Studies of an event-building algorithm of the readout system for the twin TPCs in HFRS

The High-energy Fragment Separator (HFRS), which is currently under construction, is a leading international radioactive beam device. Multiple sets of position-sensitive twin time projection chamber (TPC) detectors are distributed on HFRS for particle identification and beam monitoring. The twin TPCs’ readout electronics system operates in a trigger-less mode due to its high counting rate, leading to a challenge of handling large amounts of data. To address this problem, we introduced an event-building algorithm. This algorithm employs a hierarchical processing strategy to compress data during transmission and aggregation. In addition, it reconstructs twin TPCs’ events online and stores only the reconstructed particle information, which significantly reduces the burden on data transmission and storage resources. Simulation studies demonstrated that the algorithm accurately matches twin TPCs’ events and reduces more than 98% of the data volume at a counting rate of 500 kHz/channel.