Digital pulse processing with high-throughput and high-resolution neutron spectroscopy on DD fusion plasmas with spherical ionization chambers

The energy distribution of the neutrons emitted from a DD fusion plasma is derived by unfolding of the proton recoil spectrum measured within spherical ionization chambers. For this procedure, the response function of the detector must be determined. These measurements were performed at the Van de Graff facility, PTB-Braunschweig. To meet the physical properties of the chambers in respect of wall-, induction effect and the electrical field distortions due to the support of the inner electrode, a Monte Carlo Simulation (MCS) has been developed. Measurements and the MCS code show an excellent agreement. onally, a new pulse processing method was used. Conventional analogue processing has been replaced by digital signal processing starting at the output signal of the preamplifier. Pile up rejection is inherently included in the system. Compared with the conventional technique of pulse processing, the new system facilitates an improvement of throughput of approximately a factor of five. Accordingly, high-resolution, time-resolved and on-line spectrum measurements with spherical ionization chambers with improved statistics will become a reality.