Integrating Specific Range of Neutron Energy USRBDX Scoring

Hi everyone, my questions are related to some beginner simulations which I ran, wherein neutrons generated by a target were scored with USRBDX.

1.) I have shown my results in the attached photo. How can I go about correctly integrating the neutron flux within a specific range of neutron energies using Flair?


2.) If I want to improve the statistics, especially on the very extreme low energy neutron limit, what would be the best practice in terms of design of the simulation? Right now, the simulations shown in that plot have 10,000,000 primaries per run, 10 cycles each and I use 5 spawns for the computations. This takes me about 2 hours to run on my current set up.

Thanks so much for your help in advance!

Dear Dalini,

  1. I don’t think it is possible to calculate a partial integral in Flair at the moment. I’m afraid, you will need to do manually, whether processing the tab.lis file with a script or in excel, or calculating the difference of the two appropriate cumulative flux values from the sum.lis file.

  2. It is possible to reduce the inelastic nuclear interaction length of hadrons by a factor λ in the beryllium target with the LAM-BIAS card, but - I assume - you don’t have anything downstream of the target, so you won’t gain that much from it. However, I’m not aware if it is possible bias only the lower energy neutron production.
    See slides 19 and 20 of


Concerning 1.), as @horvathd indicated, I find quite convenient to inspect the cumulative flux printed on purpose in the sum.lis file and just make a difference between the two values referring to the specific energy range limits. The meaning of those values was clarified by @horvathd in a former thread (point 3.).