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Description
Shape evolution from spherical to deformed nuclear system as a function of neutron number has been studied to reveal the change of residual nuclear interactions in finite quantum many-body system. Neutron-rich Xe nuclei with $A$ ~ 140 are located at the northeast transitional-mass region of the doubly-magic $^{132}$Sn ($Z$ = 50 and $N$ = 82). Various nuclear structures with prolate collectivity and octupole correlation are expected to appear in these nuclei which are known in neighboring nucleus $^{144}$Ba ($Z$ = 56 and $N$ = 88). Experiment was performed as a part of EURICA campaign based on $\beta$- and isomer-decay spectroscopy. Neutron-rich nuclei were produced at RIBF, RIKEN by in-flight fission of $^{238}$U beam with energy of 345 MeV/nucleon and intensity of ~5 pnA, bombarding on a 3 mm Be target. The fragments were separated and identified through BigRIPS separator and ZeroDegree spectrometer. Ion and $\beta$ ray were detected by WAS3ABi which consists of 5 DSSSD with 60 vertical and 40 horizontal strips. The parent $\beta$ decaying nucleus was identified by the same detected position of ion and $\beta$ ray at the WAS3ABi. Gamma ray was detected by using EURICA, a $\gamma$ ray detector array consisting of 12 cluster-type Ge detectors. In this work, neutron-rich odd Xe nuclei with $A$ ~ 140 are investigated by the $\beta$ decay and the $\beta$-delayed neutron decay of I isotopes. Nuclear structure of Xe isotopes will be discussed by comparing to the theoretical calculation.
