Questions tagged [half-life]
Half-life is the time required for an attenuating quantity to reduce to half of its initial value. It is proportional to the mean lifetime, whose inverse is the decay constant. It is a constant for exponential decay.
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Which exact element makes Spent Nuclear Fuel dangerous?
I understand that beta and gamma emissions are what makes the decay of a radioisotope dangerous. However, U-238, which is what SNF is mostly made of, doesn't emit gamma or beta particles frequently ...
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Confidence level on excluded lifetime of decay
Could someone help me understand the ideas behind setting confidence levels on decay lifetimes. Like what Super K has been doing on the proton.
Given the count rate of the decays is a poisson ...
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Would a muon placed in a confinement smaller than most electron wavelengths decay slower?
We know that between two perfect mirrors certain photon frequencies become disallowed.
The casimir effect is often even described as a lack of virtual photons of certain frequencies within quantum ...
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Exponential decay of relativistic muons
I am working on an exercise that models the exponential decay of muons. The problem asks to calculate the percentage of surviving muons after $ 50 \mu s $ in two situations:
Stationary muons.
Muons ...
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Why does critical mass for radioactive isotopes seem to have little relation to half-life?
I understand that too short a half-life and flash point, becomes kind of meaningless, if the element generates too much heat, so this only applies to longer half-lives.
Also, as I understand it, flash ...
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Possible electron capture decay of $^{148}\mathrm{Gd}$?
While the nuclide $^{148}\mathrm{Gd}$ is only known to undergo $\alpha$ decay, with a half-life of $86.9$ years, I noticed that it has higher energy than its isobar $^{148}\mathrm{Eu}$: $m_{^{148}\...
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Derivation of mean life of a radioactive nucleus
How can the mean life of a radioactive nucleus be derived?
Consider R.dt number of nuclei decaying in the time interval t and t+dt. Then, isn't the lifetime of those R.dt number of nuclei is t? But, I ...
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Does antimatter have the same half-life as ordinary matter?
Antimatter is just ordinary matter but with opposite electric charge.
Scientists have created only a handful of antihelium-4 in the LHC.
I am wondering if the half-life of, say, antiRadium-226 is ...
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What do we actually mean by carrier lifetime in perovskite materials and where do charge carrier reside during that time?
During time-resolved photoluminescence studies in perovskite materials, one sometimes says that it has a microsecond carrier lifetime. What do we actually mean by that? Where does the excited electron ...
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Is there a sharp definition of an unstable nuclide?
This may be a somewhat philosophical question, but here goes.
Wikipedia claims that several nuclides (e.g. hydrogen-5) have half-lives shorter than $10^{-22}$ seconds. This is on the same order of ...
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Why does Lamb shift renormalization not affect decay rate?
As a preface, I know there are "more" correct ways to calculate the Lamb shift and decay rate through full blown QED, but this is what's most familiar with me, so I would appreciate an ...
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Why is the relaxation of coherence rate half the spontaneous emission rate?
Consider a two-level atom of which the lower and upper levels are denoted, respectively, a and b. If spontaneous emission from the upper to the lower level is the only source of relaxation, then the ...
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If the time at which a single atom decays is random, why do groups of atoms behave in predictable ways? [duplicate]
Why do groups of atoms decay at predictable rates even though a single atom’s decay point is completely unpredictable? I’m having trouble wrapping my head around this.
From my reading, it seems that ...
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Decay rate with specific helicity in rest frame and lab frame
Consider a two-body decay, such as the pion decay: $\pi^+\to \mu^+ + \nu_\mu^{}$. In the Standard Model, as there only exits left-handed massless neutrinos, the helicities of final particles are known....
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Difference between endpoints and kinetic energy in a beta minus decay
I want to understand the difference between the Q value and Endpoint energy and Kinetic energy of a beta minus decay.
I understood that the Q value is the overall energy of the reaction given by
Q ...
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