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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Does strong magnetic field cause time dilation?

Does strong magnetic field cause time dilation? If you have a strong magnetic field, and a magnetic radio active material. Does the half life of the radio active material change in a strong magnetic ...
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2k views

How to calculate gamma radiation shielding?

A device emits 0.2 μSv/h of gamma rays. How thick does an aluminum sheet need to be to completely stop radiation from coming out ? What equation is to be used to calculate this ?
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388 views

Inverse Square Law in Beta Radiation

Setup: A radioactive source is placed at alternating distances from a Geiger Counter. Counts per second for 10 different distances (each spaced 1 cm apart) were taken for preset times ranging from 200 ...
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1answer
52 views

Using $A = {\lambda}N$ to find when a the amount of a radioactive source becomes constant

The question and mark scheme I will write in bold and my own thoughts in normal sized text. I'm told that: When a $\bf{_{92}^{235}U} $ nucleus is exposed to free neutrons it can absorb a neutron. ...
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175 views

What is average life in radioactivity and what is its significance?

By definition, average life of radioactive sample is the amount of time required for it to get decayed to 36.8% of its original amount. But what is the significance of 36.8% and why has that value ...
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30 views

Does KI have to be a salt of stable I-127 isotope?

I was recently watching a TV show where some people exposed to radiation were asked to take KI. I googled for the information and discovered this and also the Wikipedia article. From what I read, I ...
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1answer
160 views

Mean stopping range of $\alpha$-particles in air

I did an experiment in university in which I determined how far $\alpha$-particles emmited from an $Am^{241}$ source penetrate into air. I want to compare my result to literature values but... I cant ...
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1answer
268 views

Radioactive decay / binding energies

If my understanding is correct, the binding energy determines a nucleus' stability and the greater the binding energy, the more stable the nucleus (e.g iron-56). The mass of the sum of nucleons that ...
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3answers
68 views

Can radioactive energies become electromagnetic

I am trying to learn about radioactive energies and wonder if, because these also seem to come under the topic of radiation, can these energies become electromagnetic. I'm pretty much a beginner, so ...
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56 views

Recover activity from photo at Fukushima

This photo was published at stern magazine online. I wonder which information about the physical quantities could be reconstructed or computed given this photograph, the exposure time, and the ...
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1answer
12k views

What did Marie Curie do for atomic theory?

There appears to be a distinct lack of agreement in the physics community on what exactly Marie Curie did for atomic theory. Many journals state that Curie was responsible for shifting scientific ...
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1answer
145 views

Number of decays in a chain reaction

It is widely known that the probability of $n$ decays from one system to another $A \rightarrow B$ (e.g., electrons decaying from one atomic energy level to another or muons decaying into neutrinos ...
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279 views

Can bad guys really hide “dirty bomb” material via bananas?

This one probably has some cross-over with Skeptics SE, but I thought it fits here a little better. The concept comes from the TV show NCIS:LA second season episode "Empty Quiver" Here, the villains ...
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104 views

Conversion of energy to mass with radioactive decay

Consider the following problem: The nuclei of Am-241 decay by the emission of $\alpha$-particles with a kinetic speed of $8.8 \cdot 10^{-19} J$. In a certain source of Am-241 there are $ 4.0 \cdot ...
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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 ...
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7answers
2k views

Changing the Half-Life of Radioactive Substances

Is there a way to extend or reduce the half-life of a radioactive object? Perhaps by subjecting it to more radiation or some other method.
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79 views

Is the fraction of radioactive isotopes on the near side of the moon higher than on the far side?

As time passes more slowly in a region of space close to the source of a gravitational field, shouldn't the moon, which always has one side facing towards the earth, have a higher fraction of ...
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1answer
222 views

Is sub critical plutonium “safe” to handle?

Apparently, in Los Alamos scientists handled sub critical masses of plutonium (for example the demon core) with little or no protection. Richard Feynman and others mentioned that plutonium spheres ...
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3answers
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What other shielding material than lead is effective against gamma rays?

As the question in the title states I am wondering what material can be effectively used to shield gamma rays apart from lead? I believe concrete is often used, but it is nowhere near as effective as ...
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370 views

Why were the fathers of quantum mechanics so sure radioactive decay was indeterministic?

The classic example of an indeterministic system is a radioactive isotope, e.g. the one that kills Schrödinger's cat. I get there are arguments against hidden variables in quantum mechanics, but how ...
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2answers
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What happens to chemical compunds that include radioactive nuclei, when those decay?

Say you have a chemical compound made up of one or more radioactive nuclei. If the nucleus decays, does the compound? Possible outcomes I can think of: the compounds continues to exist if a ...
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6answers
561 views

What needs to happen for one to ingest radioactive particles and how likely is this?

There are many stories about radioactivity and the relative danger of it in the news lately, but very little actual information. The radioactivity levels around Fukushima Daiichi are high, but seem ...
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7answers
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Since radioactive material decays how is it possible that there is any left after 4.5 billion years?

I was not able to find an answer for this question... Some radioactive elements have half-life measured in thousands of years and some others even in millions, but over 4.5 billion years all the ...
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3answers
281 views

Can one see radioactive substances with an X-ray detector?

I was wondering the other day an X-ray detector (like the ones used at airports) can detect gamma-rays lets say from a sample of uranium. I know its all electro-magnetic waves but I'm really unsure ...
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113 views

Why is there an emission of gamma rays?

