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World's first acceleration of cooled muons at J-PARC

On May 23rd, 2024, the Japan Proton Accelerator Research Complex (J-PARC) issued a press release regarding the world's first acceleration of cooled muons. In our method, cooled muons can be obtained by slowing down positively charged muons by shooting them into a silica aerogel target and then stripping off the electrons associated with the muons with a laser. By combining this cooling technique with radio-frequency acceleration technology, we have demonstrated the acceleration of cooled muons using a radiofrequency quadrupole accelerator for the first time.

In N-lab, Prof. Toru Iijima, Associate Prof. Kenji Inami, Lecturer Kazuhito Suzuki, Mai Yotsuzuka, Kazumichi Sumi, Soh Sugiyama, and Yuka Ibaraki contributed to the development of silica aerogel target, operation of cooled muon diagnostic line, and development and analysis of beam monitor. Research Fellow Kazuki Kojima (KMI(now at KEK)), Tadaki Ichikawa, Koichi Ueda, Shota Koji, and Ayaka Kondo also contributed to the setup and data acquisition in the cooling and acceleration tests.

This research is a milestone toward the realization of a muon accelerator that can accelerate to higher energies and a more directional muon beam. We will further develop the muon beam for various research applications, such as the precise measurement of muon anomalous magnetic moment or muon microscopy.

The press release by the J-PARC center is available here.

Equipment for muon cooling and acceleration

N-lab members installing equipment for measuring cooled muons