decay Definition and Topics - 72 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. F

    A How can I read ENSDF files

    Dear community, I am trying to construct the decay chains and the decay radiations from ENSDF files. Until now, I have used the ones included in the ENDF6 file format such as JEFF3 or ENDFBVIII etc... However, I have been told that ENSDF was especially done for decay data. I found the software...
  2. peguerosdc

    In 2 consecutive decays, determine max and min energies for a particle

    Hi! Instead of just describing my procedure and all my derivations, I really just want to ask if my approach makes sense (actually I have 2 options) to calculate the maximum energy. I am considering c=1 and the problem suggests to consider the neutrino massless: For the first decay, ##Z...
  3. J

    Decay Feynman Diagrams

    Δ ++ → p + π0 Ξ - → Λ0 + π-
  4. B

    A Electromagnetic transitions of ##\psi(2S)##

    When the ##\psi(2s)## particle decays also the following two transitions are observed $$\psi(2S) \rightarrow \gamma + \eta({1}^S_0)$$ $$\psi(2S) \rightarrow \gamma + \chi_{c0}({3}^P_0)$$ The branching fraction for the first decay is about ##3.4*10^{-3}## while it's ##9.7*10^{-2}## for the...
  5. P

    Particle decaying into two daughter particles - special relativity

    Right, so I thought I'd done this correctly but clearly not because my velocity is greater than the speed of light, where have I gone wrong? P = (M, 0, 0, 0) p1 = (E1, p1x, p1y, p1z) p2 = (E2, p2x, p2y, p2z) P = p1 + p2 p2 = P - p1 square each side to get (p2)2 = P2 - 2Pp1 + p12 therefore (m2)2...
  6. P

    A moving pi-meson decaying into 2 photons - finding their energy

    I've tried using gammamc^{2} = E1 + E2 but how do i find gamma?? If i try to use the kinetic energy then I just get gammamv^2 = 1gev but i dont know v? very confused
  7. H

    Finding the velocity of an emitted particle from a decay

    So I know that the total energy of the system initially is 775.5MeV, because the meson is at rest. Also by conservation of energy I know that the total final energy of the system is the same thing. I also know that the initial momentum of the system is 0 because the particle is at rest. This...
  8. A

    I Forbidden decay ##\rho^0\rightarrow \pi^0\pi^0##

    Hello everybody! I have a question regarding the forbidden decay ##\rho^0 \rightarrow \pi^0\pi^0##, but it is a general doubt. My book states that one of the reasons why the decay is forbidden is Bose-Einstein statistics, the final state of two equal pions must be in an antisymmetric state...
  9. M

    Calculate the energy release of an atom

    First of, I have no idea what I'm supposed to do with the neutrinos and the photons. Can somebody explain how to handle these? The rest of what I tried is quite straight forward $$\begin{align*}\Delta E &= 4M_p - M_{He} - 2 M_e + E_{\text{Neutrino and Photons}}\\&= 4M_p - (2[M_p+M_n]-E_B) - 2...
  10. Danny Boy

    A Concepts in a quantum synchronization setup

    In a paper on quantum synchronization, they introduce the setup given in the attached 'Fig1.png'. I would like confirm a few concepts regarding this setup. The setup is described in the following way: The general setup is shown schematically in Fig.1. Two ensembles, each containing ##N##...
  11. zehkari

    Relativistic momentum of two photons from a decay

    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...
  12. Flabbergast

    Standard deviation and probability for decay

    Homework Statement (b) A nuclear research reactor produces radiation for neutron scattering measurements. A safety procedure shuts the reactor down if a radiation level monitoring detector measures more than 3 counts per minute. In a test, 156 counts are recorded during a random 24 hour...
  13. T

    I Higgs Boson decay to two Quarks Detected
  14. S

    I Am I understanding the Geiger-Nuttall law correctly

    Geiger–Nuttall rule relates the decay constant of a radioactive isotope with the energy of the alpha particles emitted. Roughly speaking, it states that short-lived isotopes emit more energetic alpha particles than long-lived ones. - wiki I am trying to understand why there is an inverse...
  15. C

    I Activity of daugther isotope in secular equilibrium

    Consider chain of two radioactive decays ##A \to B\to C##. The equation that regulates ##N_B## is $${\frac {\mathrm {d} N_{B}}{\mathrm {d} t}}=-\lambda _{B}N_{B}+\lambda _{A}N_{A}$$ I can't understand why the activity of ##B## is get as ##\lambda_B N_B##, for example at page 20 here...
  16. C

    I Measuring characteristic time of strong and weak interaction

    Consider a scattering between two particles a and b that produces two particles c and d: d is stable, while c decays in two other different particles e and f. The first interaction is by strong force (time of interaction ##t_1\sim 10^{-23}s##, which is also the time of generation of c and d)...
  17. A

    A Quantum Anti-Zeno Effect and Decay Rates

    Hey everyone, I have a question about how "viable" the Quantum Anti-Zeno Effect (AZE) is at lowering decay rates in radioactive nuclei. We know that the AZE can, in fact, reduce the half life of radioactive isotopes, but there seems to be a barrier to that. AZE states that decay can be...
  18. Cocoleia

    Position of particles on a detector after decay

    Homework Statement A hypertriton (a bound system with a L hyperon together with a deuteron core (proton and neutron) is produced at the origin of the coordinate, (x,y)=(0,0) with a velocity of 0.94c (beta=0.94), flying along the x-axis. The mass of the hypertriton is 2.991 GeV/c2 . It decays...
  19. J

    Higgs Experiment for new particle (decay widths)

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Question: An experiment is proposed to directly measure the width (Γ) and mass (m_H) of the Higgs boson via the reaction: muon+ + muon- > H. Sketch a graph of the expected cross section as a...
  20. Cocoleia

    Particle decay, Lorentz transformations with angles

    Homework Statement I have a mother particle at rest, which decays to a daughter particle. The daughter has mass m, momentum p and energy E and is at an angle θ1. Now I have to assume that the daughter is emitted at an angle θ2, and the mother is moving along the x axis with velocity βc. I need...
  21. Cocoleia

    Momentum dealing with decay, special relativity

    Homework Statement A particle A (mother particle) with a mass of mA decays to two particles B and C (daughter particles) with mass values of respectively mB and mC. Calculate momentum of the two daughter particles, pB and pC. (at first the mother particle is at rest) Homework Equations The...
  22. G

    Ultra-Relativistic Particle Decaying to Identical Particles

    Homework Statement Show that it is impossible for an ultra-relativistic particle with ##pc>>Mc^2## to disintegrate into two identical massive particles of mass m. Homework Equations Conservation of four momentum The Attempt at a Solution The four momentum of the ultra-relativistic particle...
  23. M

    Why do 2 d not decay into alpha particle and neutral pion?

    Homework Statement The reaction dd → απ0 (where α is the Helium-4 nucleus and d denotes the deuteron) has never been observed. Why? Homework Equations The Attempt at a Solution [/B] So I checked first the masses to make sure energy/momentum are conserved and found out that mass of 2d is...
  24. M

    Mass of Hydrogen needed to determine lifetime of proton

    Homework Statement The current limit on the proton’s lifetime is determined by observing a large body of water for a long time and noticing that no one of the hydrogen nuclei in H2O have decayed. Assuming that the experiment making this measurement has been going on for 10 years, how many tons...
  25. 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?
  26. 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...
  27. 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...
  28. menniandscience

    B Time slowing because of speed

    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...
  29. 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} -...
  30. 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?