# 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. ### 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. ### 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. ### Decay Feynman Diagrams

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

30. ### 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?