IUPAP/IUPAC Joint Working Party on Discovery of Elements Validates Claims for Four New Elements

The claims for four new elements have been validated in a new report from the IUPAC/IUPAP Joint Working Party (JMP) and are to be published in Pure and Applied Chemistry [1]. The addition of the four elements 113, 115,117, and 118 is exciting because it completes the seventh row of the Periodic Table.

Elements are the basic chemical building blocks of nature; they are classified by atomic number (number of protons in nucleus). The elements we find on Earth with atomic number 1 to 92, hydrogen to uranium, were created by nuclear synthesis in stars or stellar explosions and still exist due to their stability.

Heavier elements were discovered after they were artificially produced and most of them are very unstable. The lighter ones were produced in nuclear reactors but the recently discovered heavier new elements have been produced by fusing two lighter elements together. The stability, half-life, and production probability generally decrease as atomic number increases. The method of synthesis based on fusion reactions by particle accelerators has become more and more difficult as Z increases. Its successful implementation relies on expertise in nuclear physics.

The typical procedure is the following. Heavy elements are produced by using nuclear fusion reactions with accelerated beams of heavy ions like Calcium-48, and targets whose atoms with atomic weight above 200. The products are magnetically separated and counted by their radioactive decay, which is in nearly all cases is sequential alpha decay, to trace back to known elements. The final element in the decay chain is identified by chemical analysis. The chain of radioactive decays firmly connects the new elements to known ones. In the case of the new element discoveries in this report, over 10 years of dedicated hard work at several laboratories was required to achieve and to confirm the results. Exploration of new elements is one of the main frontiers of nuclear physics and one of the driving forces of nuclear science facilities. The recent work has discovered a region of relatively stable new elements and other isotopes with very long half-lives are possible.

The recent discovery of elements 113, 115,117 and 118, and its confirmation, are excellent examples of this hard work.

The group of Morita et al. at the RIKEN laboratory in Japan produced element 113 by the fusion of zinc with bismuth in 2004[2] and confirmed the result in 2012 [3]. The reaction used is an example of “cold fusion” where the bombarding energy is relatively low and the radioactive decays can be traced to known elements.

The other new elements were produced at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia using beams of the rare calcium isotope calcium-48 with actinide targets. This was done at higher bombarding energies in so-called “hot fusion” reactions. This new approach is a breakthrough, which allowed the other three new elements to be made. The new element 115 was produced by calcium-48 fusion reactions on americium and berkelium targets [4,5]. The very rare berkelium targets were produced at Oak Ridge National Laboratory at the High Flux Reactor, but the berkelium has such a  short lifetime that after about a year and a half the target had become californium. Element 117 was also produced in Dubna with the berkelium target by a Joint Institute for Nuclear Research -Oak Ridge National Laboratory-Lawrence Livermore National Laboratory collaboration [5]. Element 118 was produced in a similar way by fusing calcium-48 and a californium target by a collaboration of the same institutions [6].

Important experiments confirming these results were performed at the Heavy Ion Research Facility in Lanzhou (HIRFL),  GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, and Lawrence Berkeley National Laboratory in collaborations involving scientists from many other institutions in Mainz, Corvallis,  Lund, Oslo, Liverpool, Tokai, and Villigen.

Now that the discoveries have been validated, the discoverers have been invited to propose the names and symbols of the new elements.

For information please contact the Chair of C12 Professor Alinka Lepine-Szily and the Vice Chair of C12 Professor Weiping Liu


[1] Paul J Karol, Robert C. Barber, Bradley M. Sherrill, Emanuele Vardaci and Toshimitsu Yamazaki, Pure and Applied Chemistry, 88, to be published (2016).

Pre-publication access is by

Element 118: http://www.degruyter.com/view/j/pac.ahead-of-print/pac-2015-0501/pac-2015-0501.xml

Elements 113, 115 and 117: http://www.degruyter.com/view/j/pac.ahead-of-print/pac-2015-0502/pac-2015-0502.xml

After publication these links are deactivated, and the papers can be accessed by the permanent DOI links:

Element 118: http://dx.doi.org/10.1515/pac-2015-0501

Elements 113, 115 and 117: http://dx.doi.org/10.1515/pac-2015-0502


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