Re: [fluka-discuss]: neutrons, reaction rates

From: Andrea Fontana <andrea.fontana_at_pv.infn.it>
Date: Wed, 31 Oct 2018 14:27:43 +0100

Hi Angel,
    in your case a normalization volume WHAT(6)=1 in the RESNUCLEI
card will not be necessary: it just just a number by which the final
score is divided.

Regarding the irradiation profile, if I understand correctly your
problem, I see that you have not defined ant DCYTIMES card nor a
DCYSCORE card: in this case, as stated in the manual under DCYSCORE,
no particles originated from radioactive decay can be scored and
any detector will only score the prompt particles. This might be
the source of the behaviour you observe. I think thst you need
to define DCYTIMES (a 0 value means EOB) and DCYSCORES associated
to your RESNUCLEI cards (details in the manual).

In addition, I suggest you to enable full ion transport with:

IONTRANS -2

to have a more accurate energy deposit by fission fragments and
fragments from Fermi break-up.

The isomers patch is not active when simulating analog decays.

I send you a second revised input, where I score, for example,
residual nuclei after 1h from EOB and I see 92mNb. I save the
output in a separate file (UNIT=24). Please, give it a try...

Hope this helps,
Andrea

Il 31/10/2018 10:46, Angel ha scritto:
> Dear Andrea,
>
> thank you so much for the help and the advice! The results I'm comparing
> with are presented as [x10^-24/nuclide/source neutron] (I suppose the
> 10^-24 stands for barn). Thus I thought there is no need to normalize it.
> Anyway normalizing it made the results to differ even with additional one
> order of magnitude.
>
> I also tried to change the irradiation profile but it doesn't seem to have
> any effect - I get the same numbers. Is this expected for this model?
> Maybe I should try to change the beam profile?
>
> What should be scored in the Nb detector/foil is the isomer 92mNb. So I
> also tried switching on the patching for isomers but it is probably
> activated by default thus that didn't have effect.
>
> To have proper results for 198Au I need much better statistics. Thus my
> idea was to deal first with the 92mNb before running the model with more
> primaries.
>
> Best regards,
> Angel
>
>> Dear Angel,
>>    you are missing the correct volumes in the RESNUCLEI cards (that
>> in your case are 0.1 for NbDet and 0.00025 for AuDet regions). This
> volume is used to normalized the results and is needed if you want to
> compare with experimental results. If you add the correct values, you
> should get more reasonable results.
>> Other minor things I noticed in your input:
>> - when defining a material, if you need the natural isotopic
>>   composition, use WHAT(6)=0 and do not specify WHAT(2)
>>   (see also the manual);
>> - you can skip Z definition in a MATERIAL for a COMPOUND:
>>   it is ignored.
>> I attach a revised copy of the input file.
>> Hope this helps,
>> Andrea
>> Il 30/10/2018 13:21, Angel Demerdzhiev ha scritto:
>>> Dear FLUKA experts and users,
>>> I am a beginner trying to calculate the reaction rates at different depths
>>> in a concrete block in Nb and Au activation foil for a 14.1 MeV neutron
> source.
>>> For a reason not known to me I get results which differ in two orders
> of
>>> magnitude of what is expected. Can you take a squiz at my .inp file and
> tell me if I am doing anything wrong.
>>> Kind regards,
>>> Angel
>> --
>> ========================================================================
> 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
>> ========================================================================
>
>
>

-- 
========================================================================
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 Wed Oct 31 2018 - 15:36:23 CET

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