Speaker
Description
We have developed the KEK Isotope Separation System (KISS) [1] at RIKEN to study the nuclear structure of the nuclei in the vicinity of neutron magic number $N$ = 126 and 152 from the astrophysical interest. These neutron-rich nuclei have been produced by using multinucleon transfer reactions [2] with the combinations of the low-energy $^{136}$Xe/$^{238}$U beams and the production targets of W, Ir, and Pt. At the KISS facility, these radioisotopes are ionized by applying in-gas-cell resonant laser ionization technique. In the ionization process, we can perform laser ionization spectroscopy of the refractory elements with the atomic number $Z$ = 72-78 such as Hf, Ta, W, Re, Os, Ir, and Pt, which can not be performed in other facilities. Laser spectroscopy can be used to effectively investigate the nuclear structure through the measured magnetic moments, isotope shifts (IS) $\Delta \nu$, changes in the mean-square charge radii $\delta$<$r^2$>, and quadrupole deformation parameters |<$\beta_2^2$>|$^{1/2}$.
We have studied the resonant ionization schemes of these elements by offline tests, and performed in-gas-cell resonant laser ionization spectroscopy of $^{199g,199m, 200, 201}$Pt [3], $^{196,197,198}$Ir [4], and $^{194,196}$Os [5] produced at KISS. By using a multi-reflection time-of-flight mass-spectrograph (MRTOF-MS) combined with resonant laser ionization technique, we could discover the new neutron-rich $^{241}$U isotope for the first time in 40 years [6].
In this workshop, we will report the results of resonant laser ionization spectroscopy at KISS, and the perspective of future plan at KISS.
References
[1] Y. Hirayama et al., Nucl. Inst. Meth. B353, 4 (2015), and B412, 11 (2017).
[2] Y.X. Watanabe et al., Phys. Rev. Lett. 172503, 1 (2015).
[3] Y. Hirayama et al., Phys. Rev. C 96, 014307 (2017), and 106, 034326 (2022).
[4] M. Mukai et al., Phys. Rev. C 102, 054307 (2020).
[5] H. Choi et al., Phys. Rev. C 102, 034309 (2020).
[6] T. Niwase et al., Phys. Rev. Lett. 130, 132502 (2023).
| Workshop Themes | RIS, scheme development, atomic spectroscopy |
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