Re: [fluka-discuss]: Properties of mgdraw

From: Andrea Fontana <>
Date: Tue, 18 Jul 2017 11:31:14 +0200

Dear Kevin,
        I am sorry to hear about these "unexpected results" and, if you
could send more details to the forum, we can try to go deeper in your
issue. Please do not forget that, in addition to the user routines
(MGDRAW and STUPRF), you can get information on the production of
secondaries also from the FLUKA output file.

I expect that changing the FLUKA model will not solve your issue:
as a general advice, to understand a problem it is better to simplify
it than to increase its complexity. The use of DPMJET and RQMD in
FLUKA is important for nucleus-nucleus interactions at medium/high
energy: in your case you have high energy neutrons on ice, that means
that the only nucleus you have is Oxygen and the FLUKA default
executable will work. You can anyway try linking also with ldpmqmd,
as explained in the manual (p. 37).

Hope this helps.


Il 17/07/2017 16:29, Kevin Crust ha scritto:
> Dear Andrea and the Fluka experts,
> Sorry for the much delayed reply, I was out of the office much of last week
> and did not get a chance to try your changes until much later.
> Unfortunately, the changes you made did not completely remedy the issue as
> I still have some unexpected results. After dedicating some time to looking
> deeper into the issue, I believe I may need to implement two extra packages:
> DPMJET and RQMD. However, I cannot find in the manual how to make this
> link.
> Could you please confirm if I am correct that this link is necessary (the
> neutron beam I am using has the energy set to 1 GeV) and if so, how to make
> said link.
> Thank you again,
> Kevin Crust
> The Pennsylvania State University
> Physics and Mathematics
> -----Original Message-----
> From: []
> On Behalf Of Andrea Fontana
> Sent: Saturday, July 8, 2017 3:10 PM
> To: Kevin Crust <>;
> Subject: Re: [fluka-discuss]: Properties of mgdraw
> Dear Kevin,
> I have looked at your files (that I re-attach also for other FLUKA users
> that might be interested) and I have made a little change in the USERDUMP
> card, in WHAT(3), that I change from 4 (source, trajectories and continuous
> energy loss) to 0 (all). In this way you are requesting all events and in
> your MGDRAW.F, if for example you generate 10 primaries, now you will get
> exactly 10 printouts with LTRACK=1.
> The meaning of your print enables to you get information of each segment of
> a track for all particles: therefore, if a track has many segments, you will
> see the same generation number on different lines.
> This is normal and actually you can do a little test, for example, by
> replacing ICE with VACUUM: in this case you will have no interactions and
> all track will start at the origin end end at the boundary of the BLOCKICE
> region.
> The variable LTRACK records the "generation number" of the particle:
> 1 is the primary, 2 is the product of the first interaction (or decay),
> 3 is the product of a secondary re-interaction (or decay) and so on.
> Any discrete event (say interaction, apart from delta/Moller/Bhabha and
> nuclear elastic scattering - but note that for low energy neutrons elastic
> scattering is not disentangled as an independent interaction type - )
> increases the generation number. Asking for LTRACK = 1 is equivalent to ask
> for particles that had no interaction at all.
> This is not exactly equivalent to a real beam particle in an experiment, as
> discussed in this thread:
> I hope this helps. To access more information on secondary particles there
> is a more advanced method, with the STUPRF.F function, that you can find
> discussed here:
> Kind regards,
> Andrea
> Il 07/07/2017 16:20, Kevin Crust ha scritto:
>> Hello Fluka experts,
>> I have been doing some simulations with Fluka in an attempt to model
>> neutron behavior when introduced into ice (I had asked a brief
>> question last month and the responses were very helpful) but I have
>> some questions regarding mgdraw and some other the variables within
>> it. The results I have been getting do not make sense based on my
>> limited theoretical understanding, so I am not sure if I have been
>> doing something wrong in the input/user routine or if I am simply
> misunderstanding my results.
>> First and foremost, what defines a new 'trajectory' by which the main
>> mgdraw will write its set of variables? Does this necessarily mean
>> that a collision has occurred? Additionally, what defines a generation in
> L track?
>> In my data I will sometimes see the same generation appear for a few
>> trajectories in a row, so I am not sure what this represents.
>> Finally, is there any way for me to have Fluka tell me what particle
>> finally absorbs the neutrons that I am introducing.
>> If it would be beneficial, I can attach my input, mgdraw.f, and/or a
>> sample output file to further clarify what I am asking about. Any
>> assistance you could provide would be greatly appreciated.
>> Thanks in advance,
>> Kevin Crust
>> The Pennsylvania State University
>> Physics and Mathematics
>> ______________________________________________________________________
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> --
> ========================================================================
> Dr. Andrea Fontana tel: +39 0382 987991
> Istituto Nazionale fax: +39 0382 423241
> di Fisica Nucleare
> Sezione di Pavia e-mail:
> Via Bassi 6 web :
> 27100 PAVIA, Italy
> ========================================================================

Dr. Andrea Fontana                    tel: +39 0382 987991
Istituto Nazionale                    fax: +39 0382 423241
di Fisica Nucleare
Sezione di Pavia                      e-mail:
Via Bassi 6                           web   :
27100 PAVIA, Italy
You can manage unsubscription from this mailing list at
Received on Tue Jul 18 2017 - 12:42:59 CEST

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