A method for digital processing of pile-up events in organic scintillators

Pile-up events in radiation detectors are those in which two or more pulses partly or completely overlap. In standard analog electronics pile-up events are rejected using a pile-up inspector. When digital acquisition techniques are used, the recorded waveforms of pile-ups can be elaborated and the contributing single pulses reconstructed. A method for the off-line digital processing of pile-ups from liquid organic scintillators (NE213) is proposed: pile-ups in which the overlapping pulses are separated more than 15 ns can be reduced to single pulses and then correctly identified as neutrons (n) or gammas (γ). An analysis of the errors introduced by the method is carried out. The method has been applied to data acquired in the mixed n-γ field of JET deuterium plasma discharges from the NE213 detector in the central line of sight of the neutron profile monitor and the results are described.