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).

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.

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 The radioactive nuclei and in the Cosmos and in the solar system

2021 ◽  
Vol 38 ◽  
Author(s):  
R. Diehl ◽  
M. Lugaro ◽  
A. Heger ◽  
A. Sieverding ◽  
X. Tang ◽  
...  
Keyword(s):  
Solar System ◽  
Nuclear Reactions ◽  
Chemical Elements ◽  
Nuclear Fusion ◽  
Cosmic Ray ◽  
Big Bang ◽  
Lessons Learned ◽  
Radioactive Isotopes ◽  
Fusion Reactions ◽  
Nuclear Fusion Reactions

Abstract The cosmic evolution of the chemical elements from the Big Bang to the present time is driven by nuclear fusion reactions inside stars and stellar explosions. A cycle of matter recurrently re-processes metal-enriched stellar ejecta into the next generation of stars. The study of cosmic nucleosynthesis and this matter cycle requires the understanding of the physics of nuclear reactions, of the conditions at which the nuclear reactions are activated inside the stars and stellar explosions, of the stellar ejection mechanisms through winds and explosions, and of the transport of the ejecta towards the next cycle, from hot plasma to cold, star-forming gas. Due to the long timescales of stellar evolution, and because of the infrequent occurrence of stellar explosions, observational studies are challenging, as they have biases in time and space as well as different sensitivities related to the various astronomical methods. Here, we describe in detail the astrophysical and nuclear-physical processes involved in creating two radioactive isotopes useful in such studies, $^{26}\mathrm{Al}$ and $^{60}\mathrm{Fe}$ . Due to their radioactive lifetime of the order of a million years, these isotopes are suitable to characterise simultaneously the processes of nuclear fusion reactions and of interstellar transport. We describe and discuss the nuclear reactions involved in the production and destruction of $^{26}\mathrm{Al}$ and $^{60}\mathrm{Fe}$ , the key characteristics of the stellar sites of their nucleosynthesis and their interstellar journey after ejection from the nucleosynthesis sites. This allows us to connect the theoretical astrophysical aspects to the variety of astronomical messengers presented here, from stardust and cosmic-ray composition measurements, through observation of $\gamma$ rays produced by radioactivity, to material deposited in deep-sea ocean crusts and to the inferred composition of the first solids that have formed in the Solar System. We show that considering measurements of the isotopic ratio of $^{26}\mathrm{Al}$ to $^{60}\mathrm{Fe}$ eliminate some of the unknowns when interpreting astronomical results, and discuss the lessons learned from these two isotopes on cosmic chemical evolution. This review paper has emerged from an ISSI-BJ Team project in 2017–2019, bringing together nuclear physicists, astronomers, and astrophysicists in this inter-disciplinary discussion.

Nuclear Processes Related to the Ap Stars and the Heaviest Chemical Elements

1976 ◽  
Vol 32 ◽  
pp. 169-182
Author(s):  
B. Kuchowicz
Keyword(s):  
Nuclear Physics ◽  
Nuclear Reactions ◽  
Chemical Elements ◽  
Fission Products ◽  
Abundance Pattern ◽  
Isotopic Shifts ◽  
Processed Material ◽  
R Process ◽  
Ap Stars ◽  
Nuclear Processes

SummaryIsotopic shifts in the lines of the heavy elements in Ap stars, and the characteristic abundance pattern of these elements point to the fact that we are observing mainly the products of rapid neutron capture. The peculiar A stars may be treated as the show windows for the products of a recent r-process in their neighbourhood. This process can be located either in Supernovae exploding in a binary system in which the present Ap stars were secondaries, or in Supernovae exploding in young clusters. Secondary processes, e.g. spontaneous fission or nuclear reactions with highly abundant fission products, may occur further with the r-processed material in the surface of the Ap stars. The role of these stars to the theory of nucleosynthesis and to nuclear physics is emphasized.

Proposed Solutions to Achieve Nuclear Fusion

Engevista ◽  
2017 ◽  
Vol 19 (5) ◽  
pp. 1496
Author(s):  
Relly Victoria Virgil Petrescu ◽  
Raffaella Aversa ◽  
Antonio Apicella ◽  
Florian Ion Petrescu
Keyword(s):  
Nuclear Reactor ◽  
Nuclear Reactions ◽  
Nuclear Fusion ◽  
Nuclear Fission ◽  
Light Nuclei ◽  
Fast Neutrons ◽  
Fusion Reactions ◽  
Nuclear Fusion Reactions ◽  
The Masses ◽  
Fusion Products

