.g. on slides 17-19 here:

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCAQFjAAahUKEwiQ3fHKqt3HAhUDVywKHfkTDzA&url=http%3A%2F%2Fgeant4.slac.stanford.edu%2FSpace06%2Fpresentations%2F05_Friday%2F04-Asai_NestedParameterization.pdf&usg=AFQjCNH_GrLaBhAYoWOUWJJXSgj2R1-Dwg&sig2=KrHniCTL5nXM5vi6U9DuyA

I have two questions. Firstly, the slides say that the moving objects should not be allowed to leave their original voxel. Therefore, voxelization should be turned off for the mother volume of the moving objects using "motherLogical->SetSmartless(number_of_daughters_or_larger);" This is confusing, and I'm sure there's something I've misunderstood. Wouldn't calling SetSmartless with a large number (10^5 in my case) lead to a huge number of voxels, practically guaranteeing that the moving volumes will leave their original voxel? Shouldn't I call SetSmartless(0) to turn off voxelization? (Note that I'm very happy if I don't have to call SetSmartless(0) because that causes the simulation to slow to a crawl!)

My second question concerns multithreading. It is my understanding that there is only one instance of the geometry, and it is shared between all threads. If I make the geometry depend on the event number as described above, won't this lead to problems with different threads trying to alter the geometry at the same time? Are parametrized volumes somehow thread-local?

Thanks in advance!

// Anders

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1 None: Re: Moving Volumes Between Events   (herr_apa - 15 Sep, 2015)
(_ More: Re: Moving Volumes Between Events   (Gabriele Cosmo - 14 Oct, 2015)
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