Decay Definition and 998 Threads

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.

View More On Wikipedia.org
Recent contents Top users
  1. spareine

    B How to pronounce a nuclear reaction written in AZE notation?

    Pronouncing a nuclear reaction like as "one,zero,neutron + 235,92,uranium yields 141,56,barium + 92,36,krypton + 3,1,0,neutron" is awkward. How is it pronounced by physicists in practice?
  2. S

    A Decay of false vacuum in new inflation

    In new inflation, the time scale for the decay of the false vacuum is controlled by ##- m^{2} = \frac{\partial^{2}V}{\partial\phi^{2}}\bigg|_{\phi=0}.## This is the negative mass-squared of the scalar field when it is at the top of the hill in the potential diagram. This is an adjustable...
  3. M

    Issue calculating the velocity of pions from K-meson decay

    Homework Statement We were supplied with several images of hydrogen bubble chamber tracks, from which we measured the length of the (invisible) K0 track, angles of departure from the K0 meson's track and curvature. As a way to limit the amount of data we're talking about, I'll only discuss the...
  4. zinq

    B Does every elementary particle eventually decay into quarks?

    Everything in the universe that has a beginning seems to also have an end. Stars, galaxies, molecules, atoms. But what about elementary particles? In case of heat death would it become a uniform quark soup?
  5. J

    I Does beta decay change spin orientation?

    If you have a free neutron viewed from a known frame of reference which is known to be spin up and it decays, is there anything in theory or experiment which indicates whether the remaining proton will be spin up or down? Thanks Jerry
  6. F

    Possible webpage title: How does energy factor into the decay of particles?

    Homework Statement [/B] A particle detector shows tracks produced by two particles X and Y that were created by the decay of a lambda particle at O. Which of the following is a correct statement about energy at the decay? The energy of X must be greater than that of Y. The combined energy...
  7. B

    Decay Widths of Neutral Vector Mesons

    Homework Statement Neutral vector mesons with ##J^{PC} = 1^{−−}## include the ##\phi## (mφ = 1020 MeV), ##J/\psi## (mJ/ψ = 3100 MeV), and ##\Upsilon## (mΥ = 9460 MeV), with quark content ss¯, cc¯, and b ¯b respectively. The decays of these mesons go largely to hadronic final states (jets)...
  8. T

    I Why Does Unstable Particle Decay Follow an Exponential Curve?

    Given that an unstable particle has a constant probability of decaying per unit time, why is it said that its chance of surviving falls exponentially?
  9. T

    I Semileptonic Lambda baryon decay suppression

    Hi there, I'm currently studying the decay modes of the Lambda baryon (uds). According to literature, the decay mode with leptons (e.g. Lambda -> p + e- + anti ve) is suppressed against the decay modes with pions (e.g. Lambda -> p + pi-) by a factor of about 10^-4. I was looking for the reason...
  10. L

    What is the kinetic energy of a proton when neutron decays?

    Homework Statement What is the kinetic energy given to the proton in the decay of a neutron when: a) The electron has negligibly small kinetic energy b) The neutrino has negligibly small kinetic energy Homework Equations Q = (mn - mp - me - mv ) c2 = .782MeV Where T is kinetic energy, and...
  11. L

    How do I use this equation? Estimating half-life of a decay

    How should I go about using equation 8.18? Link can be found below. In the book, an example is used where Th-220 --> C-12 + Po-208 with a Q value of 32.1 MeV is used, and it is said to yield t1/2 = 2.3x106 but for the life of me I cannot reproduce this result. This is what I did: Going from...
  12. menniandscience

    B Exploring the Effects of Speed on Time and Decay: Unraveling Einstein's Theory

    it is known that einstein's theory has been verified and time slows down for particles that should decay in certain time, takes more time to decay if moving fast. what makes them behave like that, how moving fast makes time to slow down, is it really time or just maybe this has not been...
  13. Jr_Particle_Hunters

    B Is our cloud chamber showing correct tracks from U-238 decay chain?

    Hi. We are using a Pb-210 needle source for our cloud chamber science project. Are we correct that the tracks we are seeing inside the chamber radiating off the needle are: 1) Beta tracks from Pb-210 decaying into Bi-210 (in the .063 MeV range) 2) Beta tracks from Bi-210 decaying into Po-210...
  14. I

    I Can a Z Boson Decay to a Photon Affect Its Weak Charge?

