From: Paola Sala (paola.sala@cern.ch)
Date: Wed May 02 2007 - 16:39:39 CEST
Hi
The problem with your input is that Uranium is not a fluka pre-defined
material ( the list of pre-def is in the fluka manual, or in the menu of
the ASSIGNMAT card in FLAIR, for instance),
and there is not a low-energy neutron data set for URANIUM. You can see
the message at the end of your geomneut_u001.out file:
**** Low energy neutron xsec not found for some media 0 1 ****
URANIUM
Low energy neutron cross sections are available for the separate Uranium
isotopes, not for the natural composition. Again, to have the list of
the available low-energy neutron cross section you can have a look in
the manual, section 10} Low-energy neutrons in FLUKA
For your target, you should define URANIUM as a compound made of the
different isotopes. For instance:
MATERIAL 92.0 235.0439 18.95 235.0 235-U
MATERIAL 92.0 238.0508 18.95 238.0 238-U
MATERIAL 18.95 URANIUM
COMPOUND 0.007 235-U 0.993 238-U URANIUM
In this way one defines uranium as 99.3 % 238-U and 0.7% 235 U . The
materials 235-U and 238-U are automatically recognized for what concerns
the low energy neutrons.
Hope this helps
Paola
On Wed, 2007-05-02 at 15:07 +0200, Feracci Vincent wrote:
> Hi,
> I am working on a simulation of an uranium target bombarded by
> neutrons and being quite new with FLUKA I can't seem to use other
> materials than those predefined by FLUKA:
> In this early simulation I am bombarding a cylindric target with a
> 40 MeV neutron beam. The simulation works fine with a carbon target but
> as soon as I try using Uranium or any other material FLUKA doesn't
> generate anything but a log file and rangeomneut_u001 (geomneut_u being
> my input file).
> I have attached geomneut_u.inp which is my file with an uranium
> target which doesn't work and geomneut_c.inp which is the same file with
> a carbon target and which works okay.
> I use Flair V 0.4 to run my simulations, could that be a source of
> problem?
>
> Would somebody be kind enough to tell me what's wrong with my simulation?
> Thank you very much for your attention,
> Vincent Feracci
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