When a spontaneous radioactive reaction happens, there is an emission of gamma rays (in most cases) What causes this emission?
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4answers
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Can you speed up radioactive decay of plutonium?

We all know the issue of deep geological repositories for fuel rods. Is there a currently feasible way to speed up the rod's decay to render them harmless in less than 10 years?
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1answer
169 views

How to make neutron activation analysis online or with free software?

i want to make a neutron activation analysis for different crystals. (MnWO4, TbMnO3, and others) how can i do this with free or open source software? Can someone recommend a online calculator for ...
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2answers
108 views

Harmlessness of a pure alpha decay particle

From my high school physics class I remember that there are some particles which exhibit pure alpha decay (i.e. alpha decay to there stable isotope), like Po-210, Po-211 and Bi-209. What I also know ...
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67 views

Calculate energy from an reaction [closed]

I'm trying to calculate the released energy from a reaction. The radioactive substance polonium decays according to this formula: $$^{210}_{84}\mbox{Po} \rightarrow \mbox{X}+^4_{2}\mbox{He} $$ At ...
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Why is radioactive decay dependent on amount of substance available?

Radioactive decay is an attribute of unstable nucleus. When we represent it in equation, we don't involve any macroscopic attribute of substance. But still, rate of radioactive decay is proportional ...
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264 views

nuclear fission and half life

Why is the alpha, beta or gamma decay of an unstable nucleus unaffected by the chemical situation of an atom, such as the nature of the molecule or solid in which it is bound? The chemical situation ...
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1answer
214 views

How was Be-8's Half-Life of 7E-17 Second Determined?

Radionuclides occur with half-lives in a vast range of over 37 magnitudes as listed in this site. In question 7584, Lubos Motl explained how Gyr half-lives were determined. This method doesn't appear ...
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245 views

Radioactive Decay

Problem:Nuclei of a radioactive element $\Bbb X$ having decay constant $\lambda$ , ( decays into another stable nuclei $\Bbb Y$ ) is being produced by some external process at a constant rate ...
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1answer
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Why is carbon dating limit only 40,000 years?

For an example, when they tried to get the carbon dating for presence of Aboriginal people in Australia they get to the number 40,000. But it could be much earlier. Why is that 40,000 years limit for ...
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Besides transmutation, is there any way to “speed up” the decay rate of radioactive material?

I'm well aware of transmutation as a way to effectively make radioactive material decay faster, however that isn't really what I mean. Doing a quick Google search I found references to several ...
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5answers
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Iodine-131 half-life and reality

Iodine is a chemical element with symbol I and atomic number 53. There is currently a lot of discussions regarding radioactivity in Japan, and iodine-131. Iodine-131 has a half-life of 9 days. Does ...
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3answers
1k views

Work of Marie Curie?

I've been reading about the work of Marie Curie recently after a friend filled me in on what she did (never having had much of an idea previously) and it's all very interesting. What I can't ...
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1answer
285 views

What is the momentum of these emitted photons?

5 x 10^7 kg of radioactive material emits energy in the form of photons of red light (700 nm). (Note: photons have no mass.) What is the momentum of each photon? ...
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strange modulation of radiactive decay rates with solar activity

Recently i found out this uber strange article about nuclear decay rates being somehow showing seasonal variations with a high correlation with sun activity. Two very precise questions: 1) has this ...
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75 views

Photons emitted by radioactive source

Can we calculate the number of photons emitted per second by a radioactive source (gamma) ? we can take 100g of barium-133 as an example
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1answer
1k views

How do you calculate the equivalent absorbed radiation dose from activity, type of emission, and the energy of the emission?

I have a sample of U-238 of which my Geiger counter detects beta activity at 700 events per second. Based on the counter's efficiency of 98.6% for U-238, the activity would be about 710 becquerels, I ...
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269 views

Is there a direct relationship between an isotope's neutron count and radioactivity?

In my textbook, it lists isotopes of Carbon: C-12, C-13, and C-14. It noted that C-14 is radioactive (C-12 and C-13 are not). Is there a direct relationship between the number of neutrons and an ...
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236 views

Was the early Earth radioactive?

I've been reading of the (surprising) fact we are uncertain on whether there is nuclear fission in the center of the Earth or not (yet we know so much detail on structures at the other end of the ...
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3answers
891 views

Do some half-lives change over time?

I was recently doing some physics tuition on radioactivity and the student claimed her chemistry teacher had said that radioactive substances can be grouped into two divisions: those whose half-life ...
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1answer
145 views

Radioactivity and quantum superpositions

In the Schrödinger's cat experiment 'there is a tiny bit of radioactive substance, so small that perhaps in the course of the hour, one of the atoms decays'. The rest of the experiment magnifies this ...
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5answers
415 views

Thorium radioactivty vs Uranium radioactivty nuclear power

May i please open this question by asking that if you intended to answer this please could you provide links based on your answer. I have read ( and posted one ) on thorium and a lot of the answers ...
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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 ...
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2answers
155 views

Energy Question

Carl throws 100 g of Bohrium-262 (Half life: 0.10 seconds, undergoes alpha decay) to Sukhdeep with a initial horizontal velocity of 20.0 m/s at an initial height of 2.00 m above the ground. What is ...
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Can electricity transfer radioactivity?

If a cable used to power something is exposed to a radioactive source will it over time make the entire cable radioactive?