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  2. Isotopes of helium - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_helium

    Some models suggest that variations in the strong force allowing a bound diproton would enable the conversion of all primordial hydrogen to helium in the Big Bang, which would be catastrophic for the development of stars and life. This notion is an example of the anthropic principle. However, a 2009 study suggests that such a conclusion can't ...

  3. Borromean nucleus - Wikipedia

    en.wikipedia.org/wiki/Borromean_nucleus

    [2] [3] These are Borromean nuclei because the removal of either neutron from the halo will result in a resonance unbound to one-neutron emission, whereas the dineutron (the particles in the halo) is itself an unbound system. [1] Similarly, 17 Ne is a Borromean nucleus with a two-proton halo; both the diproton and 16 F are unbound. [4 ...

  4. Magic number (physics) - Wikipedia

    en.wikipedia.org/wiki/Magic_number_(physics)

    An example is calcium-40, with 20 neutrons and 20 protons, which is the heaviest stable isotope made of the same number of protons and neutrons. Both calcium-48 and nickel-48 are doubly magic because calcium-48 has 20 protons and 28 neutrons while nickel-48 has 28 protons and 20 neutrons. Calcium-48 is very neutron-rich for such a relatively ...

  5. Valley of stability - Wikipedia

    en.wikipedia.org/wiki/Valley_of_stability

    One consequence of these complications is that although deuterium, a bound state of a proton (p) and a neutron (n) is stable, exotic nuclides such as diproton or dineutron are unbound. [11] The nuclear force is not sufficiently strong to form either p-p or n-n bound states, or equivalently, the nuclear force does not form a potential well deep ...

  6. Shape of the atomic nucleus - Wikipedia

    en.wikipedia.org/wiki/Shape_of_the_atomic_nucleus

    If the nucleus is assumed to be spherically symmetric, an approximate relationship between nuclear radius and mass number arises above A=40 from the formula R=R o A 1/3 with R o = 1.2 ± 0.2 fm. [6] R is the predicted spherical nuclear radius, A is the mass number, and R o is a constant determined by experimental data.

  7. Nuclear shell model - Wikipedia

    en.wikipedia.org/wiki/Nuclear_shell_model

    8 O as an example: Its nucleus has eight protons filling the first three proton "shells", eight neutrons filling the first three neutron "shells", and one extra neutron. All protons in a complete proton shell have zero total angular momentum, since their angular momenta cancel each other. The same is true for neutrons.

  8. Nuclear force - Wikipedia

    en.wikipedia.org/wiki/Nuclear_force

    Comparison between the Nuclear Force and the Coulomb Force. a – residual strong force (nuclear force), rapidly decreases to insignificance at distances beyond about 2.5 fm, b – at distances less than ~ 0.7 fm between nucleons centres the nuclear force becomes repulsive, c – coulomb repulsion force between two protons (over 3 fm, force becomes the main), d – equilibrium position for ...

  9. Neutron–proton ratio - Wikipedia

    en.wikipedia.org/wiki/Neutron–proton_ratio

    The neutron–proton ratio (N/Z ratio or nuclear ratio) of an atomic nucleus is the ratio of its number of neutrons to its number of protons. Among stable nuclei and naturally occurring nuclei, this ratio generally increases with increasing atomic number. [ 1 ]