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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Will a radioactive ball conserve its angular velocity?

Consider a uniform spinning sphere in vacuum. In principle it should spin forever, because of angular momentum conservation. However, assume that the sphere is made of radioactive material: since it ...
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What are some household sources of radiation detectable with a geiger counter?

I recently started rock tumbling with my preschool-age kids and bought a cheap geiger counter to check out rocks we find (more from curiosity than concern). Specifically it's a GQ GMC-500Plus model ...
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Variation of gamma line broadening with time of the source

What explains the broadening of the gamma linewidth as the source "gets old"? I have been using Iron-57 in my radiation studies but the source I obtained 6 months ago shows significant line ...
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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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How can a proton in a nucleus decay into neutron and positron in β+ decay if neutrons have greater mass than a proton? [duplicate]

I'm guessing it has something to do with mass defect/binding energy??
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How much faster does induced fission in a typical reactor occur than spontaneous fission in nature?

I know that the half-life of Uranium-235 is about 704 million years, but... That includes alpha and beta radiation as well as spontaneous fission, though... Also, I presume the 'spontaneous fission' ...
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Does a part of the difference in mass-energy excite the nucleus to a higher energy state during beta decay?

According to this site: https://byjus.com/physics/radioactivity-gamma-decay/ Most of the time, gamma decay occurs after the radioactive nuclei have undergone an alpha or a beta decay. The alpha and ...
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Reasoning behind alpha , beta to be not occuring at same time for any element

Is it true that Alpha decay can occur after beta decay and that Alpha decay and beta decay cannot happen at same time ? If yes is my reasoning correct : For both decays to ...
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Q-value of beta decay in different forms

Related to this previous post of mine The Beta Decay equation proper balancing , is it true that Q-value of beta decay reaction can be written in any of these two ways ? $Q $= ${m _{X}}(_{Z}^{A}\...
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The Beta Decay equation proper balancing

The beta decay reaction is given by : ${ }_{Z}^{A} \mathrm{X} \rightarrow \underset{Z+1}{A} \mathrm{X}^{\prime}+\mathrm{e}^{-}+\overline{\nu}$. I would like to know the reason why cannot we write it ...
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If plutonium-238 (Pu-238) absorbs a neutron, does it become Pu-239?

I am asking this simple question because I am always hearing about how thorium reactors are less perilous to the world because, unlike uranium reactors, they produce some Pu-238, which is not suitable ...
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How exactly Radiocarbon dating Works?

So how exactly does Carbon Dating work ? $^{14}$C is produced from $^{14}$N in the atmosphere. Since there is considerable amount of Nitrogen in the atmosphere,we can have quantifiable amount of $^{14}...
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What determines the half-life (or stability) of an isotope?

Why is it that some elements do not have any stable isotopes, while others of very similar mass have multiple stable isotopes? What determines this phenomenon and what determines the strict ...
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Which is more: Energy released by nuclear fission or fusion? [closed]

The energy released by one fission reaction is 190MeV and the energy released by one fusion reaction is 24.7MeV. Then by my common sense 190>24.7 so energy released by fission>fusion but the ...
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Half-Life for Few Nuclei in a Sample

I read somewhere in some textbook that "The concept of half life and mean half life becom meaningless ehen you have a sample containing only a few nuclei. For example, if you are given say, 100 ...
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Why is the radioactive decay formula consistently overestimating number of non-decayed particles?

The radioactive decay formula is $$ N(t) = N_{0}e^{- \lambda t} $$ My understanding is that $\lambda$ indicates the probability of decay per unit time. Let's say $\lambda = 0.5 s^{-1}$. So we would ...
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Why mean life of radioactive element is slightly greater than halflife..? [duplicate]

I was reading radioactivity where I find that half life of a radioactive material is less than mean life due the presence of $\log2$ in the numerator: $$ t_{1/2} = \frac{0.693}{\lambda} $$ But how ...
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How photon beam can be attained through Proton Accelerator?

I'm recently had been reading quite a lot about ADS and transmutation possiblity of Proton beam to neutralize nuclear waste. I came across with an Article from Big THINK https://bigthink.com/the-...
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Can the variation of count rate over distance for a disk radioactive source be treated as an electric field of a disk charge problem

So I did an experiment in which the count rate of a disk source of Sr-90 is measured using a plane detector, varied from ~0.7cm to 100cm, multiplying the count rate by the distances squared (i.e. $\...
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How was Enrico Fermi able to predict a power output from his uranium and graphite Chicago Pile 1 (CP-1) reactor?

Uranium and graphite heat engine physics - early detection methods I've been inspired by the early developments in fission heat engines which happened even before uranium enrichment methods were ...
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Time constant versus half-life — when to use which?

In some systems we use half-life (like in radioactivity) which gives us time until a quantity changes by 50% — while in other instances (like in RC circuits) we use time constants. In both cases the ...
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Isotope that decays when ionized

Some time ago, I read about a certain isotope that is stable when neutral but decays with electron emission (beta) when being completely ionized, but I can't find which one it was. Which isotope ...
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Do samples of radioactive materials in vaccum, produce ions and acquire net charges

Suppose an atom decays via a $\beta^-$ decay, it's atomic number has increased by one, and an electron is emitted. $$ _Z^AX \quad \to \quad_{Z+1}^{\quad A}X'\ + \ _{-1}^{\ \ 0}e^- \ + \ \bar v _e $$ ...
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How do I determine the half-life from a change in the activity of a sample over a known time?

If I know that the sample originally has an activity of $A_0$ and after a time $t$ has an activity of $A_1$, how can I use this to determine the half-life of the material?
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Would it be possible to have a stable atom nucleus that is hollow?

