University of Hawaiʻi Physicists Contribute to U.S.–Japan Project to Advance Accelerator Diagnostics

Researchers at the University of Hawaiʻi at Mānoa (UH) are contributing to a newly approved U.S.–Japan project to advance X-ray beam monitoring technology for SuperKEKB, the world’s leading electron-positron collider. The project, titled “Enhanced X-ray Beam Size Monitor,” has been approved by the U.S.–Japan Joint Committee for a total of $235,000, with support expected through the U.S. Department of Energy Office of High Energy Physics.

SuperKEKB, located at KEK in Japan, provides beams for the Belle II experiment, which studies rare particle processes and searches for new physics beyond the Standard Model. To achieve high collision rates, SuperKEKB must keep its beams extremely stable as they circulate through the accelerator rings. Fast X-ray monitoring is essential for understanding beam behavior, improving accelerator performance, and detecting sudden beam instabilities that could affect machine operation and detector safety.

The UH, SLAC National Accelerator Laboratory, and KEK teams will develop an enhanced X-ray beam-size monitor capable of measuring vertical beam sizes in the accelerator ring at the level of approximately 10–20 micrometers, while resolving individual beam bunches separated by only a few nanoseconds. This bunch-by-bunch capability is a major advance beyond conventional camera-based X-ray monitors, which average over many bunches.

“Sudden beam instabilities are one of the key challenges as SuperKEKB pushes toward higher luminosity,” said Keisuke Yoshihara, Assistant Professor of Physics at UH Mānoa. “With this project, we hope to turn advanced X-ray sensors and fast readout electronics into a practical diagnostic tool for accelerator operation. Seeing the beam bunch by bunch will give us a new window into beam behavior and help make future high-luminosity colliders more stable and reliable.”

The project builds on a long-standing U.S.–Japan collaboration in accelerator and particle physics. The new effort will focus on advanced X-ray sensors, including silicon and InGaAs-based detectors, together with fast readout electronics and FPGA-based processing to handle beam signals in real time. The UH group will lead the development of new X-ray sensors, fast readout systems, firmware, and AI-based data-processing techniques for the upgraded monitor.

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