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Forum: Geometry
Re: Sad Problem with large number of detectors (Petre Manescu)
Date: 12 Dec, 2012
From: John Apostolakis <John Apostolakis>

Dear Petre,

Without more information it is difficult to give you an answer.

My advice would be to:
  - check your geometry for overlaps, using one of the standard tools in the Application Developers Guide.  The best current tool, in my opinion, is the check at construction time, but the computing time to use that for 30k or 70k elements (if they are at the same level) would likely be prohibitive.

You do give any indication where the error occurs - you can use a debugger (such as gdb) to show the stack trace.  Also explaining the amount of memory of your machine, the OS and the compiler used could help others to offer advice.

How many materials do you define in your simulation ?  This could use up significant memory.

John
===================================================
John Apostolakis, SFT (SoFTware) Group, PH Department, CERN
Email:  john.apostolakis@cern.ch       Office Tel:  +41-22-767-7239
------------------------------------------------------------------------------------------

On Dec 12, 2012, at 2:03 PM, Petre Manescu wrote:

> 
> *** Discussion title: Geometry
> 
> Hello,
> 
> I have an error when I run a simulation with a large number of
> detectors. I am trying to do a radiation therapy simulation. I am
> building my "target" using a G4AssemblyVolume. I am not using any
> optimization, I am building the detectors using G4Box or G4Tet. I am
> using a very simplified physiscs list. For 30k elements, I can run the
> simulation, but for 70k elements I get the following error message:
> 
> /run/beamOn 1000
> 
> phot:   for  gamma    SubType= 12
>      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
>       PhotoElectric :  Emin=        0 eV    Emax=       10 TeV
> 
> compt:   for  gamma    SubType= 13
>      Lambda tables from 100 eV  to 10 TeV in 77 bins, spline: 1
>      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
>       Klein-Nishina :  Emin=        0 eV    Emax=       10 TeV
> 
> conv:   for  gamma    SubType= 14
>      Lambda tables from 1.022 MeV to 10 TeV in 77 bins, spline: 1
>      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
>        BetheHeitler :  Emin=        0 eV    Emax=       10 TeV
> 
> msc:   for e-    SubType= 10
>      Lambda tables from 100 eV  to 10 TeV in 77 bins, spline: 1
>      RangeFactor= 0.04, stepLimitType: 1, latDisplacement: 1
>      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
>          UrbanMsc95 :  Emin=        0 eV    Emax=       10 TeV
> terminate called after throwing an instance of 'std::bad_alloc'
>  what():  std::bad_alloc
> Abandon (core dumped) 
> 
> The weird thing is that the memory of my computer is not "full" when the
> error occurs. Moreover, if I add a more complex physics list, the
> simulation crashes even with 10k elements. Where could the problem come
> from?
> 
> Cheers, Petre
> 
> -------------------------------------------------------------
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