Timing characterization of the TOFOR S2 detectors

TOFOR is a time-of-flight spectrometer dedicated to neutron emission spectroscopy (NES) study of 2.5-MeV neutrons from D plasma experiments at JET. This thesis describes the development, installation and operation of the instrument with focus on its performance. The goal with the TOFOR project was to build a spectrometer optimized for high count rate. An expected upper limit of 0.5 MHz and an energy resolution of 7.4% at 2.5 MeV were achieved. Instrumental details and their relevance for the overall performance are discussed. NES study involves the deduction of the neutron energy (En) spectrum as emitted from the JET plasma from a measured parameter, the time-of-flight (ttof) in the case of TOFOR. Information on plasma conditions such as the ion temperature and the effect of different heating schemes can be obtained from the En spectrum. Optimization of the TOFOR performance thus means improvement of the knowledge of the relationship ttof-En and the factors that impact on this relationship. The thesis describes work done to improve the accuracy of the instrumental settings and to understand all features of the measured TOFOR spectrum, including the impact of scattered neutrons on the total neutron flux on the in-beam detector. TOFOR performance is illustrated through presentation of results that highlight the instrument's capabilities. The characteristic signatures of NB and RF heating in the ttof spectra and the impact of the scattered neutrons are demonstrated and the count rate capability is discussed.