Re: [fluka-discuss]: Proton elastic nuclear interactions in water

From: Francesco Cerutti <>
Date: Thu, 4 Jun 2015 00:19:15 +0200

Dear Joakim,

as a preliminary remark, note that switching off delta rays alters the
spatial distribution of dose.

Concerning nuclear elastic interactions, your assumption is correct (no
generation number increase for the projectile reappearing in the final
state: if it was a BEAMPART, it remains BEAMPART).

Coming to your questions:

1) It is possible to realize if an nuclear elastic reaction took place and
then inhibit the dose scoring. Nevertheless, this implies the use of user
routines: mgdraw (in the USDRAW entry, assign a specific integer value to
the user flag LLOUSE of (TRACKR) in case ICODE .EQ. 100) and comscw
(for the relevant JSCRNG value, i.e. the one corresponding to the
dose [energy density] binning you already restricted to BEAMPART -
through AUXSCORE I suppose -, set LSCZER to .TRUE. in case LLOUSE turns
out to have the above value).

2) The higher energy one.

3) Not at all, it applies only to the special case of low energy neutrons.

Hope this helps


Francesco Cerutti
CH-1211 Geneva 23
tel. ++41 22 7678962
fax ++41 22 7668854

On Fri, 29 May 2015, Joakim da Silva wrote:

> Dear Fluka users,
> I am simulating beams of protons in the therapeutic energy range (~70-250
> MeV) impinging on a water tank and am trying to separate the dose
> contribution from protons that have suffered only electromagnetic
> interactions from that of protons and other species that have been involved
> in nuclear interactions. This far I have been scoring BEAMPART together with
> delta ray production switched off to get the dose from primary particles.
> However, if I understand things correctly, elastic nuclear interactions do
> not change the particle generation, and therefore protons that have undergone
> such interactions are still counted as BEAMPART. This leads me to a few
> questions:
> 1) Is there an easy way to separate out the dose from beam particles that
> have undergone also elastic nuclear interactions? I am interested mainly in
> elastic interactions with hydrogen if this makes a difference.
> 2) Assuming the above is valid also for elastic interactions with hydrogen,
> how is it determined which of the resulting protons is the beam particle,
> i.e. is it by highest energy, random, or something else?
> 3) In a previous thread it is mentioned that no distinction is made between
> elastic and nonelastic interactions for neutrons at low energies, and thus
> that both increase the particle generation. Does this apply also to protons,
> and, if so, what is the energy threshold?
> Many thanks in advance for your help!
> Best regards,
> Joakim
> __________________________________________________________________________
> You can manage unsubscription from this mailing list at

You can manage unsubscription from this mailing list at
Received on Thu Jun 04 2015 - 01:47:02 CEST

This archive was generated by hypermail 2.3.0 : Thu Jun 04 2015 - 01:47:03 CEST