In-gas-cell laser ionization spectroscopy of Os194,196 isotopes by using a multireflection time-of-flight mass spectrograph

Abstract

We performed in-gas-cell laser ionization spectroscopy of $^{194,196}\mathrm{Os}$, which were produced by multinucleon transfer reactions at the KEK Isotope Separation System (KISS). The nuclei of interest were identified through $\ensuremath{\beta}$-decay spectroscopy and a newly applied multireflection time-of-flight mass spectrograph (MRTOF-MS). From the study of laser resonance spectra, isotope shifts (ISs) of the transition ${\ensuremath{\lambda}}_{1}=247.758$ nm for $^{194}\mathrm{Os}$ and $^{196}\mathrm{Os}$ were measured for the first time. The change in the mean-square charge radius $\ensuremath{\delta}{\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}}^{192,A}$ and the quadrupole deformation parameter ${\ensuremath{\langle}{\ensuremath{\beta}}_{2}^{2}\ensuremath{\rangle}}^{1/2}$ were deduced from the IS measurements. The results were compared with the theoretical calculations and the predicted shape transition at $^{194}\mathrm{Os}$ is discussed.