Search results for "Elements"

Studying Chemical Properties of the Heaviest Elements: One Atom at a Time

2017

The search for heavier elements has been an exciting endeavor for nuclear scientists for many decades. This was invigorated after the first predictions that nuclear shell effects might render superheavy elements to have lifetimes long enough for their experimental study, or even their occurrence in Nature. A fascinating aspect concerns the question of their chemical properties: will they conform to the well-established structure of the Periodic Table of the Elements, or will so-called relativistic effects—a result of the high velocities of electrons in the vicinity of highly-charged nuclei—lead to dramatic deviations? Chemical studies of the heaviest elements are complicated by small produc…

Search for long-lived superheavy elements in the reaction of136Xe with238U

1978

A search with radiochemical methods for long-lived superheavy elements in 238U targets bombarded with intense beams of136Xe ions produced negative results. A formation cross section of ≤1×10−35 cm2 is deduced at 95% confidence level for nuclides with half-lives between 1 and 200 d.

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

Neutrino-nuclear responses for astro-neutrinos, single beta decays and double beta decays

2019

Abstract Neutrino–nuclear responses associated with astro-neutrinos, single beta decays and double beta decays are crucial in studies of neutrino properties of interest for astro-particle physics. The present report reviews briefly recent studies of the neutrino–nuclear responses from both experimental and theoretical points of view in order to obtain a consistent understanding of the many facets of the neutrino–nuclear responses. Subjects discussed in this review include (i) experimental studies of neutrino–nuclear responses by means of single beta decays, charge-exchange nuclear reactions, muon- photon- and neutrino–nuclear reactions, and nucleon-transfer reactions, (ii) implications of a…

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.

Evolution de la circulation oécanique profonde durant le Crétacé : apport des isotopes du néodyme

2014

The Cretaceous is depicted as the warmest period of the last 300 Ma. The oceanic circulation and location of the source zones of deep-waters are essential to understand the role of oceans in the evolution of the climate during the Cretaceous, yet they remain unclear for this period. The neodymium (Nd) isotopes are used to track oceanic circulation and exchanges between water masses, in both past and modern oceans. The Nd isotope composition (εNd) in the ocean is related to the nature of the surrounding continental landmasses. The oceanic currents transport this isotopic signature, thus every oceanic basin acquires a singular εNd. Unequivocal interpretations of the Cretaceous seawater εNd va…