Detector readout system for S-2S experiments at J-PARC

A lot of experiments using the S-2S spectrometer with high momentum resolution are planned at the J-PARC K1.8 beamline for understanding baryon-baryon interactions in the S = −2 sector. The first experiment will be to precisely measure the missing mass of ¹²_ΞBe via the ¹²C(K^-, K⁺) reaction at the Active Fiber Target (AFT) and achieve the world's highest precision spectroscopy of Ξ hypernucleus (E70). In parallel with the experiment, the E96 experiment runs to observe X-rays from the Xi atom produced in the AFT target using a Ge detector for the first time.

In the experiments, we use trigger counters like hodoscopes (BH1, BH2), aerogel Čherenkov counters (BAC, AC1), a water Čherenkov counter (WC), and TOF counter for the (K^-, K⁺) trigger and take data with a network-based data acquisition system (HD-DAQ).

In this presentation, we will give an overview of the detector readout system for the S-2S experiments and report on trigger rate and DAQ efficiency based on data from the commissioning beamtime conducted in June 2023.