Hello, everyone,
Recently, I calculate the back-scattering neutron spectra from targets
by using fluka. I find that I just score few neutrons
at the place of 2500 centimeters away from the target at backward
direction. These results are useless due to too few events. I know that
it is because of too few primaries, but at this time I have used
1000000 primaries(protons in my simulation). So I consider using the
biasing card to obtain more neutrons, for example,
* bias: set 1 everywhere
BIASING 1.0 1.0 1.0 1.0 35.0 PRINT
* now bias in steps of 2
BIASING 1.0 1.0 3.0 DE4 DE4
BIASING 1.0 1.0 9.0 DE5 DE5
BIASING 1.0 1.0 27.0 DE6 DE6
BIASING 1.0 1.0 81.0 DE7 DE7
BIASING 1.0 1.0 243.0 DE8 DE8
BIASING 1.0 1.0 729.0 DE9 DE9
The biasing card is working, but I still score the few neutrons. In
fact I want to place a moderator for back-scattering fast neutrons
at 2500 centimeters away from the the target at backward
direction. Maybe there are three reasons for my problem, the first
is too few primaries, the second is too small area for the
detector, the last one is too far distant from the target to the
detector. If I increase the primaries, it will need more cpu
time. Now the 1000000 primaries simulation will spend half of a
day. Someone can given me some experiences for dealing with this
embarrassing situation. Thank you very much!
Jing Hantao
Jinght_at_mail.ihep.ac.cn
2008-11-10
Received on Tue Nov 11 2008 - 09:48:02 CET
This archive was generated by hypermail 2.2.0 : Tue Nov 11 2008 - 09:48:04 CET