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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How to set up this integral properly?
I'm trying to find the most general expression to compute the total radiant flux (in watts) that a given collector surface $S_{C}$ receives from an emitter surface, $S_E$ (see poorly draw illustration ...
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Radiation beta radiation [closed]
Beta-ray emitted by a radioactive substance is option A, an electron which was existing outside the nucleus, option B, an electron which was existing inside the nucleus, option C, a pulse of ...
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Understanding Bremsstrahlung computation in Peskin & Schroeder book
In an introduction to QFT by Peskin & Schroeder page 181 there is an approximation for the following expression:
$$\mathcal{I}(\textbf{v},\textbf{v'}) = \int{\frac{d\Omega_\hat{k}}{4\pi}\frac{2(1-\...
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Is there lower-frequency radiation than Gamma rays due to decay? [duplicate]
Why should all radiation from decay be in the same range?
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Doppler Shift in Moving Medium
Would the medium between a stationary source and observer moving cause a shift if the source and observer are on opposite sides of the medium?
The reason for this question is that I was noticing how ...
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Beta-plus decay, a many-body problem?
In the beta-plus decay, a proton turns into a neutron, a positron, and a neutrino.
But the mass of a proton is less than a neutron. This of course indicates that an isolated proton is stabel against ...
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Do the quarks in neutrons tend to have much larger momenta than the quarks in protons?
Context
The Feynman diagram for beta decay of a neutron into a proton, electron, and electron antineutrino via an intermediate
$W^-$ boson is given in many places, which includes [1]. I understand ...
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My ionizing smoke detector fell a month ago. Is it possible I've been irradiated? [closed]
My ionizing smoke detector is from Kidd, it's written it produces 0.6 microCuries in nominal conditions but a) It's expired since 2010 (I'm renting, just realised this), and b) It fell out of nowhere ...
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How well does a cavity with a hole approximate a black body?
Cavity with a hole is a frequently cited approximation to a black body (more precisely, it is the hole that is the black body here):
Is there a simple estimate of how well such a cavity approximates ...
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Regarding the absorption property of a blackbody
Consider a blackbody of surface area $S_b$ and at temperature $T_b$. It is placed inside an evacuated chamber (to neglect all the effects of convection), with walls of chamber at temperature $T_c$ and ...
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What are some highly unstable phenomena you can observe from lightyears away?
I'm currently drafting some scifi story where the protagonist is in a long timeloop and wants to figure out when the loop starts exactly based on observing some unstable phenomena, like atomic decay ...
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Neutron diffusion equation cylinder question
Hi there I was wondering if anyone could help me with how to approach this problem that I have. I'm looking to find the neutron flux outside of a cylindrical container which is made of steel, however ...
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Does the Host Rock of This Mexican Hyalite Show Signs of Uranium Minerals? I Previously Cut It and Am Now Concerned
I previously cut a Hyalite specimen from Zacatecas, Mexico. Using a Geiger counter, I measured a slightly higher level of radioactivity on the cut surface compared to the environment. Although I know ...
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Y90 and Sr90 beta emissions have the same ranges but different average energies?
Why does Y90 and Sr90 beta emissions have the same range in air if they have different energy averages (0.935 MeV, 0.196 MeV, espectively)? I would assume that their average energy would indicate ...
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Is the generation of NMR signal due to spontaneous emission?
The usual description of how NMR signal is generated is that the sample has some equilibrium magnetisation along the $z$ axis, this is then flipped into the $x$-$y$ plane by a 90° pulse and there it ...
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Why are zirconium pressure tubes stored in waste containers when removed from nuclear plants?
Hi this is probably a bit of a silly question but I've been thinking a lot about the use of zirconium in nuclear plants. I know that zirconium has a very low neutron absorption cross section and that'...
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Which exact element makes Spent Nuclear Fuel dangerous?
I understand that beta and gamma emissions are what makes the decay of a radioisotope dangerous. However, U-238, which is what SNF is mostly made of, doesn't emit gamma or beta particles frequently ...
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How to calculate mean energy of fluorine-18 positron?
