An international research team led by Professor Toshiyuki Azuma, Director of WPI-QUP, has successfully achieved the world’s first direct observation of X-rays emitted from resonant states of “muonic molecules,” consisting of two deuterium nuclei and a muon. The observation was made using a microcalorimeter with superconducting transition-edge sensors (TES).

Nuclear fusion is widely regarded as a safe and clean energy source. In particular, muon-catalyzed fusion (µCF) has attracted attention because it does not require the generation of plasma and can occur at room temperature. The present observation of the resonant states clarifies the formation process of muonic molecules, which serve as the starting point of fusion reactions, and resolves longstanding discrepancies between theoretical predictions and experimental results. These findings have been published in Science Advances.

“The TES detector is used in a variety of research at QUP. Thanks to its excellent energy resolution, we are now able to distinguish and measure individual vibrational quantum states that reflect the unique characteristics of molecules—something that was previously impossible. This has greatly expanded the scope of our research,” said Director Azuma.

Published details
Journal: Science Advances
Title: Direct observation of muonic molecules in resonance states critical to muon catalyzed fusion
Authors: Y. Toyama, T. Azuma, et al. (39 authors in total)
DOI: 10.1126/sciadv.aed3321

Related links
Press release from Chubu University (in Japanese)
https://www.u-presscenter.jp/article/124528
Press release from KEK (in Japanese)
https://www.kek.jp/ja/press/202604161115