Spectroscopy near the proton drip line in the deformed $A=130\mathrm{}$ mass region: The ${}^{126}\mathrm{Pr}$ nucleus

The near proton drip-line nucleus ${}^{126}\mathrm{Pr}$ was studied via in-beam $\gamma$-ray spectroscopy using the ${}^{40}\mathrm{Ca}{+}^{92}\mathrm{Mo}$ reaction at 190 MeV. We observed for the first time excited states above the known isomer in this nucleus, up to spin $31ħ.$ The observed band is assigned to a $\pi h_{11/2}\otimes \nu h_{11/2}$ configuration and is discussed in the framework of the interacting boson-fermion-fermion model. The calculations and the experimental information suggest a spin $8^{+}$ for the lowest observed state. With such a spin assignment the moment of inertia of ${}^{126}\mathrm{Pr}\mathrm{}$ gets larger than in the heavier Pr isotopes, suggesting a sudden change in deformation close to the proton drip line.