Decay Definition and 998 Threads

Homework Statement I have some data for "Activity(Bq * 10^4)" and "time". I have already found the half life and everything but I can't seem to see any sources of error in the data Homework Equations I need sources of error. The Attempt at a Solution I said, the half life matches the...

What does "Activity" mean in terms of radioactive decay? I came across this term "activity" in text regarding radioactive decay and half lives. It is defined as "number of nuclei in a sample that decay within a given time." That definition if fine but then when presented in a graph life...

Is there an element that does not decay but can be identified from a extremely far distance or an element with a multi-billion year half life

Hi, I was wondering whether the decay of the Pi-0 meson in QED to an electron positron pair can occur as follows: Pi-0 -> virtual photon -> e+e- or does it have to go via Pi-0 -> two virtual photons -> e+e- (the Feynman diagram has a 'square' of virtual electrons/photons)? I have...

Hello, I'm trying to figure out if an atom undergoing alpha decay can knock out its orbital electrons. I was hoping someone might give me a hand coming up with a model to figure this out. What I need to figure out is: How far out does an alpha particle tunnel can I use a classical...

Two 500μF capacitor are connected in parallel, and then to a 100kW (105W) resistor. The capacitors are momentarily charged using a 1000V D.C. supply. Find: a) The time constant of the circuit. b) The time “t” taken for the capacitor voltage to decay to 630 volts c) The current in the...

Homework Statement a) What is the energy of the neutrino, if a phosphorus-32 atom (31.97390 u) beta-decays into a sulphur-32 atom (31.97207 u), and the kinetic energy of the accompanying electron is 0.90 MeV? (answer: 0.25 MeV) b) A boron-12 atom (12.01435 u) beta-decays into a...

This is probably a dumb question, but a student asked me and I can't figure out the answer: When a nucleus decays via beta decay, for example (in poorly formatted text): 55 Cs → 56 Ba + e− + ν How is overall charge neutrality conserved? Clearly, the reaction appears to conserve...

This is really about challenging the understanding of "Time" in the physical sense. I would like to test the hypothesis that time is merely the manifestation of particles in their interaction to one another. It seems that time may be meaningless (and non-existent) in a one-particle system...

How can I find the decay rate of carbon? I have found the decay constant and I know the half life and the number of atoms. I think I have the data and I have the answer but I think I am using the wrong equation as my answer does not fit the books. The decay constant I got as -1.209x10^-4...

I know odd-odd nuclei are generally unstable against beta decay as the pairing term in the semi-empirical mass formula is less than zero, and I know even-even nuclei are generally stable, but I don't get the rules you apply for even-odd or odd-even nuclei. Do you have to work out the binding...

I've drawn up a simple system to help with my question. Suppose we prepare an atom in an excited state (| 4 \rangle in the figure), and it can spontaneously decay to the ground state (| 1 \rangle ) through either of two intermediate states (| 2 \rangle or | 3 \rangle ). Is the probability...

As I understand it, "nonradiative decay" of a system from an excited state to a lower-energy state is any type of decay that does not result in the emission of an electron. I can't think of any way that a free atom could decay without emitting a photon. Molecules, yes, (through...

So... I know that decay occurs when the nucleus of an atom has an unstable proton-neutron configuration. My question is, at the instant that decay occurs, what triggers it? Is it quantum mechanical in nature? If so, why are half lives so consistent?

I am looking for some data that identifies the most significant source of decay heat for the first few days from a reactor trip. Something similar for 1month after or more would be useful. Thanks Dave

We are studying nuclear physics right now and I don't quite understand the concept of binding energy. So, as I understand it binding energy is the work done to remove the nucleons which are bound together by the strong nuclear force. But then during radioactive decay, when you do the equations...

Homework Statement How many half-lives must elapse until (a) 90% and (b) 99% of a radioactive sample of atoms has decayed? Homework Equations N=No(1/2)^(t/t1/2) N=No(1/2)^(n) The Attempt at a Solution The part of the solution I don't understand is how to get the second...

