Decay Definition and 998 Threads

Hi, I am reading in some books that after the \beta-decay of neutrons, the maximum energy of the resulting electron is a bit less than 800 keV. In some cases, however, I see that in e.g. some studies that try to extract the electron energy from \beta-decay of neutrons with some Monte Carlo...

Homework Statement In the rare decay ∏+ → e+ + ve , what is the momentum of the positron (e+)? Assume the ∏+ decays from rest. (m∏+ = 139.6 MeV/c^2, mv ≈ 0, me = 0.511 MeV/c^2) Homework Equations Conservation of Energy: E∏ = Ee + Ev Conservation of momentum: p∏ = pe + pv...

100mbq tc 99 requires how much mo 99? Answer in number of atoms, assume equilibrium conditions: 67/6.4 *1x10^8 = 1 x10^9

Provided they aren't in an excited state (which would allow a decay via EM or strong). I had a question asking why the neutral lambda particle, consisting of uds quarks, has a lifetime characteristic of the weak. The answer being that it must decay via the weak to change the s-quark flavour into...

Ive searched in vain for a listing of what particles with which interactions decay into which particles. This is a subject I know very little on so any starting direction would be greatly appreciated

(high school level physics btw) apparently all baryons eventually decay into protons, so I was just curious to know if this was also true of anti-baryons?

Homework Statement A ##\pi^0## at rest decays into two photons, one traveling in the +z direction and the other in the –z direction. What is the angle between the photons in a reference frame moving at speed v=0.99c along the x-axis? Homework Equations The Attempt at a Solution...

If time itself slows down near the speed of light, why don't they prove this by sending a particle which decays over a short period of time around the LHC and see if it decays at the same rate as a particle not moving around the LHC? Would this not prove that time really does slow down and...

I just came across the following Quote in an introductory Quantum physics book"There are certain experiments in which behave differently in their mirror image form, this is called the Parity Violation in." Can anybody explain in detail what parity violation is and what mathematical description...

I have two sources, one (school textbook) is telling me that ''all hadrons eventually decay into a proton'', whereas a few other people have told me that ''only bayrons decay into protons''. I want to know because I originally wanted to find out whether mesons decay into protons, and mesons...

For β- minus decay Q = m_x - m_y Whereas for β+ Q = m_x - m_y - 2m_e Where the masses are atomic masses, x and y are the parent/daughter. The SEMF can be used to find a parabolic curve showing the mass excesses for an A isobar for particular values of Z, and thus show at which Z the atom...

Homework Statement I am asked to draw a feynman diagram of K^- \rightarrow \mu \nu Homework Equations K^- consist of s\bar{u} The Attempt at a Solution I wonder what the direcion of the arrows should be, my guess is something like the attached image. edit: Ah, where the left u shoudl be an...

Homework Statement Halzen & Martin, problem 2.25 Homework Equations The ρ and ω wavefunctions are u\overline{u}-d\overline{d} and u\overline{u}+d\overline{d} except for a normalization factor. The Attempt at a Solution In this problem one has to evaluate the expectation value...

Homework Statement A sample of thorium-226 is stored in a lead box. Thorium-226 undergoes alpha decay. The lead box has a small opening on the left side to allow a stream of alpha particles to escape. In the sample a nucleus of thorium-226 is at rest when it undergoes alpha decay. The daughter...

Homework Statement 1)The pion is an unstable subatomic particle whose characteristic decay time in its own frame is 26ns. A beam of such particles emerges from a source at point X in the laboratory traveling with speed ##v = \sqrt{3}/2\, c## in the laboratory frame. Determine i) the decay...

Particle can decay through many channels with probabilities p_i, where in each channel its decay time is different \tau_i. It always decays through one of the channels. Particle decays according to exponential law where probability to decay in time t is...

Homework Statement The isotope 239Pu has a half-life of 24,100 years. After 10,000 years, a sample of the isotope is reduced 1.6 grams. What was the intial size of the same (in grams)? How large was the sample after the first 1,000 years. Round your answer to four decimal places.Homework...

Determining the atomic number, mass number, and chemical name during beta decay! Homework Statement The image below shows the element Thorium with the atomic number listed above and a mass number of 233. This element undergoes two successive beta decays. The resulting nucleus will have an...