Despite research carried out around the world since the 1950s, no industrial application of fusion to energy production has yet succeeded, apart from nuclear weapons with the H-bomb, since this application does not aims at containing and controlling the reaction produced. There are, however, some other less mediated uses, such as neutron generators. The fusion of light nuclei releases enormous amounts of energy from the attraction between the nucleons due to the strong interaction (nuclear binding energy). Fusion it is with nuclear fission one of the two main types of nuclear reactions applied. The mass of the new atom obtained by the fusion is less than the sum of the masses of the two light atoms. In the process of fusion, part of the mass is transformed into energy in its simplest form: heat. This loss is explained by the Einstein known formula E=mc2. Unlike nuclear fission, the fusion products themselves (mainly helium 4) are not radioactive, but when the reaction is used to emit fast neutrons, they can transform the nuclei that capture them into isotopes that some of them can be radioactive. In order to be able to start and to be maintained with the success the nuclear fusion reactions, it is first necessary to know all this reactions very well. This means that it is necessary to know both the main reactions that may take place in a nuclear reactor and their sense and effects. The main aim is to choose and coupling the most convenient reactions, forcing by technical means for their production in the reactor. Taking into account that there are a multitude of possible variants, it is necessary to consider in advance the solutions that we consider them optimal. The paper takes into account both variants of nuclear fusion, and cold and hot. For each variant will be mentioned the minimum necessary specifications.

Ti-Induced Fusion Reactions to Synthesis Superheavy Elements

2019 ◽  
Vol 49 (3) ◽  
pp. 412-422
Author(s):  
H. C. Manjunatha ◽  
K. N. Sridhar
Keyword(s):  
Superheavy Elements ◽  
Fusion Reactions

scholarly journals Physical mechanisms of mixing in stellar interiors

1984 ◽  
Vol 105 ◽  
pp. 491-512
Author(s):  
Evry Schatzman
Keyword(s):  
Diffusion Equation ◽  
Stellar Evolution ◽  
Turbulent Mixing ◽  
Nuclear Reactions ◽  
Chemical Elements ◽  
Solar Neutrinos ◽  
Stellar Structure ◽  
Physical Mechanisms ◽  
Nitrogen Abundance ◽  
Stellar Interiors

The different mechanisms by which mixing can take place in stellar interiors are considered : the classical Rayleigh-Benard instability with penetrative convection and over-shooting, semi-convection, gravitationnal and radiative settling, turbulent mixing. The latter mechanism is thoroughly described, from the driving force of turbulent mixing to its influence on stellar structure, stellar evolution and the analysis of the corresponding observationnal data.Turbulent mixing has to be considered each time the building up of a concentration gradient takes place, either by gravitationnal or radiative settling or by nuclear reactions. Turbulent mixing, as a first approximation, can be described by an isotropic diffusion coefficient. The process is then governed by a diffusion equation. The behaviour of the solution of the diffusion equation needs some explanation in order to be well understood.A number of examples concerning surface abundances of chemical elements are given (3He, 7Li, Be, 12C, 13C, 14N), as well as a discussion of the solar neutrinos problem.The building up of a µ-barrier, which stops the turbulence allows stellar evolution towards the giant branch and explains nitrogen abundance at the surface of giants of the first ascending branch.Turbulent mixing is also of some importance for the transfer of angular momentum and has to be taken into account for explaining the abundance of the elements in Wolf-Rayet stars.

Synthesis of superheavy elements in heavy-ion fusion reactions

1981 ◽  
Vol 7 (3) ◽  
pp. 359-370
Author(s):  
M T Magda ◽  
A Pop ◽  
D Poenaru ◽  
A Sandulescu ◽  
W Greiner
Keyword(s):  
Heavy Ion ◽  
Superheavy Elements ◽  
Fusion Reactions ◽  
Heavy Ion Fusion

scholarly journals How to name new chemical elements (IUPAC Recommendations 2016)

2016 ◽  
Vol 88 (4) ◽  
pp. 401-405 ◽  
Author(s):  
Willem H. Koppenol ◽  
John Corish ◽  
Javier García-Martínez ◽  
Juris Meija ◽  
Jan Reedijk
Keyword(s):  
Inorganic Chemistry ◽  
Working Group ◽  
Chemical Elements ◽  
Important Change ◽  
Chemistry Division

AbstractA procedure is proposed to name new chemical elements. After the discovery of a new element is established by the joint IUPAC-IUPAP Working Group, the discoverers are invited to propose a name and a symbol to the IUPAC Inorganic Chemistry Division. Elements can be named after a mythological concept, a mineral, a place or country, a property or a scientist. After examination and acceptance by the Inorganic Chemistry Division, the proposal follows the accepted IUPAC procedure and is then ratified by the Council of IUPAC. This document is a slightly amended version of the 2002 IUPAC Recommendations; the most important change is that the names of all new elements should have an ending that reflects and maintains historical and chemical consistency. This would be in general “-ium” for elements belonging to groups 1–16, i.e. including the f-block elements, “-ine” for elements of group 17 and “-on” for elements of group 18.

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