2.3 \cdot 10^{10} atoms decay via alpha emission have a half-life of 150 min. How many alpha particles are emitted between t=30 min and t=160 min? \begin{flalign*} 150 &= \frac{\ln 2}{\lambda}\\ \lambda &= 0.046 \\ \\ K &= K_{0}e^{(-\lambda)(t)}\\ &= (2.3 \cdot 10^{10})e^{(-0.046)(30)}\\...

Hi everyone, There's something that's kind of been bugging me about applying exponential decay formulas to real world phenomena. For example let's say the discharging of a parallel plate capacitor. Let's consider the negative plate. As it discharges excess electrons leave the plate. The...

Homework Statement As you can see this decay is said to be possible The Attempt at a Solution but i don't get it because isn't charge conservation violated ? omega minus --> Q=-1 Xi--> Q=0 negative pion -- > Q=-1/3

I'm working on a problem involving decay of a 2 strange/2 anti-strange tetraquark particle. 4 sample decay diagrams are given and I am to describe them and choose which is most prevalent. In on diagram, two of the strange/anti-strange quarks become two down/anti-down quarks via gluon through...

Measurements of a certain isotope tell you that the decay rate decreases from 8339 decays/minute to 3037 decays/minute over a period of 4.50 days. What is the half-life T_1/2 of this isotope in days?I know that i have to relate the ratio of decay rates to the ratio of undecayed nuclei present at...

Homework Statement The technique known as potassium-argon dating is used to date old lava flows. The potassium isotope 40K has a 1.28 billion year half-life and is naturally present as very low levels. 40K decays by beta emission into 40Ar. Argon is a gas, and there is no argon in flowing...

Homework Statement I am a HS student researching the penetration depths of magnetic fields in conductors. Specifially, I am investigating the exponential decay of eddy currents induced within a conductor in the presence of a rapidly changing magnetic field. I am a bit confused as to why the...

Hi I wonder if anyone could help me with this. I'm studying a crystal whose luminescence is excitonic in nature. Since the excitation density is high (with femtosecond laser pulses) exciton-exciton interactions have to be taken into account. The following kinetic equations are used to...

Hello, Suppose you observe some foam. The foam is formed by a set of bubbles, and each bubble blows up after a random time. The density function of the time each bubble will take to blow up is probably exponential, with rate lambda. The total amount of foam (Q) must also decay exponentially...

Homework Statement Solve y''(t) - k^2 y(t) = e^{-a|t|} where a and k are both positive and real. Homework Equations The solution was obtained trough a Fourier transform. The Attempt at a Solution I got the solution y(t) = \frac{ke^{-at} - ae^{-kt}}{k(a^2 - k^2)} but when i...

I'm having some trouble with the definition of binding energy and decay energy. Consulting a nuclide table (http://atom.kaeri.re.kr/ton/nuc5.html) I found out that 53Fe has a binding energy of 458380.194 +- 2.107 keV and decays to 53Mn by electron capture. The decay energy is 3.743 MeV and...

So the pion(+)n is made up of an up quark and a down antiquark. And somehow, it emits a W+ boson, which then turns into a muon and a muon-neutrino. From the Wiki article, "W bosons can decay to a lepton and neutrino or to an up-type quark and a down-type quark." Does this mean that the...

For the basic model for exponential decay, there is a decay constant, which is related to the half-life. The decay constant multiplied by the number of particles should give the decay rate per second (activity). However, the model I want is for small periods of time. For a small enough period of...

Hey Guys, Just a quick question. Can a W boson decay to a u and anti s or does it have to decay to a quark and anti-quark of the same generation? Thanks!

Homework Statement Hi guys, I have been given the problem of drawing the feyman diagrams and finding the decay rates for the two decays: D0 \rightarrow K+ + \pi- and D0 \rightarrow K- + \pi+ D0 \rightarrow \pi- + \pi+ Homework Equations The coupling constant g = 10^-5 for the weak...

Will black dwarfs eventually quantum tunnel into neutron stars if proton decay doesn't occur?

Homework Statement Hi... I think I might be staring blind at this one. I have to calculate the theoretical halflife for the ground state alpha-decay, and compare it to the experimental value. What is know is that the nuclei Sm^{147}_{62} decays by the emission of a alpha-particle to the...

