Speaker
Description
Nuclei near the doubly magic nucleus $^{100}$Sn ($N=Z=50$) have been extensively studied to investigate nuclear structure, including shell evolution, seniority effects, and proton–neutron interactions. In this work, $^{94}$Pd with $N=Z+2$ was investigated with a focus on isovector($T=1$) and isoscalar($T=0$) neutron-proton pairing using the fast-timing measurement. Half-lives of yrast excited states in $^{94}$Pd were measured using isomeric decay spectroscopy. The experiment was performed at RIBF (Radioactive Isotope Beam Factory), RIKEN, where $^{94}$Pd ions were produced via in-flight fragmentation of a $^{124}$Xe beam impinging on a $^{9}$Be target. These ions were implanted into the GARi active stopper array, and isomeric delayed $\gamma$ rays were detected with the IDATEN fast-timing array consisting of 48 LaBr$_{3}$(Ce) detectors. The half-lives were determined using the generalized centroid difference method, yielding the $T_{1/2}$ values of $\leq 15$ ps, $13(11)$ ps, $\leq 13$ ps, $693(72)$ ps, and $\leq 19$ ps for the $(2^{+}_{1})$, $(4^{+}_{1})$, $(6^{+}_{1})$, $(8^{+}_{1})$, and $(10^{+}_{1})$ states, respectively. The half-lives of the $(2^{+}_{1})$, $(4^{+}_{1})$ and $(10^{+}_{1})$ states are reported here for the first time, and the uncertainties of the half-lives of the $(6^{+}_{1})$ and $(8^{+}_{1})$ states have been improved compared to previous measurements. Reduced transition probabilities $B(E2)$ were deduced from the measured half-lives and discussed in the context of shell-model calculations employing the JUN45 effective interaction, including $T=0$, $T=1$ and full interaction. The results suggest that $^{94}$Pd, with $N=Z+2$, lies in a transitional regime between the $N=Z$ isoscalar-pairing domain ($^{92}$Pd) and the $N=50$ isovector-dominated region ($^{96}$Pd).