Re: [fluka-discuss]: Simulate Fano theorem in Fluka

From: Ferreira De Almeida Lourenco, Ana <am.lourenco_at_ucl.ac.uk>
Date: Mon, 1 Feb 2016 11:00:41 +0000

Dear Paola and Hugo,

Thank you very much for your e-mails!

Unfortunately, I'm not familiar with writing routines. Since CYLI-VOL gives a spatially uniform distribution in volume and I need an uniform source by mass, could you please give me some advice how I should do this? Any examples that you could provide would be greatly appreciated!

Many thanks,
Ana
________________________________________
De: Paola Sala <paola.sala_at_mi.infn.it>
Enviado: 31 de janeiro de 2016 11:58
Para: Bouchard Hugo
Cc: paola.sala_at_mi.infn.it; Ferreira De Almeida Lourenco, Ana; fluka-discuss_at_fluka.org
Assunto: Re: [fluka-discuss]: Simulate Fano theorem in Fluka

Dear Hugo, Ana,
thank you for pointing to your paper. If I understand correctly, you kill
all processes, from nuclear interactions to e-m transport. It seems to me
that the only MonteCarlo aspect that is tested is the stopping power
description, that does not depend on density (for non-relativistic
particles). Multiple (or single) scattering can have a role, and I doubt
that that "angle-dependent" quantities intrinsically violate the Fano
theorem.
But probably we can continue or discussion offline, not to spam the list.
Going to technical questions,
-CYLI-VOL gives a spatially uniform distribution in volume. If you need to
do by mass, I'm afraid you'll need to write your own user routine.
-definitely do NOT use Corrfact
-for best prcision, activate single scattering everywhere and all the
corrections with the MULSOPT card.
Ciao
Paola
> Dear Paola
>
> Sorry if I introduce myself in the conversation (I am co-supervising
> Ana’s project). I just want to make sure we understand each other. There
> are basically 2 ways the Fano test can be done (in respect to Fano’s
> theorem). One way is using an external parallel beam, in which case the
> primary particles need to be “regenerated" at the site of primary
> interaction. For protons, this is not possible (due to CSDA) and therefore
> you need to create a virtual particle that triggers proton transport in
> the phantom (Sterpin et al, Med Phys 2014). The other way is simply to
> create a homogeneous source of particle, similarly to a radionuclide. In
> such source, particles are generally homogeneously (per unit mass) and
> they are sampled from angular and energy distributions which do not change
> throughout the phantom. Such test is more suitable for charged particles
> and this is what we want to use.
>
> So what Ana needs is :
>
> 1. A phantom with homogeneous atomic properties (cross sections, I-value,
> density effect parameter, etc.), but varying mass densities (her ion
> chamber setup will be overriden to water-property materials but keeping
> their original mass density). Thus, there must be a way to override the
> density effect parameter or any other density-dependent property.
>
> 2. A homogeneous source such that the number of particle per unit mass
> generated in the geometry is uniform in space.
>
> These 2 conditions allow Fano’s theorem to apply.
>
>
> Many thanks for your support!
>
> With best regards
> --
> Hugo Bouchard, PhD, MCCPM
> Professeur adjoint
> Département de physique
> Université de Montréal
> Pavillon Roger-Gaudry bureau V-220
> Tél: 514-343-6111 - ext. 34879
>
>
>
>
>
>
>
>
>
> On 2016-01-27, 2:19 AM, "Paola Sala" <paola.sala_at_mi.infn.it> wrote:
>
>>Dear Ana
>>
>>maybe I'm missing the context, but I do not think that the procedure you
>>mention is the correct one to simulate the Fano theorem.
>>
>>The Fano theorem is usually applied to the study of small cavities at low
>>density ( like TEPC detectors) for dosimetry. The smallness ensures that
>>the particle fluence is not perturbed by the cavity. To test this, the
>>"source" should be external, like a broad beam irradiation. The beam
>>should not be relativistic (density effects are present at relativistic
>>energies), The transport thresholds should be set at the same energy in
>>all the volumes, and low enough when compared to the detector dimensions
>>and density. The CORRFACT card shall NOT be used, non-relativistic cross
>>sections are already density independent.
>>
>>Ciao
>>Paola
>>
>>> Dear Fluka experts,
>>>
>>>
>>> I would like to test Fano theorem in FLUKA.
>>>
>>>
>>> ("Fano theorem states that under charged particle equilibrium
>>> conditions,
>>> the charged particle fluence is independent of the mass density of the
>>> media as long as the cross-sections are uniform." from Sterpin et al
>>> 2015)
>>>
>>>
>>> I have a few questions:
>>>
>>> 1- Will it be possible to simulate Fano theorem in FLUKA?
>>>
>>>
>>> 2- For that, I would have to simulate an uniform source per unit mass.
>>> What would be the best way to simulate this in FLUKA? I was planning to
>>> use a BEAMPOSit card with SDUM=CYLI-VOL. Will this simulate an uniform
>>> source per unit mass or volume?
>>>
>>>
>>> 3- Also, how can I be sure that the cross sections are independent of
>>> the
>>> density? Should I use the CORRFACT card?
>>>
>>>
>>> Many thanks,
>>>
>>> Ana
>>>
>>
>>
>>Paola Sala
>>INFN Milano
>>tel. Milano +39-0250317374
>>tel. CERN +41-227679148
>>
>


Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148

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Received on Mon Feb 01 2016 - 13:57:49 CET

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