I know that Fluorine-18 becomes stable when a neutron takes the place of a proton and becomes Oxygen-18 where a positron and nutrino are emitted.
Using Einstein formula, I can find the maximum energy (...
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Do alpha and beta particles have the same energy regardless of its source?
The dangers of nuclear radiation are often described in terms of its penetration power. For instance, alpha particles can be blocked by a sheet of paper, whereas gamma can be stopped by a thick piece ...
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What happens to the electric field in an accelerated capacitor?
Say we have a charged capacitor with some charge $Q$ in one of its plates (and of course the opposite charge on the other plate). It is a well-known result that the electric field inside this ...
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Geiger-Nuttall law alternative form
I've seen the two forms of Geiger-Nuttall law. which is the
$$log\;\omega = aE^{1/2} + b\hspace{5em}:(1)$$ and $$log\;\omega=a'logR_{\alpha}+b'\hspace{4em}:(2)$$
From the range-energy relation, we ...
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Why does a heated body emit a continuous spectrum of waves, while a burning body emits one color?
Why does a heated body emit a continuous spectrum of waves (as I understand it, that's why they burn red/white/blue), and a burning body is one color?
as I understood it, for example, the green flame ...
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Demonstration of constant radiance for Lambertian Surfaces
I'm approaching to radiometry and I'm struggling with one of the properties of Lambertian surfaces.
We know that the radiance is the radiant flux emitted, reflected, transmitted or received by a ...
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Radiation power emmited by a material with two different temperatures [closed]
Let's consider a cylindrical sample of a solid material surrounded by air. From $0 \leq r \leq r_1$ the temperature of the material is $T_1$ and from $r_1 < r \leq R$, $T=T_0$ which is also the ...
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Gravitational wave flux in Effective One-Body (EOB) models
I'm working for my M2 internship on gravitational waves in effective one-body approach, and I'm struggling in understanding how they compute the non-conservative flux from GW radiations. Most of the ...
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Average kinetic energy of a non-relativistic electron in beta decay
I am trying to show that (a bird told me), in a beta decay, the average kinetic energy carried off by a non-relativistic electron is $E_0 / 3$. I have derived that, for the states, a distribution
$$dN ...
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How to measure light intensity in a room?
Does anyone know how I would go about measuring the light intensity in a room? I'm not interested in knowing the lux reading, I would like to measure the $W/m^2$ due to thermal radiation in my ...
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Radiation due to charge particles
We know that accelerated charged particles emits em waves/energy.When we apply voltage across a conductor the electric field applies force on the electrons then why don't the electrons in the ...
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What force expels the negative charged particle in carbon 14?
What force expels the negative charged particle from carbon 14 as radiation ? Is it electromagnetic force, strong force or weak force ??
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Why are absorbing bodies hotter over time than reflecting bodies?
I recently learnt about energy transfer by EM Waves and came across the formula for momentum transfer, i.e.
Δp = U/c → perfect absorption
Δp = 2U/c → perfect reflection
then why do absorbing bodies ...
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Why is $^{176}\rm{Lu}$ so stable with respect to $\beta^-$ decay?
The nuclide $^{176}\rm{Lu}$ (spin $7^-$) can decay to the $6^+$ state of $^{176}\rm{Hf}$, with a $Q$ value of $593.33\,\rm{keV}$. The change in spin $J$ and parity $π$ is only $\Delta J^{\Delta\pi} = ...
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Unusual High Ionizing Radiation Levels Detected in Eastern USA
I've been monitoring radiation levels using a Terra-P MKS-05 IP30 dosimeter and have observed some alarmingly high spikes that I cannot fully explain. I'd like to see if anyone may have some insights ...
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$\beta^-$ decay of $^{247}\rm{Cm}$ to excited states of $^{247}\rm{Bk}$
The nuclide $^{247}\rm{Cm}$ is only known to be an alpha emitter with a half life of $1.56\times 10^7$ years. In theory, it is also capable of $\beta^-$ decay to $^{247}\rm{Bk}$ with a $Q$ value of $...
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Why is radiation power defined at infinity?
