Re: [fluka-discuss]: UsrMed Energy modulation

From: Yuri Simeonov <>
Date: Mon, 18 Aug 2014 14:58:36 +0200

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

2014-08-17 17:32 GMT+02:00 Paola Sala <>:
> 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
Received on Mon Aug 18 2014 - 16:22:28 CEST

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