Run-dependent timing offsets and their correction in digital data acquisition systems

Abstract Precise time synchronization among multiple electronic channels is essential for nuclear physics experiments. In digital data acquisition systems based on XIA Pixie-16 modules, the relative timing between channels is not necessarily preserved when a new data acquisition run is started. A run-dependent timing offset — typically on the order of 10 ns — can occur independently in each channel, which cannot be corrected through offline data analysis alone. To address this issue, a dedicated external electronic circuit is developed. This circuit operates as a programmable double-throw switch that routs a common reference clock signal to all channels at the start of each run, before switching to normal physics data acquisition. This procedure enables direct measurement and thus correction of relative timing offsets for all channels on a run-by-run basis without manual intervention. The method has been successfully applied in a nuclear reaction experiment using multiple Pixie-16 modules, where it effectively corrects the run-dependent timing offset and thus significantly improves the accuracy of timing-dependent observables such as Parallel Plate Avalanche Counter(PPAC) position reconstruction and beam tracking.