Spin, quadrupole moment, and deformation of the magnetic-rotational band head in 193Pb.

The spectroscopic quadrupole moment of the T1/2=9.4(5) ns isomer in 193Pb at an excitation energy Eex=(2585+x) keV is measured by the time-differential perturbed angular distribution method as ∣Qx∣=2.6(3) e b. Spin and parity Iπ=27/2¯ are assigned to it based on angular distribution measurements. This state is the band head of a magnetic-rotational band, described by the 1i13/2 subshell with the (3s1/2-21h9/21i13/2)11- proton excitation. The pairing-plus-quadrupole tilted-axis cranking calculations reproduce the measured quadrupole moment with a moderate oblate deformation ϵ2=-0.11, similar to that of the 11¯proton intruder states, which nuclei in the region. This is the first direct measurement of a quadrupole moment and thus of the deformation of a magnetic-rotational band head. [ABSTRACT FROM AUTHOR]