From: Alberto Fasso' (fasso@SLAC.Stanford.EDU)
Date: Sun Sep 24 2006 - 01:04:24 CEST
In FLUKA, neutrons with energy lower than 19.6 MeV are transported and
scored in the frame of a multigroup algorithm. In the present neutron
cross section library there are 72 energy groups.
It is not possible to score with a better resolution than offered by the 72
groups. The program "knows" that a neutron is in a particular energy group,
for instance in group 59, which means that its energy is somewhere between the
lower and upper limit of the group (in this case between 0.61442 eV
and 1.0130 eV) but its exact energy is not defined.
For neutrons with energy higher than 19.6 MeV, transport is
continuous and scoring can be done with any resolution.
So, for what concerns neutron energies < 19.6 MeV:
- it is not possible to request more than 72 energy bins
- the limits of the energy bins are forced to coincide with those
of the energy groups in the cross section library
Above 19.6 MeV you can request as many energy bins as you wish.
A new library with many more, finer groups is in preparation.
Alberto
On Sat, 23 Sep 2006, Bhushankumar Jagannath Patil wrote:
> Hello,
>
> I am using USRBDX card to score neutron fluence as
>
> USRBDX 101.0 8.0 -61.0 7.0 6.0
> 145.32PhFluenUD
> USRBDX 0.015 1e-14 100.0 &
>
> in this example i have asked for 100 energy bins between the enrgy range
> 15 MeV to 1e-5 ev. But the *.tab.lis giving only 72 energy bins in the
> enrgy range 1e-5 ev to 19.6 MeV. where i had made a mistake? when i am
> using following USRBDX card then also it is giving 72 enrgy bins with the
> same enrgy range.
>
> USRBDX 101.0 8.0 -61.0 7.0 6.0
> 145.32PhFluenUD
> USRBDX 1e-08 1e-14 100.0 &
>
> So i want to know how can i set the max and min energy limit in USRBDX
> card to score neutron energy spectrum in the energy range 1e-5eV to 10 ev
> with 100 energy bins.
>
>
> Thanks
> Patil Bhushankumar J.
>
>
>
-- Alberto Fassò SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025 Phone: (1 650) 926 4762 Fax: (1 650) 926 3569 fasso@slac.stanford.edu
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