Excited-State Half-Lives in Cd130 and the Isospin Dependence of Effective Charges

The known I π = 8 + 1 , Ex = 2129-keV isomer in the semi-magic nucleus 130 Cd82 was populated in the projectile fission of a 238 U beam at the Radioactive Isotope Beam Factory at RIKEN.The high counting statistics of the accumulated data allowed to determine the excitation energy, Ex = 2001.2(2)keV, and half-life, T 1/2 = 57(3) ns, of the I π = 6 + 1 state based on γγ coincidence information.Furthermore, the half-life of the 8 + 1 state, T 1/2 = 224(4) ns, was remeasured with high precision.The new experimental information, combined with available data for 134 Sn and large-scale shell model calculations, allowed to extract proton and neutron effective charges for 132 Sn, a doubly-magic nucleus far-off stability.A comparison to analogous information for 100 Sn provides first reliable information regarding the isospin dependence of the isoscalar and isovector effective charges in heavy nuclei.