R: [fluka-discuss]: Lead prompt gamma spectrum

From: Giuseppe Mazzola <giuseppe1.mazzola_at_mail.polimi.it>
Date: Tue, 6 Apr 2021 10:07:59 +0000

Dear Fluka discuss,

thank you for the response.
I am aware of the groupwise algorithm used by Fluka for the transport of low energy neutron and for the generation of gamma radiations from such particles (with some exceptions) and as a manner of study, I was analysing the difference between Fluka results and MCNP results, which instead uses a pointwise transport and generation algorithm.
I have made the analysis for different materials and confronted with the IAEA Database for prompt gamma radiations.
The spectrum obtained, with the differences in the discrete gamma lines from MCNP and the Fluka peak distributed along the energies of the gamma group, are correct for any materials that I studied with the exceptions of natural lead.
Confronting the two spectrum, Fluka hasn't any evidence of the 7367KeV peak, which should be the predominant peak and it is present in the MCNP spectrum and also tabled by the IAEA Database.
For this reasons, I was wondering if this is related to a problem with my input or something connected to the cross section used by Fluka.
I am sending with this email also the input text and the result comparison between Fluka and MCNP, for a better explanation of my problem.

Kindest regards,
Giuseppe

Da: Paola Sala <paola.sala_at_mi.infn.it>
Inviato: marted́ 6 aprile 2021 11:36
A: Giuseppe Mazzola <giuseppe1.mazzola_at_mail.polimi.it>; fluka-discuss_at_fluka.org
Oggetto: Re: [fluka-discuss]: Lead prompt gamma spectrum


Dear Pierfrancesco

Fluka transports

neutrons below 20 MeV with a groupwise algorithm (see the manual for

details). With this method, photons from neutron captures and

interactions are also produced in energy "groups", not as discrete gamma

lines.

A better treatment is available for a few isotopes (see the manual again).

 Extension to more isotopes is in the to-do list

Regards

Paola


On 4/2/21 7:13 PM, Giuseppe Mazzola wrote:

Dear fluka discuss,



Evaluating the prompt gamma emitted by natural lead, using thermal neutron as source, there is no evidence of the 7367 KeV gamma from Pb207, which should be the predominant peak as tabulated in IAEA database.

I'm using for the low mat card, the cross section associated to the natural lead at 296K.

Could you give me some advices?



Kindest regard,

Giuseppe Mazzola




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Received on Tue Apr 06 2021 - 13:37:54 CEST

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