Characterization of a new 4He scintillator detector prototype for the ITER Radial Neutron Camera

In ITER, the reconstruction of the neutron emissivity profile along radial Lines-Of-Sight (LOS) is performed with the Radial Neutron Camera (RNC) diagnostic system. Neutrons produced in the plasma core through D(d, n)3He and T(d, n)4He reactions are measured by the RNC Ex-Port subsystem using three different types of detectors located within modules positioned at the end of each LOS collimator: a plastic scintillator, a 4He gas scintillator and a single-crystal diamond matrix. Considering plasma scenarios foreseen in ITER, measurements during full-power operations rely on the 4He scintillator detector. A new prototype of this device, specifically designed for the ITER RNC system, has been developed and experimentally characterized. This work presents the results of the measurements performed at the Physikalisch-Technische Bundesanstalt (PTB) Ion Accelerator Facility (PIAF) in Braunschweig, focusing on the detector's response to different neutron energies, and at ENEA Frascati Neutron Generator (FNG), where its performance under high neutron fluxes was studied. The new 4He scintillator detector prototype has proven to be suitable for its installation in the ITER RNC Ex-Port detector modules, and capable of reliable operation during the full-power scenarios of ITER operation.