21/04/03
A clock that is only off by one second in 300 billion years
Nuclear Excitation with the Lowest Energy in Nature Realized for the First Time
-A major step toward the realization of an ultra-precise nuclear clock.-
Prof. Koji Yoshimura and his colleagues at the Institute for Interdisciplinary Research for Basic Sciences, in collaboration with the National Institute of Advanced Industrial Science and Technology (AIST), RIKEN, Osaka University, Kyoto University, Tohoku University, Vienna University of Technology, and Japan Synchrotron Radiation Research Institute, have succeeded in generating the nuclear state (isomer state) of thorium-229, which has the lowest excitation energy in nature, for the first time in the world using the high-brilliance X-rays of SPring-8.
They have succeeded in generating the nuclear state (isomer state) of thorium-229 with the lowest excitation energy in nature, which is the basis of a groundbreaking technology that will make it possible not only to realize a clock that is far more precise than the current one, with a deviation of only one second in 300 billion years, but also to observe changes in the natural constant due to the expansion of the universe.
Title ：X-ray pumping of the 229Th nuclear clock isomer
Journal: Nature volume 573, 238?242 (2019)
DOI：10.1038/s41586-019-1542-3
Please check following link
https://www.okayama-u.ac.jp/tp/release/release_id658.html
19/09/26
自然界で最小エネルギーの原子核励起を初めて実現 －超精密「原子核時計」実現に大きく前進－
自然界で最小エネルギーの原子核励起を初めて実現
－超精密「原子核時計」実現に大きく前進－
異分野基礎科学研究所の吉村浩司教授らは、SPring-8の高輝度X線を用い、産業技術総合研究所（産総研）、理化学研究所、大阪大学、京都大学、東北大学、ウィーン工科大学、高輝度光科学研究センターと共同して、トリウム 229 がもつ、自然界最小の励起エネルギーを持つ原子核状態（アイソマー状態）を、世界で初めて生成することに成功しました。これは、今よりも遥かに精密な、3000億年に１秒しかずれないという時計を実現するだけでなく、自然定数の宇宙膨張にともなう変化も観測可能にする、画期的な技術の基礎となる成果です。
論文題名：X-ray pumping of the 229Th nuclear clock isomer
Nature volume 573, 238?242 (2019)
DOI：10.1038/s41586-019-1542-3
詳細は下記リンクにも記載されています。
https://www.okayama-u.ac.jp/tp/release/release_id658.html