High-spin spectroscopy of ${}^{139}\mathrm{Ce}$

High-spin states in ${}^{139}\mathrm{Ce}$ have been populated using the ${}^{130}\mathrm{Te}({}^{14}\mathrm{C},5n)$ reaction. The level scheme has been extended to higher spins, including a new band of dipole transitions. The parity of several states has been changed from negative to positive, mainly based on the comparison with the level structure of the core nucleus ${}^{140}\mathrm{Ce}$ and the results of a realistic shell-model calculation. The dipole band is interpreted as a magnetic rotation band with $\pi h_{11/2}^2\otimes \nu h_{11/2}^{-1}$ configuration built on small deformation axial shape with $({\varepsilon }_2=0.12,\gamma =0^{\circ })$.

Figure 1

Level scheme of ${}^{139}\mathrm{Ce}.$ Band D1 and the levels above the cascades of positive and negative parity are new.

Figure 2

Spectra of the various structures identified in ${}^{139}\mathrm{Ce}$. (a) Sum of the spectra with gates on the 1108 and 239 keV transitions showing the high-spin states; (b) sum of the spectra with gated on the 226 and 346 keV transitions showing the band D1; (c) sum of the spectra with gates on the 897 and 193 keV transitions showing the states grouped in the cascades “Parity $=+$”; (d) sum of the spectra with gates on 271 and 188 keV transitions showing the states grouped in the cascades “Parity $=-$”. The transitions marked with an asterisk belong to ${}^{138}\mathrm{Ce}$.

Figure 3

Comparison between experimental and calculated levels in ${}^{140}\mathrm{Ce}$.

Figure 4

Comparison between experimental and calculated levels in ${}^{139}\mathrm{Ce}$.

Figure 5

Comparison between the experimental levels in ${}^{139}\mathrm{Ce}$ and in the core nucleus ${}^{140}\mathrm{Ce}$.

Figure 6

TAC calculations for the band D1 of ${}^{139}\mathrm{Ce}$. Filled (open) symbols are used for the experimental (calculated) band. The lines linking the points are used to guide the eyes. The deformation parameters for each configuration are those calculated with the CNS model. The configurations are given in terms of unpaired proton particles and neutron holes.