page_title: Tennessine
section_title: Discovery
hierarchical_section_title: Tennessine / History / Discovery
caption_attribution_description: English: It took 250 days to make enough berkelium, shown here (in dissolved state), to synthesize element 117.
context_page_description: Tennessine is a synthetic chemical element with the symbol Ts and atomic number 117. It is the second-heaviest known element and the penultimate element of the 7th period of the periodic table.
  The discovery of tennessine was officially announced in Dubna, Russia, by a Russian–American collaboration in April 2010, which makes it the most recently discovered element as of 2020. One of its daughter isotopes was created directly in 2011, partially confirming the results of the experiment. The experiment itself was repeated successfully by the same collaboration in 2012 and by a joint German–American team in May 2014. In December 2015, the Joint Working Party of the International Union of Pure and Applied Chemistry and the International Union of Pure and Applied Physics, which evaluates claims of discovery of new elements, recognized the element and assigned the priority to the Russian–American team. In June 2016, the IUPAC published a declaration stating that the discoverers had suggested the name tennessine after Tennessee, United States. In November 2016, they officially adopted the name "tennessine".
context_section_description: ORNL resumed californium production in spring 2008. Hamilton noted the restart during the summer and made a deal on subsequent extraction of berkelium (the price was about $600,000). During a September 2008 symposium at Vanderbilt University in Nashville, Tennessee celebrating his 50th year on the Physics faculty, he introduced Oganessian to James Roberto (then the deputy director for science and technology at ORNL). They established a collaboration among JINR, ORNL, and Vanderbilt; the team at the Lawrence Livermore National Laboratory (LLNL) in Livermore, California, U.S., was soon invited to join.
  In November 2008, the U.S. Department of Energy, which had oversight over the reactor in Oak Ridge, allowed the scientific use of the extracted berkelium. The production lasted 250 days and ended in late December 2008, resulting in 22 milligrams of berkelium, enough to perform the experiment. In January 2009, the berkelium was removed from ORNL's High Flux Isotope Reactor; it was subsequently cooled for 90 days and then processed at ORNL's Radiochemical Engineering and Development Center to separate and purify the berkelium material, which took another 90 days. Its half-life is only 330 days: after that time, half the berkelium produced would have decayed. Because of this, the berkelium target had to be quickly transported to Russia; for the experiment to be viable, it had to be completed within six months of its departure from the United States. The target was packed into five lead containers to be flown from New York to Moscow.
  Russian customs officials twice refused to let the target enter the country because of missing or incomplete paperwork. Over the span of a few days, the target traveled over the Atlantic Ocean five times. On its arrival in Russia in June 2009, the berkelium was immediately transferred to Research Institute of Atomic Reactors (RIAR) in Dimitrovgrad, Ulyanovsk Oblast, where it was deposited as a 300-nanometer-thin layer on a titanium film. In July 2009, it was transported to Dubna, where it was installed in the particle accelerator at the JINR. The calcium-48 beam was generated by chemically extracting the small quantities of calcium-48 present in naturally occurring calcium, enriching it 500 times. This work was done in the closed town of Lesnoy, Sverdlovsk Oblast, Russia.
  The experiment began in late July 2009. In January 2010, scientists at the Flerov Laboratory of Nuclear Reactions announced internally that they had detected the decay of a new element with atomic number 117 via two decay chains: one of an odd–odd isotope undergoing 6 alpha decays before spontaneous fission, and one of an odd–even isotope undergoing 3 alpha decays before fission. The obtained data from the experiment was sent to the LLNL for further analysis. On April 9, 2010, an official report was released in the journal Physical Review Letters identifying the isotopes as ²⁹⁴117 and ²⁹³117, which were shown to have half-lives on the order of tens or hundreds of milliseconds. The work was signed by all parties involved in the experiment to some extent: JINR, ORNL, LLNL, RIAR, Vanderbilt, the University of Tennessee (Knoxville, Tennessee, U.S.), and the University of Nevada (Las Vegas, Nevada, U.S.), which provided data analysis support. The isotopes were formed as follows:
  ²⁴⁹
  ₉₇Bk
   + ⁴⁸
  ₂₀Ca
   → ²⁹⁷117* → ²⁹⁴117 + 3 ¹
  ₀
  n
   (1 event)
  ²⁴⁹
  ₉₇Bk
   + ⁴⁸
  ₂₀Ca
   → ²⁹⁷117* → ²⁹³117 + 4 ¹
  ₀
  n
   (5 events)
caption: The berkelium target used for the synthesis (in solution)
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