Still, for roughly half a century, nuclear scientists have been searching for an elusive "island of stability," somewhere among the superheavies, in which long-lived elements with new chemical properties might exist. Dr. Loveland said that the new results indicated that scientists might be closing in on that island.

"We're sort of in the shoals of the island of stability," said Dr. Kenton J. Moody, a Livermore nuclear physicist who was one of the experimenters in the work.