Re: [fluka-discuss]: Neutrons

From: Francesco Cerutti <>
Date: Sat, 24 Oct 2015 22:37:17 +0200

Concerning your modified input, I reiterate that RADDECAY has no point (I
guess you wanted 6He to decay but this does not look useful and it is
irrelevant with respect to your scoring cards). The hard job here is to
achieve a meaningful statistics for your (gamma,p) reaction, to this
purpose you may have to suitably adjust your LAM-BIAS parameter (in LiF
only), and if needed bias also in advance bremsstrahlung photon production
(in tungsten) as mentioned below. On the other hand, your importance
biasing (BIASING cards) can be dropped.

Concerning the electron energy loss through an aluminum foil, let me point
out that this is not the energy deposited in the foil. The latter can be
scored on average by USRBIN (per region) and on a event-by-event basis by
EVENTBIN. For the energy loss, there is not a specific command. It can be
obtained event-by-event by writing the primary electron energy at the
entrance and at the exit of the foil. This can be done in mgdraw.f (ENTRY
BXDRAW), but it goes beyond a beginner usage of the code and one should
wonder if this is really what he needs.

Good luck

Francesco Cerutti
CH-1211 Geneva 23
tel. ++41 22 7678962
fax ++41 22 7668854

On Sat, 24 Oct 2015, kabytayeva wrote:

> Thank you very much for your help !!!
> 1)I ask you again, please check the following code, there is also obtaining
> helium-6 in 7Li(y,p) reaction. I am a student so I need your help.
> 2) Can I calculate the energy loss of an electron when passing through the
> foil by using Fluka (for example aluminum foil)? If so, how (what command)?
> Once again, thank you very much!
> Francesco Cerutti ΠΙΣΑΜ 22.10.2015 22:07:
>> Hallo
>> First of all, the reaction of your interest - as any other *low energy
>> neutron* reaction, apart from few exceptions documented in the manual
>> - is not simulated *explicitly* in FLUKA. So, out of your USRYIELD
>> scoring, you will never see alpha particles produced by neutrons in
>> Be.
>> You can find instead (uncorrelated) nuclear residues (like 4He and
>> 6He) by RESNUCLEi.
>> Conversely, in principle you can get neutron production in lead from
>> your electron beam, provided that your photon generation (that can be
>> biased by EMF-BIAS with SDUM=LAMBBREM) and photon nuclear interaction
>> length biasing (LAM-BIAS, in lead) is enough. And you can score the
>> neutron spectrum for instance by USRTRACK.
>> Concerning your input:
>> - I would lower the electron/photon transport threshold down to 5 MeV
>> (instead of 10 MeV), below the photonuclear threshold in lead (with
>> EMFCUT). No need for a specific EMFCUT/ELPO-THR card.
>> - your LOW-MAT makes no sense (you assign to the predefined LEAD
>> material ... no set of low energy neutron cross sections; anyway the
>> ones of natural lead at 296K are taken)
>> - LOW-NEUT is useless (with DEFAULTS/PRECISIO, neutrons are
>> transported down to thermal energies)
>> - I do not see the point for RADDECAY, which is intended to ask for
>> radionuclide decay.
>> - In your region definitions, there is no point in repeating more than
>> one time +void (or +target) inside the same zone.
>> - RESNUCLE in the VOID region (VACUUM) makes no sense.
>> - Back to your useless USRYIELD mentioned at the beginning, remember
>> for general use that WHAT(12) (translated by Flair as "Kind") must be
>> 3.0 (double diff. yield) and not 1.0 (double diff. cross section,
>> obtained by multiplying the aforementioned yield by the reaction cross
>> section - in hydrogen, if not differently specified in the same
>> USRYIELD - of the beam, i.e. 22 MeV electrons in your case!).
>> Kind regards
>> Francesco Cerutti
>> **************************************************
>> CH-1211 Geneva 23
>> Switzerland
>> tel. ++41 22 7678962
>> fax ++41 22 7668854
>> On Wed, 21 Oct 2015, kabytayeva wrote:
>>> Hello everyone!
>>> Dear,FLUKA experts!
>>> At the moment I am studying production of helium-6 in the reaction
>>> 9χΕ(n,4He) 6ξΕ, ie, electrons with energy 22MeV are bombarded the
>>> converter, which is made of lead. As a result neutrons are interacted with
>>> the Be target, which is diameter 10cm. And I have the following questions:
>>> 1) Please, check my input file, because I am working with FLUKA recently,
>>> especially the reaction threshold
>>> 2) Can I obtain energies of the neutrons with which they are emitted from
>>> the lead via FLUKA?
>>> Thank you so much!!!

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Received on Sat Oct 24 2015 - 23:53:08 CEST

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