# Beta decay Definition and 41 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 Beta Decay, why did they have to resort to Neutrinos?

I'm reviewing history of subatomic physics. By 1931AD the nuclear physics community had decided to propose the neutrino because they couldn't explain beta decay without it. Alpha and Gamma decays were more confined wrt the energy they would extract from the nucleus i.e. they had energy bands. By...
2. ### I Gamma radiation decay intensity (IAEA nuclide chart)

I was looking at the gamma radiation data from IAEA's website: (https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html) and was confused by the absolute intensity listed in the page. I Googled it and it seems to be the probability of emission but why it doesn't add up to 100%? For example...
3. ### I Energy reduction/deflection of beta particles due to isotope geometry

Hello all. I'm an undergraduate student looking to conduct an experiment with an isotope that undergoes beta decay. I am curious as to the degree to which the isotope geometry will reduce the energy of/deflect beta particles emitted from the isotope. By geometry, I mean the "shape" of the...
4. ### B Where does the mass of a W boson come from in beta decay?

During beta decay an electron and neutrino are emitted at very high speeds. I thought that the electron and neutrino were the product of w boson decay but I recently learned w bosons are over 80 GeV worth of energy. My question is, where does this mass come from? I know that atoms get enough...
5. ### B Prevalence of nuclear decays accompanied by gamma emission

Some alpha or beta decays produce an excited daughter nucleus, which typically immediately emits one or more gama rays to reach a ground state. This is the case for beta decay of Co-60 or Na-24 for example. While the table of cobalt isotopes on Wikipedia mentions the gamma emission, the one for...
6. ### Forbidden beta decay form factors

My idea was to consider first the structure of the matrix element and to see if there are any possible constraints that we could use for parametrization. If I am not mistaken, we are dealing with the hadronic decay governed by QCD which conserves parity. Since we have a derivative operator...
7. ### Beta Minus and Beta Plus Decay Disintegration Energies

I am confused about the disintegration energies of beta minus and beta plus decay. Regarding beta minus decay, the textbook says that "the number of electron masses has been accounted for in Equation (12.38)." What does that mean? Usually the disintegration energy is simply the mass of the...
8. ### I What are these directional energetic particles?

In addition to the usual alpha and beta particles visible in my condensation cloud chamber, I see occasional tracks that seem highly energetic -they easily penetrate the entire width of the cloud chamber (10-12 inches) going in one side and out the other. More mysteriously, their orientation is...
9. ### I Loss of electron & proton energy due to radiation

Can you compare the energy loss of electrons and protons due to the radiation they emit? In fact, I want to know which of the two loses more energy when it emits radiation.
10. ### I Understanding crossing symmetry: inverse beta decay

Hi! This is a very very noob question, but I am starting to get into particle physics and I don't understand the application of crossing symmetry in the inverse beta decay. Crossing symmetry says (from Griffiths) that, in a reaction "any of these particles can be 'crossed' over to the other...
11. ### A "Reversal" of Nuclear Decay in Beta Emitters

Hello all, I've got a question on nuclear decay "reversal" in beta emitters. I've been researching the Cowan-Reines experiment, which used neutrinos to convert protons into neutrons. Recently, I found out that the particle which hits the proton need not necessarily be a neutrino in order to...
12. ### B Beta decay and the down quark.

I was learning about beta decay, and how a down quark decays into an up quark by emitting a W- boson which then becomes an electron and an electron antineutrino. I have two main questions - Firstly, how can the down quark be considered a fundamental particle, when it can break down to produce...
13. ### Implications of mass energy not being conserved for ##\beta^+## decay

##\beta^{+}## decay (a proton decays to a neutron + positron + electron neutrino) is a decay in which mass energy is not conserved. I've been taught that if that ought to be the case for a decay/reaction, it would be forbidden (please see solution manual below): But ##\beta^{+}## decay is...
14. ### Calculating the integrated Beta dose in dense materials (radiolysis)

I have plastic which contains large amounts of Co-60 and Cs-137. I have already calculated the integrated (50k years) deposited dose from the gamma radiation using Monte-Carlo methods (SCALE). I am now interested in the contribution to deposited dose from the Beta emissions. -I am assuming that...
15. ### Where does energy come from in QFT?

