Speaker
Description
Over the last years the advance in experimental techniques allowed to refine the experimental knowledge on $^{133}$Sn, which is a key nucleus to deduce neutron single-particle (SP) energies above the doubly magic $^{132}$Sn core. The different adopted techniques allowed to obtain mutually consistent information about SP energies for $\nu p_{3/2}$, $\nu p_{1/2}$, $\nu h_{9/2}$ and $\nu f_{5/2}$ neutron orbitals relative to the $\nu f_{7/2}$ ground state of $^{133}$Sn [1-5]. Still, the knowledge about neutron SP states is not complete and the question of the position of the neutron-unbound $\nu i\, _{13/2}$ state remains open for investigation [6]. Moreover, information about other unbound states, corresponding to neutron-hole configurations, is also limited. The need to revise studies of $^{133}$Sn via $\beta$ decay of $^{133}$In and $^{134}$In emerges from the recently-reported significant role of $\gamma$ ray emission from states at excitation energies more than 1 MeV above the neutron separation energy [1].
Our experiment was performed at the ISOLDE Decay Station, where excited states in $^{133}$Sn were studied via the $\beta$ decay of $^{133}$In and complemented by studies of the $\beta$n decay branch of $^{134}$In. Isomer-selective ionization using the ISOLDE RILIS ion source enabled the $\beta$ decays of $^{133g}$In (I$^{\pi}$=9/2$^+$) and $^{133m}$In (I$^{\pi}$=1/2$^-$) to be studied independently for the first time [7]. Preliminary results on $\gamma$ decay of unbound states in $^{133}$Sn are presented and discussed.
[1] V. Vaquero et al., Phys. Rev. Lett. 118, 202502 (2017).
[2] J. M. Allmond et al., Phys. Rev. Lett. 112, 172701 (2014).
[3] K. L. Jones et al., Phys. Rev. C 84, 034601 (2011).
[4] K. L. Jones et al., Nature (London) 465, 454 (2010).
[5] P. Hoff et al., Phys. Rev. Lett. 77, 1020 (1996).
[6] A. Korgul et al., Phys. Rev. C 91, 027303 (2015).
[7] M. Piersa et al., Acta Phys. Pol. B 49, 523 (2018).
