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Questions tagged [radioactivity]

The property of some materials by which individual atoms decay, emitting energy or particles often transforming into different elements in the process.

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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 ...
BigBox989's user avatar
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How is an $\alpha$-particle formed inside a nucleus and with what probability?

While Gamow's theory successfully describes the radioactive $\alpha$-decay by quantum tunnelling, it leaves a key question unanswered. The theory assumes that the $\alpha$ particles pre-exist inside ...
Solidification's user avatar
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The $\alpha$ particle's energy inside a nucleus is lesser than the Coulomb barrier height. Justify

The $\alpha$-decay is usually explained via quantum tunnelling. This is because the $\alpha$ particles do not have sufficient energy to climb over the Coulomb barrier. But how do we know this? We can ...
Solidification's user avatar
11 votes
2 answers
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Was the "demon core" hot?

The demon core was a sphere of plutonium (Pu-239, not Pu-238 that is known to get hot and is used in RTG) that weighed 6.2 kilograms (14 lb) and was 8.9 centimeters (3.5 in) in diameter. It was made ...
Nightrider's user avatar
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1 answer
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Why is $^{176}\rm{Lu}$ so stable with respect to $\beta^-$ decay?

The nuclide $^{176}\rm{Lu}$ (spin $7^-$) can decay to the $6^+$ state of $^{176}\rm{Hf}$, with a $Q$ value of $593.33\,\rm{keV}$. The change in spin $J$ and parity $π$ is only $\Delta J^{\Delta\pi} = ...
Jianing Song's user avatar
2 votes
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123 views

$\beta^-$ decay of $^{247}\rm{Cm}$ to excited states of $^{247}\rm{Bk}$

The nuclide $^{247}\rm{Cm}$ is only known to be an alpha emitter with a half life of $1.56\times 10^7$ years. In theory, it is also capable of $\beta^-$ decay to $^{247}\rm{Bk}$ with a $Q$ value of $...
Jianing Song's user avatar
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1 answer
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The sharing of energy between beta particle and its neutrino

the answer to this is that the KE is constant, and that beta has a continuous range of energy. I understand that the energy in beta particle decay is distributed between the neutrino and the beta ...
Safa yousif's user avatar
3 votes
2 answers
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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 ...
userLTK's user avatar
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Why does an alpha particle traveling at the same speed as a beta particle have 'only' about twenty times the energy? Rather than over seven thousand? [closed]

An alpha particle travels at about half the speed as a beta particle, right? ~5% of light speed versus ~10%? Therefore, if you doubled its velocity, its energy would roughly quadruple, correct? (Or ...
Kurt Hikes's user avatar
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Radioactive Decay Chain for the special case of equal decay constants (parent-daughter)

I have been trying to obtain an analytic solution for a daughter radionuclide's activity (or just the number of daughter atoms), as a function of $t\geq0$, resulting from the decay of a parent ...
Username134's user avatar
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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}\...
Jianing Song's user avatar
1 vote
2 answers
171 views

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 ...
Vinay5101's user avatar
-1 votes
1 answer
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Why does beta particles deviate more than alpha particles?

So two figures are given in my book, One is Deflection of radioactive radiations in magnetic field and the other is deflection of radiations in an electric field So the question is why does beta ...
Animesh's user avatar
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In the Compton effect, the spin of the electron can influence the polarisation of the resulting photon? [closed]

I'm new here! I am trying to demonstrate what is the influence of spin-down (Helicity -1) of photons in radiotherapy using LINACs. The question is, when an electron interacts with a photon in a ...
AnnLee's user avatar
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if decay rates were somehow increased, would neutron flux proportionally increase in a reactor?

I've heard people argue that decay rates in the past could have been faster. Despite not having a mechanism for this, I am curious about it. The oklo reactor is commonly cited as proof that decay ...
Hurdlegreen2's user avatar
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2 answers
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Understanding the decay of Na-22

When looking at data for Na-22 decay (e.g. here: https://www.nndc.bnl.gov/nudat3/DecayRadiationServlet?nuc=22Na&unc=NDS ) it shows that for every 100 decays, there should be: 99.94 gammas with ...
ProgrammingMachine5000's user avatar
1 vote
3 answers
192 views

How accurate is radioactive decay rate formulae and is there room for error?

So, lets ay I have 4 different samples of 1 mole of a radioactive element, and i check them after time of 1 half life has passed before checking them can I be absolutely sure that all the 4 ...
Arul Rana's user avatar
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1 answer
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Would the observations made on the Oklo reactor be impossible with uniformly sped up nuclear decay?

