Hallo Angel,
the number of groups is 260 in the range of 1e-5 eV = 1e-14 GeV (not 10
keV as you write or 1 MeV as in your scoring) to 20 MeV.
You did not specify the minimum kinetic energy for scoring, so you get the
default value of 1 MeV for your log choice. This way you are cutting all
the spectrum below and you get only the 102 pre-defined bins between 1 MeV
and 20 MeV.
Concerning the additional number of bins above 20 MeV, this is calculated
by FLUKA according to your desired energy interval width, determined by
the energy limits (20 MeV and - by default - 1 MeV) and the number of
intervals (100) you input in USRBDX (keeping in mind that you asked for a
log binning).
About integration, this is already provided in the _sum.lis file and your
recipe is wrong, since you take the double differential distribution and
you forget to integrate over the solid angle interval.
Best regards
Francesco
**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. +41 22 7678962
From: Angel <a.demerdzhiev_at_phys.uni-sofia.bg>
Date: Wed, 13 Feb 2019 18:33:09 +0200
Dear FLUKA users and experts,
I need to score the neutron fluence enegy spectrum, but in my case most of
the neutrons are bellow 20 MeV. For the test I used the option -
Phi2,Log(E),Lin(Omega) (attached .inp file). But since the upper energy of
the USRBDX card is above 20 Mev and I have selected that the number of the
energ bins is 100 how much energy bins I should expect to obtain? In the
presentation about low energy neutrons I have found that the number of
energy groups is 260 (in the range of 0.01MeV to 20 MeV). In the
CERN-2005-10. pdf is mentioned 72 groups. When I look at the tab.lis file
with the results the number of energy intervals for my case is 108. My
point is that I am clearly misunderstanding something probably even in the
definition of energy group and energy interval.
My other issue is that I need to integrate the fluence. For the purpose if
I should take the parts of the .tab.lis file which start with the
following:
# double differential distributions
# number of solid angle intervals 1
# Block n: 1 0.00000000 : 12.5663710
9.778E-04 1.003E-03 3.542E-03 1.338E-01
1.003E-03 1.054E-03 3.548E-03 1.198E-01
1.054E-03 1.108E-03 4.369E-03 6.623E-02
1.108E-03 1.165E-03 5.045E-03 7.337E-02
and here the first two columns are the intervals of the energy bins, the
third is the fluence, and the forth one is the error. So from here I just
should take the difference from the first two columns and multiply it to
the third?
Best regards,
Angel
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Received on Mon Feb 18 2019 - 11:43:22 CET