When we say energy is applied to that field to create an excitation which is a particle, where does that energy come from and how is it applied? For example on beta decay where a new electron is formed, where does the energy come from the create an excitement in the electron field?
16. ### A Beta Decay Rates Changing by Ionization?

I recently read about a beta decay isotope (Rhenium-187),whose half life was changed from 42 X 109 years to 33 years, just by stripping the nucleus of all it's electrons. Why does this allow for a faster decay, and does this apply to all beta decay nuclei, or just Rhenium 187?
17. ### B What happens to Fermions during Beta decay radiation?

I recently started learning about quarks and leptons and was wondering what happens to the fermions (specifically the quarks and leptons) during a beta decay. How is the electron/positron created and what causes the up quarks and down quarks to change flavours? If this is a bad question please...
18. ### How to determine if this is β- or β+ decay?

Homework Statement [/B] The problem states that 24 11Na is radioactive. The question asks if it's a β- or β+ emitter. The 24 is the atomic mass number and the 11 is the atomic number. Homework Equations I know that in β- decay, the atomic number increases by 1 and it emits an electron and...
19. ### I Double Beta Decay Rates

Hey everyone, I've learned about double beta decay and neutrinoless double beta decay recently. So we have two "conditions" for decay, 2v decay and 0v decay. Now, to the question I have: There have been a lot of experiments measuring 2v decay rates, and there have been many experiments...

Good evening. I'm currently studing dense matter and nuclear matter above 10^8 g/cm^3, and i know well how to insert a beta equilibirum condition in a free Fermi gás at T=0. \sqrt{K^2_{F,n}+m^2_n}=\sqrt{K^2_{F,p}+m^2_p}+\sqrt{K^2_{F,e}+m^2_e} But how do i insert the same condition of...
21. ### I Probabilities Associated with Sudden Changes in Potential

Hi, I have a question about calculating probabilities in situations where a particle experiences a sudden change in potential, in the case where both potentials are time independent. For example, a tritium atom undergoing spontaneous beta decay, and turning into a Helium-3 ion. The orbital...
22. ### I Calculation Of the energy Of beta decay in tritium

Hi! I hace been trying to calculate how many energy in form of beta radiation is emitted in one if those "Tritiglows" sold in Amazon. I did the following math (imatge) and got a really high energy. How is that posible? Where did I failed...
23. S

### B Explaination of beta + decay in layman language

QUESTION: I read in book that in beta + decay proton decays to neutron But i can't understand how it is possible if proton mass is less than neutron mass.I read on net but it says 'quarks' and 'd u p' things which i don't study about currently. Also why it only happen inside nucleus?What...
24. ### I End Point Energy and Q value in beta decay

I know that Q value of a reaction is the difference between total initial mass-energy and total final mass-energy of all the products. Then shouldn't be this also the maximum kinetic energy and hence endpoint energy of an electron in beta decay. But what I have read endpoint energy ##E_0 = Q +...
25. ### I Time invariance of weak interaciton e-p->\nu n

The question is rather simple, but I cannot seem to find a solid answer. I need the cross section of the following interaction: e^- + p\rightarrow n+ \nu . I need the cross section using the form factors. There are many solutions for the interactions like: n+ \nu\rightarrow e^- + p or...
26. ### I Do Fermi and Gamow-Teller transitions only refer to isospin

Do Fermi and Gamow-Teller transitions only refer to changes in isospin , as in beta decay and orbital electron capture
27. ### A Is beta decay a weak charge-current processes?

