Building Time Difference Spectra Between Two Detectors

The spectrum of the time differences between the signals produced by two detectors may give additional information, especially in coincidence measurements. Although the time resolution of Geiger counters does not allow precision measurements of the time associated with the arrival of physical events in the detector, it is possible to better understand the meaning of true and random coincidences looking at the time spectrum of the signals produced by two such counters, employing the internal clock of an Arduino board.