Figures from references [51], left, and [52], right. The left figure shows the effect of taking into account the Doppler broadening with the SVT technique on the scattering angle of the neutron on a 12C free gas target; the upgraded version of Geant4 becomes in excellent agreement with the reference code TRIPOLI-4^® [57]. The right picture shows the energy distribution after scattering on a heavy 238U target at 300°K of 6.52 eV incident energy neutrons. In here, Geant4 has been upgraded with the DBRC technique; a very good agreement is shown with TRIPOLI-4^®.