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  2. 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 ...

  3. Nuclear shell model - Wikipedia

    en.wikipedia.org/wiki/Nuclear_shell_model

    The same is true for neutrons. All protons in the same level (n) have the same parity (either +1 or −1), and since the parity of a pair of particles is the product of their parities, an even number of protons from the same level (n) will have +1 parity. Thus, the total angular momentum of the eight protons and the first eight neutrons is zero ...

  4. Mirror nuclei - Wikipedia

    en.wikipedia.org/wiki/Mirror_nuclei

    Since the strong interaction is invariant to protons and neutrons one can expect these mirror nuclei to have very similar binding energies. [1] [2] In 2020 strontium-73 and bromine-73 were found to not behave as expected. [3] The ground state of 73 35 Br has spin and parity 1/2−, whereas the ground state of 73 38 Sr

  5. Atomic nucleus - Wikipedia

    en.wikipedia.org/wiki/Atomic_nucleus

    Protons define the entire charge of a nucleus, and hence its chemical identity. Neutrons are electrically neutral, but contribute to the mass of a nucleus to nearly the same extent as the protons. Neutrons can explain the phenomenon of isotopes (same atomic number with different atomic mass). The main role of neutrons is to reduce electrostatic ...

  6. Proton - Wikipedia

    en.wikipedia.org/wiki/Proton

    For free protons, this process does not occur spontaneously but only when energy is supplied. The equation is: p + + e − → n + ν e. The process is reversible; neutrons can convert back to protons through beta decay, a common form of radioactive decay. In fact, a free neutron decays this way, with a mean lifetime of about 15 minutes.

  7. Nuclear matter - Wikipedia

    en.wikipedia.org/wiki/Nuclear_matter

    Nuclear matter is an idealized system of interacting nucleons (protons and neutrons) that exists in several phases of exotic matter that, as of yet, are not fully established. [2] It is not matter in an atomic nucleus, but a hypothetical substance consisting of a huge number of protons and neutrons held together by only nuclear forces and no ...

  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. Proton decay - Wikipedia

    en.wikipedia.org/wiki/Proton_decay

    Free neutrons—those not inside an atomic nucleus—are already known to decay into protons (and an electron and an antineutrino) in a process called beta decay. Free neutrons have a half-life of 10 minutes (610.2 ± 0.8 s) [17] due to the weak interaction. Neutrons bound inside a nucleus have an immensely longer half-life – apparently as ...