RE: [fluka-discuss]: Neutron activation in Fluka

From: Joachim Vollaire <>
Date: Tue, 2 Jun 2015 19:56:55 +0000

Maybe to complement Mikhail suggestions. If you have the energy dependant neutron spectra information, you can fold the spectra to radionuclides production cross sections. If you consider, all production channels in the concerned material (reactions on different target nuclei leading to the same produced isotopes) and associated atomic density of the target nuclei you can calculate the production yield for the concerned isotopes.
Now if you want to score the radionuclides inventory for a given irradiation pattern and cooling time, you need to resolve the Bateman equations looking at the decay scheme of each produced radionuclides determined with the previous method. Consider that some radionuclides can be produced by decay of several radionuclides…. You can use the WHAT(4) of the LOW-NEUT card with maximum details printed to have information on the produced radionuclides by low energy neutrons in your material (it will create big .out file so do it for a single run) ….

So as you can see both the production yield calculations and resolution of the Bateman equation requires a lot of post-processing, thus I would strongly recommend using the built-in method available in FLUKA to avoid mistakes. I would only do it “manually” for radionuclides produced on traces for which the statistics may not be sufficient with the built-in method….
Hoping this help

From: [] On Behalf Of "Mikhail Polkovnikov <?????? ???????????>"
Sent: 02 June 2015 15:26
To: Ngoc-Duy Trinh;
Subject: Re: [fluka-discuss]: Neutron activation in Fluka

On 02.06.2015 10:46, Ngoc-Duy Trinh wrote:
Dear FLUKA users,

I want to calculate the residual nucleides due to neutron activation with a given neutron spectra in 260 groups calculated before by another FLUKA simulation ? I dont want to put all my simulation in the same time to reduce the time of calculation, so i want to know is it possible to calculate like this ? and how can i do it ?

Best regards.

TRINH Ngoc Duy
Stagiaire - Service de Physique - Grand accélérateur national d'ions lourds
Master 2 Instrumentation nucléaire - Université de Bordeaux<> -<> -<>
Tél : 0783188922
Dear Ngoc-Duy Trinh,

There are two ways.

The first one is to use the "two-step methods" as described in (slides 43-49). The second one is to sample a given neutron spectrum into SOURCE routine within a new geometry (which is a part of the whole simulation).

In both cases you have to use SOURCE routine, but the second approach might be much easier.

Best regards.

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Received on Tue Jun 02 2015 - 23:29:41 CEST

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