scholarly journals Superheavy elements

2019 ◽  
Vol 89 (6) ◽  
pp. 563-570
Author(s):  
Yu. Ts. Oganessian
Keyword(s):  
Periodic Table ◽  
Nuclear Reactions ◽  
Nuclear Research ◽  
Superheavy Elements ◽  
Superheavy Nuclei ◽  
Fusion Reactions ◽  
Nuclear Theory ◽  
Oak Ridge ◽  
Flerov Laboratory ◽  
Heaviest Elements

Synthesis of superheavy elements predicted by microscopic nuclear theory is investigated. The heaviest elements with Z = 114–118 were synthesized by fusion reactions of actinide nuclei with 48Ca ions accelerated using the U-400 complex at the Flerov Laboratory of Nuclear Reactions (FLNR), one of seven laboratories that comprise the Joint Institute for Nuclear Research (JINR) located in Dubna, Russia. The experiments were carried out in collaboration with physicists and chemists working at the Livermore and Oak Ridge national laboratories in located in California and Tennessee, respectively. Discovery of these elements allowed completion of the seventh period of the periodic table. The microscopic nuclear theory’s fundamental predictions about the possible existence of superheavy elements received the experimental confirmation. A new laboratory, i.e., the "STE Factory" associated with the JINR FLNR, has been established to research superheavy nuclei.

scholarly journals Synthesis and Study of the New Superheavy Elements of D.I. Mendeleev Periodic Table of the Elements

Vestnik RFFI ◽  
2019 ◽  
pp. 87-104
Author(s):  
Yuri Ts. Oganessian
Keyword(s):  
Periodic Table ◽  
Nuclear Reactions ◽  
Chemical Properties ◽  
Nuclear Research ◽  
Superheavy Elements ◽  
Fusion Reactions ◽  
Flerov Laboratory ◽  
The Sixties ◽  
Experimental Complex ◽  
Physical And Chemical

In the sixties of the XX century, the possibility of existence of the region of increased stability of superheavy nuclei in the vicinity of Z | 114 and N | 184 was proved. For the first time a successful synthesis of superheavy elements was carried out in the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research (JINR). Superheavy elements of D.I. Mendeleev Periodic Table of the Elements with atomic numbers 114–118 were synthesized in the fusion reactions of the nuclei of the transuranic elements with calcium-48 nuclei. The article deals with the choice of reactions for the synthesis of new elements, methods of studying their nuclear-physical and chemical properties. The experimental complex “Factory of superheavy elements” created in JINR and prospects of further research development are described.

Superheavy elements

2004 ◽  
Vol 76 (9) ◽  
pp. 1715-1734 ◽  
Author(s):  
Yu. Ts. Oganessian
Keyword(s):  
Nuclear Reactions ◽  
Chemical Elements ◽  
Magic Nucleus ◽  
Superheavy Elements ◽  
Nuclear Chemistry ◽  
Fusion Reactions ◽  
Spherical Shells ◽  
Flerov Laboratory ◽  
Theoretical Predictions ◽  
Chemistry Division

One of the fundamental outcomes of nuclear theory is the predicted existence of increased stability in the region of unknown superheavy elements. This hypothesis, proposed more than 35 years ago and intensively developed during all this time, significantly extends the limits of existence of chemical elements. “Magic ”nuclei with closed proton and neutron shells possess maximum binding energy. For the heaviest nuclides, a considerable stability is predicted close to the deformed shells with Z = 108, N = 162. Even higher stability is expected for the neutron-rich nuclei close to the spherical shells with Z = 114 (possibly also at Z = 120, 122) and N = 184, coming next to the well-known “doubly magic ”nucleus 208 Pb. The present paper describes the experiments aimed at the synthesis of nuclides with Z = 113–116, 118 and N = 170–177, produced in the fusion reactions of the heavy isotopes of Pu, Am, Cm, and Cf with 48Ca projectiles.The energies and half-lives of the new nuclides, as well as those of their daughter nuclei (Z < 113) qualitatively agree with the theoretical predictions. The question, which is the nucleus, among the superheavy ones, that has the longest half-life is also considered. It has been shown that, if the lifetime of the most stable isotopes, in particular, the isotopes of element 108 (Hs), is ≥ 5 ×107 years, they can be found in natu ral objects. The experiments were carried out during 2001–2003 in the Flerov Laboratory of Nuclear Reactions (JINR, Dubna) in collaboration with the Analytical and Nuclear Chemistry Division (LLNL, Livermore).

The transuranic elements and the island of stability

2020 ◽  
Vol 378 (2180) ◽  
pp. 20190535 ◽  
Author(s):  
Kit Chapman
Keyword(s):  
Periodic Table ◽  
Nuclear Research ◽  
Superheavy Elements ◽  
Magic Numbers ◽  
Nuclear Shell Model ◽  
Theme Issue ◽  
Protons And Neutrons ◽  
Historical Developments ◽  
The University ◽  
Nuclear Shell

Since the 1930s the synthesis of nuclides too unstable to exist naturally on Earth has stretched the periodic table to 118 elements. While the lighter transuranic elements have found uses, the isotopes of those past lawrencium, the superheavy elements, are too unstable to exist outside the laboratory. In the 1970s, leading element discoverers Glenn Seaborg at the University of California, Berkeley, USA, and Georgy Flerov, at the Joint Institute for Nuclear Research in Dubna, USSR, took interest in a supposed ‘island of stability’, leading from the nuclear shell model of Maria Goeppert Mayer and Hans Jensen, and predicted elements with so-called magic numbers of protons and neutrons would be far more stable. This review shall look at the historical developments that led to the field of element discovery, the attempts to discover superheavy elements in nature based on the island of stability, and the subsequent successful synthesis of elements and the implications of their half-lives and properties. This article is part of the theme issue ‘Mendeleev and the periodic table’.

