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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Is Arc reactor really possible?? and do the findings fit onto it? [on hold]

Since this is a fictitious device, and it has no "official" scientific explanation in the Iron Man canon that I'm aware of, I'm going to make something up. I'm mixing real science and fake science ...
1
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1answer
123 views

How hot is Plutonium-238 in Radioisotope Thermoelectric Generators (RTGs)?

As I understand it, Plutonium-238 is used to provide power through heat generation in radioisotope thermoelectric generators. My question is... how hot is a pellet of Plutonium-238? Does the heat ...
0
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3answers
60 views

Why do only heavy radioactive elements perform fission or fusion?

Why do only heavy radioactive elements perform fission or fusion? I mean what's so special about heavy elements which makes them ideal for nuclear fission? Also why do only neutrons show ...
3
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1answer
120 views

Probability density of detection of collinearly emitted photons in two detectors

Update: As proposed by @dmckee, I added equation numbers and improved the display of some equations. The answer by @Trimok inspired me to look at coordinate systems which are not specific to the ...
0
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1answer
25 views

ionising atom(s) with gamma rays

if a gamma ray hits an electron and transfers energy, does it hit that electron (ionising the atom), transfer all its energy and stop or does it pass through multiple electrons, transferring a portion ...
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1answer
38 views

Can only radon-222 decay into polonium-218?

Is radon-222 the only element that can decay into polonium-218?
2
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3answers
413 views

How do particles “know” when to decay?

So, as I understand it, in a substance that is made of radioactive elements, the half-life tells us how long until the half of those atoms decay into their next atom [is there a name for that: the ...
1
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1answer
18 views

Can an ensemble of meta-stable systems be prepared so their survival probability drops approx. linearly right after preparation?

In this answer dealing with details of decay theory (incl. references) it is shown that [Given] a system initialized at $t = 0$ in the state [...] $| \varphi \rangle$ and left to evolve under a ...
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4answers
2k views

Does average lifetime even mean anything?

So today I was trying to derive an expression for the number of radioactive atoms remaining after a time $t$ if I began with $N_0$ atoms in total. At first I tried to assume that they had an average ...
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3answers
133 views

Can we find the exponential radioactive decay formula from first principles?

Can we find the exponential radioactive decay formula from first principles? It's always presented as an empirical result, rather than one you can get from first principles. I've looked around on the ...
5
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1answer
305 views

True randomness via Radioactive decay [duplicate]

Is radioactive decay able to be used for true randomness? And do we know if radioactive decay is truly random? Edit. Here is a example true random number generator made using radioactive decay. ...
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1answer
113 views

Radiation level risk: mSV, exposure and current status of chernobyl area

I was watching this two videos from youtube. One is a documentary about Chernobyl disaster: https://www.youtube.com/watch?v=d5vlk_d6hrc Another is a random personal video: ...
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4answers
131 views

Why aren't we affected by radium?

1)We have radium clocks, watches, wrist bands and many things which glow because of radium but we know that radium is radioactive so why isn't it harmfull for us when in bands, watches etc. 2)Does it ...
0
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1answer
22 views

What physical quantity can be deduced from an activity vs. time half-life decay graph?

I have a simple theoretical question regarding half-life decay graphs for radioactive substances. If the graph plots activity versus time (not mass versus time), then what physical quantity can ...
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2answers
48 views

Can we predict the half-lives of radioactive isotopes from theory?

Is there any way to predict the half-lives of radioactive isotopes from theory (that is, using only theoretical considerations, without using data about the decay)? For example, could we predict that ...
2
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1answer
34 views

Carbon-14 formation in atmosphere

Wikipedia says Carbon-14 is formed in the atmosphere by the reaction: 1n + 14N → 14C + 1p This looks like neutron capture. However, I would expect neutron capture to result in 15N. However, "proton ...
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23 views

help calculate the Rydberg constant for hydrogen [closed]

The wavelength difference between the longest lines in the Balmer and Lyman series for hydrogen is 534.7mm. Calculate the Rydberg constant for hydrogen.
35
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3answers
5k views

Is it possible that every single isotope is radioactive, and isotopes which we call stable are actually unstable but have an extremely long half-life?

