Start of the Stable User Operations at 900 kW in the MR
Stable user operation at a beam power of 900 kW has been achieved in the Main Ring (MR) accelerator. This means that stable operation with a more powerful beam than before is now possible, and the beam power upgrade is progressing as planned.
Adjustments of the main magnet power supplies, necessary for shortening the operation cycle, have been implemented step by step over the past year. Starting on January 14, the repetition cycle of operation was shortened from 1.36 seconds to 1.28 seconds, initiating beam tuning at higher beam power. By carefully adjusting the beam path and motion, including the operating point (tune at injection), beam optics, tune control in the early stage of acceleration, intra-bunch feedback, and collimators, beam loss was successfully reduced to less than 1% even during operation at 910 kW. In addition, further beam tuning was carried out in the latter half of the acceleration process, and beam loss in the neutrino beamline after beam extraction was also reduced to within acceptable levels. These achievements have confirmed that stable user operation at 900 kW is feasible.
User operation began on January 17, and the beam power was gradually increased. Since January 27, stable operation at 900 kW has been continuously maintained.
Toward the Hyper-Kamiokande experiment scheduled to start in 2028, beam power upgrade will continue with the goal of achieving 1.3 MW operation.
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