Re: [fluka-discuss]: Isotope energy spectrum simulation

From: Andrea Fontana <>
Date: Fri, 12 Jul 2019 10:07:16 +0200

Dear Francesco,
  your input file looks fine, but I send you a revised version that
contains a few adjustements the should put you in the right direction.

A few comments:

- Fluka provides a set of well designed and optimized
   scorers, far more powerful than ascii EVENTBIN (which by the
   way would require extra work for post-processing the reults
   to produce a plot): I suggest you to try the DETECT card,
   as in the example I send you;

- your e-/e+ production threshold (1 MeV) with EMFCUT was to high
   to reproduce the multiple Compton part of the spectrum:
   I reduced it to 1 keV;

- consequently, the FUDGEM parameter is set to 0 to
   correctly take into account the atomic electrons;

The result is the attached spectrum which is automatically
processed and plotted by Flair. If I am not mistaken, one
can recognize the 661.6 keV line from Ba-137m, the 625.67 keV
from internal conversion and the 32.19 keV line from the K_alpha
X ray.

Hopefully this helps: you could try to simplify the problem
by using a single element material or a different geometry.
Do not forget that Fluka gives you the ideal lines, i.e.
witout any detector effect like finite resolution or efficiency:
so lines will never be broadened in case you put a NaI detector,
for example. These effects must be further simulated by including
for example a Gaussian smearing of the line as detector response:
in Fluka you can do it in the MGDRAW routine.

Kind regards and ciao,

On 11/07/2019 19:23, Pierfrancesco Ulpiani wrote:
> Dear Fluka Experts and Users,
> I would like to reproduce an experimental energy spectrum of different
> radioactive sources (i.e Cs, Na).
> I tried to use the card BEAM with sdum=ISOTOPE together with the
> mandatory cards (hi-prope,raddecay...) but it doesn't reproduce the
> expected spectra. Attached the input file where I tried to simulate
> the Cs energy spectrum (the detector is just an RPP).
> May you help me to find out were I am wrong?
> Thank you all
> Pierfrancesco

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

(image/png attachment: cesio_isotope_17_plot.png)

Received on Fri Jul 12 2019 - 11:45:46 CEST

This archive was generated by hypermail 2.3.0 : Fri Jul 12 2019 - 11:47:30 CEST