Re: [fluka-discuss]: All Particle GCR Simulations

From: Answers <answers_at_pcfluka.mi.infn.it>
Date: Wed, 2 Sep 2020 17:35:27 +0200 (CEST)

Dear John

the way Fluka interpolates those number is basically a 4 point, two
weighted parabols, log-log interpolation.
Take into account that the code does not sample from the
spectra in an analogue, way, rather it samples from a less steep
distribution correcting properly the particle weights in such a way to
avoid to oversample the low energy part and only rarely sample the highest
energies (the natural spectrum is very steep).

Anyway, I'll privately send you the relevant routines so that you can see
by yourself what the code does. If you plan to prepare GCR spectra updated
to the most recent results (eg AMS ones) wrt those presently distributed,
we are interested in updating our spectra as well. The best would be to
have so called "interstellar medium" spectra, that is spectra with the
solar modulation unfolded, indeed our modulated ones are produced out
of "interstellar" ones derived with some adjustement from NASA work of the
late 90's.

Concerning Dpmjet2.5, indeed it is no longer part of the distribution. The
latest version of Dpmjet3, thanks to the work of Anatoli Fedynitch, is now
able to deal with all projectile/target combinations up to the highest
energies. It has been cross-checked with LHC data where it performs
significantly better than Dpmjet2.5 or previous Dpmjet3 versions.
Therefore there is no longer any need for Dpmjet2.5 which is now obsolete.

Concerning the module for the source access, indeed there was a problem,
thanks for reporting it. Now it should be solved, let us know if you
still meet issues.

                    The Fluka developers

  On Tue, 25 Aug 2020, Brittingham, John M. wrote:

>
> Dear FLUKA experts,
>
> I am trying to run a simulation in free space using the all-particle GCR
> spectrum at 500 MV. The two available sets of zzphi####.spc files each show
> a list with 50 items, with the first number in the list is the energy of the
> incident particles (in MeV/n), with the second number representing the
> abundance in /cm2/s/sr/(MeV/n).
>
> From the provided files, I am trying to make my own spectrum for 500 MV, and
> it would be helpful to be certain of some of the details about how FLUKA
> reads these files and samples the spectrum based on the numbers in these
> files. For instance, it appears that some sort of curvefit is applied
> between the energy points, but I have not been able to discern how the fit
> is produced.
>
> Also, I do not see the DPMJET-II.5 model in the 2020.0 distribution. I have
> searched for the file ldpm2qmd but have not located it. Was it removed from
> earlier distributions?
>
> Finally, I am trying to fill out the form on fluka.org to request the source
> code so that I can examine these issues more closely, but the required pdf
> is not loading properly when I enter my information.
>
> Thank you in advance for your help.
>
> John
>
>
>

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Received on Wed Sep 02 2020 - 19:23:50 CEST

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