GEM detector as a neutron spectrometer for fusion plasmas: some modelling and design aspects

Abstract Measuring fusion neutron spectra can give essential information on ion fuel ratio and ion temperature in the plasma core, which are the goals of the High-Resolution Neutron Spectrometry (HRNS) on ITER. At the highest fusion powers, this role is foreseen to be fulfilled by a Thin-foil Proton Recoil (TPR) system with ΔE-E silicon detectors. The concept of performing TPR neutron spectroscopy with a Gas Electron Multiplier (GEM), so-called NS-GEM, instead of solid-state detectors has recently been proposed in [6]. Based on simulation results, the concept of a compact NS-GEM detector has been developed and a demonstrator has been prepared, starting with a standard 3-stage GEM detector. Modelling efforts allowed evaluating the reachable energy resolution for such NS-GEM demonstrator, considering the following issues: neutron collimation, recoil proton generation efficiency, recoil proton scattering and energy losses in the converter and detector. In this contribution, some design and modelling aspects are briefly reviewed and directions of future research to improve the NS-GEM performances are drawn.