Earlier this month, D. Steppenbeck and colleagues published a paper in Nature on "Evidence for a new nuclear 'magic number' from the level structure of 54Ca. Leo Vuyk requested that we open a new forum thread on this topic -- thank you Leo!

From the paper's abstract:

"Atomic nuclei are finite quantum systems composed of two distinct types of fermion--protons and neutrons. In a manner similar to that of electrons orbiting in an atom, protons and neutrons in a nucleus form shell structures. In the case of stable, naturally occurring nuclei, large energy gaps exist between shells that fill completely when the proton or neutron number is equal to 2, 8, 20, 28, 50, 82 or 126. Away from stability, however, these so-called 'magic numbers' are known to evolve in systems with a large imbalance of protons and neutrons. Although some of the standard shell closures can disappear, new ones are known to appear. Studies aiming to identify and understand such behaviour are of major importance in the field of experimental and theoretical nuclear physics. Here we report a spectroscopic study of the neutron-rich nucleus 54Ca (a bound system composed of 20 protons and 34 neutrons) using proton knockout reactions involving fast radioactive projectiles. The results highlight the doubly magic nature of 54Ca and provide direct experimental evidence for the onset of a sizable subshell closure at neutron number 34 in isotopes far from stability."

Scientific American also ran a news item on the paper.

    8 days later

    DEAR ZEEYA AND LEO!

    I think this is an important issue.

    This link,http://fqxi.org/community/forum/topic/794 is My essay that I explained much about similar things toward fundamentals of nature, including magic number and relating nuclei properties, focusing on Geometry, structure, shape, quantity, etc.

    I agree that magic number is related to number of nucleons.

    Leo! I appreciate the way you explained, very interesting!

    I would be so thankful if you give me some comment.

    Kind Regards,

    Bashir.

    DEAR ZEEYA AND LEO!

    I think this is an important issue.

    This link,http://fqxi.org/community/forum/topic/794 is My essay that I explained much about similar things toward fundamentals of nature, including magic number and relating nuclei properties, focusing on Geometry, structure, shape, quantity, etc.

    I agree that magic number is related to number of nucleons.

    Leo! I appreciate the way you explained, very interesting!

    I would be so thankful if you give me some comment.

    Kind Regards,

    Bashir.

    4 months later

    I agree that magic number is related to number of nucleons.

    5 years later

    The protons and neutrons inside the atomic nucleus exhibit shell structures in a manner similar to electrons in an atom. For naturally stable nuclei, these nuclear shells fill completely when the number of protons or the number of neutrons is equal to the 'magic' numbers 2, 8, 20, 28, 50, 82 or 126.

    However, it has recently been shown that the traditional magic numbers, which were once thought to be robust and common for all nuclei, can in fact change in unstable, radioactive nuclei that have a large imbalance of protons and neutrons.

    David Nash | Dissertation UK

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