Discovery of highly excited long-lived isomers in neutron-rich hafnium and tantalum isotopes through direct mass measurements

Abstract

A study of cooled Au197 projectile-fragmentation products has been performed with a storage ring. This has enabled metastable nuclear excitations with energies up to 3 MeV, and half-lives extending to minutes or longer, to be identified in the neutron-rich nuclides Hf183,184,186 and Ta186,187. The results support the prediction of a strongly favored isomer region near neutron number 116. © 2010 The American Physical Society.