Search results for "uranium"
showing 10 items of 260 documents
The impact of the properties of the heaviest elements on the chemical and physical sciences
2012
Abstract The unique role of the heaviest elements in chemical and physical sciences is discussed. With the actinide series (Z = 90-103) and the superactinide series (Z = 122-155), the heaviest elements have significantly shaped the architecture of the Periodic Table of the elements. Relativistic effects in the electron shells of the heaviest elements change the chemical properties in a given group in a non-linear fashion. Relativistically stabilized sub-shell closures give rise to a new category of elements in the Periodic Table: volatile metals. The prototype for this property is element 114 which, due to the relativistic stabilization of its 7s2 7p2 1/2 electron configuration, is volatile…
Syntheses of transuranium isotopes with atomic numbers Z≤ 103 in multi-nucleon transfer reactions
2015
Abstract In Section 1 we will discuss multi-nucleon transfer reactions with light heavy ions, which can be thought of as competing with complete fusion at higher impact parameters. Quasi-elastic and multi-nucleon transfer reactions with the heaviest projectiles will be discussed in Section 2 . In Section 3 we will cover recent developments focusing on theoretical predictions of cross sections of superheavy nuclei, cover some new possibilities and look into the existing experimental challenges.
Mass mapping of a new area of neutron-deficient suburanium nuclides
2002
Abstract The masses of 64 short-lived neutron-deficient nuclides covering the element range from tungsten to uranium have been obtained for the first time. They have been evaluated by combining directly measured masses from Schottky mass spectrometry with linked experimental Q-values in α-decay chains. Based on these new mass data we have determined the one-proton and two-proton drip-lines as well as the size of the “littoral shallow” of the sea of instability. No evidence of a Thomas–Ehrman shift has been found in the region of the investigated heavy nuclides. A peculiar behavior of two-proton separation energies has been observed in the lead region. The predictive power of various mass mo…
SHIPTRAP—a capture and storage facility for heavy radionuclides at GSI
2002
Abstract SHIPTRAP will be an ion-trap facility for heavy radionuclides delivered from SHIP. Ion traps are a perfect instrument for precision measurements since the ions can be cooled to an extremely small phase space and can be stored for a very long time. In addition one can achieve very high purity by removing contaminant ions. SHIPTRAP will extend the possibilities of measurements in traps to transuranium nuclides and provide cooled and isobarically pure ion bunches.
First superheavy element experiments at the GSI recoil separator TASCA: The production and decay of element 114 in thePu244(Ca48,3-4n) reaction
2011
Experiments with the new recoil separator, Transactinide Separator and Chemistry Apparatus (TASCA), at the GSI were performed by using beams of Ca-48 to irradiate targets of Pb206-208, which led to the production of No252-254 isotopes. These studies allowed for evaluation of the performance of TASCA when coupled to a new detector and electronics system. By following these studies, the isotopes of element 114 ((288-291)114) were produced in irradiations of Pu-244 targets with Ca-48 beams at compound nucleus excitation energies around 41.7 and 37.5 MeV, demonstrating TASCA's ability to perform experiments with picobarn-level cross sections. A total of 15 decay chains were observed and were as…
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.
A critical assessment of global uranium resources, including uranium in phosphate rocks, and the possible impact of uranium shortages on nuclear powe…
2013
International audience
Nuclear Forensics: A methodology applicable to Nuclear Security and to Non-Proliferation
2011
Nuclear Security aims at the prevention and detection of and response to, theft, sabotage, unauthorized access, illegal transfer or other malicious acts involving nuclear material". Nuclear Forensics is a key element of nuclear security. Nuclear Forensics is defined as a methodology that aims at re-establishing the history of nuclear material of unknown origin. It is based on indicators that arise from known relationships between material characteristics and process history. Thus, nuclear forensics analysis includes the characterization of the material and correlation with production history. To this end, we can make use of parameters such as the isotopic composition of the nuclear material…
Gas-filled separators – An overview
2003
Gas-filled recoil separators have been used in nuclear physics studies since the early fifties. Most notably, they have found use in the separation of evaporation residues of heavy and very heavy elements from unwanted background. Gas-filled separators, alone or coupled to a detector array, offer an efficient, fast, compact and relatively inexpensive solution for nuclear structure studies. A new application is the use of a gas-filled device as a pre-separator in the study of chemical properties of the heaviest elements. Other uses include systematic study of fusion evaporation cross sections and accelerator mass spectrometry. In this contribution, an overview on gas-filled recoil separators…
Fast and nonselective on-line mass separation of neutron-rich isotopes produced in proton-induced fission
1989
Abstract On-line mass separation of short-lived radionuclides, based on the use of thermalized primary ions from nuclear reactions, termed as an ion guide method, has recently been widely applied in the spectroscopy of both proton-rich and neutron-rich exotic nuclei. The technique has been found to be applicable to all elements and it has allowed the detection of the mass-analyzed activities with half-lives as short as 0.1 ms. The ion guide isotope separator on-line, IGISOL, has recently been used to discover over ten new short-lived isotopes or isomers produced in the nearly symmetric fission of uranium induced by 20 MeV protons. In addition to applications in nuclear-structure physics and…