Energy distribution of photoneutrons in laboratory frame from the fundamental (γ, n) energy peak for 20 MeV photons on ¹⁴N from JENDL-5, simulated with MCNP6 (blue lines), PHITS (green lines), TRIPOLI-4 (red lines) and sampled from the nuclear data (black lines). The vertical dotted grey line represents the kinetic energy of the outgoing neutron in the center-of-mass reference frame for this peak, derived using equation (7).