# 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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### Energy as a function of half-life?

How much energy is released in the radioactive substance's decay of one cycle of its half life? I'd like the plot the energy released of a radioactive substance over time. What must I reference to ...
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### Question on the life-time of a super-symmetric particle [duplicate]

I was watching a random video on SUSY. In the video, they were discussing that SUSY explains dark matter. That DM is probably a SUSY particle. How is this possible? We know that the life of a Top ...
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### Do unstable nuclei affect each other for decaying?

I am thinking about beta decay. If we graph decayed nuclei count over time, we don't see a linear line. Rather, it would be a curved line. I imagine myself as an unstable nucleus. If I don't care ...
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### Does every element have a half-life?

Will every element slowly decay into something else? Or do some isotopes have infinite half-lives?
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### Average time between the decay of 2 atoms

I want to calculate the average time ($\bar{t}$) between the decay of two atoms. These atoms are part of a larger number ($N_0$) atoms whose Half-life is $T$. My idea: you can calculate $\bar{t}$ by ...
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### Electronic quantum jump time = transition time = lifetime?

Naively I assumed that an electron would sit in an excited state (in the shell of an atom) having some stochastic lifetime, so nothing changes and suddenly the electron would jump back into the ground ...
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### Does the equivalent dose of radiation have the same half-life as the radioactive material?

I know that if I have a sample of a certain radioactive isotope with total mass $x_0$, then I can calculate how much of that mass is left after $t$ hours using $x = x_0 \cdot e^{- \lambda t}$. I ...
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### Carbon Dating - Same age but different original radioactive nuclide left

2 same trees but diferent sizes fell 2000 years ago. We are trying to find their age using carbon dating. So my understanding is that their age will come to be same approx 2000 years but percentage of ...
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### If radioactive decay is measured by halflife does it mean that few atoms of a radioactive material are practically stable?

If radioactive decay is measured by halflife does it mean that few atoms of a radioactive material can be considered practically stable? If we try to measure the time when 0,1% of the atoms of the ...
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### How radioactive dating works? [duplicate]

Often in geology & archaeology we listen that they calculated the age of things (bones, pots) using radio active dating. Radioactive dating works using half life of unstable isotopes. And what ...
1 vote
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### Should all radioactive elements with HL smaller than 1000 years have 90% of their atoms already decayed on Earth?

Should all radioactive elements with HL smaller than 1000 years have 90% of their atoms already decayed on Earth? If that kind of radioactive source is found today should almost all of its atoms be ...
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### Conceptual half-life Question

So I have this word problem and I’m a bit confused about it. I have the answer and explanation but I still don’t understand: The half-life of carbon-14 is approximately 5730 years, while the half-life ...
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I was given the following word problem: If the half-life of a certain isotope is four years, what a fraction of a sample of that isotope will remain after 12 years? This was simple for me. 12 years ...
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### Determining half-life of a sample

The following question is from grade $10$ science textbook: A student wants to measure the half-life of a radioactive isotope. He is told the isotope has a half-life of between $10$ and $20$ minutes. ...
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### Why doesn’t nucleus $^{160}$Tb fission from its ground state?

Why doesn’t nucleus $^{160}$Tb( β decay with a half-life 72 days) fission from its ground state? (assuming a mass-symmetric split in two nuclei, $^{80}$As and $^{80}$Ge) And how could $^{160}$Tb be ...
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### Finding out the Lifetimes/Decay Widths of Quarks?

Usually, PDG has the lifetimes/decay widths of all kinds of particles. However, for quarks, they don't seem to be there, not even in this 2014 PDG Quarks Review (except for the top quark $t$). But I ... 14k views

### Can 1 kilogram of radioactive material with half life of 5 years just decay in the next minute?

I wondered this since my teacher told us about half life of radioactive materials back in school. It seems intuitive to me to think this way, but I wonder if there's a deeper explanation which proves ...
1 vote
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### What's the limit for half-time measurement in CMS or other detectors?

