Re: Fluka_neutron_fluence_always_zero

From: Alberto Fasso' <fasso_at_SLAC.Stanford.EDU>
Date: Wed, 29 Feb 2012 10:35:41 -0800 (PST)

Dear Vahan,

to get neutrons and protons with an incident electron beam, you need to
switch on photonuclear reactions in the materials present:
And since photonuclear reactions have a very small cross section compared
to other photon reactions, you need also to bias the photon hadronic
mean free path:
LAM-BIAS 0.0 0.02 1.0 PHOTON

Look up these two commands in the manual to understand better how they
are used.

You say also that you cannot get photon fluence. Your input is set for protons,
not photons, so the above explanation is valid.
To calculate photon fluences, you cannot use USRCOLL: it can be used only for
neutrons and hadrons. Use USRTRACK instead.


On Tue, 28 Feb 2012, vahan petrosyan wrote:

> Hi I am a student and try to use Flair under XP with VirtualBox. I setuped
> it successfully but I have One problem.
> My example: Electron beam with 3Gev energy falls on COOPER target.
> Whatever I do, I changed electrons energy and particle number, I get always
> ZEROES in output for neutron or photon fluence.Why? Is it a bug or I did
> something wrong? I followed according flair documentation.
> I tried both USRCOLL and USRTRACK card without luck. I tried these cards for
> Photon fluence they worked. Problem with neutrons.
> I attached my input file. If you have a time could you take a look?
> If you help me I will be very appreciate.
> With regards V. Petrosyan
Received on Thu Mar 01 2012 - 10:34:35 CET

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