Thermal neutron detection using MCNP

In summary, to detect thermal neutrons with an energy of 0.025 Ev using MCNP, it is recommended to use an energy bin card for the tally. This will result in three tallies for different energy ranges, with the lowest being everything under half an eV. It should be noted that thermal neutrons are a distribution, so it is not expected to have neutrons at exactly 0.025 Ev. Therefore, it is necessary to include the cutoff or PHYS:N cards in the input file to handle the low energy bin. It is worth mentioning that while the traditional cutoff for photons and electrons is 1keV, there is no default low energy cutoff for neutrons. The ACE data tables traditionally have a lower energy