Re: [fluka-discuss]: IONSPLIT option

From: Francesco Cerutti <Francesco.Cerutti_at_cern.ch>
Date: Thu, 24 Jan 2019 19:37:15 +0100

Hi Paolo,

indeed it has been recently added a check to prevent to unintentionally
simulate ions above 150 MeV/n without having linked into the executable
the respective interaction models (provided by the RQMD and DPMJET
libraries).

In your case, the code suspects that you may have ions (A>1 nuclei) above
150 MeV/n (possibly generated by coalescence) and sees that on one hand
the mentioned libraries were not linked and on the other hand you did not
request to split them (as a crude alternative to nuclear interactions).
If in fact you have such high energy ions, you must link those libraries
by ldpmqmd.
If instead you happen not to have a high energy ion beam and in your
problem actually coalescence cannot produce such energy ions, then the
aborting message was triggered with no valid reason (let us know if this
is the case). The solution to overcome it is still to link RQMD and
DPMJET.

Unless you have specific reasons to split all ions (which, as you
correctly guessed, is NOT an innocent choice), IONSPLIT should be used in
all cases (being coalescence activated) ONLY to split deuterons (A=2)
below 150 MeV/n (based on the manual instructions Andrea recalled below),
for which there is no interaction model available.

Kind regards

Francesco

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. +41 22 7678962

On Thu, 24 Jan 2019, Andrea Fontana wrote:

> 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:
>
> For
> SDUM
> = IONSPLITting:
>
> WHAT(1)
> : flag for activating ion splitting into nucleons
> < 0.0 : false, no ion splitting
> = 0.0 : ignored
> > 0.0 : true: ion splitting is activated
> Default
> = -1.0 (no ion splitting)
>
> WHAT(2)
> : minimum energy for ions (GeV/n) above which splitting into
> nucleons will be performed
> =< 0.0 : ignored
> Default
> = 0.1 GeV/n
>
> WHAT(3)
> : maximum energy for ions (GeV/n) below which splitting into
> nucleons will be performed (default: 5 GeV/n)
> =< 0.0 : ignored
>
> WHAT(4)
> : minimum ion mass for splitting (default: 2)
>
> WHAT(5)
> : maximum ion mass for splitting (default: 500)
>
> WHAT(6)
> : flag for the spliting algorithm
> = 0.0 : deprecated since Fluka2011.2x (default)
> = 1.0 : probability according to 1 - exp(- Ek/n / Emnspi)
> where Emnspi=
> WHAT(2)
> 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,
> Andrea
>
>
> 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 don’t 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: andrea.fontana_at_pv.infn.it
> Via Bassi 6 web : www.pv.infn.it/~fontana
> 27100 PAVIA, Italy
> ========================================================================
>
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Received on Thu Jan 24 2019 - 20:52:54 CET

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