    If a Z can decay to a photon, what happens to the Z's weak charge?
  15. C

    B Calculating heat from decay of a radioactive isotope

    How would one go about determining the amount of heat generated by the decay of a radioactive particle, such as Cesium 137, Polonium 210, or Strontium 90? How would you determine how much of the radioactive material would be needed to heat, say, a cup of water to a certain temperature, taking...
  16. S

    A What Are the Possible Decay Processes of the W⁻ Boson?

    The decay processes of the ##W## bosons are completely governed by the charged current interaction terms of the Standard model: $$\mathcal{L}_{cc} = ie_{W}\big[W_{\mu}^{+}(\bar{\nu}_{m}\gamma^{\mu}(1-\gamma_{5})e_{m} + V_{mn}\bar{u}_{m}\gamma^{\mu}(1-\gamma_{5})d_{n})\\...
  17. K

    I Decay of the Bs0 particle and supersymmetry

    14 February 2017: First single experiment observation of the decay Bs0→ μ+μ-. From discovery to precision measurement. [ Branching fraction Bs0→ μ+μ- = (2.8±0.6)x10-9 ; B0→ μ+μ- < 3.4x10-10 ] "“We love this decay because it is one of the most promising places to search for any new effects of...
  18. S

    A Matching interaction terms and decay processes in standard model

    I would like to consider the interaction terms in the Standard Model which allow the following decay process: The only interaction terms in the Standard Model which allow this decay process are contained in the charged current interactions: $$\mathcal{L}_{cc} =...
  19. Comeback City

    B Understanding Beta Decay: The Role of Quarks, Leptons, and Bosons

    These questions came to mind after my physics teacher told us that a neutron is actually a "proton-electron" pair. He then said in beta minus decay, when the neutron decays, the electron is released and only the proton remains. I'm pretty sure this is incorrect, though, but can any confirm it...
  20. F

    Decay of a particle of mass M into two particles

    Homework Statement A particle of mass M and 4-moment P decays into two particles of masses m1 and m2 1) Find the total energy of each particle (lab frame). 2) Show that the kinetic energy T1 of the first particle in the same reference frame is given by $$T_1= \Delta M (1 - \frac{m_1}{M} -...
  21. B

    Neutral Pion Mass from Its Decay into Two Photons

    Homework Statement A ##\pi^0## meson decays predominantly to two photons. Suppose the energies (E1, E2) and angle (##\theta##) between the emitted photons are measured. Find an expression for the ##\pi^0## mass in terms of E1, E2, and ##\theta##. Homework EquationsThe Attempt at a Solution...
  22. C

    Tug-of-war with competing decay of force equations

    Homework Statement Two frats compete in a tug of war. Each team has 5 players of mass 80kg each. Each person is capable of pulling with 100N of force. The force of one team decays according to F(t) = F0(e^(-t/2)) and the other, F(t) =F0(e^(-t/1)). What is the position of the (very lightweight)...
  23. H

    B What is the meaning of decay mode IT in nuclear physics ?

    I showed beta decay in decay mode of Nuclear chart..but I couldn't find what is the meaning if IT 100%..
  24. Safinaz

    I ## \mu~\to e~ \gamma ## decay width and neutrino propagator

    Hi all, I'm studying ## \mu \to e~ \gamma ## decay from cheng & Lie' book " gauge theory of elementary particles ". In Equation (13.84), he wrote the neutrino propagator ## \sum_i \Big ( \frac{U^{*}_{ei} U_{\mu i}}{(p+k)^2-m_i^2} \Big), ## (where the sum taken over neutrinos flavors) in the...
  25. R

    Pi meson decay (relativistic momentum)

    Homework Statement A charged π meson (rest mass = 273me) decays into a neutrino (zero rest mass) and a μ meson (rest mass = 207me). Find the kinetic energies of the neutrino and the mu meson. Homework Equations E = moγc2 K = mo(γ-1)c2 v = pc2/E p = moγv The Attempt at a Solution In the rest...
  26. Eric Putney

    I Can a (uuu) baryon exist? If so, why wouldn't protons decay

    Is this some sort of issue with color or another quantity that needs to be conserved?
  27. karush

    MHB What is the age of the tree to the nearest year?

