Dubna

In 1964, workers at the Joint Nuclear Research Institute at Dubna (U.S.S.R.) bombarded plutonium with accelerated 113 to 115 MeV neon ions. By measuring fission tracks in a special glass with a microscope, they detected an isotope that decays by spontaneous fission. They suggested that this isotope, which had a half-life of 0.3 +/- 0.1 s might be 260-104, produced by the following reaction 242Pu + 22Ne —> 104 +4n. 

New data, reportedly issued by Soviet scientists, have reduced the half-life of the isotope they worked with from 0.3 to 0.15 s. The Dubna scientists suggest the name kurchatauium and symbol Ku for element 104, in honor of Igor Vasilevich Kurchatov (1903-1960), former Head of Soviet Nuclear Research. 

In 1969 Ghiorso, Nurmia, Harris, K.A.Y. Eskola, and P.E. Eskola of the University of California at Berkeley reported that they had positively identified two, and possibly three, isotopes of Element 104. The group indicated that, after repeated attempts, they produced isotope 260-104 reported by the Dubna groups in 1964. 

In 1967 G.N. Flerov reported that a Soviet team working at the Joint Institute for Nuclear Research at Dubna may have produced a few atoms of 260-105 and 261-105 by bombarding 243Am with 22Ne. The evidence was based on time-coincidence measurements of alpha energies. 

In June 1974, members of the Joint Institute for Nuclear Research in Dubna, U.S.S.R., reported their discovery of Element 106, which they reported to have synthesized. Glenn Seaborg was part of this group, and the element was named in his honor. Seaborgium is often still referred to as Element 106 because the international committee in charge of names changed the rules. They decided retroactively it couldn t be named after a living person. 

At Dubna, 280-MeV ions of 54Gr from the 310-cm cyclotron were used to strike targets of 206Pb, 207Pb, and 208Pb, in separate runs. Foils exposed to a rotating target disc were used to detect spontaneous fission activities. The foils were etched and examined microscopically to detect the number of fission tracks and the half-life of the fission activity. 

Other experiments were made to aid in confirmation of the discovery. Neither the Dubna team nor the Berkeley-Eivermore Group has proposed a name as of yet for element 106 (unnilhexium). 

In 1967, Flerov and associates at the Dubna Laboratory reported their inability to detect an alpha emitter with a half-life of 8 s which was assigned by the Berkeley group to 257-103. This assignment has been changed to 258Lr or 259Lr. 

In 1965, the Dubna workers found a longer-lived lawrencium isotope, 256Lr, with a half-life of 35 s. In 1968, Thiorso and associates at Berkeley used a few atoms of this isotope to study the oxidation behavior of lawrencium. Using solvent extraction techniques and working very rapidly, they extracted lawrencium ions from a buffered aqueous solution into an organic solvent — completing each extraction in about 30 s. 

Nobelium, No< > Workers at Dubna, 1965 Bombardment of gjAm Alfred Nobel (benefactor... 

Elements beyond 103 are expected to be 6d elements forming a fourth transition series, and attempts to synthesize them have continued during the past thirty years. All 10 (including, of course, actinium) are now known and are discussed in the section on transactinide elements on p. 1280. The work has required the dedicated commitment of extensive national facilities and has been carried out at the Lawrence-Berkeley Laboratories, the Joint Institute for Nuclear Research at Dubna, and the Heavy-Ion Research Centre (GSI) at Darmstadt, Germany. 

The first (inconclusive) work bearing on the synthesis of element 104 was published by the Dubna group in 1964. However, the crucial Dubna evidence (1969-70) for the production of element 104 by bombardment of 94PU with loNe came after the development of a sophisticated method for rapid in situ chlorination of the product atoms followed by their gas-chromatographic separation on an atom-by-atom basis. This was a heroic enterprise which combined cyclotron nuclear physics and chemical separations. As we have seen, the actinide series of elements ends with 103 Lr. The next element should be in Group 4 of the transition elements, i.e. a heavier congenor of Ti, Zr and Hf. As such it would be expected to have a chloride... 

Work at Berkeley-Livermore in 1974 first convincingly demonstrated the synthesis of this element via the reaction " Cf( 0,4n) 106. Contemporaneous work at Dubna applied their novel cold fusion method (p. 1280) to reactions such as 82 Pb - - 24 Cr although this methodolgy was crucial to the synthesis of all later elements (107-112) it did not at that time demonstrate the formation of element 106 with adequate conviction. Very recently, element 106 was resynthesized by a new group at Berkeley using exactly the same reaction as employed in 1974. The isotope 106 decays with a half-life of 0.8 0.2 s to 104 and then by a second... 

In October 2006, a research team of scientists from the Lawrence Livermore National Laboratory in California, USA, and the Joint Institute of Nuclear Research in Dubna, Russia, reported the indirect detection of Uuo-294 (Element 118). It is reported to be produced by the following collisions. 

Breskrovny, A.I., Lebedev, N.A., Ostanevich, Y.M.L. Joint Institute for nuclear research report, Dubna (1971) (private communication)... 

