Study of sapphire and MgO as thermal neutron filters for the moroccan TRIGA research reactor beam

In this contribution, the optimization of sapphire filter thickness was performed, for fast neutrons,with GEANT4. For thermal neutrons, interaction cross sections, based on the S(α,β) model, are not yet implemented in GEANT4. The present word focuses on the thermal neutrons interaction with Al₂O₃ and MgO crystals, which are usually used are thermal neutron filters.The LEAPR module of NJOY code has been used to generate the thermal cross sections for Al₂O₃ and MgO crystals, at different temperatures. The phonon density-of-state, required by the LEAPR module, has been calculated using the ABINIT package.The generated cross sections allowed us to study the temperature effect on the quality of each filter and to compare the filtering powers of the two considered crystals.