Proceedings

EPJ A Highlight - Unresolved puzzles in exotic nuclei

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Closed points are matter radii extracted from experiments for isotopes of Helium (diamonds), Lithium (squares), and Beryllium (triangles).

A new review highlights the historical developments in our understanding of the nuclear structure of unstable and unbound forms of helium, lithium and beryllium

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?

H. T. Fortune (2018), Structure of exotic light nuclei: Z = 2, 3, 4, European Physical Journal A 54: 51, DOI 10.1140/epja/i2018-12489-2

This was our first experience of publishing with EPJ Web of Conferences. We contacted the publisher in the middle of September, just one month prior to the Conference, but everything went through smoothly. We have had published MNPS Proceedings with different publishers in the past, and would like to tell that the EPJ Web of Conferences team was probably the best, very quick, helpful and interactive. Typically, we were getting responses from EPJ Web of Conferences team within less than an hour and have had help at every production stage.
We are very thankful to Solange Guenot, Web of Conferences Publishing Editor, and Isabelle Houlbert, Web of Conferences Production Editor, for their support. These ladies are top-level professionals, who made a great contribution to the success of this issue. We are fully satisfied with the publication of the Conference Proceedings and are looking forward to further cooperation. The publication was very fast, easy and of high quality. My colleagues and I strongly recommend EPJ Web of Conferences to anyone, who is interested in quick high-quality publication of conference proceedings.

On behalf of the Organizing and Program Committees and Editorial Team of MNPS-2019, Dr. Alexey B. Nadykto, Moscow State Technological University “STANKIN”, Moscow, Russia. EPJ Web of Conferences vol. 224 (2019)

ISSN: 2100-014X (Electronic Edition)

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