Decay Definition and 998 Threads

I think that when an atom of polonium (Po-216) is moving slowly enough that it can be considered to be at rest. The Po-216 undergoes alpha decay and becomes lead ( Ph-212 ), via the reaction 깝 Po → Pb + ta. After the decay. the lead atom is moving to the left with speed v. and the alpha particle...

I have seen "radioactivedecay.py" python library which employs measured experimental data for its calculations. I have seen models that solve the system of differential equation with numerical algorithms to predict the proportion of nuclides at any given time. But I have yet to see a...

I am studying the following process: pion decays (mediated by the charged ##W## boson) into a muon and anti-muon neutrino (i.e. ##\pi^- \to \mu + \bar{\nu}_{\mu}##). The Feynman diagram associated to it is And its Feynman amplitude is (where we of course neglected...

Hello, I have a very basic question : why a top quark for example cannot decay into a charm or up quark ? The fact is that I don't really understand where the concept of up- and down-type quark come from (except that they have the same charge). Why a up-type quark cannot transform into...

I am trying to understand my results for my muon experiment. I conducted the experiment using a plastic scintillator photomultiplier detector. I have four different data sets, with different discriminator thresholds: 148 mV, 190 mV, 260 mV and 550 mV. I made a histogram of the counts of all four...

I know for muons that the the probability that a muon decays in some small time interval ##dt## is ##\lambda dt##, where ##\lambda## is a decay rate. Thus the change in the population of muons is just ##dN/N(t) = −\lambda dt##. Integrating gives ##N(t) = N_0 \exp(−\lambda t)##. This makes sense...

I'm not too sure where to start, do I differentiate the equation?

If individual atoms are indistinguishable from one another, then how can you tell if atom A will experience radioactive decay before identical atom B? ISTM there would have to be some underlying structure beyond electrons and quarks and unique to each atom / particle to be able to do this...

Summary:: I have been provided with the table in which N and occurence are given. I have been asked to calculate the 1. Total count 2. mean count 3. mean count. Now, assuming our distribution described by Poisson's we need to calculate the tasks. The Poisson's distribution is given by...

I'm interested in knowing where can i find the information on decay time of (possibly every?) different type of bosons, hadrons and fermions, which is available to the public (tiletles of books, articles, ...). Any suggestions or ideas?

Hi community, I've been looking through this question And I have a conceptual if I may (this is not homework I'm a 52 year old programmer just trying to learn and understand). You can calculate the mass loss of 0.006 u when you go from the Radon nucleus to the Polonium and alpha particle. You...

Hello everyone. First my english is not good, sorry for that. So i am not a physician, i am just somebody who wants to learn things by myself, and therefore i don't have many people to ask from, if i am stuck. So here it goes. There are many threads about this question already, and i am still...

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...

I'm not sure where to start

In the experiment, if when the box is opened and the cat is dead, won't the cat's body have started to decay and therefore we could determine exactly when it had died. This could have been a long time before we resolved the cat alive / cat dead question by opening the box. Therefore the state...

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...

Hello! I haven't really seen a feynman diagram with a higgs boson decaying to a top-anti top quark pair. The mass of a top pair is much higher than the Higgs mass on shell, but is there any reason why we can't have a Higgs boson (very) off-shell decay to 2 top quarks. The probability of that...

Hello! I read that in the rest frame of a positive muon, decay positrons are preferentially emitted in the direction of the muon spin. Why is that the case? The decay is ##\mu^+\to e^+\nu_e\bar{\nu_\mu}##. Assuming that the positron is emitted at almost the speed of light, it will be a left...

Hello! Tau decay has a branching ratio to a charged pion + neutral pion + tau neutrino much bigger than to a charged pion and a tau neutrino. Based on consideration of available phase space, I would imagine that adding an extra pion would decrease the branching ratio. Why is this happening...

This problem really confused me, since I can't get the link between particles emitted(alpha and beta, but which are the differences between those?) and changes in mass and atomic number of the isotope. For this one, I can't really show you my attempt since there ain't one...

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...

I was looking at the decay scheme (https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html) of ##^{112}Ag## which ##\beta##-decays to ##^{112}Cd##. ##Cd## is most likely left in an excited states, so it decays to its ground state by ##\gamma##-emission. As you can see there are tons of...

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...

https://www.asi.edu.au/wp-content/uploads/2015/03/PhysicsASOE2013soln.pdf Q12 e) Working backwards, P = Ae^kt form, i.e. EAts = Emin e^(ln2/τ x t). Not sure how they get this formula in the first place with these values.

