Search results for "superheavy element"
showing 10 items of 56 documents
Cold fusion of heavy ions paving the way to superheavy elements
2001
Abstract Significant progress has been made approaching superheavy elements. A shell-stabilized region near hassium has been discovered. Element 112 has been synthesized. Recently evidence for the creation of elements 114, 116, and 118 has been reported. The way to these superheavy nuclei was paved by the cold fusion of heavy ions. In this paper experimental methods for heavy-element research, which is essentially physics with single atoms, are presented together with recent experimental results. The observed nuclear properties are discussed in the framework of theoretical models. New instrumental developments including accelerators and radioactive beams are be addressed.
Search for Superheavy Elements in theU238+U238Reaction
1980
A search was made for spontaneously fissioning superheavy elements in damped collisions of two uranium nuclei. Different techniques were applied covering the elements 108 to 118 and approx. =126, and a half-life range from 1 ms to more than 1 yr. No evidence for superheavy elements was found at upper cross-section limits of 10/sup -32/, 10/sup -33/, and 10/sup -35/ cm/sup 2/ for half-lives from 1 to 100 ms, 100 ms to 1 d, and 1 d to 1 yr, respectively.
Study of Superheavy Elements at the GSI-SHIP
2006
STATUS OF SUPERHEAVY ELEMENT RESEARCH
1982
ABSTRACT A review is given on the search for superheavy elements in nature. Attempts to arrive at conclusive proofs have failed thus far, however. Attempts to produce superheavy elements in the laboratory by heavy-ion reactions proved negative results although a detection sensitivity of 10−35 cm2 corresponding to a production of a few atoms per experiment has been achieved. Two approaches have been followed: complete fusion and transfer of nucleons during damped collisions. The former is illustrated by the 48Ca + 248Cm reaction, the latter by the 238U + 238U and 238U + 248Cm reactions.
ATTEMPTS TO PRODUCE SUPERHEAVY ELEMENTS IN REACTIONS BETWEEN HEAVY NUCLEI
1978
Nuclear structure physics at GSI-challenges and perspectives
2001
Some characteristic examples from the ongoing GSI nuclear structure research programme are presented such as recent experimental results from nuclear reactions with exotic beams to explore the structure of halo nuclei, direct mass measurements in the storage ring, and the structure of heavy-elements. A brief outline of a next generation exotic beam facility will be given.
Understanding the nuclear structure of heavy elements
2013
The study of heavy and superheavy elements has always been one of the cornerstones of nuclear physics studies. These studies are driven by a desire to create new elements and to determine the limits of nuclear stability. Current experiments to synthesize new elements aim at the fabled ?Island of Stability? which should be found in the region of the next ?magic? numbers for protons and neutrons beyond Z?=?82 and N?=?126 (208Pb). The island is predicted to be around proton number 114?126 and neutron number 184. In recent years, another approach to understanding heavy nuclear systems has gained momentum, whereby nuclei with a much lower proton number of around 100 are studied in detail. The mo…
Quasifission in heavy and superheavy element formation reactions
2016
Superheavy elements are created in the laboratory by the fusion of two heavy nuclei. The large Coulomb repulsion that makes superheavy elements decay also makes the fusion process that forms them very unlikely. Instead, after sticking together for a short time, the two nuclei usually come apart, in a process called quasifission. Mass-angle distributions give the most direct information on the characteristics and time scales of quasifission. A systematic study of carefully chosen mass-angle distributions has provided information on the global trends of quasifission. Large deviations from these systematics reveal the major role played by the nuclear structure of the two colliding nuclei in de…
Laser Resonance Chromatography of Superheavy Elements.
2020
Optical spectroscopy constitutes the historical path to accumulate basic knowledge on the atom and its structure. Former work based on fluorescence and resonance ionization spectroscopy enabled identifying optical spectral lines up to element 102, nobelium. The new challenges faced in this research field are the refractory nature of the heavier elements and the decreasing production yields. A new concept of ion-mobility-assisted laser spectroscopy is proposed to overcome the sensitivity limits of atomic structure investigations persisting in the region of the superheavy elements. The concept offers capabilities of both broadband-level searches and high-resolution hyperfine spectroscopy of s…
Mechanisms Suppressing Superheavy Element Yields in Cold Fusion Reactions.
2019
Superheavy elements are formed in fusion reactions which are hindered by fast nonequilibrium processes. To quantify these, mass-angle distributions and cross sections have been measured, at beam energies from below-barrier to 25% above, for the reactions of $^{48}\mathrm{Ca}$, $^{50}\mathrm{Ti}$, and $^{54}\mathrm{Cr}$ with $^{208}\mathrm{Pb}$. Moving from $^{48}\mathrm{Ca}$ to $^{54}\mathrm{Cr}$ leads to a drastic fall in the symmetric fission yield, which is reflected in the measured mass-angle distribution by the presence of competing fast nonequilibrium deep inelastic and quasifission processes. These are responsible for reduction of the compound nucleus formation probablity ${P}_{CN}$ …