Hi so I am doing a presenation, on the indirect search for the neutralino from the sun at amanda In short: neutralinos are graviationally captured and settle int he sun.. they decay to produce neutrinos.. we detect the neutrinos at the amanda detector through muon productionSo what I am...

The proper mean lifetime of a muon is 2.20 µs, which is denoted as τ. Consider a muon, created in Earth's upper atmosphere, speeding toward the surface 8.00 km below, at a speed of 0.980c. What is the likelihood that the muon will survive its trip to Earth's surface before decaying? The...

In the early universe electrons and protons would combine to form neutrons and few, if any, protons would remain. If the mass difference were greater than the binding energies of nuclei, neutrons inside nuclei would decay leaving no nuclei behind. Does anyone know why the above...

this is just something has been bugging me for the last few days. it seems like it has a very basic solution. Muons decay randomly, but have a mean lifetime of about 2 us. If I plot the # of muons that decay vs. time (say the axis spans from 0 to 20 us), why is the plot exponential decay...

Homework Statement A experiment was carried out to detect the alpha particles in the decay of Radium-226, it was left for 24 hours overnight. In the end, four decay spectrums were detected. However, none of them matched the energies of decays in astatine-218, and Radon-218. But the alpha...

Papers such as http://arxiv.org/PS_cache/arxiv/pdf/0904/0904.1503v2.pdf talk of 2 photon decay from 2s to 1s or 2p to 1s. "The probabilities for the spontaneous two-photon decay in hydrogen atoms and hydrogen-like ions are under investigation since the theoretical formalism has been...

Homework Statement I hope that I'm posting it in the right section... I did an experiment in class using a Geiger-Muller counter with the objective to find the amount of counts (how many photons hit the detector) due to natural radioactivity around my work station. I recorded 45 values of...

Homework Statement if the decay of nucleuse with A=210, what is the alpha energy emited when the Q of the decay is 5Mev Homework Equations The Attempt at a Solution by energy and momentum conservation: parent=daughter+alpha decay+Q from the question the parent has A=210, in...

[SIZE="1"]Homework Statement It is found that when a 6.3 x 10–5 g sample of radium-226 is placed in a vacuum and exposed to a screen of area 1.0 mm2 placed 1.5 m away from the sample, an average of 46 α-particles hit the screen in 10.0 minutes. Calculate the total number of decays per gram...

Homework Statement If we have the following partial decay chain: N1 -> N2 -> N3 where N1 is the number of nuclei of species 1, etc. and N1 -> N2, not via a decay but by the reaction such as N1 + neutron -> N2 + photon and we know this rate of formation of N2, say 'a'. I then get the...

If we have the following partial decay chain: N1 -> N2 -> N3 where N1 is the number of nuclei of species 1, etc. and N1 -> N2, not via a decay but by the reaction such as N1 + neutron -> N2 + photon and we know this rate of formation of N2, say 'a'. I then get the following rate...

For beta minus decay, I know the reaction is given by neutron -> proton+electron+anti(electron)neutrino. This is an image of the Feynman diagram for the reaction: http://tmp.kiwix.org:4201/I/280px_Beta_Negative_Decay_svg.png I get that the neutron changes to a proton releasing a w-...

Homework Statement A radioactive substance has a half-life of 20 years. If 8 mg of the substance remains after 100 years, find how much of the substance was initially present. Homework Equations A=A0ekt The Attempt at a Solution I set the equation up so that 8=A0e100k and...

The A level book that AS students have for the AQA course has a Feynman diagram of a proton decaying into a neutron - via a W boson, producing a beta+ and a neutrino. afaiaa, protons have a lifetime of 1033 years, so this doesn't seem a likely event. Is this just a 'fictional' event, put in the...

Homework Statement An unstable sysemt may have two or more decay modes, with a Rate R1 for decay through mode 1 and R2 for decay through mode 2. Use the meaning of the rate to show that the total lifetime \tau of the system is given by 1/\tau=1/\tau1+1/\tau2. Homework Equations...

Hi, Radioactive materials will decay to datughter products. in the mean process they emit alpha or beta particles with some energy and then decay to new products. In my problem i am just observing U(238) decay process. I need to find the energy values for each decay and also i need...