Discovery of 'Missing' Element 117 Hints at Stable Isotopes to Come

摘要

Russia strikes again. In the past decade, the Joint Institute for Nuclear Research in Dubna, Russia, has bagged new elements 113, 114, 115, 116, and 118 by firing up a fantastically intense beam of neutron-heavy calcium-48 isotopes and blasting away at the periodic table's radioactive actinide elements. Last week in Physical Review Letters, a multi-institution team there announced that it had filled a gap by making element 117 as well.rn"They devoted very, very long beam times and very hard work," says nuclear chemist Heino Nitsche, who leads the heavy-element group at Lawrence Berkeley National Laboratory in Berkeley, California. At other labs, Nitsche says, heavy-element scientists vie with other experimenters for beam time, but Dubna physicists enjoy a cyclotron largely dedicated to element-hunting. "You won't find that anywhere else in the world," he says.