Re: [fluka-discuss]: IONSPLIT option

From: Andrea Fontana <>
Date: Thu, 24 Jan 2019 15:53:09 +0100

Dear Paolo,
 ††††† the IONSPLIT option has been recently improved (since the FLUKA
version 2011.2x), in particular for what concern the meaning of the
parameters WHAT(4)-WHAT(6) in the PHYSICS card: they were not used
in previous versions of Fluka and I suspect that in your input files
you have the condition WHAT(6)=0, which is now deprecated.

The online manual was also recently updated and reads as follows:

  = IONSPLITting:

  : flag for activating ion splitting into nucleons
              < 0.0 : false, no ion splitting
              = 0.0 : ignored
> 0.0 : true: ion splitting is activated
  = -1.0 (no ion splitting)

  : minimum energy for ions (GeV/n) above which splitting into
                nucleons will be performed
              =< 0.0 : ignored
  = 0.1 GeV/n

  : maximum energy for ions (GeV/n) below which splitting into
                nucleons will be performed (default: 5 GeV/n)
              =< 0.0 : ignored

  : minimum ion mass for splitting (default: 2)

  : maximum ion mass for splitting (default: 500)
  : flag for the spliting algorithm
              = 0.0 : deprecated since Fluka2011.2x (default)
              = 1.0 : probability according to 1 - exp(- Ek/n / Emnspi)
                        where Emnspi=
  and Ek/n is the kinetic energy
                        per nucleon of the current ion
              = 2.0 : not implemented
              = 3.0 : deuteron splitting performed at interaction
                        point computed according to a parameterized
                        formula, like 1.0 for heavier ions

You could try with these new settings.

Hope this helps.
Kind regards,

On 24/01/2019 11:24, Paolo Giunio Pisano wrote:
> Good morning,
> I received two different Fluka input files used for activation
> calculations. If I try to run them as they are, the execution is
> terminated right away and I get the following message:
> Coalescence activated and beam above BME† limit with no rQMD
> And no or incompatible IONSPLIT option!
> The problem is quickly solved if I switch on the IONSPLIT card (as
> suggested by the error message). However, it is my understanding that
> these two input files were running just fine (i.e. without IONSPLIT
> option) a few years ago (ca. 2013?). Is that possible? If yes, has the
> IONSPLIT option become strictly needed once the coalescence is
> activated in more recent versions of the code?
> From what I have read on the manual, the IONSPLIT option handles ions
> interactions by treating the nucleons one at the time and by
> superimposing their effects. Can someone, please, tell me if I should
> be careful in using this option or it is not expected to possibly
> affect the results in a negative way? Since I donít really know the
> physics behind it and I cannot run the model without it, it is hard
> for me to get a feeling about it.
> Thanks in advance,
> Paolo Pisano

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
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Received on Thu Jan 24 2019 - 17:14:19 CET

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