Tracking the $\nu i_{13/2}$ orbital in the neutron-deficient polonium isotopes with the high-precision ISOLTRAP mass spectrometer at CERN-ISOLDE

The measurements that will be presented investigate the neutron-deficient polonium isotopes in the region of $A = 195 − 199$, with a special emphasis on $^{195}$Po and $^{197}$Po. These isotopes were produced at ISOLDE/CERN and delivered to the ISOLTRAP experiment where mass measurements and $\alpha$-decay spectroscopy were performed. The decay-spectroscopy studies were carried out for the first time at ISOLTRAP with the support of the multi-reflection time-of-flight mass spectrometer (MR-TOF MS). The masses of $^{(195,197)g,m}$Po were measured precisely with Penning-trap mass spectrometry, from which the state ordering and the energy of the $13/2^+$ states in $^{195,197}$Po were determined for the first time. Furthermore, the state ordering and the energy of the $13/2^+$ state in lead, radon, and radium were obtained through $\alpha$-decay chains. The new data complete the knowledge of the energy systematics in this region. The presented mass measurements provide information on the behaviour of the $13/2^+$ states in the lead region near $N = 104$, which remain excited states. Additionally, $^{195}$Po half-life measurements were performed in isobarically pure conditions. The resulting $^{195g}$Po half-life value is in agreement with the one in the literature, with improving in the precision of the value, whereas the $^{195m}$Po half-life value is significantly smaller than the literature value.