Measurement of the g(21+)-factor in 140Ba with the ''Recoil-in-Vacuum'' method

The ''Recoil-in-Vacuum'' method as described recently in is used to determine the unknown magnetic moment of the 21+ state in the neutron-rich nucleus 140Ba. A Coulomb excitation experiment in inverse kinematics was performed at REX-Isolde (CERN) in 2007. Beams of 140,142Ba were impinging on a 0.9 mg/cm296Mo target and a 1 mm Cu stopper. Gamma rays were detected by the MINIBALL array, a DSSSD was used for particle identification. The microscopic structure of the 21+ state is investigated by the magnetic moment, which is sensitive to the composition of the wave function regarding proton and neutron configurations, and is compared to predictions from various calculations.