I am doing a simulation that checks the number of alpha particles by irradiating neutrons in silicon. The Physics list is using FTFT BERT HP. The neutron irradiation below 20 MeV seems to be similar to the experimental results, but above 20 MeV seems to produce less alpha particles. So I am wondering if I can change the cross section data above 20 MeV. Or I am wondering if there is another way to do a different neutron cross section above 20 MeV.
I am currently using version 10.5.