Speaker
Description
We present recent online results obtained in the IS595 experiment performed in October 2023. Aim of this work is the investigation of excited states in $^{133,134}$Sb and, possibly, $^{134,135}$Te, by employing a cluster transfer reaction of a $^{132}$Sn beam (at 3.9 MeV/A) on a $^7$LiF target (1.5 mg/cm$^2$ thick). The experiment ran for 7 days very smoothly, with a very pure and stable $^{132}$Sn beam, with an intensity of ~5$\times$10$^6$ pps. The experimental setup consisted in the MINIBALL array coupled to the CD and PAD Si detectors of T-REX. Alpha particles and tritons emitted in the transfer processes, leading to the population of $^{133,134}$Sb and $^{134,135}$Te isotopes, respectively, could be well identified using the Si array. A total number of ~ 10$^6$ $\alpha-\gamma$ coincidences was measured, which will allow us to perform $\alpha-\gamma-\gamma$ studies with rather high statistics. In one single shift, online, it was already possible to identify $\gamma$ transitions from $^{133}$Sb and $^{134}$Sb. The main aim of the experiment is to locate states arising from the coupling of the valence proton of $^{133}$Sb to the collective low-lying phonon excitations of $^{132}$Sn (in particular the 3$^-$) via $\gamma$-ray spectroscopy. In addition, for the case of $^{134}$Sb, multiplets arising from the coupling of the one-valence proton and one-valence neutron will be searched for, to test effective proton-neutron interactions above $Z$=50 and $N$=82 employed in realistic shell-model calculations.