scholarly journals Chemistry of the superheavy elements

2015 ◽  
Vol 373 (2037) ◽  
pp. 20140191 ◽  
Author(s):  
Matthias Schädel
Keyword(s):  
Periodic Table ◽  
Nuclear Reactions ◽  
Noble Gas ◽  
Relativistic Quantum ◽  
Chemical Properties ◽  
Relativistic Effects ◽  
Electron Shell ◽  
Heavy Ion ◽  
Superheavy Elements ◽  
Shell Effects

The quest for superheavy elements (SHEs) is driven by the desire to find and explore one of the extreme limits of existence of matter. These elements exist solely due to their nuclear shell stabilization. All 15 presently ‘known’ SHEs (11 are officially ‘discovered’ and named) up to element 118 are short-lived and are man-made atom-at-a-time in heavy ion induced nuclear reactions. They are identical to the transactinide elements located in the seventh period of the periodic table beginning with rutherfordium (element 104), dubnium (element 105) and seaborgium (element 106) in groups 4, 5 and 6, respectively. Their chemical properties are often surprising and unexpected from simple extrapolations. After hassium (element 108), chemistry has now reached copernicium (element 112) and flerovium (element 114). For the later ones, the focus is on questions of their metallic or possibly noble gas-like character originating from interplay of most pronounced relativistic effects and electron-shell effects. SHEs provide unique opportunities to get insights into the influence of strong relativistic effects on the atomic electrons and to probe ‘relativistically’ influenced chemical properties and the architecture of the periodic table at its farthest reach. In addition, they establish a test bench to challenge the validity and predictive power of modern fully relativistic quantum chemical models.

ENTRANCE CHANNEL EFFECT AND FUSION CROSS SECTIONS IN THE SYNTHESIS OF HEAVY AND SUPERHEAVY NUCLEI

2010 ◽  
Vol 19 (08n09) ◽  
pp. 1603-1615
Author(s):  
SAI-SAI DU ◽  
FENG-SHOU ZHANG
Keyword(s):  
Cross Sections ◽  
Nuclear Reactions ◽  
Large Mass ◽  
Entrance Channel ◽  
Superheavy Nuclei ◽  
Fusion Reactions ◽  
Combined System ◽  
Mass Asymmetry ◽  
Channel Effect ◽  
Heavy And Superheavy Nuclei

The entrance channel effect, mainly involved the mass asymmetry, the neutron-excess and the collision orientation of the combined system, are presented by summarizing the recent theoretical results about the fusion reactions leading to the same compound nuclei and the neutron-rich fusion reactions in the synthesis of heavy and superheavy nuclei through various models. It is concluded that the system with large mass asymmetry and neutron-rich nuclear reactions is favorable for the compound nucleus formation.

scholarly journals The nuclear channel effect in the isomeric ratio of the reaction products

2019 ◽  
Vol 9 (1) ◽  
pp. 9-20
Author(s):  
Duc Thiep Tran ◽  
Thi An Truong ◽  
Minh Hue Bui ◽  
Viet Cuong Phan ◽  
Belov A. G. ◽  
...  
Keyword(s):  
Nuclear Reactions ◽  
Nuclear Research ◽  
Isomeric Ratio ◽  
Nuclear Data ◽  
Photon Flux ◽  
Reaction Products ◽  
Model Interpretation ◽  
Channel Effect ◽  
Epithermal Neutrons ◽  
Flerov Laboratory

This work presents the experimental study of the isomeric ratio of 115mCd to 115gCd produced in 116Cd(γ, n)115m,gCd photonuclear reaction and 116Cd(n, γ)115m,gCd neutron capture reaction by thermal, epithermal and mixed thermal and epithermal neutrons. The investigated samples were natural cadmium irradiated at the bremsstrahlung photon flux, in the neutron source constructed at the electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The results were analyzed, discussed, compared and combined with those of other authors in the existing literature to examine the role of the nuclear channel effect in the isomeric ratio and provide the nuclear data for theoretical model interpretation of nuclear reactions and applied research.

DECAY PROPERTIES AND STABILITY OF HEAVIEST ELEMENTS

2012 ◽  
Vol 21 (02) ◽  
pp. 1250013 ◽  
Author(s):  
A. V. KARPOV ◽  
V. I. ZAGREBAEV ◽  
Y. MARTINEZ PALENZUELA ◽  
L. FELIPE RUIZ ◽  
WALTER GREINER
Keyword(s):  
Superheavy Nuclei ◽  
Fusion Reactions ◽  
Β Decay ◽  
Α Decay ◽  
Experimental Identification ◽  
Nuclear Ground State ◽  
Decay Properties ◽  
Experimental Facilities ◽  
Neutron Rich Isotopes ◽  
Heaviest Elements

Decay properties and stability of heaviest nuclei with Z≤132 are studied within the macro-microscopical approach for nuclear ground state masses and phenomenological relations for the half-lives with respect to α-decay, β-decay and spontaneous fission. We found that at existing experimental facilities the synthesis and detection of nuclei with Z>120 produced in fusion reactions may be difficult due to their short half-lives (shorter than 1 μs). The nearest (more neutron-rich) isotopes of superheavy elements with 111≤Z≤115 to those synthesized recently in Dubna in 48 Ca -induced fusion reactions are found to be β+-decaying. This fact may significantly complicate their experimental identification. However it gives a chance to synthesize in fusion reactions the most stable superheavy nuclei located at the center of the island of stability. Our calculations yield that the β-stable isotopes 291 Cn and 293 Cn with a half-life of about 100 years are the longest-living superheavy nuclei located at the island of stability.

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