Im try to understand this paper http://citeseerx.ist.psu.edu/vie... and see if I correctly understand which processes are charge-current processes, and which are charge neutral, as listed in Figure 1. Thanks
28. ### Compute the energy of the emitted alpha for Na20 decaying to an excited state

I think I got this right, I just want a second opinion to know if my concepts are correct 1. Homework Statement 20Na decays to an excited state of 20Ne through the emission of positrons of maximum kinetic energy 5.55 MeV. The excited state decays by ##\alpha## emission to the ground state of...
29. ### 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...
30. ### I Why use the mass of 2 electrons in calculation of Q for beta

When dealing with a beta ^+ decay in the calculation of the disintegration energy Q, one includes the mass of 2 electrons. But the output result is 1 electron in the fundamental reaction: p => n + ( e^+ ) + v Where the neutron n has a neutral charge and the neutrino v has Z = 0. So why does...
31. ### A Nuclear stability equations?

Are there equations that detail the stability of nuclei against beta decay? On a related point, I'm familiar with the chart that shows all the isotopes and their half-lives (with a good chunk undergoing beta decay), but I was wondering if that can be derived from first principles, just using the...
32. ### I Does the mass of a neutron vary?

The mass of a neutron is approximately 1.674927471×10−27 kg, but is this always the case? For example if a neutron undergoes negative beta decay (i.e. an electron and an electron anti-neutrino is emitted) and then positive beta decay, will this not mean that the final mass of the neutron is now...
33. ### I Beta decay and CPT symmetry

I read that CP-symmetry violation occurs (or can occur) in beta decay. Does that mean that, since CPT-symmetry must hold, there is no T-symmetry?
34. ### A Accelerating an electron in beta decay

The electron created and emitted in the beta decay of a proton has an initial velocity close to the speed of light. When I try to calculate, not taking into account relativity, the force needed to accelerate an electron to that velocity over a distance the size of a proton, I get about 45 N...
35. ### I Can electron beam accelerate electron capture beta decay?

Some nuclides undergo decay of electron capture or beta plus. Can electron beam with appropriate energy accelerate electron capture beta decay? Same scenario: If I am looking for something, and my friend kindly hands it over to me, then I say thanks, because my seeking time is shorten.
36. ### B How do beta particles remove electrons?

Hello all, I'm just learning about beta decay and the emission of beta particles. I have come to an understanding that this is ionising radiation because it has the ability to remove electrons and turn the molecules it interacts with into ions. I've looked on the Internet for this information...
37. ### I How do neutrinos conserve angular momentum?

I'm learning about beta decay and as I understand in beta decay we get: neutron → proton + electron And since all these have spin 1/2 we have that the conservation of angular momentum is not conserved. The neutrino with spin 1/2 is proposed to also exist in the process to solve this so that...
38. ### Fermi theory

Could you explain what's the interpretation of a before \gamma^{5} in this current: J_{\alpha}=\bar{\psi_{e}}\gamma^{\alpha}\left(1-a\gamma^{5}\right)\psi_{\nu_{e}} +\bar{\psi_{\mu}}\gamma^{\alpha}\left(1-a\gamma^{5}\right)\psi_{\nu_{\mu}}? And will this factor complicate calculations of decay...
39. ### Why doesn't Rubidium decay to Strontium?

Both ##^{87}_{37}Rb## and ##^{87}_{38}Sr## are odd-even nuclei, so we can ignore the pairing term ##\delta##. I tried to calculate the most stable Z for a given A by finding ##\frac{\partial B}{\partial Z} = 0##. That gives the most Z-stable value of ##Z_0 = \frac{2\gamma A}{4\gamma + \epsilon...
40. ### Fermi Golden Rule - Beta Decay

We consider the following beta decay: ^A_ZX \rightarrow ^A_{Z+1} Y + e^{-} + \nu_e The Fermi golden rule is given by: \Gamma = \frac{2\pi}{\hbar} |A_{fi}|^2 \frac{dN}{dE_f} Reaction amplitude is given by ##A_{fi} = G_F M_{nucl} ## while density of states is given by ##dN = \frac{4 \pi...
41. ### Proton to neutron conversion at relativistic energies

The reaction p→n+e++νe is common inside nucleus. But it not considered when we talk about free particle and reason is simply given mass of products being larger than reactants. Now my question is if there is a high energy proton having total energy in order of 2 GeV or let it to be 100 GeV (To...