Questions tagged [radiation]

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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Does the mass of a particle change when emitting a photon?

question is in the title. It came up since we're currently dealing with 4-vectors and collision/decay processes. At a first glance I thought that it should be possible because of the energy/mass ...
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Modelling error in inverse scattering problem [closed]

An inverse problem in science is the process of calculating direct and indirect observations from the phenomenon through the mathematical model. Inverse problem consists of data (observation), ...
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Can we uniquely determine the particles emitted in a neutron induced binary fission of a radioactive element?

Can we uniquely determine the particles emitted in a neutron induced binary fission of a radioactive element? For example, if we have $ \newcommand{\U}{\mathrm U} \newcommand{\Mo}{\mathrm{Mo}} \...
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Why does the maximum of Planck's distribution function depend on how it is plotted?

I was reading Fundamentals of Atmospheric Radiation by Craig F. Bohren and Eugene E. Clothiaux and in page 20-23 they discuss the idea that the maximum of the Planck's distribution varies depending on ...
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Objects react different to different types of radiation

I am a bit confused about the different types of radiation and how objects react to it. In class, the professor showed us a cube with white, black and reflecting sides (the Leslie cube). Inside the ...
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How would a neutral hydrogen gas interact with a relativistic spacecraft?

Inspired by a discussion from the comment thread of a gaming youtube video, I've been thinking about what kind of radiation environment a relativistic spacecraft would be exposed to as it passes ...
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How does Collisional Ionization cause cooling?

I am trying to understand the different forms of radiative cooling such as recombination, collisional excitation, collisional ionization etc. In recombination and collisional excitation, the cooling ...
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When the decay constant is not constant. Limit definition of the exponential of an integral?

In radioactive decay (for example) the probability for a particle to decay per unit time is $\Gamma$. When this is a constant the probability to not decay after time $T$, $P(t)$, is derivable by ...
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Why doesn’t nucleus $^{160}$Tb fission from its ground state?

Why doesn’t nucleus $^{160}$Tb( β decay with a half-life 72 days) fission from its ground state? (assuming a mass-symmetric split in two nuclei, $^{80}$As and $^{80}$Ge) And how could $^{160}$Tb be ...
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1answer
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Why does water easily absorb THz radiation?

It is stated that water is extremely sensitive to THz radiation, absorbing big amounts of this radiation, this being a reason why skin measurements are safe to do using this range of frequencies (1) (...
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Stefan Boltzmann law and absorptivity

I have this really big confusion , and it is about the Stefan Boltzmann law Does this law works for absorption? Or is it only radiation I have seen my textbook replacing emissivity with absorptivity ...
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Where, in the standard model, do resonance widths come from?

For example, the Z boson decays and hence the propagator is: $$ \frac{1}{p^2-m^2-i \Gamma} $$ Where does this arise in QFT, is it that the lagrangian mass is complex or is it that when we compute the ...
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What truly is spectral blackbody emissive power?

I read that a blackbody at a temperature T, would emit thermal energy in the form of Electromagnetic waves. This thermal energy emitted per unit the area per unit time is called blackbody emissive ...
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Area under the Wien's Law graph

Before I proceed, in the Wien's law graph is the Y-axis Emittance[$E=Q/(A*t)$] or Power density ($Watt/M^3$)? According to several Google pages, The Y-axis is Power density but my book has used ...
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What is the difference between thermal and electromagnetic radiation?

In my understanding thermal radiation and electromagnetic radiation is same, for example suppose we heat up a knife to high temperature then it glows red. This means the thermal radiation / ...
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Forming of helium in radioactive decay

I have just came across a question, where 1mole of Uranium (238 92) gets converted to Pb(206 82) now after balancing we get that during this decay in presence of air, 8 alpha particles and 6 beta ...
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Spectral Radiation Intensity and Energy Density

I'm trying to prove the following relation $$ I_{v} = \frac{c}{n} u_{v} $$ where $I_{v}$ is the (spectral) radiation intensity and $u_{v}$ is the respective energy density, $n$ is the refractive index ...
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Energy balance in radiation heat transfer (Radiosity method)

I was doing some simulations with the Radiosity method, using Southwell relaxation, and got puzzled by a model that didn't converge. I checked every subtle setting, until... I realized the problem was ...
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What is the difference between areal density and attenuation coefficient?

