This research involved the production of berkelium at ORNL and bombardment with high-power calcium-ion beams in an accelerator at GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany. The discovery paper included 33 authors from six institutions: JINR (15), ORNL (7), LLNL (6), Vanderbilt (2), RIAR (1), and University of Nevada Las Vegas (2).Ī group of 72 scientists from 16 institutions in Australia, Finland, Germany, India, Japan, Norway, Poland, Sweden, Switzerland, the United Kingdom and the United States conducted confirmation experiments to independently verify the discovery of element 117. The international research team announced its discovery of element 117 in April 2010 in a Physical Review Letters publication. The element 117 nuclei were implanted into silicon detectors, where distinctive radioactive decays were measured.Įventually, the detectors turned up six short-lived but history-making atoms of element 117, which then decayed into elements 115, 113, 111, 109, 107 and 105. These compound nuclei were separated from the calcium beam by a set of strong magnets at the Dubna Gas Filled Recoil Separator. Under very rare conditions, the calcium nuclei (containing 20 protons) interacted with the berkelium nuclei (containing 97 protons) to create a few compound nuclei with atomic number 117. The 249Bk target was bombarded for 150 days with an intense beam of 7 trillion calcium-48 ions per second at one of the world's most powerful heavy ion accelerators. The target was sent from RIAR to JINR at Dubna, where the experiment began on July 28, 2009. This material was forwarded to the Russian Research Institute of Atomic Reactors in Dimitrovgrad, which fabricated a target by applying the berkelium radioisotope to a thin film of titanium. On June 15, 2009, ORNL sent 22 milligrams of berkelium-249, with the clock ticking away on its 327-day half-life, to JINR. The berkelium was produced through 250 days of irradiation at ORNL’s HFIR and 90 days of processing at the adjoining Radiochemical Engineering and Development Center (REDC) to separate and purify the berkelium material. Lawrence Livermore National Laboratory, which had collaborated with JINR on previous superheavy element research, also joined the team in late 2008, adding nuclear data analysis capabilities. ORNL and JINR formally agreed to collaborate on superheavy element research in December 2008, including production of berkelium target material at ORNL and participation in the accelerator experiments at JINR. But element 117 identification was not possible without berkelium. Actinide target materials for all of these discoveries came from ORNL and Dimitrovgrad in Russia. Oganessian’s earlier work led to the discovery of elements 114, 116 and 118 in 2000-2004 in collaboration with Lawrence Livermore National Laboratory. This meeting formed the basis of the ongoing collaboration among the three institutions. Vanderbilt University professor Joe Hamilton noted when californium production resumed at ORNL in 2008 and introduced ORNL’s Jim Roberto to Yuri Oganessian, who successfully pioneered the “hot fusion” approach to synthesize superheavy elements by bombarding actinide targets with heavy ions accelerated in a cyclotron at the Joint Institute for Nuclear Research in Dubna, Russia. Berkelium is a byproduct of californium production at ORNL’s High Flux Isotope Reactor (HFIR). ORNL is the only place in the world that can produce sufficient quantities of the radioactive element berkelium, a synthetic element that is essential for the creation of element 117. The experiment that produced the first evidence of element 117 could not have happened without multiple world-class scientific facilities, including a unique accelerator complex in Russia and the nuclear research reactor and processing facilities at the Department of Energy’s Oak Ridge National Laboratory. The discovery of element 117, a synthetic element that does not occur in nature, required many years of collaborative research by dozens of scientists from several international institutions.
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