Radiation is a process in which energetic particles or energetic waves travel through a medium or space. The particles or waves radiate (i.e., travel outward in all directions) from a source.

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Deflection Effects on a Spinning Solar Sail

Suppose I have a solar-sail-powered starship flying directly away from a star. The sail is flat and perpendicular to the direction of travel. Now, in order to make the trajectory more stable (we ...
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22 views

How to calculate material depth at which penetrating radiation direction becomes randomized?

Consider a very light particle impinging on a material composed of atoms which are effectively infinitely heavy (e.g., because they are bound together and stiff). If the scattering with nuclei is ...
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42 views

How do experimental physicists know the decay path of transuranium elements ahead of time?

I have been watching (and enjoying) Dr. Poliakoff's YouTube videos on the synthesis of transuranium elements like Roentgenium and Copernicium, which decay so quickly that they are identified (if I ...
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80 views

Why does a damped quantum harmonic oscillator have the same decay rate as the equivalent classical system?

$\newcommand{ket}[1]{|#1\rangle} \newcommand{bbraket}[3]{\langle #1 | #2 | #3 \rangle}$ Why does the decay rate for a damped quantum harmonic oscillator exactly match the classical limit? Background ...
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37 views

How do we 'watch ' atomic interactions?

I'm relatively new to objective physics and it's measuring and imaging abilities.. Specifically I don't know if we can 'watch' inter/or intra molecular exchanges like the photonic and electronic. I ...
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122 views

Gamma Spectrum: What is causing this behavior?

In my radiation detection lab we're identifying a unknown source, based on the gamma spectrum it's an activated gold foil. You can clearly see 4 peaks: 411.78 keV (Au-198), 675.93 keV (Au-198), 823.51 ...
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102 views

Model to convert radiation data from one tilted surface to a different one?

I have measuring data of global radiation on a tilted surface (a solar collector surface). Now I need to do 2 things: split the tilted global radiation into its diffuse and beam parts calculate ...
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168 views

Is WiFi safe for humans? [closed]

I have wifi on at my home almost all the time. I learned that the frequency of visible light is around several hundreds of THz, while the frequency of wifi is only several GHz, which is only ...
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2answers
82 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 ...
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184 views

Effects of microwaves on optical properties of human eye [closed]

I have read a long series of paragraphs on wiki. Previously I thought that microwaves are not harmful to living beings but Wiki does not claim this explicitly. while doing an experiment in my college ...
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3answers
68 views

Do molecular bounded systems shield or reduce neutron cross-sections?

When talking about neutron cross-sections, literature is usually investigating isolated cases of Neutron + Atom. Here, the abundance of hydrogen is dominating neutron fluxes through material. I ...
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163 views

Interaction of coherent X-rays with matter

If we could irradiate a metal or a plasma with a coherent beam of hard X-rays, would the main effect be an ordered oscillation of the electrons like with a classical EM wave, or "compton-style" ...
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175 views

The equal opposite reaction of radiation pressure

If the photons of a laser would produce a radiation pressure upon whatever it shown upon wouldn't it be accurate to say that the laser would be propelled in the opposite direction of its beam?
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55 views

Effect of Background Radiation on a Transmitted Signal

I'm coding a basic simulation of using error correcting codes to transmit data from a satellite back to earth. I'm not sure what to set the "noise level" to. Let's say a satellite orbiting Mars ...
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1answer
2k views

Finding electric power generated using heat transfer

I'm working through an example I have been given to study. Suppose I have a 2m X 4m photovoltaic panel on my roof that is irradiated with a solar flux of $G_s = 700W/m^2$. Given: $\alpha_s = 0.83$ ...
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228 views

How is the “negative dispersion” derived?

I'm looking at Kopfermann H., Ladenburg R., Nature, 122, 338-339 (1928) and it appears Ladenburg in Ladenburg R., Z.Physik, 4, 451-468 (1921) was the first to discover the phenomenon of "negative ...
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3answers
2k views

How can there be heat in a vacuum?

