Observation of a rotational band in the odd-Z transfermium nucleus Md101251

A rotational band has been unambiguously observed in an odd-proton transfermium nucleus for the first time. An in-beam γ-ray spectroscopic study of Md101251 has been performed using the γ-ray array JUROGAM combined with the gas-filled separator RITU and the focal plane device GREAT. The experimental results, compared to Hartree-Fock-Bogolyubov calculations, lead to the interpretation that the rotational band is built on the [521]1/2- Nilsson state. © 2007 The American Physical Society.