Energy of the ^{229}Th Nuclear Clock Isomer Determined by Absolute γ-ray Energy Difference.

  title={Energy of the ^\{229\}Th Nuclear Clock Isomer Determined by Absolute $\gamma$-ray Energy Difference.},
  author={Atsushi Yamaguchi and Haruka Muramatsu and T. Hayashi and N. Yuasa and K. Nakamura and Masaki Takimoto and Hiromitsu Haba and Kenji Konashi and M. Watanabe and Hidetoshi Kikunaga and Keisuke Maehata and Noriko Y. Yamasaki and K. Mitsuda},
  journal={Physical review letters},
  volume={123 22},
The low-lying isomeric state of ^{229}Th provides unique opportunities for high-resolution laser spectroscopy of the atomic nucleus. We determine the energy of this isomeric state by taking the absolute energy difference between the excitation energy required to populate the 29.2-keV state from the ground state and the energy emitted in its decay to the isomeric excited state. A transition-edge sensor microcalorimeter was used to measure the absolute energy of the 29.2-keV γ ray. Together with… 

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