PAPER / ARXIV:2609.08427
Claudio Campagnari , Sungwoong Cho , Suyong Choi , Seokju Chung , Matthew Citron , Albert De Roeck , Martin Gastal , Seungkyu Ha , Andy Haas , Christopher Scott Hill , Insung Hwang , Hoyong Jeong , Jaebak Kim , Jeonghwa Kim , Hyunki Moon , Ryan Schmitz , David Stuart , Eunil Won , Jae Hyeok Yoo , Jinseok Yoo , Ayman Youssef , Ahmad Zaraket , Haitham Zaraket
RESUMO
A dedicated data acquisition (DAQ) system has been developed for the SUB-Millicharge ExperimenT (SUBMET) at the Japan Proton Accelerator Research Complex (J-PARC), a search for particles carrying a fractional electric charge $Q = \epsilon e$ with $\epsilon$ below $\mathcal{O}(10^{-3})$, hereafter referred to as millicharged particles (mCPs). Because such particles are expected to produce at most a few scintillation photons, the system is optimized for single-photoelectron detection from the photomultiplier tubes (PMTs), combining high-speed waveform digitization with precise timing. To capture eight consecutive proton bunches of the 30 GeV J-PARC beam within a single trigger, the eight channels of the Domino Ring Sampler 4 (DRS4) chip are cascaded in groups of four to form two readout inputs, each sampling 4096 points continuously at 820.5 MHz over an effective time window of 5 us. After calibration, timing differences between channels are within 1 ns on the same DRS4 chip, 2 ns on the same board, and 8 ns across different boards, well within the 30 ns coincidence window of the experiment. The front-end electronics achieve an RMS noise below 0.4 mV. The baseline is deliberately offset upward such that the negative-going pulses span a larger fraction of the digitizer range, improving voltage resolution and dynamic range. A trigger control board aggregates data from multiple readout boards and sustains the data-transfer rate required for beam operation. The measured performance confirms that the DAQ system meets the timing, noise, and throughput requirements of the experiment.
NO MESMO MAPA