I keep reading in the Physics World focus issue on vacuum technology about scientists creating high temperatures in the vacuums etc. If heat is caused by thermal energy being radiated from particles ...
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2answers
153 views

Why does light fade from a room?

So basically in my toilet I have this really bright ceiling light, but when I turn it off it doesn't just instantly plunge me into darkness, but rather sort of fades out over a few seconds. It looks ...
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269 views

Radioactive decay as pure radiation of neutrinos and antineutrinos?

Is it possible with radioactive decay as pure radiation of neutrinos and antineutrinos? From a theoretical point of view? I'm not asking for processes since I'm convinced there are no known processes ...
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1answer
373 views

Is there any difference between a proper photon and a photon of thermal radiation?

Does a thermal photon radiate spherically whereas a photon radiates in a circle/beam? How do you tell a thermal photon of, say 3 eV, from a photon of light?
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724 views

What does the decay constant mean?

In my curriculum, the decay constant is "the probability of decay per unit time" To me, this seems non-sensical, as the decay constant can be greater than one, which would imply that a particle has a ...
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437 views

Nuclear decay rate affected by sun and quantum randomness

If nuclear decay rate were affected by sun, then emission probabilities would be subject to sun state and its influence, so quantum randomness would depend on it, Would it still be truly random? One ...
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2answers
108 views

Earth's and Moon's outgoing radiation

Does Earth or Moon emmit/reflect anyother form of radiation than IR into space? I am especially curious if they emmit/reflect UV radiation. And if they do, where could I find an irradiance spectrum ...
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419 views

How to detect radiation on the metal (coin)?

I've got metal coin : http://www.worldpeacecoin.org/ Ruble/dollar, a coin of disarmament with certificate. But, I am very spleeny person, I fear of it's radiance level and I don't know if I can trust ...
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3answers
526 views

How to detect Iodine 131?

$I_{131}\rightarrow \beta \text{ 333.8 KeV(7.27%)}\rightarrow \gamma\text{ 636.989 KeV(7.17%)}$ $I_{131}\rightarrow\beta\text{ 606.3KeV(89.9%)}\rightarrow\gamma\text{ 364.489KeV(81.7%)}$ (you can ...
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252 views

Reconstruction of information stored in an evaporating black hole from the emission spectrum?

For simple setups, where the radiation field deviates not too far from thermodynamic equilibrium (< 10 %), corrections to the Planckian thermal emission spectrum can be calculated (and measured) ...
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350 views

Creation of the Electromagnetic Spectrum [closed]

After seeing this image: http://mynasadata.larc.nasa.gov/images/EM_Spectrum3-new.jpg And reading this: "The long wavelength limit is the size of the universe itself, while it is thought that the ...
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1answer
72 views

Highest background gamma ray energy?

What is the highest naturally occurring gamma ray energy that you would see in background? And what is it is source?
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497 views

Is data which rides on the carrier frequency dangerous?

My understanding of broadcasting data via electromagnetic radition is, that the data "rides" on a carrier frequency on which it is radiated. I am aware of the fact, that those carrier frequencies are ...
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3answers
504 views

Any real life demonstrations of radioactive decay? [duplicate]

I'm skeptical about a lot of things in physics, but I have a great interest in it and I'm studying it in college next year. However I am very skeptical about some things. I find that for physics, it ...
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143 views

Extreme heating by Sun on Earth- Can eggs be fried?

Will it be possible to fry eggs in Sahara desert by just keeping them under the sun? If so, then will the radiated eggs be any different? Or will we have to use the solar cooking concept to some ...
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1answer
56 views

What's the idea behind Wu's experiment?

Madame Wu discovered the parity violation in beta-decays. To do so, she took some Co-60 nuclei, which decay via beta-decay in Ni-60 with emission of electron, antineutrino and 2 gamma rays. She ...
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1answer
47 views

Quantum mechanics prediction for Bremsstrahlung?

