Speaker
Description
The Tokai-to-Kamioka (T2K) experiment is a long-baseline neutrino oscillation experiment. It observes a neutrino beam produced at J-PARC with the Super-Kamiokande detector, located 295 km away, to search for CP violation(CPV) in the lepton sector. T2K has already obtained results suggesting CPV with more than 90% confidence level, and the goal is to confirm this indication with higher significance, up to 3σ. Achieving this requires more statistics, making an increase in beam intensity essential. At J-PARC, an upgrade to the magnet power supplies in 2021 reduced the repetition time from 2.48 s to 1.28 s. This improvement enabled higher beam power, and the beam is currently stably operated 900 kW. Further upgrades are planned to reduce the cycle to 1.16 s and reach a beam power of 1.3 MW by 2028.
High-intensity beam operation requires improvements to the target protection system. T2K produces its neutrino beam by impinging a high-intensity proton beam on a graphite target, which causes thermal shock in the target material. If the proton beam is delivered with unintended position or beam width, the resulting thermal shock may deform or damage the target. Therefore, the beam position and width at the target must be continuously monitored, and the next beam pulse must be immediately stopped when these parameters exceed predefined thresholds. The current protection system reconstructs the beam position and width using software, and this processing takes more than one second. In future high-intensity operation, the repetition cycle will become shorter, so taking more than one second to compute and make a decision will not be fast enough. Thus, the development of a faster protection system is necessary. Previous studies have developed FPGA-based modules, but they have not yet progressed to operational use. Our work aims to make this system ready for deployment in actual beamline operation. This contribution reports the current development status together with the results of beam tests conducted this year.