Decay Definition and 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?
31. I Beta decay and 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...

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...
33. 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...
34. Alpha emission decay: maximum possible delay

Homework Statement A tube containing a isotope of radon, 22286Rn, is to be implanted in a patient. The radon has an initial activity of 1.6 * 104 Bq, a half-life of 4 days and it decays by alpha emission. To provide the correct dose, the tube, containing a freshly prepared sample of the...
35. Calculate momentum, kinetic energy, speed etc. for a decay

Homework Statement I have the decay K+ → μ+ + νμ Calculate: 1. Momentum of μ+ 2. Total energy of νμ 3. Mass of K+ 4. Speed of μ+ 5. Speed of νμ Homework Equations The only thing we get are the kinetic energy of μ+ so Kμ+ = 152.53 MeV and the mass of mμ+ = 105.658 MeV/c2 The Attempt at a...
36. Insights LHC Part 4: Searching for New Particles and Decays - Comments

mfb submitted a new PF Insights post LHC Part 4: Searching for New Particles and Decays Continue reading the Original PF Insights Post.
37. I Lambda baryon decays

I've been asked to find the ratio between the cross sections of the two folowing decais: Using the CKM matrix and the feynman diagrams for both decays, I reach the conclusion that the Ratio is exactly 1. However, consulting this document...
38. I Why do we need time dilation to explain muons reaching earth

As I understand it muons have a half life of 2.2 microseconds, thus, at the speed of light cannot get to the earth. But based on exponential decay, of every billion muons which head or way, about 70 will actually get here. Using time dilation the full billion will get here. Do we need a billion...
39. I How bosons decay?

Hey! I'm studying some particle physics. I ran into this example of a gluon decaying into a u - anti-u pair. (According to example 9: http://teachers.web.cern.ch/teachers/archiv/HST2002/feynman/examples.htm) How come this happens via strong force. Why isn't a Z0 boson doing this instead? Thanks!
40. How do I determine if a certain nuclear decay is allowed?

Hi, I am struggling with a question where they want me to determine whether or not three different decay are allowed. From what I have understood all decays must follow a set of conservation law. These laws are: 1 Conservation of Baryon number 2 Conservation of Lepton number 3 Conservation of...
41. Atom charge after ionizing (nuclei/particle) radiation

Homework Statement When an instable atom emits alpha or beta particles. Doesn't the overal electrical charge of the remaining atom change? For example when an atom emits alpha decay, a helium core is emitted, this results in the lose of two protons (forthe radiating atom). But doens't this mean...
42. Rearranging x=x0e^-lambda t in the form y=mx+c

Hi, How could I rearrange x=x0e^-lambda t into the form y=mx+c, where y is equal to ln x and x is equal to t? Thank you in advance I tried to solve the problem myself, by taking the natural log of both sides, this left me with: ln x = -lambda t * lnx0 However, I am not sure if this answer is...
43. I Actual measurement of radioactive decay

Hello, Are there any anthropologists, archaeologists, or geologists around on this board for help? I am trying to teach myself about radioactive decay via beta emission whereby a neutron spontaneously transmutes into a proton, releasing an electron. But, I do not understand the practical side...
44. B Hamiltonian of Carbon-14?

Hey, here's a quick question: What is the Hamiltonian operator corresponding to a decaying Carbon-14 atom. Any insight is quite appreciated!
45. How to derive formula for nucleus decay using this equation?

Homework Statement The formula being derived is N=No*e^k*t, from the equation Nn=No/2^n where No is the initial number of particles and the lowercase n in the second equation is the number of half lives. The n in Nn just indicates the number of particles after so many half lives. You might also...
46. W boson decay

Hi, i'm trying to compute the differential decay of W boson at rest $$W^+ \rightarrow e^+ \nu_e$$ where the boson has fixed spin along z axis, and so specific cirular polarization. Using Feynman rules i get...
47. Relativistic decay

Homework Statement Hi- i've been doing some questions and came across the following A high energy particle, travelling towards an observer with velocity v decays to produce a photon with energy E in the rest frame of the particle. Find the frequency at which this photon would be detected by...
48. Inflaton Decay

Inflation , as proposed, leaves the universe cold and empty. The compensating theory of reheating or preheating then needed to operate after inflationary era. Such theories prefer three legs bosonic decays φ→χχ, which doesn't have any analogy with standard model processes as much as I know. How...
49. Homework Nuclear Physics

Homework Statement What initial mass of 23592U is required to operate a 350 MW reactor for 3 yrs? Assume 46% efficiency. Homework Equations I used Mass* C* efficiency as a decimal= power (e^-6) * time (in seconds) and got 800 as the mass, however, this was incorrect The Attempt at a...
50. Power produced from alpha decay

Homework Statement Assume that a 14 kg sample of 240Pu is used to produce electrical power from its α decay. If your device is 60% efficient in producing electrical power, how much power can be produced? (in watts) Homework Equations Q=mass of plutonium-mass alpha-mass daughter; 240 plutonium=...