The Data Acquisition System for the KOTO Experiment

We developed and built a new readout and trigger electronics system, based on a waveform digitization and pipeline readout, for the KOTO experiment at J-PARC, Japan. KOTO aims at observing the rare kaon decay
${K_L} \rightarrow {\pi ^0}\nu \bar \nu $
. A total of 4000 readout channels from various detector subsystems are digitized by 14 bit 125 MHz ADC modules equipped with 10 pole Bessel filters to reduce the pile-up effects. The trigger decision is made every 8 ns using the digitized waveform information. To avoid dead time, the ADC and trigger modules have pipelines in their FPGA chips to store data while waiting for a trigger decision. The KOTO experiment performed the first physics run in May 2013. The data acquisition system worked stably during the run.