Does quantum mechanics predict the Bremsstrahlung Phenomena? I know it is predicted by classical mechanics through Maxwell's equations, but does QM predict this phenomena and how so?
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33 views

Carbon 14 disintegration

When $\beta^-$ disintegration happens to a Carbon 14 atom, a neutron "turns into" a proton, and an electron is emitted. Therefore the result of the disintegration is a Nitrogen atom plus an electron ...
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1answer
63 views

What is the energy threshhold to produce Cherenkov radiation?

I am in a nuclear course right now and am getting some misleading information from different sources. I am trying to figure out what the minimum total energy is that a proton must have in order to ...
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1answer
28 views

Does the W boson in beta decay affect the gravity generated by the system?

During beta decay we now know a heavy W boson gets involved temporarily. Would this potentially impact the gravitational field generated by the system as a whole? It doesn't seem like it should. Just ...
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1answer
40 views

What process happens in an IT nuclear decay?

I've been researching medical isotopes and alot of them decay by an IT path. Does anyone know what IT stands for? And what physical process is happening? Example: ...
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1answer
148 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, ...
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1answer
39 views

Explanation of binding energy in decays

Everyone knows that the mass of a system is less than the mass of its components, with the equation: $M = \sum_i m_i - BE(M) $ Now, if we consider a general decay, lets say $A \rightarrow \sum_i ...
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93 views

What causes different decays?

Nuclei spontaneously decay according to a certain decay rate. There are however different kinds of decay, alpha, beta, gamma... What causes then the nuclei, when they decay, to do so in one way of ...
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1answer
107 views

Is it possible to calculate the half-life of a nucleus?

Is it possible to calculate theoretically the half life of a nucleus (how?) or they are all known through measurements? As an example how do you calculate the half life of Carbon-14?
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1answer
60 views

Proof of the inverse square law for a uniformly bright sphere

On page 8 of "Radiative processes in Astrophysics" by Rybicki and Lightman they have a proof that the flux of a uniform sphere is inversely proportional to the distance of the sphere from the ...
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1answer
428 views

Conservation of mass-energy and nuclear transmutation

This may just be beyond the grasp of the everyman, but I'm trying, and failing, to grasp how conservation of mass-energy works in cases of beta decay and electron capture. A neutron has a mass of one ...
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2answers
3k views

A hot object exposed to low temperature in a vacuum doesn't lose heat?

I heard somewhere that if the human body were exposed to outer space where the temperature is extremely low, the human won't actually feel cold because in a vacuum, the heat energy doesn't have ...
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295 views

$\alpha$ and $\beta$-decay, why don't they neutralize each other?

$\alpha$ radiation consist of positive charged helium nuclei, $\beta$ radiation of negative charged electrons. So why don't the $\alpha$ particles take those electrons to get neutral?
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57 views

How does “contamination” through (radioactive) radiation work?

Physically, what does it mean when people or objects are contaminated with radiation? Is it because they actually carrying heavy metal particles?
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1answer
52 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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1answer
617 views

Does tin foil keep heat out?

For example, if i were mailing a box of chocolates and lined the inside of the box with foil, then wrapped the chocolate in bubble wrap and placed it inside the foil lined box, would the box heat up ...
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1answer
46 views

Why is 0 $\nu \beta\beta$ decay often written with electron emission and not positron?

According to http://www.cobra-experiment.org/double_beta_decay/ I can see that double $\beta$+ decay is possible, but I often find neutrinoless double beta sources with the double $\beta$- decay ...
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214 views

Calculating the Sun's emitted power in a wavelength range?

Is there an equation that describes the Sun's emitted power on the surface [in $\frac{W}{m^2}$] over a selected wavelength range (from $\lambda_1$ to $\lambda_2$) ? I am guessing this can be ...