[fluka-discuss]: Neutron interaction cross section at energies below 2 MeV

From: Saneesh N <saneesh_at_iuac.res.in>
Date: Mon, 21 Oct 2019 14:10:54 +0530 (IST)

Dear FLUKA experts,

I am using FLUKA to calculate the efficiency of neutron detector, BC 501A (5" x 5" in dimension) below 20 MeV. EVENTBIN card was used for scoring event by event energy deposition. Then proper detection threshold was applied using 'readbin.f'. Efficiency at a given energy bin was obtained as the ratio of number of neutrons detected above threshold energy to number of neutrons incident. The result was compared to literature reported value (NIM A 608 (2009) 440–446) for identical detectors at similar threshold energies. Please find the attached image file (comparison.png).
It has been observed that FLUKA results deviated considerably at lower neutron energies (below 2 MeV) and GEANT4 shows a reasonably good agreement with the data. Above 2 MeV up to 12 MeV range, we have seen that both FLUKA and GEANT4 simulate experiment data quite well.
Is FLUKA overpredicting neutron interaction cross section at lower energies ? Kindly help me to understand if any mistake happened in the simulation. I have used LOW-MAT card to see changes when H2 from H2O or CH2 are used. But it was not making remarkable difference in efficiency.
Expecting your valuable suggestions to understand the discrepancy,

Thanks in advance ...
Saneesh N
New Delhi







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comparison.png
(image/png attachment: comparison.png)

Received on Mon Oct 21 2019 - 12:17:26 CEST

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