Evidence for the microscopic formation of mixed-symmetry states from magnetic moment measurements

Abstract

Using the transient field technique, the magnetic moments of the second excited 2(+) states in (92,94)Zr have been measured for the first time. The large positive g factors, g( 2(2)(+); (92)Zr) = + 0.76(50) and g(2(2)(+); (94)Zr) = + 0.88( 27), which are in contrast to the known negative g factors of the 2(1)(+) states, are found to be a consequence of weak proton-neutron coupling combined with the Z = 40 subshell closure. From their large M1 transition strengths to the 2(1)(+) states, in earlier works an assignment to the 2(2)(+) states as proton-neutron symmetric and mixed-symmetry states has been made, which are now found to be polarized in their proton-neutron content. This fact allows to identify the underlying microscopic main configurations in the wave functions, which form the building blocks of symmetric and mixed-symmetry states in this region as valence nucleons are added and shell structure changes.