Accelerator physics · High-intensity proton linacs
Associate Professor
Accelerator Laboratory, Inter-University Research Institute Corporation High Energy Accelerator Research Organization (KEK)
J-PARC Center
I work to make powerful accelerators understandable, controllable, and reliable—by following the beam from its microscopic physics to the way a kilometer-scale machine behaves.
About
I am an accelerator physicist at KEK. My work spans the full life of a large scientific machine: design, construction, commissioning, diagnosis, improvement, and long-term operation. Earlier work at the HIRFL-CSR heavy-ion storage-ring complex gave me this system-wide view; at J-PARC, I apply it to one of the world's leading high-intensity proton accelerator facilities.
The goal is clear and ambitious: carry more beam while keeping loss, activation, and uncertainty firmly controlled. I combine beam dynamics, experiments, simulation, machine measurements, and structured inference to turn that goal into settings an operating team can use.
Long-term purpose
My long-term goal is to make charged-particle accelerators more intense, precise, dependable, and easier to understand—so they can serve research across:
Research stories
01 · Long-term beam-loss mitigation
Aperture improvements removed local bottlenecks, while lattice optimization reduced the distributed source. Across sustained operation, the maximum 1 MW-equivalent residual surface dose fell from about 6.5 to 2.2 mSv/h as beam power advanced.
This is beam physics translated into safer access, easier maintenance, and greater operating margin for the next stage of power upgrades.
02 · A controllable knob
Intra-beam stripping grows when particles crowd one another. We turned this interaction into a controllable variable by redistributing the beam's transverse and longitudinal “temperature” through the focusing lattice.
The machine measurements followed the model: candidate settings reduced the observed loss by 26% and 34% under the reported test conditions. The wider achievement is a repeatable bridge from phase-space physics to an operational knob.
03 · Distributed beam loss
When an H⁻ ion loses its electrons, it becomes neutral H⁰ and travels beyond magnetic steering. It can continue for tens of metres before reaching the beam pipe, connecting an upstream stripping event to a downstream radiation signal.
Transport calculations showed that, under the studied conditions, more than 40% of the relevant H⁰ trajectories could reach a dedicated downstream collection point. This source-to-impact picture guides aperture design, loss-monitor interpretation, and next-generation high-power H⁻ linacs.
04 · DTL beam-loss elimination
Residual-dose surveys revealed a sharp hotspot around DT56. Beam-envelope analysis identified a local mismatch, and a 160% correction reshaped the beam through the affected section and removed the loss source.
Successive surveys tracked the residual dose down to about 15 µSv/h in the reported 500 kW period. The result closes the loop from diagnosis, to optics correction, to radiation measurement.
05 · Toward the next power stage
The goal is higher current with beam quality preserved throughout the accelerator. In repeated 60 mA studies, re-optimizing the DTL focusing improved transverse emittance by 26%, bringing beam quality close to the 50 mA operating level.
These 60 mA beam studies provide an experimentally tested foundation for the J-PARC linac's 1.5 MW upgrade path.
06 · Structured inference
The J-PARC linac has 46 independently controlled RF cavities and 87 phase-monitoring points. A conventional static network captured the forward response; the decisive advance came from representing the accelerator's ordered structure.
The sequence model recovered distributed RF errors and constructed a global compensation in realistic high-fidelity simulation. This validation establishes the method and sets the next milestone: measurement calibration and online application.
Professional roles
KEK Accelerator Laboratory
High-intensity accelerator physics, beam dynamics, commissioning, beam loss mitigation, and machine optimization. Official site ↗
J-PARC Center
Beam physics and R&D for reliable high-power accelerator operation. Official site ↗
SOKENDAI Accelerator Science
Research guidance and graduate supervision in accelerator science. Official program ↗
Selected publications and presentations
Invited speaker, LINAC 2026 · Research lead
IPAC 2026 · Research lead
Contributed oral speaker, IPAC 2025 · Linac commissioning lead
Graduate supervision
I supervise doctoral and master's research in accelerator science, including work by international students. Projects connect beam-dynamics theory and numerical models with diagnostics, commissioning data, and operational constraints.
Students work within the SOKENDAI Accelerator Science environment at KEK, where research is closely integrated with large accelerator facilities.
Academic profiles
Reserved for the preferred public profile URLs of KAKEN, J-GLOBAL, and JACoW.