EXISTENCE OF LONG-LIVED ISOTOPES OF A SUPERHEAVY ELEMENT IN NATURAL Au

Abstract

Evidence for the existence of long-lived isotopes with atomic mass numbers 261 and 265, and abundance of (1-10)×10 -10 relative to Au, has been found in a study of natural Au using inductively coupled plasma-sector field mass spectrometry. The measured masses match the predictions for the masses of 261 Rg and 265 Rg (Z=111), and those of some isobars of nearby elements. Based on chemical arguments, it is proposed that they are most probably isotopes of Rg. It is deduced that long-lived isomeric states exist in these isotopes. The hypothesis that they belong to a new class of long-lived high spin super- and hyperdeformed isomeric states is discussed.