Hi all, I'm studying Laplace transform right now. And I am trying to understand the s variable in the s-plane. I found online that s = σ + jω where ω is the frequency and σ is the decay rate. Frequency is pretty easy to understand but I can't seem to find anywhere that explains what is the...

Homework Statement consider a pion decaying into 2 photons. In the rest frame of the pion, the two photons must emerge back-to-back photons are equally likely to emerge in any direction. determine the rest frame angular distribution of the emerging photons. Homework Equations ΔP=f(θ)Δθ is...

Homework Statement Given the Lagrangian \mathcal{L}=\frac{1}{2} ( \partial_{\mu} \Phi)^2-\frac{1}{2}M^2 \Phi ^2 + \frac{1}{2} ( \partial_{\mu} \phi)^2-\frac{1}{2}M^2 \phi ^2-\mu \Phi \phi \phi, [The last term, the interaction term allows a \Phi particle to decay into 2 \phi particles...

Homework Statement Radioactive nuclei A are produced at a rate R per second in a nuclear reactor. They decay with probability λ per second. (Qu 1-2 involving deriving the rate of change and number particles at any given time, I've done this). 3) Show the activity tends to R, a constant, as...

I'm studying the decay K->ππ and I have some doubts on the isospin decomposition. We know that the state (\pi\pi) can have total isospin 0 or 2. Now, if we remember that in the isospin representation we have |\pi^+\langle=|1,1\langle, |\pi^0\rangle=|1,0\rangle and |\pi^-\rangle=|1,-1\rangle...

Hi I have been looking into particle physics and i came across this question but i can not find the answer, the quetsion is as follows: the xi particle decays into the following \Xi -> \wedge + \Pi^{-} dds -> sud + \overline{u}d the quark numbers are conserved but the...

BBC News reported this http://www.bbc.co.uk/news/science-environment-20300100 Here's the actual paper https://cdsweb.cern.ch/record/1493302/files/PAPER-2012-043.pdf What does this actually mean for Susy etc?

Homework Statement A meteor contains 2.45kg of plutonium-239. It has a half-life of 24065 years. Calculate: a) The number of plutonium molecules currently present in the meteor (at. mass = 239.052) b) How long ago the meteor struck the Earth if originally it contained 10kg of plutonium...

Homework Statement 2. A meteor contains 6kg of molybdenum-93. Calculate: a) The number of molybdenum molecules currently present in the meteor. b) How long ago the meteor struck the Earth if the original amount contained 20kg of molybdenum.Homework Equations Answers: 2. a) 3.884x1022...

Hi all, I have a question regarding to the branching ratio of neutral D-meson decay. Give three decays: 1. D --> negative kaon + positive pion 2. D --> positive pion + negative pion 3. D --> positive kaon + negative pion The one with highest branching ratio is 1. due to its non-cross...

I'm currently studying the pion leptonic decay and I'm getting a bit confused about some factors. Firstly, le correct lagrangian that describe the pion decay \pi^+\rightarrow l^+ + \nu_l is: $$L=\frac{4G_F}{\sqrt{2}}V_{ud}^* \bar{d}_L\gamma^\mu u_L \bar{\nu}_L \gamma_\mu l_L$$ We can't...

TA sample of 24Na has a half-life of 234 hours, How much time elapses before a 5μg sample contains 1μg of undecayed atoms? I have calculate the decay constant (8.23x10-7) What do I do now?

Homework Statement Cosmic muons are produced when protons in cosmic rays hit the atmosphere about 10km above us. How fast do muons have to travel in order to reach the Earth before decaying if they live 2.2μs before decaying? Consider the analysis for the rest frame of a) the Earth and b) the...

Hi guys, essentially I have been talking with my Physics teacher about Beta Decay and she was saying that sometimes electrons come from the nucleus because of the quarks in the protons and the neutrons? I didn't fully understand it so I have likely got it wrong what she was trying to explain. Do...

I've been looking at some sections in GR textbooks that deal with the orbital decay of the binary pulsar PSR B1913+16 (Straumann's General Relativity: With Applications to Astrophysics and Padmanabhan's Gravitation have some pretty good sections on this) , and I noticed something strange to do...

