Extruder proton-hole band in the near-drip-line nucleus127Pr

Abstract

The near-drip-line nucleus ${}^{127}$Pr was populated with the reaction ${}^{92}$Mo${(}^{40}$Ca,$\ensuremath{\alpha}p)$ at a beam energy of 175 $\mathrm{Me}$V. Particle-$\ensuremath{\gamma}$-$\ensuremath{\gamma}$ coincidences were collected, and the total energy plane gating technique was used to enhance events associated with the $\ensuremath{\alpha}p$ exit channel. This enabled two new rotational bands to be assigned to ${}^{127}$Pr, including a strongly coupled structure. Its similarity with analogous bands in heavier Pr isotopes suggests this structure is most likely based on a hole in the extruder $[404]{9/2}^{+}$proton orbital. The occupancy of this orbital is associated with enhanced quadrupole deformation in this mass region.