Left panel: A selection of pulses registered from the thin BF₃ tube. Red pulses are assumed to be observations, while blue pulses indicate noise. Right panel: A 2D pulse width-amplitude histogram as registered from the same tube. The distribution is also projected onto each plane. The dashed lines show the cut applied to the pulses in order to discriminate between measurements and noise. On the projected histograms, all the pulses are indicated by a black histogram, while the red histogram indicated pulses assumed to be measurements free from noise.