Dear Niklas,
if the binning is by region, the result is not "displacements per atom",
it is DPA*Volume. It means, that the code correctly applies the
normalization for density, not the one for total mass.
I take the occasion to rectify my previous answer: for cartesian/r-phi-z
binning the result is normalized per cm^3 for most quantities, it is
directly in DPA for DPA-Scoring.
Both methods are correct, the scoringf by region means that you'll have to
insert a normalization offline.
Scoring with a "grid" binning gives also the possibility to look at the
space distribution of DPAs within your scoring region.
Hope this helps
Paola
> Dear Paola,
>
> thanks for your answer!
>
> If Fluka does not calculate the volume, how can it then know the proper
> amount of atoms it needs to relate the number of displacements to? Is
> there a need to further process a value from the region binning?
> I want to have an average dpa value for the whole region (target). What
> would be the "correct" value then in your point of view, that one obtained
> by region binning or by binning with a bin number of 1 (which represents
> the whole target)?
>
> Kind regards,
> Niklas
> ________________________________________
> Von: Paola Sala [paola.sala_at_mi.infn.it]
> Gesendet: Sonntag, 1. März 2020 21:25
> An: Ophoven, Niklas
> Cc: fluka-discuss_at_fluka.org
> Betreff: Re: [fluka-discuss]: DPA-SCO card
>
> Hello
> Results from USRBIN by region are not normalized. Fluka does not calculate
> the volume of each region. On the contrary, results from cartesian or
> r-phi-z binning are normalized per cm^3, since the bin dimensions are
> known to the code.
> Regards
> Paola
>> Dear experts,
>>
>> Iam a Fluka beginner and Iam using the DPA-SCO card to evaluate the
>> number
>> of displacements per atom in an accelerator target irradiated with
>> protons. Previous SRIM simulations gave me a dpa value of ~50dpa/year
>> for
>> protons, Fluka simulations gave me a value of ~1000 dpa/year for protons
>> (both values are with respect to the average beam current). So far I
>> thought this huge discrepancy (~factor 50) is due to the fact that SRIM
>> lacks the prediction of nuclear reactions, however these seem not to
>> play
>> a huge role for my simulations.
>>
>> I have evaluated the dpa with the USRBIN card for the whole region
>> (region
>> binning) of interest (the target) with the following input sequence:
>>
>> --------------------------------------------------------------
>>
>> USRBIN 12. DPA-SCO -21. TAR
>> DPATARPr
>> USRBIN TAR
>> &
>> AUXSCORE 2.0 PROTON
>> DPATARPr
>>
>> --------------------------------------------------------------
>>
>> In order to clarify the discrepancy above further I have done a
>> simulation
>> with one single bin inside the region (target), which means I evaluate
>> the
>> whole region and that should lead to the same result as the region
>> binning
>> in principal or? The input sequence part for that is shown in the
>> following lines:
>>
>> --------------------------------------------------------------
>>
>> USRBIN 11. DPA-SCO -21. 5.64
>> 100.5DPAtarPr
>> USRBIN 0.0 100.0 1.
>> 1.0 &
>> AUXSCORE 2.0 PROTON DPAtarPr
>>
>> --------------------------------------------------------------
>>
>> However, the value I obtain then seems to be much more correct with
>> respect to my SRIM simulation, with ~20dpa/year. It is interesting, that
>> the factor between these values (1000 and 20) is ~50, which is exactly
>> the
>> volume of the region (target). Once the geometry with all regions and
>> bodies is properly defined without any errors (and that is the case)
>> Fluka
>> should automatically take the according volume or? Is it necessary to
>> divide dpa values obtained with a region binning and the DPA-SCO card by
>> the value (without units) of the volume of the corresponding region? If
>> so, why does Fluka not automatically perform that division?
>>
>> I would be very thankful if someone is able to answer my question or
>> could
>> give me a hint.
>>
>> Kind regards,
>>
>> Niklas Ophoven
>>
>>
>>
>>
>>
>>
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>>
>
>
> Paola Sala
> INFN Milano
> tel. Milano +39-0250317374
> tel. CERN +41-227679148
>
>
>
Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
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Received on Mon Mar 02 2020 - 10:19:33 CET