Speaking of beta electrons, their attenuation is usually described by the areal density $\sigma$, i.e. "how much" g/cm^2 of a certain material they can pass through before stopping. I've ...
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Radiation attenuation parameters for beta and gamma rays

I know that to describe the attenuation radiation undergoes while passing through a material, we use the areal density (which is basically the penetration depth * density of the material) for beta ...
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1answer
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Radiation in nuclear power system [closed]

What are the 3 high level groups of sources of alpha, beta and gamma radiation in nuclear power systems?
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Absorption of Beta decay and characteristic exponential absorption law

It has been discovered that Beta decays are a continuous spectrum of electrons and its absorption follows an exponential law with thickness of material (eg. Aluminium). This observation was often ...
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1answer
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Picturing Photon Gas

Consider a photon gas inside a cavity with diathermal walls which is held at temperature $T$. I want to picture everything that's going on. More like the picture, We have for molecular gas. So I can ...
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Can you ionise air via thermionic emission of electrons?

Assuming air is made up only of 78% $N_2$ and 22% $O_2$, what percentage of the $N_2$ and $O_2$ would gain a negative charge if held in a container with a high density of free electrons?
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Irradiation damage produced by the decay of an alpha-emitter radionuclide

I calculated the irradiation damage produced inside a material by the decay of some radionuclides in contact with a surface. I want to measure the damage in terms of dpa (displacements per atoms), ...
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1answer
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Energy Density of radiation and Flux

How can I prove the relation: $$\epsilon=\frac{3}{4}\frac{Q}{c}\tau$$ where: $\epsilon$ is the energy density of radiation, $Q$ is the flux and $\tau$ is the optical thickness.
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Why is the alpha particle in alpha decay considered to be in a potential well?

I understand that when modelling alpha decay, it is useful to consider the $\alpha$ particle as being preformed, in a region confined to the daughter nuclei. I also understand that the term $V_{0}$ ...
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If radio signals attenuate when travelling through space, then what kinds of emissions are we looking for when searching for extraterrestreal life?

My understanding is that radio waves travel forever, like ripples in a pond, but attenuate with distance. They get mixed with other signals and become cosmic noise. I'm looking at these answers, which ...
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1answer
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Can I make device which receives all Sun ligth and changes it in electricity? [closed]

Is possible to make a device which recives all surround emg radiation in the same time? I'm not thinking about a radio. Rather something very silmilar but able recive all emg radiation in same time.
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1answer
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How to find the energy of white light? [duplicate]

If we have a single frequency of light, then the energy associated with that light ray can be given as: $$ E = h \nu$$ However, white light is a mixture of different frequencies of light in 'some' ...
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Can an object in space have a high kinetic energy, but at the same time not release heat?

Can an object in space have a high kinetic energy, but at the same time not release heat? If the answer is no and the body has to radiate heat, why and how does it happen?
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How can I estimate local solar time from direct solar radiation, knowing only latitude and longitude?

If I know the location (latitude and longitude) of a panel that measures solar radiation (in $\mathrm{W/m^2}$) and that it is at $0$ degrees to the horizon (i.e. facing skyward), can I estimate the ...
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1answer
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Thermal radiation vs emission spectra of gases

I am a high school student and I am very confused in absorption and emission spectrum of gases, for e,g take hydrogen at room temperature for simplicity, so that we can talk in terms of Bohr's model ...
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In what scenario could two particles cause fluorescence to each other?