I've read that tellurium-128 has an half-life of $2.2 \times 10^{24}$ years, much bigger than the age of the universe. So I've thought that maybe every single isotope of every single atom are ...
4
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4answers
91 views

Is an atom charged after undergoing beta emission?

After beta emission, an atom's mass number remains the same while the number of protons increases by one. As far as I know, the beta particle (electron) is too energetic to be recaptured. If this is ...
5
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3answers
306 views

Would 2 entangled atoms decay at the same time?

I have a very basic understanding of entanglement and radioactivity. But say 2 uranium atoms are entangled and then 1 of them decays, what would happen? Would the other atom decay as well? Or if not ...
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1answer
47 views

Working out the penetration of radioactive decay products

From my understanding of the products of radioactive decay (alpha particles, beta particles, and gamma are all I know of), the particles (or energy I guess?) are stopped by a medium according to it's ...
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4answers
1k views

Time dilation at zero velocity (and zero gravity)

From what I've learned, the more an object travels closer and closer to the speed of light, the more time will slow down for that object.. at least from an outside perspective.. It was shown that ...
15
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6answers
2k views

What happens before a radioactive element decays?

What happens to a radioactive element just before it decays? In school, I've been told that the decay process of an element is absolutely random, and it is impossible to determine which unstable ...
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2answers
126 views

If earth's magnetic field disappeared, would cosmic radiation lead to increased radioactivity?

This is about the effect of cosmic radiation on earth. Is it the type of radiation that could make things radioactive? So if earth's magnetic field weakened considerably (such as could happen if it ...
13
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2answers
4k views

How do we know that some radioactive materials have a half life of millions or even billions of years?

If a radioactive material takes a very long time to decay, how is its half life measured or calculated? Do we have to actually observe the radioactive material for a very long time to extrapolate its ...
2
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1answer
35 views

Activity of a radioactive source - distribution of number of impulses per unit time

I have the following problem: The activity of a radioactive isotope was measured with the result $N=625$ impulses/second. If this measurement were to be repeated, state the interval where we can say ...
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1answer
34 views

Device to Test Radioactive Beverage

In one scene of the movie "Edge of Darkness", the protagonist uses a device to test the radioactivity of milk in a glass container by placing the device near but outside the container. What is this ...
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2answers
52 views

Photon yield of NaI

We have to calculate the photon yield of the scintillator NaI. We have measured his pulse height spectrum but we have no idea how to solve this problem. Can someone explain it? The source that we used ...
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1answer
151 views

Polonium tea emergency [closed]

Let's assume that I just realised that tea I drunk 30 minutes ago during meeting with a secret agent was doped with radioactive polonium. What should I do? What the doctors will do? Are there ...
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2answers
688 views

Is it a problem with radiometric dating that carbon 14 is found in materials dated to millions of years old?

The preferred method of dating dinosaur fossils is with the radiometric dating method. And the result of this accepted method dates dinosaur fossils to around 68 million years old. However: Consider ...
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3answers
438 views

Verifying radiation measurement smart phone applications

I've stumbled upon a strange class of Android applications lately. (And I'm sure such applications are available for other platforms too.) These apps claim the ability of detecting radiation. The ...
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2answers
2k views

Artificial planetary magnetic field

I wonder how difficult it is to create an artificial planetary magnetic field with generators? What power they would need? The question is inspired by thinking about possible colonization of ...
0
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1answer
80 views

When will an atom emit alpha particle, beta particle, or gamma rays?

How can we predict which particle the radioactive element will emit?
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3answers
92 views

We don't know when a nucleus will decay. Then how can find its half life? [duplicate]

I mean how can we say that in 5730 years, 1/2 the no. of C14 nucleus will decay because in reality we don't know when a particular nucleus will decay
22
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3answers
6k views

Why is technetium unstable?

