Studio MC di sorgenti neutroniche con spettro energetico continuo e discreto per applicazioni a SPES

This thesis work illustrates the progress in the development of NEPIR (Neutron and Proton IRadiation facility), a proposed future facility to be built at the Legnaro National Laboratories of INFN to study the Single Event Effects induced by energetic neutrons in microelectronic devices. This facility includes a Quasi Monoenergetic Neutron (QMN) source and ANEM (Atmospheric Neutron Emulator), a continuous energy neutron source with a spectrum similar to that of neutrons naturally present in the atmosphere at sea level in the 1-70 MeV energy range. The thermo-mechanical simulations of the ANEM high power target are here illustrated, together with MCNPX Monte Carlo code simulations of the neutron yields of the candidate materials to build the source. With what concerns the QMN source, the performance of MCNPX in describing neutrons produced by protons in thin Lithium and Beryllium targets was extensively evaluated and found to be unsatisfying: an experimental approach to the problem is necessary. A preliminary study of the capability of the QMN source in reconstructing the cross section of the device under test was performed, using a conservative approach. This study identified the critical factors involved in the determination of the uncertainty of the cross section parameters and indicated the direction of future in-depth investigations to be performed. In particular the possibility to extend the energy range of the facility, thanks to a graphite energy degrader, towards values lower than the current 35 MeV limit of the cyclotron was found to be strategic.