Re: [fluka-discuss]: UsrMed Energy modulation

From: Paola Sala <paola.sala_at_mi.infn.it>
Date: Wed, 20 Aug 2014 10:39:43 +0200

Dear Yuri,
sorry, but I have to confirm that changing the energy in usrmed is NOT
possible. It may seem to work, but it doesn't, it spoils preset
quantities.
There is a better and safer way to perform what you plan, that is to
change the thickness of your foil event by event. In this way all the
simulation will be self-consistent. I'll explain you how to do, only I
would like to know if you are already using a "source.f" routine or not.
Regards
Paola


> Dear Paola,
>
> thank you for your answer!
> We have the following idea: There is a thin foil in the nozzle of a
> particle therapie device. This foil has mesh structure and therefore:
> 1. shifts the Bragg Peak of C12 Ions
> 2. modulates(broadens) the BP
> We want to take these 2 effects into account in Fluka. As it is quite
> difficult to modell the mesh foil geometrically, we decided to replace
> the mesh foil with a homogeneous one. This will only shift the BP. In
> order to broaden it we want to use the UsrMed routine. The modulation
> function of the foil (probability vs. particle range shift) is already
> known. We want to sample from this function delta_z ("particle shift"
> in cm) and convert it to delta_E using an ICRU49 equation. Delta_E
> will be then added to the original Energy of the particle. This way we
> can artificially broaden the BP.
> Actually we already tried this and it seems to work fine. The only
> problem is that I still use in my equation Z and A from the projectile
> (IPROZ, IPROA), whereas I need the specific Z and A of each particle
> flying into the material. Do you know how I can access them?
>
> Best regards
> Yuri
>
> 2014-08-17 17:32 GMT+02:00 Paola Sala <paola.sala_at_mi.infn.it>:
>> Dear Yuri Simeonov,
>> The energy of particles cannot be changed inside usrmed.f, attempting
>> to
>> do s it would make the program crash or give meaningless results. If you
>> could explain in more detail your problem could try to see if there is
>> a
>> way to solve it.
>> Regards
>> Paola
>>
>>> Dear fluka experts,
>>>
>>> I want to use UsrMed.f routine to modulate the energy of each particle,
>>> which is transported into a user-defined material (Initial source is
>>> C12).
>>> As I calculate the energy using an equation, I need to know the
>>> specific Z
>>> and A of each particle inside the UsrMed (Z will vary due to
>>> fragmentation). Which variables should I use?
>>>
>>
>>
>> Paola Sala
>> INFN Milano
>> tel. Milano +39-0250317374
>> tel. CERN +41-227679148
>>
>


Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
Received on Wed Aug 20 2014 - 12:04:37 CEST

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