Neutron binning near the thermal energy

Scoring
1

Dear Fluka experts.

I would need a distribution of neutron energies below 1keV, particularly around thermal neutron energies. I get this area as one bin up to 10keV. What am I doing wrong?

Best regards
Adam
test.flair (5.8 KB)
test.inp (2.6 KB)
LinLog
LogLog

2

Dear Adam,

you need to select logarithmic binning (…,LogE,…) in the Type option of the USRBDX scoring, with a minimum energy (Emin) of 1.0e-14 GeV to score thermal neutrons.

Cheers,
David

P.S.:

  • The LOW-NEUT card is not needed
  • since you have electrons as primaries, you may want to enable the electronuclear interaction by selecting the ELECTNUC option on the PHOTONUC card.
3

Thanks for the hint. That’s what I thought, it should be a simple matter. Last time I worked on this issue Fluka was returning the low energy neutron spectrum by default.
Regards
Adam

4

Dear Adam,

the different behavior is because starting with the current (4.4-0) version, the point-wise treatment of the low-energy neutrons is turned on by default.

With this, the scoring of the neutrons is only done for the requested energy ranges and binnings, similarly to any other particle types.

Cheers.
David