RE: [fluka-discuss]: Problem with neutron radiation and the Nuclear Photoeffect

From: Anton Lechner <Anton.Lechner_at_cern.ch>
Date: Sun, 10 Dec 2017 20:15:39 +0000

Dear Konstantin,

There are some examples at the end of the PHOTONUC section how to use the LAM-BIAS card: on WHAT(2) of the LAM-BIAS card you can apply a reduction factor for the interaction length. The interaction length is given by 1/(N*sigma), where N is the atom density and sigma is the microscopic cross section (in your case the cross section for the giant dipole resonance, which is roughly a few hundred mb in heavy elements). As a rough guidance, one could reduce the interaction length such that it is comparable to the layer thickness.

Cheers, Anton


________________________________
From: Konstantin Rönsch [konstantin.roensch_at_tu-ilmenau.de]
Sent: 10 December 2017 19:09
To: Anton Lechner; fluka-discuss_at_fluka.org
Subject: Re: [fluka-discuss]: Problem with neutron radiation and the Nuclear Photoeffect

Dear Anton,
Thanks for your help!
After some research on fluka.org i use the Card Photonuc and i also choose the Defaults: Precision.
Your Advice with the LAM-BIAS Card is very good, i read the informations for the card but i´m not shure, which settings i should use form my simulation. Could you help me with an advice?
Thank you for your help.
Konstantin, from GER

Am 10.12.2017 um 17:49 schrieb Anton Lechner:

Dear Konstantin,

As already pointed out in the Email below, you have to use the PHOTONUC card in order to activate photo-nuclear interactions. However, there is another issue with the DEFAULTS card: you are using SDUM=NEUTRONS which is only suitable for pure low-energy neutron simulations while electrons are not transported in this case (they are dumped at the spot). Rather use PRECISIO on the DEFAULTS card.

Another important point to consider is that photo-nuclear interactions have small cross sections, so it is recommended to use the LAM-BIAS card for the target in order to bias the interaction length (see the PHOTONUC and LAM-BIAS description in the manual).

Cheers, Anton


________________________________________
From: owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi.infn.it> [owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi.infn.it>] on behalf of Sébastien Wurth [wurth_at_ipno.in2p3.fr<mailto:wurth_at_ipno.in2p3.fr>]
Sent: 05 December 2017 11:49
To: Konstantin Rönsch; fluka-discuss_at_fluka.org<mailto:fluka-discuss_at_fluka.org>
Subject: Re: [fluka-discuss]: Problem with neutron radiation and the Nuclear Photoeffect

Hello Konstantin,

Photonuclear reactions have to be turned on in FLUKA since they are not
by default. See PHOTONUC and PHYSICS cards sections in the manual.

Hope it helps.

Best.

Sebastien.


Le 05/12/17 ŕ 10:24, Konstantin Rönsch a écrit :


Dear Fluka and Flair experts,

as a student at TU Ilmenau, Germany, I am currently working on the
simulation of a Linac-Head.
I want to shoot an 15 MeV electron-beam at a Tungsten-Copper target
and simulate the neutran radiation that occurs because of the Nuclear
Photoeffect.

Unfortunately none of the different produced detectors detected a
neutron radiation,
even when I choose a high number of particals or a very high electron
energy.
I use the Fluka through the Flair Program and a VMBox.
Is it possible that Fluka does not take into consideration the Nuclear
Photoeffect,
or could anyone find a mistake with the Input-File?
I would be very thankful for any feedback or hint.
Yours sincerely,
Konstantin Rönsch,
TU Ilmenai, Biomedical Engineering.


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Received on Sun Dec 10 2017 - 22:30:17 CET

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