What is Decay: Definition and 999 Discussions

In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For example, beta decay of a neutron transforms it into a proton by the emission of an electron accompanied by an antineutrino; or, conversely a proton is converted into a neutron by the emission of a positron with a neutrino in so-called positron emission. Neither the beta particle nor its associated (anti-)neutrino exist within the nucleus prior to beta decay, but are created in the decay process. By this process, unstable atoms obtain a more stable ratio of protons to neutrons. The probability of a nuclide decaying due to beta and other forms of decay is determined by its nuclear binding energy. The binding energies of all existing nuclides form what is called the nuclear band or valley of stability. For either electron or positron emission to be energetically possible, the energy release (see below) or Q value must be positive.
Beta decay is a consequence of the weak force, which is characterized by relatively lengthy decay times. Nucleons are composed of up quarks and down quarks, and the weak force allows a quark to change its flavour by emission of a W boson leading to creation of an electron/antineutrino or positron/neutrino pair. For example, a neutron, composed of two down quarks and an up quark, decays to a proton composed of a down quark and two up quarks.
Electron capture is sometimes included as a type of beta decay, because the basic nuclear process, mediated by the weak force, is the same. In electron capture, an inner atomic electron is captured by a proton in the nucleus, transforming it into a neutron, and an electron neutrino is released.

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  1. lLehner95

    Why is eta meson decay into 3 neutral pions forbidden?

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  2. B

    Why didn't radioactive decay probabilities cause the same uproar as QM

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  3. The forgetful one

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  4. qnach

    A The time between when the neutrinos are emitted in double-beta decay?

    Double-beta decay will emit two neutrinos. But, are they simultaneously released or separated?
  5. D

    B Is Radioactive Decay Uncaused/Causeless?

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  6. jdou86

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  7. A

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  8. JackDixon

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  9. XLAYZ

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  10. A

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  11. mPlummers

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  12. A

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  13. JD_PM

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  14. A

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  15. A

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  16. M

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  17. W

    How Does Conservation of Momentum Apply to Particle Decay?

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  18. K

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  19. A

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  20. C

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  21. TheBigDig

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  22. J

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  23. E

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  24. D

    What is the branching ratio for alpha decay to Pu-237?

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  25. M

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  26. K

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  29. O

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  30. Bheshaj

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  31. dRic2

    B Thought experiment -- A radioactive decay detector and randomness

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  32. J

    B Deriving Exponential Decay Equation

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  33. S

    B Entanglement Decay of a proton pair

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  34. S

    Rate of emission of alpha particle in uranium decay

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  35. M

    B When does an isotope begin to decay?

    Take 60Fe found in meteorites. Does it start to decay the moment it is created. Or does it start to decay when it cools to a solid (a meteorite)? Does heat have anything to do with it? Thanks
  36. S

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  37. D

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    Hi, I have questions on the neutron decay What prevent the neutron to decay in udc or udt except mass/energy consideration ? If we do the assumption that (udc) and (udt) have the same mass than the proton (yes I know, this doesn't make sense) the three decay (p, udc, udt) woulld have the same...
  38. S

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  39. R

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    Homework Statement You have 0.0625 grams of an unstable element and 0.9375 grams of the stable daughter product. How many half-lives has it undergone？ Homework Equations N=No (1/2)^(t/(t1/2)) In which N represents the final activity for a period of time No is the original activity t...
  40. J

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  41. M

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  42. JesW87

    B Is radioactive decay truly random?

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  43. C

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  44. zehkari

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    Homework Statement Homework Equations (1) E2 = p2c2 + m02c4 (2) E = γm0c2 (3) E = Eγ1 - Eγ2 (4) p = E / c (5) E = hf (6) λ = c / f The Attempt at a Solution a) Using eqn (1), rearranged p = (E - m0c2) / c , I obtained 2.9 MeV c-1. Not sure if I have the right answer here as I...
  45. Peeter

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  46. Flabbergast

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  47. S

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  48. A

    B Radioactive decay characteristics as measured by a dosimeter

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  49. Mahavir

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  50. W

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