Rotational bands and signature inversion in odd-odd Re-172

High-spin states in the odd-odd Re-172 have been investigated via the Sm-149(Al-27,4ngamma)Re-172 reaction through excitation functions, x-gamma and gamma-gamma coincidence measurements. A level scheme consisting of three rotational bands has been identified for the first time extending the high-spin studies of Asimilar to160 odd-odd nuclei to the currently lightest rhenium isotope. The three bands have been assigned to be built on the pih(11/2)circle timesnui(13/2), pih(9/2)circle timesnui(13/2), and pi1/2(-) [541]circle timesnu1/2(-) [521] configurations according to their rotational properties in quasiparticle alignments, signature splitting, in-band B(M1)/B(E2) ratios, level spacing systematics, band crossing frequencies, as well as the existing knowledge in neighboring nuclei. Low-spin signature inversion has been confirmed in the first two bands due to the observation of signature crossing at high-spin states. The general features of inversion phenomenon in the semidecoupled bands are presented and discussed with reference to theoretical calculations of two quasiparticle plus rotor model including p-n interactions.