Yes, namely elastic interactions by low-energy neutrons (the word ‘reaction’ implies the inelastic nature of the interaction).
Most likely your post-processing. By the way, where does your ‘expected’ curve come from?
Please upload your source routine too, and the mgdraw routine that you are actually using, since the one indicated in the flair file has a different name.
Also, note that PKAs - as repeatedly discussed on the occasion of your previous posts - shall be looked at in the fheavy stack, being their energy tkheav(1).