Core-proton coupled nature of the 11/2+ state in 131Sb probed by lifetime measurements

The structure of the 11/2(1)(+) state in Sb-131 was investigated at the LOHENGRIN spectrometer of Institut Laue-Langevin via neutron-induced fission of U-235 and lifetime measurements, yielding T-1/2=3(2) ps, at the edge of the sensitivity of the experimental method. This first result for the 11/2(1)(+) state half-life in neutron-rich Sb isotopes provides a quadrupole reduced transition probability to the ground state of B(E2)=1.4(-0.6)(+1.5) W.u., very close to the B(E2;2(1)(+) -> 0(1)(+)) in Sn-130. Realistic shell-model calculations reproduce well both the experimental level scheme of 131 Sb and the B(E2;11/2(1)(+). 7/2(1)(+)) value, indicting a dominant 2+(Sn-130) circle times pi g(7/2), core-proton coupled configuration for the 11/2(1)(+) state.

Automated summary

The structure of the 11/2(1)(+) state in Sb-131 was studied using neutron-induced fission of U-235 and lifetime measurements. The measured lifetime T-1/2=3(2) ps, at the edge of the experimental method's sensitivity, provides a quadrupole reduced transition probability B(E2)=1.4(-0.6)(+1.5) W.u. to the ground state, similar to the B(E2;2(1)(+) -> 0(1)(+)) in Sn-130. Shell-model calculations show good agreement with the experimental level scheme of 131 Sb and the B(E2;11/2(1)(+). 7/2(1)(+)) value, indicating a dominant 2+(Sn-130) circle times pi g(7/2) core-proton coupled configuration for the 11/2(1)(+) state.