I've been trying to get reantiquated with electormagnetics to understand RF communications better. I have a question about TEM plane waves. The funtions which describe the plane waves in the z dirrection are: e-α cos(ωt-βz) ; in the time domain where is the rate of decay. In free...

Homework Statement Show that the energy momentum conservation forbids the reaction (gamma)-> positron + electron, Gamma is a photon, which is chargeless and massless Homework Equations E(photon)=hf p(photon)=hf/c Conservation of Energy Conservation of Momentum 4-momentum The Attempt at a...

Homework Statement An atom of mass M decays from an excited state to the ground state with a change in mass of ΔM<<M. In the decay process, the atom releases a photon. Use the laws of energy and momentum to determine the energy of the photon, assuming the atom decays from rest. Homework...

Homework Statement S(t) = S(0)e^{-i \pi f_{o}t} e^{-t/T^{*}_{2}}, 0 \leq t < \infty S(t) = 0, t < 0 Show that the spectrum G(f) corresponding to this signal is given by: G(f) = S(0) { \frac{T^{*}_{2}}{ 1 + [2 \pi (f- f_{o} )T^{*}_{2}]^{2}} + \frac{i2 \pi (f- f_{o} )...

I understand that the Tau lepton is considered to be an elementary particle. Yet, it can decay into muons and nutrinoes, etc. I can understand composit particles decaying into constituent particles. But I thought that what makes a particle elementary is the fact that it does not decay. So I'm...

In experiments with polarized beams of particles, I suppose one knows the spin orientation probabilities of those particles, is that the case? When physicists make experiments with polarized beams of unstable particles, how do they treat spin in a decay of such a polarized particle? If the...

So i was watching Susskind lectures on entanglements http://www.youtube.com/watch?v=CaTF4QZ94Fk and there he mention decay (electron in magnetic field emits a photon whit certain probability ) That made me wonder : 1. How long you have to wait for emission to occur ? (for probability of...

Homework Statement Suppose that you wish to find out how much gasoline is in an underground storage tank. You pour in one gallon of gasoline that contains some half-life radioactive material that causes a Geiger constant to register 48400 counts per minute above background radiation. The next...

Homework Statement I have to figure how many beta particles are released and how much energy is released as gamma rays in the complete decay of 1000 atoms of (12/5) Boron. Homework Equations Mass of one boron atom is 10.811 g. I think we may be able to use E = mc^2 somehow but I'm not sure...

Homework Statement A culture of bacteria have a growth rate (as a percent) given by kb per year, constant k>0 and b is the number of bacteria. A virus removes bacteria at a rate of m bacteria per year. I am trying to model this information using an ODE, but might be making a mistake. Homework...

i am looking at the decay scheme of Sn126 > Sb 126 > Te126 and would like to know how many gamma rays Sb126 throws out on average and see if I've understood the diagram correctly;- Sn128 -> decays to (126m-Sb) 19.5min half life, where 14% decays through IT with 17.7 kev gamma and then 12.46 day...

Hi, I am studying the soft neutrino spectrum from WIMP annihilation in Earth through the b-bbar channel as a part of my research. Can some one please tell me what is the decay tree for the b-bbar from neutralino WIMP or just the decay tree of the b quark. This seems like a simple...

I'm trying to understand the concept of exponential decay. To clarify, the decay of Uranium is not the same as say pulling the plug in a tub full of water. The water will drain out of a tub at a steady rate from start to finish. I assume Uranium doesn't do that. So you COULD say the water has a...

Hey now! I have just calculated the lifetime of a resonance state using its total width. I want to work out which force this decay is due to. How would one go about doing this? Thanks

New here, guys. I anterospectively appreciate your patience with me. I am neither a professional physicist nor even a student (at least not formally) of physics. However, after some perusing I just now understand the rudiments of special and, I think, general relativity. And, like a child...

Hi, This isn't a homework problem - this is to help with the design of an experiment. I know the questions below are probably fairly simple physics questions, but I've got lost in laws and units! Please help me out. The experiment A cylinder 20cm long and 2cm wide is filled with 6cm of...

Hi, Does anyone know why the decay of hypochlorite/free chlorine in pool water due to UV light might show a logarithmic decay (natural log) as opposed to an exponential one? I did a chemistry experiment with scaled up concentrations of chlorine and cyanuric acid (scaled up 25x). Even in...