Excited-State Half-Lives in Cd 130 and the Isospin Dependence of Effective Charges

Abstract

The known Iπ=81+, Ex=2129-keV isomer in the semimagic nucleus Cd13082 was populated in the projectile fission of a U238 beam at the Radioactive Isotope Beam Factory at RIKEN. The high counting statistics of the accumulated data allowed us to determine the excitation energy, Ex=2001.2(7) keV, and half-life, T1/2=57(3) ns, of the Iπ=61+ state based on γγ coincidence information. Furthermore, the half-life of the 81+ state, T1/2=224(4) ns, was remeasured with high precision. The new experimental information, combined with available data for Sn134 and large-scale shell model calculations, allowed us to extract proton and neutron effective charges for Sn132, a doubly magic nucleus far-off stability. A comparison to analogous information for Sn100 provides first reliable information regarding the isospin dependence of the isoscalar and isovector effective charges in heavy nuclei.