Signature Partners in Superdeformed ¹⁴⁹Tb

Abstract：

Five superdeformed bands observed in ¹⁴⁹Tb were investigated comprehensively. A large-amplitude fluctuation in the observed transition energies and hence in the extracted dynamic moments of inertia was found in most of these bands. The smoothed transition energies were deduced by removing the fluctuation. The spins of these bands were assigned conclusively by the ab-fitting and/or its modification. Two pairs of superdeformed bands in ¹⁴⁹Tb, i.e. bands 3,5 and bands 2,4,were proposed to be signature partners. The exit spins are 59/2 and 61/2 for the former pair,and 49/2 and 63/2 for the latter pair. These values are different by one unit from those given from a comparison with ¹⁵⁰Tb(1). In fact,the spins of ¹⁵⁰Tb(1), which have not been determined experimentally,are different by different theoretical approaches of assignment. The de-coupling constants were extracted from the modified ab-fitting. Responsible Ω=1/2 orbit in the vicinity of the Fermi surface of ¹⁴⁹Tb seems to be ν[640]↑ for bands 2 and 4,and π[301]↓ for bands 3 and 5. The exit spin of band 1 was assigned as 53/2 or 55/2,which may be picked out from the observation of its signature partner. Good correspondence between these bands(especially bands 2,4 and 5) and their identical bands was obtained.