Investigation of the $i_{13/2}$ neutron orbital in the ${}^{132}\mathrm{Sn}$ region: New excited levels in ${}^{135}\mathrm{Sb}$

Excited states in ${}^{135}\mathrm{Sb}$, populated in spontaneous fission of ${}^{248}\mathrm{Cm}$, are studied by means of prompt $\gamma$ spectroscopy, using the EUROGAM2 detector array. New excited states containing the neutron $i_{13/2}$ orbital in their wave functions are proposed. A more accurate value of the $i_{13/2}$ neutron single-particle energy in the ${}^{132}\mathrm{Sn}$ core potential is determined.

Figure 1

A summed $\gamma$ ray spectrum doubly gated on all pairs of 225.1-, 411.2-, and 706.9-keV $\gamma$ lines in ${}^{135}\mathrm{Sb}$. Lines in the spectrum are labeled in keV.

Figure 2

A summed, doubly gated $\gamma$ ray spectrum with the first gate set on the 629.5-keV line and the second gate set on the 225.1-, 411.2-, and 706.9-keV lines of ${}^{135}\mathrm{Sb}$. Lines in the spectrum are labeled in keV.

Figure 3

Partial level scheme of ${}^{135}\mathrm{Sb}$ as obtained in the present work in comparison with the shell model predictions. See text for details.

Figure 4

(a) Systematics of excitation energy of various $13/2^{+}$ states in Sn-to-Sm, $N=83$ isotones and $3^{-}$ excitations in their respective $N=82$ cores. Solid symbols denote experimental values and open symbols denote estimated energies. (b) Systematics of the energy of the residual interaction with linear extrapolation. Solid symbols are calculated using experimental data and open ones are estimated. One can note that the systematics is well described by a linear trend. Results obtained in Refs. [2, 27] are presented to the right of the dashed line. The data are taken from Refs. [2, 3, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27]. See text for more details.