    $\tiny{242.7x.14}$ $\textsf{The charcoal from a tree killed in a volcanic eruption contained 62.8 percent of the carbon-14 found in living matter. }\\$ $\textsf{ How old is the tree to nearest year? Use 5700 years for the half-life of carbon-14}$ \begin{align*}\displaystyle 1&=2e^k(5700)...
  28. B

    How can a pi_0 meson decay into 2 photons?

    Homework Statement Earlier my teacher put this equation on the board, π_0 --> γ+γ It appears to work until you consider spin. Homework Equations a quick google search reveals that the spin of a photon is +1 and the spin of a pi meson is 0 The Attempt at a Solution This appears to work for...
  29. K

    B Alpha decay produces electron surplus?

    Hi! I recently learned about the Alpha decay, where the atomic Nukleus emittes Alpha-Particles. I was wonderin if a material, which emittes such Alpha Particles has a surplus of electrons and so a negativ electronic charge after the decay. Because it loses Protons but stays with the...
  30. J

    I Is proton decay considered in neutron star models (and LHC)?

    Although it is definitely not simple, there are many reasons to consider that baryon number can be violated, for example: - while baryogenesis there was created more matter than antimatter, - hypothetical Hawking radiation can finally turn any matter (mainly baryons) into massless radiation...
  31. ORF

    I In a nuclear decay, where the dM energy goes?

    Hello Let's suppose a beta-decay. The mother nucleus is dM heavier than the daughter nucleus. What happen if the excitation energy does not match any combination of excited states in the daughter nucleus? Example: the daughter nucleus has 100keV of excitation energy, but the first exited...
  32. iHaveQuestions88

    The Decay Rate of a Hypothetical Antimatter Container

    Hi All, First time poster here, and I've got a couple questions. Straight up, I'm writing a sci-fi story where antimatter is utilised as fuel (feel free to laugh at the cliche), and I want to portray it as realistically as possible. To that end, I've come up with a storage method and I want to...
  33. C

    B Can I find experimental data for the decay of Iodine-131?

    I'm currently undergoing an assignment in maths were it is is necessary to apply mathematical concepts to aspects in reality. Hence, I have chosen to model the radioactive decay of iodine 131, however I am required to plot the data of the radioactive decay of iodine 131, in order to find the...
  34. K

    I Implications of no proton decay, simplest GUT ruled out

    Search for Proton Decay via p→e+π0 and p→μ+π0 in 0.31 megaton⋅years exposure of the Super-Kamiokande Water Cherenkov Detector M. Miura (The Super-Kamiokande Collaboration) (Submitted on 12 Oct 2016) We have searched for proton decay via p→e+π0 and p→μ+π0 using Super-Kamiokande data from April...
  35. D

    Can Beryllium-7 Decay Be Controlled for Energy Production?

    Beryllium-7 decay with electron capture, if you strip away all the electrons, no decay will occur. Suppose that we can somehow turn the generated gamma ray into usable energy, what does it take to confine Beryllium ions into an electron free medium and only feed electron into it when power is...
  36. S

    I Is the decay of a muon always a 1 to n process?

    Decay processes are quite common in particle physics. Is the decay process always a ##1 \rightarrow n## process? In other words, can we call the reaction $$\mu^{-} + \mu^{+} \rightarrow \phi,$$ where ##\phi## is some scalar particle, the decay of the muon?
  37. S

    A Possible decay process for a cubic scalar self-interaction

    Consider the Lagrangian $$\mathcal{L}=\frac{1}{2}\partial_{\mu}h\partial^{\mu}h-\frac{1}{2}m^{2}h^{2}-\frac{\lambda}{3!}h^{3}$$ for a real scalar field ##h##. This is the Klein-Gordon Lagrangian with a cubic self-interaction term. Does this model allow the decay process $$h \rightarrow h +...
  38. S

    A What are the different decay processes shown in this Feynman diagram?