The name was debated. The priority for the production lay with the Institute for Nuclear Research in Dubna (Russia), under the leadership of G. N. Flerov, where 238U was bombarded with 22Ne. The half-life was about 2.7 seconds. At the University of California, bombardment of curium with carbon gave rise to an isotope with a half-life of 58 minutes. The IUPAC commission suggested the name "lerovium", but nobelium persisted. 

The element was generated by bombardment of californium with boron in a linear accelerator. The priority is debated. Isotopes of the elements were observed both by the group of Glenn T. Seaborg and by that of G. N. Flerov in Dubna. IUPAC proposed that the priority be shared. The longest-lived isotope has a half-life of 200 minutes. Lawrencium ends the series of actinides, as the 5f level is fully occupied with 14 electrons. 

Back to the facts. The use of accelerators as fusion reactors first in 1940 in Berkeley (USA), later in Dubna (Russia), and then in Darmstadt (Ge-sellschaft fur Schwerionenforschung Institute for Heavy-Ion Research) allowed the expansion of the series of elements up to atomic number 116. This means that 24 artificial elements after uranium have been produced and identified. In most cases, the half-lives are extremely short and the few at-... 

Scientific chemistry has its roots in the European Enlightenment. All 92 naturally occurring elements were discovered and identified here. The map shows that England, France, and Sweden played central roles, whereas in Germany research was carried out in the various regional centers. With the advent of atomic research, the emphasis on the discovery of the artificial elements shifted to the USA. They were later joined by Russia (Dubna) and Germany (Institute for Heavy-Ion Research). 

Bogoliubov Laboratory of Theoretical Physics, JINR Dubna, 141980 Dubna, Russia... 

Gordanskii, V. I., Proc. Dubna Conf. Mossbauer Effect, Consultants Bureau, New York, 1963. 

Dubnium - the atomic number is 105 and the chemical symbol is Db. The name derives from the location of the Russian research center, the Joint Institute for Nuclear Research lab in Dubna , Russia. The first synthesis of this element is jointly credited to the American scientific team at the University of California in Berkeley, California imder Albert Ghiorso and the Russian scientific team at the JINR (Joint Institute for Nuclear Reactions) lab in Dubna, Russia, imder Georgi N. Flerov in 1970. The longest half-life associated with this unstable element is 34 second Db. 

Element 110 - no name has been proposed or accepted by lUPAC for element 110. This element was first synthesized in a November 1994 experiment by a multi-national team of scientists working at the Gesellschaft fur Schwerionenforschung (GSI) in Darmstadt, Germany. The scientific teams were from the GSI (Heavy Ion Research Center), Darmstadt, the Joint Institute for Nuclear Research (JINR), Dubna, Russia, Comenius University, Bratislava, Slovakia and the University of Jyvaskyla, Finland. They used the nuclear reaction ° Pb ( Ni, n) 110. The longest half-life associated vdth this unstable element is 1.1 minute 10. 

MSN.194. E. Karpov, G. Ordonez, T. Petrosky, and 1. Prigogine, Microscopic entropy and nonlocality, in Proceedings International Workshop Quantum Physics and Communication, Dubna 2002, Particles and Nuclei Lett. 1 (116), 8-15 (2003). 

The chemical and physical properties of Unq (or rutherfordium) are homologous with the element hafnium ( jHf), located just above it in group 4 (fVB) in the periodic table. It was first claimed to be produced artificially by the Joint Institute for Nuclear Research (JINR) located in Dubna, Russia. The Russian scientists used a cyclotron that smashed a target of plutonium-242 with very heavy ions of neon-22, resulting in the following reaction Pu-242 + jjjNe-22 —> jj, Unq-260 + 4 n-1 (alpha radiation). The Russians named Unq-260 kurcha-tovium (Ku-260) for the head of their center, Ivan Kurchatov. (See details in the next section, History. )... 

The Lawrence Berkeley Laboratory and other groups were unable to confirm the spontaneous-fission reaction of Ku-260, so the Dubna groups discovery was disputed. The Berkeley equipment was unable to accelerate neon ions to the speeds required to produce Ku-260, and thus they tried a different reaction in a new automated rapid chemistry apparatus that identified and confirmed new isotopes of heavy metals. The procedure involved bombarding the element californium-239 with a mixture of the isotopes carbon-12 and carbon-13 ions, as follows ... 

ORIGIN OF NAME Unnilquadium follows the transitional naming system of lUPAC but originally was named "hahnium" by the Berkeley group in honor of Otto Hahn, who discovered nuclear fission. The American Chemical Society endorsed the name "hahnium" for element 105, but as the Berkeley group continued its work and more isotopes of Q Unp were formed, the lUPAC changed the name "hahnium" to "dubnium" after the city Dubna, Russia, where the first isotopes of unnilpentium were formed. 

In 1967 the scientists of the Joint Institute of Nuclear Research in Dubna, Russia, bombarded americium-243 with neon-22 to produce two isotopes of unnilpentium, then known as hahnium. The reaction is as follows jAm-243 + Ne-22 —> jjjjHahnium-260 and 261 (Unp-260 and 261). In 1970 Albert Ghiorso and his team at Berkeley bombarded califor-nium-249 with heavy nitrogen (N-15) in their Heavy Ion Linear Accelerator (HILAC). The reaction is as follows gCf-249 + -15 —> j jHa-260 (Unp-260). 

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