The observation of the VUV signal from the isomeric state of 229 thorium nuclei toward realizing the atomic clock
ORAL
Abstract
Toward the nuclear clock’s realization, the problem of ambiguity of isomeric energy and its lifetime must be overcome by experimental measurement of de-excitation from the isomeric state of thorium-229 nuclei with emitting photons.
In our experiment, the thorium-229 nuclei are excited to an isomeric state via the 2nd excited level(29 keV) by irradiation of X-ray as synchrotron radiation from SPring-8. A dedicated measurement system captures the decay events in which the isomeric thorium nucleus emits photons within the VUV region. Finally, we have demonstrated the measurement of the VUV signal and determined both isomeric energy and lifetime. In our presentation, the current status and recent results would be reported.
In our experiment, the thorium-229 nuclei are excited to an isomeric state via the 2nd excited level(29 keV) by irradiation of X-ray as synchrotron radiation from SPring-8. A dedicated measurement system captures the decay events in which the isomeric thorium nucleus emits photons within the VUV region. Finally, we have demonstrated the measurement of the VUV signal and determined both isomeric energy and lifetime. In our presentation, the current status and recent results would be reported.
*The experiment was conducted at SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (proposals 2019B1619, 2020A1284, 2021A1389, 2021B1516, 2022A1401, 2022B1418, 2022B1936, 2023A1415 and 2023A1358) and RIKEN. This work was supported by JSPS KAKENHI grant numbers JP19H00685, JP19K21879, JP19K14740, JP21H04473, JP21H01094, JP22K20371 and JP23K13125. The research was supported by the Austrian Science Fund (FWF) Projects: I5971 (REThorIC) and Itoh Science Foundation.
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Presenters
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Koichi Okai
- Okayama University
- Okayama Univ