Is there a simple account of why technetium is unstable? From the Isotopes section of Wikipedia's article on Technetium: Technetium, with atomic number (denoted Z) 43, is the lowest-numbered ...
0
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0answers
20 views

Determine the number of grays absorbed by human emitted by Uranium 238

I want to count the estimated value of gamma radiation (in Grays) absorbed by human emitted by Uranium 238. Weight of it's ore is about 20 grams. The human weight is about 70 kilograms, he was about 5 ...
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30 views

Identify this radioactive-particle filter?

I am wondering if anyone can provide further info as to the preliminary principle involved in the filter shown below, any internet links would be appreciated. Is taken from a magazine related to ...
7
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3answers
139 views

In a radioactive Bose-Einstein condensate, would all the atoms disintegrate simultaneously?

They're all supposed to do the same thing - so I suppose they would? Also, would the resulting half-life be the same as that of the individual atoms it is made up of?
0
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1answer
44 views

Problems with calculating Strontium-90 leakage due to Fukushima accident

Not long ago there was a spill of radioactive water at the Fukushima plants. Here are the data: $230 \times 10^6 \,\,\mathrm{Bq}$ of beta radiation are found in a liter of water. $t_{1/2} = 28.79 ...
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1answer
51 views

Identification of massless, chargeless $x$ in a nuclear reaction

On Friday, we had our Physics test. We (the tenth grade students) have the basic introduction to Radioactivity and a few nuclear reactions in our syllabus. In the test, the following question was ...
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4answers
184 views

What does the exponential decay constant depend on?

We know the law of radioactivity: $$N=N_0e^{-\lambda t}$$ where $\lambda$ is the exponential decay constant. My question is: This constant depends of what?
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2answers
37 views

Detecting radioactive material at a distance

I have heard a lot about the failures of even the best-funded anti-ballistic missile technology. The usual explanation is that ABM is very hard after the boost phase because of evasion techniques and ...
5
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4answers
617 views

Why does an atom remain uncharged after emission of an alpha particle?

When an alpha particle is emitted, two protons and two neutrons leave the nucleus but the electrons remain the same in number. Why does the atom remain uncharged although it appears it should have a ...
2
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2answers
84 views

What is the distribution of energy between the alpha, beta and gamma particles emitted in nuclear fallout per one RAD?

I have been trying to find a relation to be able to convert from RAD to REM. What I found is that I need to know the "quality factor" as some sources call it, which is the effect of different ionizing ...
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1answer
81 views

Use of fission products for electricity generation

Why can't we use fissions products for electricity production ? As far has I know fissions products from current nuclear power plants create enough 'waste' heat to boil water; and temperature ...
13
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2answers
704 views

Long time deviations from exponential decay in radioactivity

Are there any examples of common substances whose decay is not exponential? We're used to thinking about radioactivity in terms of half-lives. This is a concept that makes sense only for a decay that ...
1
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1answer
133 views

Cobalt 60 beta decay

In the beta decay of an atom of Co60, the radiation you would expect is one or two gamma rays, plus an electron plus an electron neutrino (and in the nucleus Ni60+, if I understand it well). However, ...
3
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3answers
208 views

Radioactive decay - What mechanism decides when an unstable nucleus decays?

My first question on Stackexchange (if it is formatted wrong or something please tell me so I know in future) - here it is: Given an unstable nucleus (exactly which nucleus is not particularly ...
12
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4answers
594 views

Why are alpha particles such a prominent form of radiation and not other types of nucleon arrangement?

It is said in many textbooks that alpha decay involves emitting alpha particles, which are very stable. Indeed, the binding energy (~28.3 MeV) is higher than for $Z$-neighboring stable isotopes. But ...
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2answers
30 views

Radioactivity features

What happens if someone would make a wire coil around nuclear reactor core? What are the possibility to capture radioactivity directly?