Investigation of the rare-abundant naturally-occurring long-lived radioisotopes by nuclear laser spectroscopy

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The rare-abundant naturally-occurring long-lived radioisotopes, such as ^<50>V,^<138>La,^<176>Lu are the nuclei near the neutron magic numbers. Such nuclei are of particularly interests not only for nuclear physics but for dating and astrophysics. In this project, we carried out nuclear laser spectroscopy in order to understand hyperfine structures, charge distribution and nuclear moments of such nuclei. Using our developed high-resolution diode-laser spectroscopic setup, we expanded our measurements to light elements, such as ^<89>Y, and determined its hyperfine constants and g factors. The Stark effect, related to the parity non-conservation, was also investigated. Stark spectra were observed for the Rb 5s^2S_<1/2>→5p ^2P_<1/2> transition at 795 nm and for the Cs 6s^2S_<1/2>→6p^2P_<3/2> transition at 852 nm with the change of the electric field up to 40 keV/cm, and scalar and tensor polarizabilities were derived for Rb and Cs. In particular, in order to measure the rare-abundant naturally-occurring radioisotopes, we combined a frequency-doubling system with the diode laser, and a high-resolution UV laser source, up to 100 μW, was obtained. Using the high-resolution experimental setup together with the UV laser source, we succeeded in performing high-resolution nuclear laser spectroscopy of ^<27>Al in the UV region. Hyperfine constants of 4 atomic levels of ^<27>Al, included the ground state, were determined for the first time. Nuclear laser spectroscopy of the rare-abundant naturally-occurring long-lived nucleus ^<176>Lu was performed using the strong optical UV transition, and hyperfine constants of ^<176>Lu and ^<175>Lu were derived and isotope shifts of ^<176-175>Lu were obtained. Some of our results have been reported and most of them will be published elsewhere.