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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Radioactive half lifes

What is the typical half life of material released from nuclear fission? This is a question I received for yr 12 physics and I can't find a proper answer telling me what the material released is and ...
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76 views

Rutherford alpha scattering?

From Rutherfords alpha scattering, where alpha where fired at a thin peace of metal foil, he concluded that the nuclie was positivly charged. He made this conclution from the fact that alpha particles ...
2
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1answer
58 views

Decay/Counts/Number of Nuclei

I'm writing up a lab report and have a question about the following formula $$N = N_0e^{-\lambda t}$$ $N$ indicates the number of nuclei left after a time $t$ and $N_0$ indicates how much there was ...
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3k views

Would being underwater help survive a nuclear bomb?

If I jump in my pool, on the river near my house knowing that a nuclear bomb, or atomic or H-Bomb exploded around 10 km from my house, would I survive? The way I see it is that water will protect me ...
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36 views

Beta Decay Energy

Consider $\beta ^-$ decay. \begin{align*} ^{198} Au \rightarrow ^{198} Hg + e^- + \bar{v_e} \end{align*} The decay energy is given by the difference in mass between multiplied by the speed of light. ...
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26 views

Time scale when measuring total activity from radioactive sample

I have measured the total activity from a radioactive sample during an experiment by counting the number of decays happening in 3 seconds intervals. I got data as: Time bin: 0 1 2 3 4 5 6 7 ... ...
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1answer
345 views

Calculating a radioactive sample's mass from its activity [closed]

The question reads as such: "What is the mass of a 1.05 µCi carbon-14 source?" First I convert to decays/s: $R = 1.05 µCi=3.885 \times 10^4 decays/s$. The half-life for carbon-14 that we've been ...
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1answer
134 views

Energy balance for beta decay of cobalt-60

I am confused by a simple fact about the $\beta^{-}$ decay of ${}^{60}{\rm Co}$ nucleus. According to Wikipedia, the most likely decay branch is to an excited state of ${}^{60}{\rm Ni}$, see the ...
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1answer
2k views

Is radioactive decay spontaneous or random?

When the count rate of a radioactive isotope is measured, the readings fluctuate. Do the fluctuations demonstrate the random nature of the decay or the spontaneous nature? (This question was asked in ...
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225 views

How clean will first generation fusion reactors be compared to fission reactors?

Googling the topic seems to indicate that fusion reactors will produce less waste and less toxic radioactivity, but this fact never seems to be mentioned during the current debate over nuclear power. ...
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4answers
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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 ...
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80 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 ...
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61 views

Why does Se-82 undergo double beta decay?

Looking at the decay chain, I saw it undergoes double beta decay. How is it feasible for something to undergo a simultaneous double decay?
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How does a half-life work?

Carbon-14 has a half-life of 5,730 years. That means that after 5,730 years, half of that sample decays. After another 5,730 years, a quarter of the original sample decays (and the cycle goes on and ...
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1answer
127 views

What is the theoretical wattage output of a Tokamak fusion reactor?

By that I mean the complete radiative wattage of any type of energetic radioactivity or electromagnetic wave or even particle if that's what they output. My purpose is to compare this to the suns ...
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1answer
31 views

Differentiating between mass number (A) and activity (A) in a nomenclature/glossary [closed]

I'm not sure if this is the best place to ask this question, but as it's related to the terminology of nuclear physics I thought it would probably be a logical place to start. I'm currently writing ...
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133 views

Why tritium doesn't undergo $\beta^-$ decay to form $He^3$?

In my textbook it is written that Tritium is an isotope of hydrogen whose nucleus Triton contains 2 neutrons and 1 proton. Free neutrons decay into p + electron + anti-neutrino . If one of the ...
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24 views

How does beta+ decay actually occur? [duplicate]

I'm having difficulty in understanding beta plus decay. How can a proton which has slightly less mass than neutron transform into a neutron, positron and neutrino? Form where does the extra mass for ...
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2answers
344 views

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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1answer
60 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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2answers
673 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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1answer
34 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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3answers
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How can a proton be converted to a neutron via positron emission and yet gain mass?

The mass of a neutron is greater than mass of a proton so how is it possible in positron emission for a proton to form a neutron and a positron?
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1answer
372 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
79 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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57 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
164 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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1answer
210 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
569 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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2answers
375 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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1answer
117 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 ...
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1answer
2k views

Nuclear reactions conservation laws

I'd want to know the basic rules to apply the conservation laws in nuclear reactions (nuclear fusion, nuclear fission, radioactive decays, etc.) to determine parity and angular momentum of the ...
0
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1answer
45 views

Where can I find a device or how can I make a device that measures only Alpha particles?

Are there special muller tubes that only measure alpha for example?
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1answer
100 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
311 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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471 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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144 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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131 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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1answer
73 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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2answers
283 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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2answers
189 views

$\require{mhchem}$ $\ce{\beta^{+}}$ decay for $\ce{_9^18F}$, computing $\Delta m$

For the decay: $$\require{mhchem}\ce{_9^18F\to_8^18O +e+ +{v}}$$ To compute $E$, I need $\Delta m$, the provided answer looks like: $$m_i = 18.000938~u$$ $$m_f = 17.999159~u + 2~(5.49 \times ...
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4answers
572 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 ...
2
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1answer
114 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 ...
8
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1answer
3k views

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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0answers
111 views

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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2answers
304 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 ...
12
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3answers
378 views

Radio-dating and the age of the earth

I understand there are a few radio-dating methods to determine the age of the earth, uranium-lead to name one (maybe not the best though). The ratio Pb206 + Pb207 to U allows you to find when the ...
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1answer
384 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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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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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 ...