A study on the pulse height resolution of organic scintillator digitized pulses

Highlights: ► The frequency analysis of pulses from a liquid scintillator detector is performed. ► The minimum sampling rate required to avoid PH degradation is determined. ► It is shown that interpolation methods increase the FoM for n/γ discrimination. -- Abstract: Organic scintillator detectors are widely used for neutron spectroscopy in fusion devices due to their good energy resolution and capability of neutron/gamma discrimination. Nowadays, scintillator pulses are commonly recorded by means of digital acquisition systems. These have several advantages, and in particular the possibility of off-line data reprocessing: however, the signal digitization can be a cause of degradation of the pulse height (PH) resolution (and therefore of the energy resolution obtained after pulse height spectra unfolding). In this work, the problem of how pulse digitization may influence the pulse height resolution is investigated. First, through downsampling of digitized scintillator pulses, we determine the minimum sampling rate required to avoid any degradation of the pulse height resolution. Secondly, we find that the application of interpolation methods to the digitized pulses does not affect the pulse height resolution, whereas it increases the figure of merit for neutron/gamma discrimination. These results are relevant to define the specifications for the digital acquisition systems of neutron detectors in present and future fusion devices such as JET and ITER