Over 240 transitions and three new rotational bands have been observed in the well-deformed, odd-odd ${}_{59}^{128}{\mathrm{Pr}}_{69}$ nucleus. The high-spin states were populated in two experiments using the ${}^{92}\mathrm{Mo}{(}^{40}\mathrm{Ca},3pn)$ reaction at beam energies of 170 and 184 MeV. Several structures were confirmed in the former experiment using the Clarion and HyBall arrays with the recoil mass spectrometer at Oak Ridge National Laboratory. Gammasphere, in conjunction with the Microball, were employed in the latter experiment at Argonne National Laboratory to extend the sequences to very high spins. Rotational structures in ${}^{126}\mathrm{Pr}$ were also identified in the $\alpha \mathrm{pn}$ channel of the same reaction. The recent discrepancies of spin assignments for the yrast bands in ${}^{126,128}\mathrm{Pr}$ and the interpretation of the lowest crossing in the $\pi h_{11/2}$ band in ${}^{127}\mathrm{Pr}$ are discussed. An adiabatic crossing of the intruder $i_{13/2}$ neutron with one of the normal-deformed bands in ${}^{128}\mathrm{Pr}$ is observed at high rotational frequency. Experimental trends in the signature inversion phenomenon of the $\pi h_{11/2}\nu h_{11/2}$ bands in the $A\approx 130$ region are defined and prove to be surprisingly irregular with respect to those found in the $\pi h_{11/2}\nu i_{13/2}$ bands of the $A\approx 160$ region.

• Received 4 December 2001

DOI:https://doi.org/10.1103/PhysRevC.65.044329