Flerovium

Flerovium

Element number 114: flerovium (symbol Fl) and element number 116: livermorium (symbol Lv)

The International Union of Pure and Applied Chemistry (IUPAC) has recommended names for elements 114 and 116. Scientists from the Lawrence Livermore National Laboratory (LLNL) and at Dubna proposed the names as Flerovium for element 114 and Livermorium for element 116.

Flerovium (atomic symbol Fl) was chosen to honor Flerov Laboratory of Nuclear Reactions, where superheavy elements, including element 114, were synthesized. Georgiy N. Flerov (1913-1990) was a renowned physicist who discovered the spontaneous fission of uranium and was a pioneer in heavy-ion physics. He is the founder of the Joint Institute for Nuclear Research. In 1991, the laboratory was named after Flerov - Flerov Laboratory of Nuclear Reactions (FLNR).

Livermorium (atomic symbol Lv) was chosen to honor Lawrence Livermore National Laboratory (LLNL) and the city of Livermore, Calif. A group of researchers from the Laboratory, along with scientists at the Flerov Laboratory of Nuclear Reactions, participated in the work carried out in Dubna on the synthesis of superheavy elements, including element 116. (Lawrencium -- Element 103 -- was already named for LLNL's founder E.O. Lawrence.)

In 1989, Flerov and Ken Hulet (1926-2010) of LLNL established collaboration between scientists at LLNL and scientists at FLNR; one of the results of this long-standing collaboration was the synthesis of elements 114 and 116.

The creation of elements 116 and 114 involved smashing calcium ions (with 20 protons each) into a curium target (96 protons) to create element 116. Element 116 decayed almost immediately into element 114. The scientists also created element 114 separately by replacing curium with a plutonium target (94 protons).

The creation of elements 114 and 116 generate hope that the team is on its way to the "island of stability," an area of the periodic table in which new heavy elements would be stable or last long enough for applications to be found.

The new names were submitted to the IUPAC in late October. The new names will not be official until about five months from now when the public comment period is over.

Discovery of the Elements with Atomic Number 114 and 116

A news reports from IUPAC indicates the confirmation of the discoveries of elements 114 and 116. Proposals for the names of the two elements will follow in due course:

News: Discovery of the Elements with Atomic Number 114 and 116

Priority for the discovery of the elements with atomic number 114 and 116 has been assigned, in accordance with the agreed criteria, to collaborative work between scientists from the Joint Institute for Nuclear Research in Dubna, Russia and from Lawrence Livermore, California, USA (the Dubna-Livermore collaborations). The discovery evidences were recently reviewed and recognized by a IUPAC/IUPAP joint working party. IUPAC confirmed the recognition of the elements in a letter to the leaders of the collaboration.

The IUPAC/IUPAP Joint Working Party (JWP) on the priority of claims to the discovery of new elements has reviewed the relevant literature pertaining to several claims. In accordance with the criteria for the discovery of elements previously established by the 1992 IUPAC/IUPAP Transfermium Working Group, and reiterated by the 1999 and 2003 IUPAC/IUPAP JWPs, it was concluded that “the establishment of the identity of the isotope 283Cn by a large number of decaying chains, originating from a variety of production pathways essentially triangulating its A,Z character enables that nuclide’s use in unequivocally recognizing higher-Z isotopes that are observed to decay through it.” From 2004 Dubna-Livermore collaborations the JWP notes: (i) the internal redundancy and extended decay chain sequence for identification of Z = 287114 from 48Ca + 242Pu fusion (Oganessian et al. Eur. Phys. J. A 19, 3 (2004) and Phys. Rev. C 70, 064609 (2004)); and (ii) that the report of the production of 291116 from the fusion of 48Ca with 245Cm is supported by extended decay chains that include, again, 283Cn and descendants (Oganessian et al. Phys. Rev. C 69, 054607 (2004)). It recommends that the Dubna-Livermore collaborations be credited with discovery of these two new elements.

A full synopsis of the relevant experiments and related efforts is presented in a technical report published online in Pure and Applied Chemistry on 1 June 2011. With the priority for the discovery established, the scientists from the Dubna-Livermore collaborations are invited to propose a name for the two super-heavy elements, elements 114 and 116. The suggested names will then go through a review process before adoption by the IUPAC Council.

Review of the claims associated with elements 113, 115, and 118 are at this time not conclusive and evidences have not met the criteria for discovery.

Independent Verification of Element 114 (ununquadium)

Workers in the USA verify the production of element 114 in the reaction of 244-MeV 48Ca with 242Pu. Two chains of time- and position-correlated decays were assigned to 286114 and 287114. The observed decay modes, half-lives, and decay energies agree with the original claims of researchers at the Joint Institute for Nuclear Research at Dubna in Russia. The Russian results were first reported in 1999. Such independent verification is vital for verification purposes. The measured cross sections at a center-of-target energy of 244 MeV for the 242Pu(48Ca,3–4n)287,286114 reactions were 1.4(+3.2, -1.2) pb each, which are lower than the reported values.1

Independent Verification of Element 114 Production in the Ca-48 + Pu-242 Reaction

Independent verification of the production of element 114 in the reaction of 244-MeV 48Ca with 242Pu is presented. Two chains of time- and position-correlated decays have been assigned to 286114 and 287114. The observed decay modes, half-lives, and decay energies agree with published results. The measured cross sections at a center-of-target energy of 244 MeV for the 242Pu(48Ca,3–4n)287,286114 reactions were 1.4(+3.2, -1.2) pb each, which are lower than the reported values.

Independent Verification of Element 114 Production in the Ca-48 + Pu-242 Reaction, Stavsetra, L., Gregorich K. E., Dvorak J., Ellison P. A., Dragojević I., Garcia M. A., and Nitsche H. , Physical Review Letters, Volume 103, Number 13, p.132502, (2009)

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