The Higgs boson couples to mass, muons are relatively light, that makes a decay to a pair of muons (muon+antimuon) very rare. In addition there are many other processes that produce pairs of muons, making this decay mode challenging to find. For a long time it was expected that the experiments...

I tried momentum conservation, which gives: -pα = pdaughter <=> 2mKα = 2mKdaugther (squaring two sides) Using the given mass ratio, I found Kdaughter to be 0.0864MeV Adding the two Kinetic energy of the product particles and converting it to Joules, I got A But I don't understand why adding the...

For a system to undergo quantum decay, is the energy change and energy barrier fixed?

I've been reading about decay chains and I have confused myself on how decay works. Take a sample of 238U for example.. its half-life is 4.5 billion years. At that point half of the sample is now 238U and the other half is 206Pb. But looking at a decay chain, (and maybe I am reading it wrong)...

https://arxiv.org/abs/2002.04856 It's proposed that topological defects like cosmic string enhance vacuum decay. I do not quite believe it.

Most scientists believe neutrinos don't get their mass from the Higgs field due to their tiny mass compared to the next lightest particle(electron).During the electroweak epoch the rest particles were massless but neutrinos shouldn't be. The neutrinos would then decay to the other massless ( i...

I'm currently writing a research paper about the speed of light. I have researched universe expansion, specifically, the quantised redshift spectral index fluctuations of distant galaxies and other structures over time, however, I need to suggest why universe expansion possibly causes a recorded...

A prior closed post inquired as to precisely what determines the time of any given decay. I wasn't able to comment during that thread, but most responses were about probability and other aspects of the problem. I did not see however any mention of quantum fluctuations as possibly participating...

I recognize that radioactive decay is a spontaneous process in which an unstable atomic nucleus breaks into smaller, more stable fragments, but exactly what is it that causes an atom to decay at a particular time rather than at some other time?

Question: Is it believed a "quark star" exists within all neutron stars, or just heavier neutron stars. Do protons actually decay under this pressure (quark soup)? Are Hexaquark bosons able to remain stable beyond the limit of a proton, or would they decay at the same time of a regular...

I'm trying to make up an example for my students to illustrate that in nuclear decay, mass-energy and momentum are both conserved. I found this problem: https://physics.stackexchange.com/questions/304277/calculate-velocity-of-radon-220-nuclear-after-decay I am trying to modify it so that they...

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...

I'm currently reading various papers on the violation of Lepton Flavour Universality in rare B-decays and I would appreciate some help in understanding the methodology for measuring the ratios in these decays. Here is a quote from a recent paper from the LHCb collaboration (p.5): My question...

This is just a representative diagram to visualize Surely a very tough one for me to solve. The number of nickel atoms are not mentioned. if the number of decays are ##3.78∗10^8## and with each decay depositing 100keV. The total energy deposited is ##100keV∗3.78∗10^8=6.048∗10^6## I have to...

Why is it possible for a sigma hyperon to decay into either 2 or 3 gamma hyperons?

Alpha particle has two protons and neutrons so mass = 4. 4x = 238 -206. x = 1/4(238-206) = 8 Alpha decays. How would I determine the number of Beta decays? Since the mass doesn't change here.

Homework Statement:: I am studying how to compute the meson-decay amplitude worked out in Tong's notes (pages 55 and 56; I attached the PDF). Relevant Equations:: $$<f|S|i>=-ig<f| \int d^4 x \psi^{\dagger} (x) \psi (x) \phi (x) |i>$$ The initial and final states are given by $$|i > = \sqrt{2...

Δ ++ → p + π0 Ξ - → Λ0 + π-

The phys.org summary had me intrigued and the resulting new paper makes for heavy reading at my level of knowledge, but it was the underlying reasoning of the methodology that I really question: One of the authors notes "It's so rare, that they should not have seen any." From that, the...

I have been amateur reading about beta decay. The example given for electron capture was krypton-81 into bromine-81. Going from a noble gas to a halogen gives rise to a big change in chemical potential energy. How is this energy accounted for in the equations of the reactant particles and...

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...

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...

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 don't know v? very confused

Dear all, in my teaching of nuclear physics at high school level I noticed that I never really wondered about why alpha decay consists of helium nuclei. So I consulted a lot of lecture notes online, but couldn't find a satisfying answer. The texts I used in the past are "concepts of modern...