Ni $K$ X-rays have higher energies than Fe $K$ X-rays, thus, Ni $K$ X-rays cause Fe $K$ X-ray fluorescence, meaning that there are more Fe $K$ X-rays than expected and the Fe concentration appears ...
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What qualifies an x-ray line as “useful for quantification” in a material's x-ray analysis?

Original question: Knowing the energy values for the different X-ray lines for Mo and for S in the analysis of bulk MoS$_2$ ($K_{\alpha 1}$, $K_{\alpha 2}$$K_{\beta1}$, $L_{\alpha 1}$, $L_{\beta1}$, ...
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$Q$-value in Beta decay

I was reading about the mass defect or $Q$-value in Beta Decay and the book that I was following said this, It iscalled beta minus decay as negatively charged beta particles are emitted. The rest mass ...
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1answer
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Can Uranium-238 undergo ordinary (single) beta decay?

Can U-238 undergo regular, single beta decay? Are there isotopes which can only undergo double, never single, beta decay? Not even two normal beta decays in quick succession?
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1answer
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Could cosmic rays be used for power on Mars?

Most studies of radiation levels of Mars that I can easily find focus on it as a hazard for potential human visitors. As such, a figure in rads or Sieverts is provided, which lumps together all of the ...
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1answer
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How can the amplitude of a wave determine if it is plane, spherical or cylindrical?

it's known that typical expressions for plane, spherical and cylindrical waves are (for instance in terms of electric field uniformly propagating along r axis, in frequency domain): Plane Wave: $E(r) ...
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Earth's surface radiation

Earth's surface radiation I have been researching Earth's energy balance at various latitudes and have posted my work so far on Wordpress at https://hotgas.club with the title "Earth's Radiative ...
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Deflection angle of an alpha particle when colliding with a stationary nucleus

Is it possible to calculate the deflection angle of an alpha particle after colliding with a stationary nucleus with atomic number,Z,without actually knowing Z or for that matter without knowing the ...
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1answer
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Since matter and energy are interchangable and elements naturally decay into energy does energy naturally decay into matter?

Matter decays into energy in the form of radiation. Does this happen in reverse with energy collapsing back into matter naturally in our universe (the theory that this is what happened in the big bang ...
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3answers
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How warm are radioactive metals?

I read that radium is warm to the touch -- is that because of actual heat or is that because, for example, the radiation it emits creates the sensation of warmth? How high of a temperature can a ...
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5answers
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$E=mc^2$ Shouldn't high energy decay GAIN mass not lose it? [closed]

I feel I've hit a bit of a paradox. I've learned that alpha decay releases a lot of energy, and that energy comes from the mass of the daughter products via $E=mc^2$. But, if the decay has more energy,...
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Steps behind meson decay amplitudes

I am a graduate student with a somewhat basic level of exposure to qft. As part of my degree I have been tasked with calculating meson decay amplitudes in a paper provided to me by my supervisor but ...
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2answers
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What is black-body equivalent of UV part of solar spectrum?

If all non-UV light was filtered from sunlight, does this approximate a different type of black body radiation? Regular sunlight has a black-body temperature of 5777 K. This is in relation to the ...
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1answer
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Why was a third particle, the neutrino, necessary to explain the continuous energy spectrum of beta-decay? [duplicate]

Question pretty much in title. I am confused as to why it couldn't just be that the energy is shared between the 'leftover' particle and the beta particle hence creating a continuous energy spectrum ...
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Is it safe to keep uranium ore in my house?

I bought 5.6 gr of uranium ore. The measured gamma radiation is 1µSv/h, we didn't have the instruments to measure alpha/beta radiation. EDIT: The gamma radiation was measured at 1cm distance. I also ...
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Does alpha decay have anything to do with weak interaction?

In alpha decay, an atomic nucleus emits an alpha particle (identical to a helium-4 nucleus). This happens in large nuclei because the nuclear force keeping the nucleus together is outweighed by the ...

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