Element 117 discovered

Physics Today : Updated 4/7/2010: According to sources at Lawrence Livermore National Laboratory, element number 117 has been successfully synthesized.There were hints that element 117 had been discovered at the recent 31st meeting of the Program Advisory Committee for Nuclear Physics , but the news became public when a paper describing the research was accepted for publication in Physical Review Letters. The international research team consisted of Yuri Oganessian of the Joint Institute for Nuclear Research in Dubna, Russia, and associates from LLNL, Oak Ridge National Laboratory (ONL), Vanderbilt University, and the University of Nevada, Las Vegas. The same group have also discovered other superheavy elements, such as element 114. “The discovery of element 117 is the culmination of a decade-long journey to expand the periodic table and write the next chapter in heavy element research,” said Oganessian.The existence of element 117 was deduced from the decay patterns observed after a radioactive berkelium target was bombarded with calcium ions at the JINR U400 cyclotron in Dubna. The berkelium-249 (see right image. credit ONL) was provided by ONL, who had one of the few facilities in the world that could produce and separate the isotope, with the help of the High Flux Isotope Reactor . The reactor produced 22 mg of berkelium-249 after irradiating a sample for 250 days with an intense beam of neutrons, which was processed and purified before sending to Dubna.LLNL helped analyzed the data. “This is a significant breakthrough for science,” said LLNL director George Miller. 6 into 117Berkelium-249 only has a 320-day half-life, which put some constraints on the amount of material produced in the experiment. Only 6 atoms of element 117 were created.For each atom, the team observed the alpha decay from element 117 to 115 to 113 and so on until the nucleus fissioned, splitting into two lighter elements. In total, 11 new “neutron-rich” isotopes were produced, bringing researchers closer to the presumed " island of stability ” of superheavy elements.The island of stability is a term in nuclear physics that refers to the possible existence of a region beyond the current periodic table where new superheavy elements with special numbers of neutrons and protons would exhibit increased stability.Such an island would extend the periodic table to even heavier elements and support longer isotopic lifetimes to enable chemistry experiments.Element 117 was the only missing element in row seven of the periodic table. On course to the island of stability, researchers initially skipped element 117 due to the difficulty in obtaining the berkelium target material.The observed decay patterns in the new isotopes from this experiment, as close as researchers have ever approached the island of stability, continue a general trend of increasing stability for superheavy elements with increasing numbers of neutrons in the nucleus. This provides strong evidence for the existence of the island of stability."It fills in the gap and gets us incrementally closer than element 116—on the edge,” said Ken Moody, one of the LLNL collaborators and a long term veteran of superheavy element research. “The experiments are getting harder, but then I thought we were done 20 years ago."This discovery brings the total to six new elements discovered by the Dubna-Livermore team (113, 114, 115, 116, 117, and 118, the heaviest element to date).This is the second new element discovery for Oak Ridge (61 and 117). In addition, Oak Ridge isotopes have contributed to the discovery of a total of seven new elements.Since 1940, 26 new elements beyond uranium have been added to the periodic table."These new elements expand our understanding of the universe and provide important tests of nuclear theories,” said Vanderbilt University Professor of physics Joe Hamilton. “The existence of the island of stability, a pure theoretical notion in the 1960s, offers the possibility of further expansion of the periodic table with accompanying scientific breakthroughs in the physics and chemistry of the heaviest elements."A more detailed story will appear on the Physics Today website later this week.Paul Guinnessy Related news stories An atom at the end of the material world Inside Science Scientists discover heavy new element New York Times Russian physicists synthesize new superheavy element 117 ScienceNews Synthesis of element 117 U400 press release International team discovers element 117 ONL press release