Discovery of the new chemical elements with numbers 113, 115, 117 and 118
World science, 06 January 2016
Press Release of the Joint Institute for Nuclear Research
On 30 December 2015 the IUPAC issued an official press release concerning the discovery of the new chemical elements with atomic numbers 113, 115, 117 and 118.
It is officially announced that based on the results of work of the Joint Working Party of the International Union of Pure and Applied Chemistry and of the International Union of Pure and Applied Physics, the IUPAC confirmed the discovery of the new chemical elements of the D.I.Mendeleev Periodic Table with atomic numbers 113, 115, 117 and 118.
The assigned priorities of discovery are follows:
- Element 113 – collaboration of RIKEN institute (Japan);
- Elements 115 and 117 – collaboration of the Joint Institute for Nuclear Research (Dubna, Russia), the Lawrence Livermore National Laboratory (USA) and the Oak Ridge National Laboratory (USA);
- Element 118 – collaboration of the Joint Institute for Nuclear Research (Dubna, Russia) and the Lawrence Livermore National Laboratory (USA).
Synthesis of elements 115, 117 and 118 was carried out in JINR, Dubna employing the U-400 accelerator complex of the Flerov Laboratory of Nuclear Reactions in reactions of accelerated ions of Ca-48 with actinide targets (Americium-243 – element 115, Berkelium-249 – element 117, Californium-249 – element 118). Further, the results obtained in Dubna were confirmed by researchers in Germany (GSI, Darmstadt) and the USA (Berkeley).
Earlier, in 2011, the IUPAC recognized the priority of our collaboration with the Lawrence Livermore National Laboratory (USA) in the discovery of elements 114 and 116 that were given the names Flerovium, Fl, for element 114 and Livermorium, Lv, for element 116.
The name Flerovium, Fl, honors the Flerov Laboratory of Nuclear Reactions, JINR that is a recognized leader in synthesis of superheavy elements and its founder – prominent physicist Academician G.N.Flerov (1913-1990) who was the discoverer of the new type of radioactivity – spontaneous fission of heavy nuclei, pioneer in several new directions of science, the founder and first director of the JINR Laboratory of Nuclear Reactions that now bears his name.
The name Livermorium, Lv, honors the Lawrence Livermore National Laboratory and its location – the city of Livermore (California, USA). For more than 20 years researchers of Livermore have been taking part in the work carried out in Dubna on the synthesis of new elements.
In general, synthesis of elements 114 through 118 (the recognized leader of this work is Prof. Yu.Ts.Oganessian) was the first experimental discovery of “the islands of stability” in the domain of superheavy elements that is of principal fundamental importance for nuclear physics (study of nuclear structure), for chemistry (verification of the fundamental D.I. Mendeleev law of periodicity of properties of chemical elements), for understanding of one of the key questions of the modern science that is the formation of heavy nuclei (process of nucleosynthesis), etc.
All in all, in the last 50 years, D.I.Mendeleev Periodic Table was replenished by 17 new elements (102 – 118), 9 of which were synthesized in JINR; among the latter are the heaviest (superheavy) five elements of the Periodic Table produced in the recent decade.
Regarding the names of new elements 115, 117 and 118
According to the regulations, the authors are invited by IUPAC to suggest names of the new elements.
Regarding element 115, our proposal has been repeatedly announced; this is Moscovium that honors the Moscow Region as a whole (Moscow and Moscow Oblast) – the place where this research has been carried out and whose officials and organizations strongly contributed to its development (support of the Russian Academy of Sciences, grants of the Ministry for Education and Research of Russian Federation, of Rosatom, of the Russian Foundation for Basic Research, of the Governors of the Moscow region B.V.Gromov and A.Yu.Vorobyov). As for elements 117 and 118, the question is open at the moment and is to be discussed with our colleagues of Livermore and Oak Ridge.
Regarding the discovery of the element 113
In fact, element 113 (an isotope with mass number 284 and lifetime of about one second) has been registered for the first time in 2003 in JINR in the reaction of Calcium-48 with Americium-243 as a daughter product of the decay of the isotope of the element 115 with mass 288.
Somewhat later, in 2004, our colleagues from RIKEN, the group of Prof. K. Morita, have carried out their first experiment on the irradiation of bismuth-209 target by accelerated ions of zinc-70; here they registered an isotope of element 113 with mass 278 and lifetime of several milliseconds. In whole, their experiment took more than 10 years; as a result, a total of just 4 events of synthesis of new element could be registered. At the same time, during the same period, about 100 events of birth of element 113 have been detected in Dubna; moreover, pioneering experiments were carried out with the aim of studying its chemical properties. The fact of synthesis of the isotope of element 113 with the mass 284 was confirmed in GSI (Germany) and Berkeley (USA). As to the experiment of our Japanese colleagues, this will hardly be reproduced by anyone, since production of a millisecond-living isotope that demands several years of beam time for observing a single nucleus looks not a very promising activity.
However, the IUPAC-IUPAP Party (JWP) has assigned the priority to RIKEN. To us, this is somewhat unexpected decision. Moreover, in the IUPAC practice, there are enough precedents of acknowledging “joint” priority (examples can be the cases with elements 103, 104 and 105 with authorship of discovery shared between JIND (Dubna) and Berkeley (USA)). We are glad for our colleagues from RIKEN especially, because the leader of the work, Prof. K.Morita is to a certain extent the trainee of Dubna; here, in JINR he for quite a long time learned the basics of synthesis of new elements. However, the method of synthesizing the superheavy elements, chosen by RIKEN researchers is completely exhausted; moreover, today they plan future experiments using only the method proposed in Dubna.
We respect the decision of IUPAC. However, our position regarding the decision on element 113 will be determined only after the reports of the IUPAC-IUPAP JWP are officially published and studied in detail.
Prospects of developing of works on synthesis of superheavy elements
Today FLNR JINR is the recognized world leader in synthesis and study of the properties of new superheavy elements of D.I.Mendeleev Periodic Table. However, scientific competition in this field increases, and today (taking into account the results obtained in FLNR JINR) the corresponding programs are approved in Germany, Japan, China, France and the USA. Further progress of these studies here in JINR is connected with the development in our institute of the first in the world Factory of Superheavy Elements. This is to be based on the new accelerator of heavy ions, the most powerful in this energy range, with intensity 10 times higher than has been achieved by today, that will allow to set goals of synthesizing new elements with atomic number 119 and 120 and further, that are the first elements of the eighth period of D.I.Mendeleev Periodic Table.