RE: USRBIN and geometry

From: Alberto Fasso' <>
Date: Thu, 14 Oct 2010 17:03:13 +0200

Dear Leena,

if the explanation I have given before is correct (I think it is, but I am
not 100% sure) then all differences are due to particles slowed down below
transport threshold. The question then is not "which geometry is more correct"
but "which threshold is more correct". Try making lower thresholds, and see
if the differences become less important.


On Thu, 14 Oct 2010, wrote:

> Dear Alberto,
> Thanks very much for your quick response. In your opinion which geometry is
> more correct and closer to the reality? I have also tried to do the same
> comparison but without beam line geometry for aluminium (and some other
> materials of one element). The results of USRBIN were exactely indentical but
> when I done it for water (and some compounds) again I found a difference like
> a sharp cut after distal edge. Again would you please give me a reason of this
> difference in case of materails type? and tell me what is the best geometry to
> simulate the dose by USRBIN. Is it one body target or a taget with subregions.
> Best regards
> Leena
> ________________________________________
> From: Alberto Fasso' []
> Sent: 13 October 2010 23:33
> To:
> Cc: Al-Sulaiti L Ms (PG/R - Physics)
> Subject: Re: USRBIN and geometry
> Dear Leena,
> particle tracks are cut at boundaries, and your two inputs had a different
> number of boundaries. For particles with energy larger than the cutoff,
> the result should be the same: but a check that the energy is below the
> cutoff is done at boundaries, and when you have less regions the checks
> are less frequent. So, a small difference could arise due to particles
> below threshold.
> A similar, although not identical, effect was explained by Paola Sala
> a few days ago (Oct. 7). See:
> Alberto
> On Wed, 13 Oct 2010, wrote:
>> Dear FLUKA experts,
>> As I knowm, USRBIN is geometry independent. However, when I changed the
>> target geometry and sliced it by XYP palts I have found some differences in
>> all USRBINs ( for dose, protons fluence, primary proton fluence and all
>> particles). I have attached two files 1- with one body ''water traget''
>> 2- the target was divided into many subregion. The question is why USRBIN
>> results are not the same in both files. Do I have any error in the geomety
>> that caused this difference? Would you please help me find it.
>> Best regards
>> Leena
Received on Thu Oct 14 2010 - 17:35:38 CEST

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