I've been working with data from $\mu^+ \bar{nu_\mu}$ detections. I noticed one can't determine the mass width of a particle that produces neutrinos. Then it occurred to me how one can measure the ...
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### Theoretically maximum atomic number and its stability?

Is there a theoretical maximum to the atomic number? Is it possible to reach $Z = 150$ or $Z = 200$? I am not really asking about our experimental, but theoretical limitations that possibly prevent us ...
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### $b$ mesons lifetime

I read about a technique called $b$-tagging in which one can check if a $b$ meson was produced in a collision by looking for a jet which has a secondary vertex within it. The reason is that b mesons ...
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### Why can't I find the moment $t_1$ where the radioactivity is gone? [closed]

Let's say $t_1$ is the moment the radioactivity is gone: $A(t_1) = A_0 e^{-kt}$ $A(t_1) = 0$ since it's gone But then what? How do I find $t_1$? Since $A_0 e^{-kt} = 0$ then I can't "$\ln$" ...
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### Is there any simple way to predict beta decay half lives?

Question For nuclides that decay by alpha emission, the Geiger-Nuttall law gives a simple and reasonably accurate estimate of the half-life. Essentially, one can model the alpha particle as a ...
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### Does the halflife time of a radioactive material decrease if its temperature increases?

If at high temperatures atoms are more intensely interacting with each other or emitted photons that also could make the core vibrate. Is in these circumstances the radioactive material more likely to ...
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### Radioactive secular equilibrium and the relationship between the half lives of the parent and the daughter nucleus

It's known that In nuclear physics, secular equilibrium is a situation in which the quantity of a radioactive isotope remains constant because its production rate (e.g., due to decay of a parent ...
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Does the process of decaying in radioactive elements occur every second? The equation consists of $\rm e$, so it must mean that decay due to radiation must occur every second, right?
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### How can light travel the distance of nuclear size in negative time? [closed]

at first i thought time cannot be negative or zero but after going through the statement "time taken by light to cross a distance of nuclear size is 10^-23" iam confused
1 vote
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### What is the lifetime of the deuteron with respect to sphaleron-induced decay

As far as I've understood, instantons like the sphaleron can give rise to processes that violate $B+L$ but conserve $B-L$, where the baryon and lepton number can only change by a multiple of three. ...
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### How to measure the lifetime of a particle experimentally?

I'm wondering in experiment, how can one measure the lifetime of a particle, because it is a very short time. Also, I'm wondering how experimentalists measure the mass of the particle, which is also ...
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So i'm currently researching nuclear power and nuclear energy as it is a topic that has always interested me, but when researching nuclear fission waste, and hearing about waste that has a half life ...
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### Two-body decay: Heavier particles live longer than light particles

From Fermi's Golden Rule one can derive that the decay rate for a two-particle decay ($A\to B+C$) is given by $$\Gamma = \frac{p^*}{32\pi^2m_A^2} \int |{\cal M}|^2 d\Omega,$$ where the absolute value ...
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### Why is this way of calculating mean life of radioactive atoms incorrect?

Suppose there are $N$ radioactive atoms and the half life of decay is $t$. Then after one half life the number of remaining atoms will be $\frac{N}{2}$. And so after each half life the number will be ...
1 vote
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### Converting width in $\rm GeV$ to lifetime in years

I am trying to reproduce the results of this paper1. In particular Eqs. (25) and (26). I would like to convert the proton decay width (given in units of $\rm GeV$) to a lifetime in years. The formula ...
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### Half-life vs mean lifeitme. Book error?

This text is from an scholar book (to editors: please, keep original and translated text): La vida mitjana d'un isotop es de 50 anys. Calcula el temps necessari perque l'activitat es reduexi al ...
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### Lifetime of Excited states [closed]

Which of the transitions will have a higher lifetime?