Six isotopes, never seen before, of the superheavy elements 104 through 114A have been detected by a team of scientists at the U.S. Department of Energy's Lawrence Berkeley National Laboratory.
Starting with the creation of a new isotope of the yet-to-be-named element 114, the researchers observed successive emissions of alpha particles that yielded new isotopes of copernicium (element 112), darmstadtium (element 110), hassium (element 108), seaborgium (element 106), and rutherfordium (element 104). Rutherfordium ended the chain when it decayed by spontaneous fission.
Information gained from the new isotopes will contribute to a better understanding of the theory of nuclear shell structure.
The theory underlies predictions of an “Island of Stability,” a group of long-lasting isotopes thought to exist amidst a sea of much shorter-lived, intrinsically unstable isotopes of the superheavy elements.
The group that found the new isotopes is led by Heino Nitsche.
Ken Gregorich, a senior staff scientist in NSD, is responsible for the group's day-to-day research operation at the 88-inch Cyclotron and the Berkeley Gas-filled Separator, the instrument used to isolate and identify the new isotopes. Paul Ellison of NSD was first author of the paper reporting the results in the 29 October 2010 issue of Physical Review Letters, now available online to subscribers.
“We were encouraged to try creating new superheavy isotopes by accelerating calcium 48 projectiles with Berkeley Lab's 88-Inch Cyclotron and bombarding plutonium 242 targets inside the Berkeley Gas-filled Separator here,” Nitsche says.