. | . |
Unresolved puzzles in exotic nuclei by Staff Writers Washington DC (SPX) Mar 29, 2018
Research into the origin of elements is still of great interest. Many unstable atomic nuclei live long enough to be able to serve as targets for further nuclear reactions - especially in hot environments like the interior of stars. And some of the research with exotic nuclei is, for instance, related to nuclear astrophysics. In this review published in EPJ A, Terry Fortune from the University of Pennsylvania, in Philadelphia, USA, discusses the structure of unstable and unbound forms of Helium, Lithium, and Beryllium nuclei that have unusually large neutron to proton ratios - dubbed 'exotic' light nuclei. The author offers an account of historical milestones in measurements and the interpretation of results pertaining to these nuclei. Each chemical element is composed of atoms. At the centre of each atom is a nucleus containing nucleons, namely neutrons and protons. Some nuclei are unstable and are prone to emitting an electron, via beta decay, particularly when they have a large number of neutrons compared to protons. For example, Helium-8, with six neutrons and two protons, is unstable. It beta decays into a form of lithium with 3 protons and 5 neutrons, dubbed Lithium-8. Eventually, as more and more neutrons are added, the nucleus becomes unbound to neutron emission. But the properties of these unbound nuclei can still be investigated by producing them in a nuclear reaction and detecting their decay products. In this review, the author outlines the available experimental information and the models that have been applied to 'exotic' nuclei. The laws of physics relating to the nuclear properties of these nuclei prevail even though some of them are not typically observed in normal nuclei. The author also delineates some of the unresolved puzzles concerning the connection between microscopic structure and the values of quantities that are observable experimentally - particularly the interplay between energies, widths or strengths and microscopic structure. For example, physicists have yet to resolve what is the occupancy of an orbital, called 2s1/2, in the ground state of beryllium-12 Or what is the nature of the unbound ground state of helium-10. Reference: H. T. Fortune (2018), Structure of exotic light nuclei: Z = 2, 3, 4, Eur. Phys. Jour. A, 54: 51, DOI 10.1140/epja/i2018-12489-2
Scientists separate atoms with smallest sieve ever Washington (UPI) Mar 20, 2018 Scientists have found a way to turn 2D materials into a sieve capable of separating different atoms from each other. When pushed through the tiny gap between the layers of 2D materials like hexagonal boron nitride or molybdenum disulphide, the atoms of two different hydrogen isotopes can be separated. Like graphene, hexagonal boron nitride or molybdenum disulphide form sheet-like layers the width of a single atom. The 2D layers feature unique structural patterns, each with different phys ... read more
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |