Dear Fluka team,
I calculated a neutron spectrum outside the shielding of an electron accelerator (1.7 GeV) and used that spectrum for sampling in a simple geometry:
an isotropic irradiating neutron source in the center of the coordinate system, surrounded by vacuum and a sphere just used for USRBDX
counting. It is just a test to see, if the sampled spectrum is the same as the original one.
What I found is a similar spectrum, but it has several zero bins in the low energy region < 20 MeV. (This behaviour is not a statistic effect, it occurs also
when 7E9 neutrons are sampled and it is not an effect of a wrong integrated and normalized spectrum function used in source.f, using source.f outside Fluka, an almost identical spectrum is returned).
It seems to be an artefact of the neutron transportation similar to the one described in chapter 10 of the manual, which is in that case a result of the interaction of neutrons with matter.
Could you recommend optimized transport/threshold parameters to reduce/avoid this problem?
Best regards
Klaus Ott
HZB/BESSYII Berlin Germany
________________________________
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
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Received on Mon Dec 12 2016 - 17:13:37 CET