Speaker
Description
Several nuclei in the highly neutron-deficient W--Os--Pt region exhibit anomalously low values of the ratio $\frac{B(E2;4^+_1\rightarrow2^+1)}{B(E2;2^+1\rightarrow0^+{\mathrm{gs}})}$ ($B{4/2}<1$), forming a contiguous region of the Segr'e chart for which no consistent theoretical explanation currently exists. This raises the possibility of similar anomalies in other regions.
A few cases of $B_{4/2}<1$ have also been reported in neutron-deficient Sn--Te--Xe nuclei. Remarkably, these nuclei have similar valence particle/hole numbers relative to the $N=Z=50$ shell closure as the anomalous W--Os--Pt nuclei have relative to $N=Z=82$, suggesting a possible valence-particle symmetry. The 24.031 experiment at LNL was performed in June 2025 at LNL with the AGATA+SAURON+Plunger setup. The main goal was to investigate the extent of this anomaly in the Sn--Te--Xe region with significantly improved experimental precision. In this presentation, preliminary results from the experiment will be discussed.