Some context around my understanding: Protons and neutrons clump together in the core of the atom due to the strong nuclear force. Protons also repel each other, but the strength of this is not strong ...
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Radioactivity inside black hole

This is thought experiment. I know we can not insert or watch happening inside black hole. But for sake of thought experiment let's think this is possible. Suppose we have 1 kg of material X with half ...
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How might one stop a radioactive agent from radiating?

Source There have also been grim signs of things to come from the Russian government. A new national standard for “Urgent burial of corpses in peacetime and wartime” has been introduced by the ...
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Why does the product nucleus lose an electron during beta positive decay process?

The question describes the beta positive decay for Nitrogen-13 into Carbon-13. After reading the explanation for the answer, it says that carbon ion will lose an electron in the decay process; ...
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Question about third Newton's law applied to nuclear fission

My question is about the energy that is gained by fission of Uranium 235.Suppose we have a box opened on one side where the radiation is emitted...so if that side looks to the sky that box should be ...
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What is the *fundamental* reason, at particle level, of the radioactivity?

When giving fundamental reason for radioactivity, books or references most often state that this is due to the fact that nucleus is not in a stable enough state thus it goes back to the stability. ...
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Why $\beta^+$ radioactivity is possible while lifetime of proton is expected to be infinite?

In the Standard Model, protons are considered to have an infinite lifetime. See https://en.wikipedia.org/wiki/Proton#Stability "The spontaneous decay of free protons has never been observed, and ...
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Is Radon a gas due to its radioactivity?

I think most gases are light but Radon is really heavy. I of course know that plenty of gases are not radioactive, but could the reason that Radon is a gas be due to the radiation contributing to the ...
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Decay probability

If I have a nucleus that have a constant probability per unit time to decay $q$ (to simplify is the probability to decay per day), Me and my friend decided to make a bet: the nucleus is alive at the ...
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How nucleons get excited? [duplicate]

Gamma rays can be released when nucleons at higher energy states fall down to lower energy states, but how do nucleons get that much high energy to release gamma rays?
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How to model radiation from non point sources?

For radioactive decay, if we assume a point source, then the number of particles at a distance $d$ away from the source scales as $1 \ /$ $d^2$. The assumption of a point source is only valid when d ...
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What happen if all the carbon-14 atoms in a person body decays at once?

What happens if all the carbon-14 atoms in a persons body decays at once? Would they die or will they be unaffected?
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Does Half life apply for all kinds of radioactive material?

Correct me if I am wrong, but for example when half of a sample U-235 undergoes alpha decay, it marks its half life. However, what if a sample undergoes gamma decay? Wouldn't its mass always stay the ...
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Does beta decay have an explanation similar to that of the atomic transitions?

Atomic states are eigenstates of the atomic Hamiltonian. They are stationary states. Transitions from one atomic state to another are possible only in presence of an external perturbation e.g., the ...
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Why isn't there any decay process in which nuclei of elements other than Helium nucleus are ejected? [duplicate]

I think this might be a stupid question but I have this doubt regarding the radioactive decay. I had gone through some introductory classes on alpha decay process few days ago and this question popped ...
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Average lifetime of particles [duplicate]

I have heard that If I have $10^{24}$ particles (for instance) and I observe them for 1 years, I can say that they have an average lifetime at least of $10^{24}$ years. How this is derived? So with $\...
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How can radioactive-dating techniques, such as uranium-thorium analysis, tell you when a human fashioned a tool out of a rock or coral?

This is an archaeology or anthropology question.... Scientists in a recent 'Nature' said they compared recent genetic analyses of theirs, concerning when Polynesian islands were first settled, with ...
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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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Is mass really lost in favor of energy after fission?

If in nuclear fission, the sum of the masses of the resulting atoms is the same as the parent ($\text{U}_{236}$, after fission is $\text{Cs}_{93}$ + $\text{Rb}_{140}$ + 2 neutrons), where does the ...
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Why is energy produced from uranium not exactly mass times velocity squared?

Our technology teacher explained why $1 \;\text{kg}$ of enriched uranium does not produce $$E=(1 \;\text{kg})*c^2$$ [where $c$ is the speed of light], but I didn't get it, so why is this so? (Nuclear ...
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Which among alpha, beta and gamma emitters is most dangerous for human body?

Lets say we have three candies: One with alpha emitter in it, one with beta emitter in it and one with gamma emitter in it. All have similar activities. You must eat one, put one in your pocket and ...
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Using photographic film to measure radioactivity

I'm asking a similar question on the Photography SE, but here I'm more curious about a measurement setup. In short, some lens manufacturers used thorium in some of the lens elements to increase the ...
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Question about potential additives to a very relative Covid 19 m R N A patent (i.e. radio active Ions: Iodine 125 or 131, Strontium 89, cesium, etc.) [closed]

I am a genuinely concerned citizen with barely any scientific background concerning radioactive isotopes. However, I have a question about items listed in an mRNA 1273 patent on Moderna's website. ...
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Can someone explain this tweet about activated fusion reactor materials?

This tweet is a joke, I assume: https://twitter.com/scipython3/status/1422923046113927170 but I don't understand why it would be a good thing to make a reactor out of a material that becomes low-level ...
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Contradiction about decay constant

According to my textbook: $\text{decay constant } k = \frac{A}{N}$ ,where $A$ is activity, $N$ is no. of undecayed nuclei $ = \frac{\text{no. of nuclei decayed per unit time}}{\text{total no. of ...
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Where does the new electron come (beta particle) from in beta decay?

In beta decay neutrons convert into proton, in that process they'll release an electron (called beta particle) but mass still remains same $$_zX^A \longrightarrow\; _{z+1}Y^{A}+ e^- $$ The question ...
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