Rotational bands in the proton emitter Ho-141

Rotational bands feeding the ground state and the isomeric state in the pro ton emitter Ho-141 were observed using the recoil-decay tagging method. Thi s constitutes direct evidence that Ho-141 is deformed. A quadrupole deforma tion of beta (2) = 0.25(4) was deduced for the ground state from the extrac ted dynamic moment of inertia. Based on observed band crossings and signatu re splittings the 7/2(-)[523] and 1/2(+)[411] configurations were proposed for the ground state and the isomeric state, respectively. Comparison with particle-rotor calculations for beta (2) = 0.25 indicates, however, that Ho -141 may have significant hexadecapole deformation and could be triaxial in the 7/2(-)[523] ground state.