Figure 4

Afterpulsing histogram of SAP500S2-2. The histogram of the time difference between APD output pulses shows the APD’s dead time from 0 to roughly \(0.8~\mu\mathrm{s}\), followed by a recharge time of \({\approx}150~\mathrm{ns}\). The following peak is formed of afterpulses. The count rates then settle down to the background count rate of \({\approx}200~\mathrm{Hz}\). A possible reason for a slight increase in the count rate at the end is the high voltage supply rebounding after being slightly sagged by the charge being drawn by the single avalanche. The black shaded area is the afterpulsing probability.