Dottorato in FISICA DEGLI ACCELERATORI

Titolo della tesi: Upgrade of the accelerator-driven Frascati Neutron Generator: α/n correlation measurements for the installation of a trigger system

This PhD dissertation is devoted to the upgrade of the Frascati Neutron Generator (FNG). The research and development activity carried out at the FNG facility is composed of two parts: i) The production of a code to make available for the FLUKA software a source routine able to simulate accurately the whole FNG spectrum (both neutrons and α/He^3); ii) A simulation activity devoted to study the feasibility of the new upgrades for FNG. In particular, I performed a feasibility study for the installation of a trigger system at FNG to make time and space correlated measurements between α particles and neutrons generated by the DT fusion reactions. To this aim, it is of extreme importance to study the time and spatial correlation between them. First, I converted a code that reproduce the FNG’s neutron spectrum from the MCNP software to FLUKA. Then, I extended the code to allow it to reproduce the whole fusion reaction spectrum Second, I set up a series of dedicated Monte Carlo simulations using the FLUKA code to validate the new source routine. After, I used it to study the α/n spatial correlation. The conversion and validation of the source code were successful. The upgrade of the source allowed now to represent a more realistic fusion spectrum produced at FNG. The measurement of the α/n correlation showed that this is maintained between the ~50%÷70% of the cases. The main cause of the decreasing of the α/n correlation has been the neutron scattering with air.