I've read that if radiometric decay rates were different in the past, the observations that we make on the oklo reactor would be different. Things such as different isotope ratios, etc. if all ...
Hurdlegreen2's user avatar
1 vote
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Offset in fortuitous coincidences in Na22 PET scan

I'm doing a PET scan for a Na22 radioactive sample and analysing the fortuitous coincidences. To measure the fortuitous coincidences I put both detectors in a 90º angle and gathered the number of (...
ludicrous's user avatar
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What is the importance of excited states in the emission of gamma radiation during alpha decay?

Let's suppose that during a hypothetical alpha decay of a nucleus X, has two excited states (such as 2.3 mEV and 0.9 mEV) are respectively fed. The question arises here: what would would be the energy ...
VruMises's user avatar
2 votes
3 answers
320 views

Could you wash away nuclear fallout with rooftop fire sprinklers?

My understanding of radiation is that is travels in a straight line. So a basement buried on three walls with no windows is a great shelter because you have thick dirt on three sides. but the radio ...
Dan Anderson's user avatar
1 vote
3 answers
602 views

Why doesn't the water in a nuclear reactor become radioactive?

Why is it that the water which constantly passes through the core of a nuclear reactor doesn't become radioactive? Despite passing so closely to the active nuclear fission reaction, as gamma ...
Sumit Yadav's user avatar
1 vote
2 answers
415 views

How is rate of radioactive decay constant?

If I understand correctly, the rate of radioactive decay depends on the amount of the radioactive element. How then can it be constant, if it depends on concentration?
xxx's user avatar
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Two Particles with identical temperatures at different points in the atmosphere

Quick question with probably a simple answer. For context, I am currently in undergraduate classical mechanics studying potential energy. My question is, if a conservative force is one in which is ...
Naeem's user avatar
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1 answer
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When Beta(Negatron) decay occurs from what location do radiated electron start its movement?

I know that the Heisenberg Uncertainty principle states that the position of an electron is uncertain, however, if an electron is created due to beta decay, then at what location is it more likely to ...
medical physics's user avatar
8 votes
2 answers
685 views

What might be the half-life of observationally stable nuclei with energetically favorable decay modes?

For example, a reaction $${}^{132} \mathrm{Ba} \rightarrow {}^{128}\mathrm{Xe} + \alpha + 22.19\mathrm{keV}$$ would be energetically favorable, contrary that ${}^{132} \mathrm{Ba}$ is observationally ...
peterh's user avatar
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Are their pairs of Nuclear Isobars that differ in energy by less then the Lighter Nuclides Characteristic X-ray?

Isobars are atoms (nuclides) of different chemical elements that have the same number of nucleons. According to the https://en.wikipedia.org/wiki/Mattauch_isobar_rule if you have two adjacent elements ...
blademan9999's user avatar
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Radioactive decay: calculating probability of decay from half life/decay constant

Let's say due to a nuclear reaction a radionuclide of half-life $T_{1/2}$ was created. I am trying to find out what will be the probability of that radionuclide undergoing radioactive decay within ...
uran42's user avatar
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1 answer
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Is there a way to determine whether a given nucleus is radioactive?

When a nucleus decays it is finding a more stable configuration, as all nature is. But is there a way of finding whether a specific configuration will decay? I know that there is a specific proton-to-...
Saksham's user avatar
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1 answer
263 views

Where are the Gamma rays in Beryllium-7 decay coming from? [closed]

Beryllium-7 decays via electron capture. This gives of Neutrino and later a Auger electron/Extreme ultraviolet photon. So where does the Gamma rays that occur 10% of time according to here come from?
blademan9999's user avatar
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Alpha decay must be quantum tunnelling. Why?

By measuring the energies of the emitted alpha particles, how can we say that they have energies less than the height of the nuclear potential well when they are inside the well? How can we be sure ...
Solidification's user avatar
1 vote
1 answer
111 views

How radioactive are Heisenberg cubes?

I recently went to a museum that had a $2 \times 2 \times 2$ Heisenberg cube on display. I was surprised since it’s about $5 ~\mathrm{lbs}$ of raw uranium and people were coming right up to the ...
M00mind's user avatar
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3 answers
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What is the difficulty of determing the products of nuclear fission?

In my impression, initially many people did not believe that an Uranium nucleus disintegrates into two halves when bombared with neutrons. Experimentally, there must be some difficulty to determine ...
poisson's user avatar
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4 votes
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How much Uranium would a country like Iran need to produce for supplying its Technetium needs?