    Consider the following momentum-space Feynman diagram https://upload.wikimedia.org/wikipedia/commons/b/b5/Lepton-interaction-vertex-eeg.svg This Feynman diagram is the leading-order contribution to the any of the following processes: 1. ##e^{-} \rightarrow e^{+} + \gamma## 2. ##e^{+}...
  39. SigurdScience

    I Is Beta Decay Happening Inside My Glow-in-the-Dark Key Chain Made of Plexiglass?

    Hi, I recently bought a glow-in-the-dark key chain, similar to http://tinyurl.com/zqf5sxb (image link). It is made from solid plexiglass, with a hollow cylinder in the middle, containing tritium. The electrons from the beta decay presumably hit a fluorescent wall on the inside of the cylinder...
  40. Anchovy

    A Why lower limits on proton decay lifetimes depend on channel

    If I look at the lower limits on the proton decay lifetime \tau set by, say, Super-Kamiokande, I'll see different lower limits depending on what the proton could decay into, eg. \tau_{min}(p \rightarrow K^{+} \overline{\nu}) < \tau_{min}(p \rightarrow \mu^{+} \pi^{0}) < \tau_{min}(p \rightarrow...
  41. A

    I Dimensions of the pion decay constant

    The pion decay constant f_{\pi} is defined by <0|\overline{d}\gamma^{0}\gamma^{5}u|\pi^{+}>=f_{\pi}m_{\pi} where I have set the momentum \boldsymbol{p}=0 (and used the temporal component of the axial vector). Now, at the right-hand-side the dimension is two (the decay constant and the mass are...
  42. E

    What is the maximum energy of the Λ particle after the Σ0 baryon decay?

    Homework Statement A Σ0 baryon, traveling with an energy of 2 GeV, decays electromagnetically into a Λ and a photon. What condition results in the Λ carrying the maximum possible energy after the decay? Sketch how the decay appears in this case, and calculate this energy. Explain your...
  43. C_Pu

    I How Do Silicon Radiation Detectors Work in Detecting Beta and Gamma Radiations?

    So we are doing Radioactivity lab at second year undergraduate. I am confused about the workings of the silicon radiation detects we are using even though the demonstrators tried to explain. We are detecting beta and gamma radiations by placing sources above a silicon detector that have a small...
  44. J

    Three-particle decay and momentum

    Homework Statement The decay of a neutron into a proton, an electron, and a neutrino is an example of a three-particle decay process. Use the vector nature of momentum to show that if the neutron is initially at rest, the velocity vectors of the three must be coplanar (that is, all in the same...
  45. M

    MCNP Gamma Decay: Neutron & Photon Calculation in Reactor Cores

    Hi , This is my first post in this forum, I am new and happy to be in this forum :) My question is, during the calculation of neutron and photon of a single-point reactor core, does MCNP5 taking into account the gamma decay? because during fission process, fission product can emit gamma. Does...
  46. Recycler

    I What triggers a radioactive nucleus to decay spontaneously?

    what conditions must occur randomly to allow a radioactive nucleus to decay spontaneously?
  47. Recycler

    I Can Nuclear Decay Be Controlled?

    Is it theoretically possible to stimulate a radioactive nucleus so that it decays on demand instead of randomly?Could this be used to accelerate decay of dangerous fission by-products?
  48. pac0master

    Calculating Half life Decay in an Open system

    [Question] So I was thinking about Physics for some time and for the sake of curiosity I've came with this problem: Let's say we have a liquid flowing into a system with infinite space. The flow is constant ( F ) The liquid decays over time with a half life ( λ ) We're looking for the Total...
  49. Isomorphism

    Particle decay: Relativistic or classical?

    This question was asked in an competitive exam in India. The relevant equations are momentum conservation in the classical sense and the 4 momentum conservation. My attempt: Classical momentum conservation would seem inaccurate since the kinetic energies are high. However, a straightforward...
  50. V

    Muon decay in flight - distribution of distance

    Homework Statement The average lifetime of muons at rest is τμ0 = 2.2 μs. A laboratory measurement on the decay in flight of muons in a beam emerging from a particle accelerator yields an average lifetime of τμ = 6.6 μs, as measured in the lab frame Σ. (g) [3 points] Given a large ensemble of...
Back
Top