Wednesday, March 28, 2018

Unresolved Puzzles in Exotic Nuclei

Artist's impression of exotic nuclei. Credit: cenbg.in2p3.fr

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 center 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?

Credit: springer.com

3 comments:

  1. Why are there many protons neutrons in many chemical elements? If science has not understood it so far, it is no wonder that many phenomena in the universe can not be understood. First, we need to know how a neutron is produced. How can a neutron be ruined? This explanation requires a much higher level of institution than this place is here. It is necessary to start from the very beginning of the formation of matter from the substance AETHER, from which the matter is formed. In a series of thermodynamic processes, subatomic six are formed, of which the nuclei of the atoms are formed and under the action of magnetism (carriers are gluons in neutrons) formation or dissolution of various chemical elements occurs.

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  2. Why are there many protons neutrons in many chemical elements? If science has not understood it so far, it is no wonder that many phenomena in the universe can not be understood. First, we need to know how a neutron is produced. How can a neutron be ruined? This explanation requires a much higher level of institution than this place is here. It is necessary to start from the very beginning of the formation of matter from the substance AETHER, from which the matter is formed. In a series of thermodynamic processes, subatomic six are formed, of which the nuclei of the atoms are formed and under the action of magnetism (carriers are gluons in neutrons) formation or dissolution of various chemical elements occurs.

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  3. Hallo, zelf lijk dat die wetenschappers kennen niet dat er bestaat element zonder neutron? Waarom is die helium of water stof op eerste schaal van natuur periodeke schaal van elementen. Dat is niet alleen dat atoom van helium normaal heeft een orbitele elektron in cirkels beweging om eigen proton ,maar ook dat aggregaten toestand van alles vullende ,koude ,doorzichtige ,reagens massa is in bijna natuurlijk aggregaten toestand met zelfde massa in omgeving en universum in geheel .Dat komt doordat orbitale elektron van Helium heeft grootste radius van beweging ,zo dat elektron komt minder keer op zelfde plaats in zelfde tijd tip en temperatuur is lagere dan bij alle andere elementaire atomen .Met die aggregaten toestand van massa in subatomaire ruimten ,dat in contra beweging ten opzicht van orbitele richting van elektron kan niet schept vorm van draaiend kolk of te wel van neutron. Wetenschap zou nooit een neutron gevonden ,buiten atoom stelsels omdat neutron wordt geschept door zelfde massa en na verval van atoom zich smolten in zelfde massa in omgeving en universum . .

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