Application of a digital pileup resolving method to high count rate neutron measurements

The possibility of working in high count rate conditions is an important issue for neutron measurements applied to fusion experiments in order to extend the measurement dynamic range and time resolution. One of the main issues of high count rate operation is the overlapping of closely spaced events (pileup) that produces a distortion in their amplitude and therefore in the pulse height spectra. The usual way to deal with such pileup events using standard analog electronics is to reject them in the energy analysis process. Thanks to digital acquisition techniques, the waveforms of pileup events can be recorded and elaborated in order to reconstruct the contributing original single events. This work presents the results of the application of a pileup resolving method for the reconstruction and analysis of overlapping events to pulses acquired digitally from a NE213 liquid scintillator detector. The measurements have been carried out at the PTB accelerator facility with 14 MeV neutrons at total count rates over 400 kHz.