First measurements of the g factors of the 2+1 and 3−1 states of semi-magic 9040Zr

The g factors of the 2+1 and 3−1 states in semi-magic 90Zr have been measured for the first time with the technique of Coulomb excitation of 90Zr beams in inverse kinematics in combination with transient magnetic fields. The resulting g factors, g(2+1)=+1.25(21) and g(3−1)=+0.986(56), are both consistent with a dominant g9/2 proton configuration and a closed N=50 neutron shell. The lifetime of the 2+1 state was measured by the Doppler shift attenuation method, τ=0.126(3) ps.