Influence of high-j intruder orbitals in odd mass transfermium nuclei No-253 and Md-251

Rotational bands of No-253 and Md-251 are studied by the cranked shell model with particle-number conserving treatment for monopole and quadrupole pairing correlations. Observed bands are reproduced very well by theoretical results. A backbending of kinematic moment of inertia f(1) is predicted at h omega approximate to 0.275 MeV in bands of No-253. This is attributed to the simultaneous alignment of neutron (2h)11/2(1/2[761]) and proton (1j)15/2(1/2[770]) pairs. Only one signature band was observed in Md-251. We predict its signalure partner band with a sharp backbending at very low frequency of h omega approximate to 0.15 MeV. Backbendings of sigma(1) in Md-251 are the consequence of crossing between the proton 1/2[521] and 1/2[770] configurations. The sudden rise of sigma(1) is mainly due to the large alignment of proton 1/2[770] pair. (C) 2008 Elsevier B.V. All rights reserved.Physics, NuclearSCI(E)11ARTICLE45-6081