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From: Ferreira De Almeida Lourenco, Ana <am.lourenco_at_ucl.ac.uk>

Date: Tue, 23 Feb 2016 17:43:43 +0000

Hi Chetaine and All,

The purpose of my simulations is to calculate ionization chamber perturbation factors for proton beams. For that purpose, I want to study first the accuracy of particle transport in FLUKA by performing a self-consistency test called the "Fano cavity test". "The Fano cavity test is based on the Fano theorem, which states that under charged equilibrium conditions, the charged particle fluence is independent of the mass density of the media as long as the cross-sections are uniform."

Therefore, even if in reality the cross-sections are dependent on the mass density, for the purpose of these simulations the cross sections must be independent of the density.

Many thanks,

Ana

________________________________________

De: chetaine <chetaine_at_fsr.ac.ma>

Enviado: 23 de fevereiro de 2016 17:28

Para: Ferreira De Almeida Lourenco, Ana

Cc: fluka-discuss_at_fluka.org

Assunto: Re: [fluka-discuss]: Fw: RHOR factor vs CORRFACT

dear Ferreira

i am a new user and the question is not very clear but with my little

experience

i can say that the cross section that we use is macroscopic cross

section and macroscopic cross section depend on the number of atoms /cm3

the density is g/cm3 equivalent to the number of atoms /cm3

so the cross section depend on the density

best regards

"De Almeida Lourenco, Ana" <am.lourenco_at_ucl.ac.uk> a écrit :

*> Dear Fluka experts,
*

*>
*

*>
*

*> I'm sorry to e-mail you again but I was hoping to get some feedback
*

*> regarding my post from last week (please see below). How can I make
*

*> sure that the cross sections in the simulations are independent of
*

*> the density?
*

*>
*

*>
*

*> Any feedback would be greatly appreciated!
*

*>
*

*> Many thanks,
*

*>
*

*> Ana
*

*>
*

*> ________________________________
*

*> De: Ferreira De Almeida Lourenco, Ana
*

*> Enviado: 16 de fevereiro de 2016 11:07
*

*> Para: fluka-discuss_at_fluka.org
*

*> Assunto: RHOR factor vs CORRFACT
*

*>
*

*>
*

*> Dear Fluka experts,
*

*>
*

*>
*

*> I'm simulating in FLUKA a proton beam (energies ranging from 60-250
*

*> MeV) on a phantom made of water. The phantom is divided into
*

*> different water regions with different mass densities (all regions
*

*> have same composition, same I-value, same Sternheimer density effect
*

*> parameters).
*

*>
*

*>
*

*> For the purpose of my simulations, I need to have homogeneous atomic
*

*> properties through the phantom, i. e. the cross sections must be
*

*> independent of the density. For that, I override the RHOR factor
*

*> (from MAT-PROP) so RHOR*RHO is the same in all the regions of the
*

*> phantom.
*

*>
*

*>
*

*> The manual states:
*

*>
*

*> WHAT(2) = RHOR factor : this factor multiplies the density of the
*

*> material(s) when calculating the density effect parameters
*

*>
*

*> Is the RHOR factor just used to calculate the density effect on
*

*> stopping power, or are other density-dependent properties also
*

*> included?
*

*>
*

*> How can I make sure that the cross sections are independent of the
*

*> density (nuclear interactions, scattering, etc)? By looking at the
*

*> CORRFACT description it seems to me that this card could do the job
*

*> but I have been advised in the past to not use it.
*

*>
*

*>
*

*> Any thoughts or suggestions?
*

*>
*

*>
*

*> Many thanks,
*

*>
*

*> Ana
*

*>
*

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Received on Tue Feb 23 2016 - 20:00:08 CET

Date: Tue, 23 Feb 2016 17:43:43 +0000

Hi Chetaine and All,

The purpose of my simulations is to calculate ionization chamber perturbation factors for proton beams. For that purpose, I want to study first the accuracy of particle transport in FLUKA by performing a self-consistency test called the "Fano cavity test". "The Fano cavity test is based on the Fano theorem, which states that under charged equilibrium conditions, the charged particle fluence is independent of the mass density of the media as long as the cross-sections are uniform."

Therefore, even if in reality the cross-sections are dependent on the mass density, for the purpose of these simulations the cross sections must be independent of the density.

Many thanks,

Ana

________________________________________

De: chetaine <chetaine_at_fsr.ac.ma>

Enviado: 23 de fevereiro de 2016 17:28

Para: Ferreira De Almeida Lourenco, Ana

Cc: fluka-discuss_at_fluka.org

Assunto: Re: [fluka-discuss]: Fw: RHOR factor vs CORRFACT

dear Ferreira

i am a new user and the question is not very clear but with my little

experience

i can say that the cross section that we use is macroscopic cross

section and macroscopic cross section depend on the number of atoms /cm3

the density is g/cm3 equivalent to the number of atoms /cm3

so the cross section depend on the density

best regards

"De Almeida Lourenco, Ana" <am.lourenco_at_ucl.ac.uk> a écrit :

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Received on Tue Feb 23 2016 - 20:00:08 CET

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