EFDA-JET-CP(04)01/12
Neutron Measurements on JET using an NE213 Scintillator with Digital Pulse Shape Discrimination
A Digital Pulse Shape Discrimination system (DPSD) has been used in conjunction with collimated NE213 scintillators for neutron spectroscopic measurements at high count rates (MHz range) in JET discharges (DD and DT fueled, NBI and RF heated). The system, developed at ENEA-Frascati, is based on a commercial 200 MHz 12-bit A/D transient recorder card, which digitizes the direct output signal from the anode of a photomultiplier. Among the unique features of this novel DPSD system are the possibility of post-experiment data re-processing, high count rate operation and simultaneous neutron and gamma (g) spectroscopy. Separation between g and neutron (n) events is performed by means of dedicated software exploiting the charge comparison method; separate n and g pulse height distributions and an example of neutron spectrum unfolding are shown. Implications of the DPSD in future neutron diagnostic systems on large and next step tokamaks are discussed. Subject Classification: Fusion products, neutrons