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Question Re: electron range in TestEm18  

Forum: Documentation and Examples
Re: Question electron range in TestEm18 (Yannick Arnoud)
Re: None Re: electron range in TestEm18 (Isabelle Fonteille)
Date: 07 May, 2009
From: Isabelle Fonteille <Isabelle Fonteille>

On Thu, 07 May 2009 07:56:18 GMT, Isabelle Fonteille wrote:
> On Tue, 05 May 2009 17:16:35 GMT, Yannick Arnoud wrote:
> >    Attachment:
> >
> >
> >
> > 
> > Dear Geant 4 experts,
> > 
> > We are testing the energy loss of electrons in water. We used the
> > TestEm18 example and obtained a very weird result for "low" energy
> > electrons. All the 1 keV electrons we generate experience one
> > interaction after 63.1 microns, and lose all their energy. The stepcut
> > we use is 1 nm, far smaller than this 63 microns length.
> > 
> > Is our set of parameters wrong ? (see attached electron.mac) Do you have
> > any piece of advice ?
> > 
> > Cheers,
> > 
> > Yannick and Isabelle
> > 
> You have got 1 step only, because you were using the default
>   step limitation for the energy loss. I propose to add the next line
>   to your macro
>   /process/eLoss/StepFunction 0.1  1. nm 
>   You can play the parameters of this command of course. The meaning and 
> usage of this command can be found in the Physics Reference Manual,
>   Electromagnetic Interactions, section 7.1.
>   Hope this helps
>   Laszlo
>  P.S. BTW your question would be in a better place in the EM forum.


I'm working with Yannick and testing TestEM18 too. We tried the StepFunction command (/process/eLoss/StepFunction 0.1 1. nm) and it works well : not all the electrons stop at the same deth anymore (see attachement 1_Vis_Standard).

After that, we change the physic from Standard to Livermore (/testem/phys/addPhysics livermore in electron.mac), and the result is not the same. None of the 1.keV electrons stop in our 100nm water volume (see attachement 2_Vis_Livermore_DetSize100nm and 3_Text_Livermore_DetSize100nm). I also notice that if I change the size of the water volume from 100.nm to, nearly all the step size are equal to 215um (see attachement 2_Vis_Livermore_DetSize1mm and 3_Text_Livermore_DetSize1mm), and the result is the same with or without the StepFunction command line.

Is the StepFunction not appliquable for LowEnergy Livermore PhysicList? If so, is there an equivalent command that works with this PhysicList?



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