Re: [fluka-discuss]: Dysprosium causing problems

From: Answers <>
Date: Sat, 7 Mar 2020 09:15:57 +0100 (CET)

Dear Benji

actually the warning about not linking rQMD is present both when running
with Dysprosium and Terbium, and it is just a warning. For the former,
the reason why the code stops is written in the output file, where
it claims:

   **** Low energy neutron xsec not found for some media 0 1 ****

Indeed the Fluka low energy neutron cross section library does not
contain cross sections for Dysprosium, while they are available for
Terbium. You can find in the manual which low energy neutron cross
sections are available.

You can run using another element/isotope for the low energy neutron cross
sections instead of those of Dysprosium, either by "cheating" the code
with the name (as you did), or (better) by using the LOW-MAT card. In both
cases the results will be wrong for all what concerns neutrons below 20 MeV.
If you really need Dysprosium for neutrons, we could investigate whether
it could be added to the neutron cross section library for the next respin.

BTW the RQMD card is irrelevant and it does not activate/link rQMD, rather
in order to link and use rQMD please use the script flutil/ldpmqmd
which produces an executable named flukadpm3 with both rQMD and Dpmjet-3
linked. If you stick to proton energies =< 100 MeV, like in the example
you sent, you can safely ignore the warning and skip linking rQMD.

On Wed, 4 Mar 2020, Benji Leenders wrote:

> Dear FLUKA users,
> I am running into a strange problem while determining particle production
> per proton on dysprosium.
> When using terbium as a target material the program runs without any
> problems and the same goes for gadolinium-oxides. However when using
> dysprosium the simulation stops with an error without ever producing
> results.
> The error is as follows:
>  Coalescence activated and beam above BME  limit, products badly
>  treated with IONSPLIT
>  link  rQMD  !
> While this error does not show up for the other two cases.
> If I change the name to terbium but give the material the mass and Z number
> of dysprosium the simulation runs but I am not sure that this method is
> proper and will give me reliable results.
> Attached is my input file.
> Kind regards,
> Benji Leenders

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Received on Sat Mar 07 2020 - 11:00:31 CET

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