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Question Too many particles causing Segmentation Error 

Forum: Particles
Date: 18 Mar, 2009
From: Daniel O'Brien <Daniel O'Brien>

Hi, I new here so I may as well introduce myself first. I'm Daniel O'Brien and I'm a Medical Physics PhD student with UCD and St Luke's Hospital in Dublin, Ireland working on small field dosimetry. I'm using Geant4 to investigate the dosimetry of the fields coming from a LINAC at fields sizes which are too small to measure reliably.

This involves modeling a LINAC which I am presently attempting to do but I ran into a problem when I increased the number of electrons I started off with. When I ran the model with 200000 electrons initially the program runs fine, but If I increase it to 300000 a segmentation fault occurs. When running the model properly I intend to use much more than 300000 electrons.

In order to determine what was causing it, I removed all but the bare essentials from the program, leaving only a Tungsten target surrounded by air and a single point source of mono-energetic electrons pointed towards the target, with no visualisation or tracking elements what-so-ever. The problem still occurs!

I've put the code online for you to easily check out at the following address:

http://www.efmods.com/geant4/models/LINACModel/

As you can see the code is very very basic now that I've removed all of the complexities. I've only been using Geant4 for a couple of months so hopefully people with greater experience can see the problem.

Perhaps it is a hardware issue?

My system is Ubuntu Linux, Linux-g++ compiler, 1 GB of RAM and 2 x 2.0 GHz processor (however the program does not use multi-threading so only one processor is being utilised). Using the Gnome system monitor I checked to see if the RAM was an issue but the RAM usage reached about 70% and never increased beyond that during the course of the program.

I have intended to run the program on a computer with higher specs but I haven't had the opportunity so far.

I would really appreciate any help anybody can offer. Thank you taking the time to read this.

Daniel

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1 Note: Re: Too many particles causing Segmentation Error   (Juan - 19 Mar, 2009)
(_ None: Re: Too many particles causing Segmentation Error   (Paul Nicholas Colin Gloster - 19 Mar, 2009)
(_ None: Re: Too many particles causing Segmentation Error   (Daniel O'Brien - 19 Mar, 2009)
(_ Feedback: Re: Too many particles causing Segmentation Error   (Gumplinger Peter - 19 Mar, 2009)
(_ Agree: Re: Too many particles causing Segmentation Error   (Daniel O'Brien - 20 Mar, 2009)
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