Speaker
Description
The neutron-deficient region around the $Z=50$ major shell closure provides fertile grounds for nuclear structure studies, as single-particle degrees of freedom compete with collective phenomena to form several of the observed spectroscopic properties. Pd isotopes, sitting 4 protons below the shell closure,present especially attractive study cases, with recent theoretical and experimental work highlighting their complex structure. Evidence for shape coexistence appears in the neutron region $N=60-66$, while substantial triaxiality is predicted for $N=56-74$. The overlap of these phenomena points to a rich interplay between nuclear shapes, collectivity, and phase transitions. Motivated by the above, an experiment was conducted at the 9 MV Tandem Accelerator Laboratory of IFIN-HH, aimed at investigating the nuclear structure of $^{106,108}$Pd through measurements of lifetimes and $B(E2)$ reduced transition probabilities of low-spin states. A proton-pickup reaction with a 35~MeV $^{11}$B beam impinging on a $^{nat}$Ag target was used to populate excited states in $^{106,108}$Pd. The $\gamma$ rays de-exciting these levels were detected by the ROSPHERE array, in its mixed 15 HPGe + 10 LaBr$_3$(Ce) detector configuration. Additionally, the SORCERER particle detector array was coupled to ROSPHERE, enabling the study of $p-\gamma$ and $p-\gamma-\gamma$ coincident events. The lifetime of the $2^+_1$ state in $^{106}$Pd was determined with the fast electronic scintillation timing (FEST) technique, and compared to theoretical predictions, to probe quadrupole collectivity in the $^{106}$Pd nucleus.