According to Griffiths in chapter 11 , given a source of radiation enclosed by a sphere, the power passing through the sphere is
$$ P(r) = \oint \mathbf{S} \cdot d\mathbf{a} = \frac{1}{\mu_0} \oint (...
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How were luminous intensity changes for each EM frequency measured in the blackbody experiments of the late 19th c., which led to up to Planck’s Law?
If in today’s parlance it would be either ‘spectral density’ or ‘spectral radiance’ that was in fact measured then as opposed to ‘luminous intensity’ please feel free to clarify.
Kindly note that my ...
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Defining Nuclear Reaction and Beta Decay
I use a school textbook that defines nuclear reaction in the following way. I will go through what does make sense to me, and then point out the thorns.
"When an atom changes into a different ...
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Exponential decay of relativistic muons
I am working on an exercise that models the exponential decay of muons. The problem asks to calculate the percentage of surviving muons after $ 50 \mu s $ in two situations:
Stationary muons.
Muons ...
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Absorption and emission spectrum
I was wondering how do you see a spectrum when light is passed through a substance. Like most of the substances we use are opaque, so how does light pass through them without being reflected? Also ...
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The sharing of energy between beta particle and its neutrino
the answer to this is that the KE is constant, and that beta has a continuous range of energy. I understand that the energy in beta particle decay is distributed between the neutrino and the beta ...
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What is heat in radiation?
In any system, to interact with the matter present in it, force will inevitably be involved no matter what kind of field or collision was it caused by (well collision also involve some field in almost ...
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Can a region of electromagnetic waves alone be considered a thermodynamic system? Can work and heat interactions be made sense for them?
Consider an ideal antenna producing coherent radio waves, and suppose the waves are not received by any body (they are sent off to space). Can we say a work interaction/transfer has been done? Or is ...
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Transition from positive energies to negative energies in Dirac equation
In textbooks, the criticism of the Dirac equation is that it may allow transitions from the positive energy state $m c^2$ to its corresponding negative energy state by releasing one or more photons. ...
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Self-interference of nuclear decay
Consider a stationary atom undergoing radioactive decay. The probability density function for decaying at time $t$ is given by an exponential distribution:
$$p(t)=\lambda e^{-\lambda x}$$
When ...
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Calculating the efficiency of a solar cell based on the wattage of the lamp powering it [closed]
I am working to characterize some solar cells I have access to based on their material structure by measuring the IV curve of the cells. I can generally compare the cells by comparing their $P_{max-...
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Why is the temperature of electron-proton recombination obtained from Saha equation so small?
I read a blog about the temperature of the Universe at recombination phase.
The ionization potential of a hydrogen atom is $13.6\, eV$, throw it into the thermal energy equation $E=\frac{3}{2}kT$, ...
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Beta decay in Au-198 element
Book "Atoms, radiation, and radiatuon protection" shows decay modes in appendix.
In case of Au-198, there is only one type of decay β-.
β- : 0.255max (avg 0.079) (1%)
0.961max (avg 0.315) (...
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Photons and Bremsstrahlung radiation
When fast electrons goes into a target, part of their kinetic energy is converted into electromagnetic radiation, that we call Bremsstrahlung radiation, as they change their velocity. The energy ...
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Electromagnetic radiation exposure power density per wavelength
Does anyone know a theoretical study or an experimental study of the electromagnetic ambient power density at different wavelengths? To ask simply, how much electromagnetism are human usually exposed ...
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Why does an alpha particle traveling at the same speed as a beta particle have 'only' about twenty times the energy? Rather than over seven thousand? [closed]
An alpha particle travels at about half the speed as a beta particle, right? ~5% of light speed versus ~10%?
Therefore, if you doubled its velocity, its energy would roughly quadruple, correct? (Or ...
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Why do we see a black hole shadow despite the fact that there is hot gas all around it and not all radiation is absorbed by the horizon?
If the accretion disk surrounds the black hole (like that seen in M87 by the Event Horizon Telescope) but is too far away from the black hole to have its light captured, why do we still see a black ...
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