This is not a question about politics, although the motivation is a political situation. Iran, which enriches Uranium to a level of $60\%$ $\rm{^{235}U}$, is claiming it has civilian uses for this ...
einpoklum's user avatar
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Detection the age of fossils using the carbon dating method

The life of carbon-14 isotope is about 5 thousand years. But we still are able to detect traces of it in fossils which are older, more than 10 thousand years. Why?
Nikku's user avatar
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2 votes
1 answer
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Why don't we employ electrostatics to reduce radon in homes? [closed]

This popular question got me wondering if there is a simpler way to reduce radon in homes. Our house has a fairly standard radon mitigation system. It has a lot of parts. There is a hole cut in the ...
SlowMagic's user avatar
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-1 votes
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Direction of recoil in $B$-decay [closed]

What is the direction of recoil of product nucleus in $B$-decay? I believed it to be by intuition, opposite to the direction of emission $B$-particle but when I wrote that in my exam, it turned out to ...
Elizabeth Huffman's user avatar
168 votes
2 answers
80k views

Why is my dryer radioactive?

My Geiger counter measures a background radiation level in my home of 0.09–0.11 μSv/h. When I stick it inside the dryer right after it finishes a cycle (while the clothes are still inside), it ...
Marsroverr's user avatar
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1 answer
60 views

Can we 'see' a fast radioactive decay live (as a spectacle)?

What I mean is that are there any elements which we can actually observe decaying into other elements, like a magical transmutation? Just like how a paper burns into ash.(or some other interesting ...
Rohit Shekhawat's user avatar
2 votes
1 answer
129 views

6-day curie to grams?

I am a pre-med interested in nuclear medicine. I recently came upon this wonderous radioisotope called Mo-99 (which decays into Technetium-99m), but in their industry, they measure the quantity of ...
Young Jun Lee's user avatar
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2 answers
69 views

Excitation of Nucleus on emission of alpha or beta particles

I was reading my notes (the topic is called 'nuclear chemistry') today when I noticed a line "alpha (He2+) and beta (e-) can't be emitted simultaneously. After emission of alpha or beta, gamma ...
Arnav Tyagi's user avatar
8 votes
4 answers
2k views

Non-irradiative methods to create radioactive isotopes?

My understanding is that the primary methods with which one can create a radioactive isotope are 1) just waiting for the isotope you want (by means of nuclear decay), or 2) some kind of induced ...
DataScienceNovice's user avatar
4 votes
1 answer
111 views

Is crossing symmetry violated in the difference between positron emission and electron capture?

As discussed in the relevant Wikipedia article, beta decay via electron capture is possible in circumstances when positron emission is not. From a simple (and perhaps naive) point of view, the two ...
Geoffrey's user avatar
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Is the rate of radioactive decay inversely proportional to the stability of an isotope?

Is the rate of radioactive decay inversely proportional to stability of the isotope?
Eman H's user avatar
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4 votes
1 answer
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How to explain different, seemingly inconsistent, values for the mass of the alpha particle in different books?

I’m trying to calculate the energy of an $\alpha$ particle after the decay of Ra-226 following an example in a german school book and came across different values for the mass of an $\alpha$ particle. ...
Tobi's user avatar
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2 votes
1 answer
63 views

Radioactive decay : question [closed]

yo for this question, I'm unsure how to approach. We cannot just say that in 1200 years, x has 3 half lives and its daughter y has 4 half lives, therefore x is double y. This approach assumes that the ...
mar01's user avatar
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Nuclear binding energy and natural radioactive decay

I have just started to learn about nuclear binding energy. While I believe I understand the concept well, there is one thing I do not still fully grasp. I understand that the nuclear binding energy ...
user12277's user avatar
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1 vote
1 answer
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Why does Americium-241 not exist naturally?

A few searches says that it's because "the half life is too short with respect to the age of the universe." I don't understand what that means. Note that the half life of Americium-241 is ...
photon's user avatar
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0 answers
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Having problems to find an equation for radioisotope production yield

I'm trying to find the required target mass for a specific nuclear reaction with a fixed yield and cross-section. I am trying to get a plot, or a result for target like this: I've found some ...
fissile_uranium's user avatar
3 votes
1 answer
429 views

How does the intensity of radioactive decay vary with distance?

I have a Sr-90 source which undergoes beta-decay. I measure the number of counts (n) detected by the detector as I increase the distance between source and detector. I then plot a graph of d vs (n/Δt)...
gemini's user avatar
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