Development of a neutron/gamma diagnostic for RFX-mod2

Magnetic Confinement Fusion aims to provide a virtually limitless, low-carbon energy source by harnessing nuclear fusion reactions of light nuclei under extreme temperature and pressure conditions, where matter exists as plasma. Magnetic Reconnection (MR) events are fast transient phenomena which directly impact plasma stability, energy losses, and overall efficiency of fusion devices, making their study relevant for the realization of commercial fusion energy. The world's largest Reversed-Field Pinch (RFP) fusion device is currently under development in Padova, Italy, and is called RFX-mod2. In this work, the development of a neutron/gamma diagnostic system for RFX-mod2 is presented. The diagnostic system aims primarily at obtaining experimental information on ion and electron acceleration to suprathermal energies driven by MR events. However, it could also be useful for other purposes, such as enabling neutron yield estimation and, in future RFX-mod2 tokamak discharges, the study of runaway electrons. The main results of neutron and gamma-ray measurements related to MR events, performed in the past at RFX-mod and the Madison Symmetric Torus (MST), are briefly summarized. Their main limitations are identified and the requirements for the new neutron/gamma diagnostic are outlined. The three-dimensional CAD (Computer Aided Design) model of the diagnostic system is presented, along with the need to develop a detector prototype to obtain experimental data at RFX-mod2 before assembling and commissioning the complete diagnostic system. An experimental characterization of the detector prototype is presented, including a neutron/gamma discrimination test.