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Questions tagged [scattering]

Scattering is a general term for several physical processes in which radiation of some sort changes direction due to an interaction with a particle. Scattering can be classified by the type of radiation (ie, electromagnetic, x-ray, neutron), or by the relative sizes of the wave and the particle (ie, Rayleigh, Mie, geometric).

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Thomson's Plum Pudding and Rutherford's scattering [duplicate]

Why did Rutherford's scattering experiment disprove the plum pudding? Assuming a gold-atom to be a large homogeneous ball and hitting it with small homogenuous $\alpha$-balls should lead to the ...
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Why is a diagonal scattering matrix preferable?

Maybe it is a trivial question, but it is not so clear to me why (if it is so) I would rather want a diagonal S-Matrix. Thanks
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electron free mean path understanding

I am having difficulties to grasp the idea that the probability a particle is absorbed between $x$ and $x + dx$ is given by $$dP(x) = \frac{I(x) - I(x+dx)}{I_0} = \frac{1}{l} e^{-\frac{x}{l}}dx$$ ...
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Division by 0 when calculating wave transmission and reflection coefficients

Perhaps more like a mathematical issue here... When we consider a wave propagating from medium 1 to a medium 2, boundary located at $x=0$, we have the following wave equations for the incident, ...
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Elastic X-ray diffraction: Where does the Photon Momentum go to?

lately I was discussing the following situation. Let's suppose you are doing X-Ray diffraction experiments on a crystal. So what you basically do is shooting a high energy photon with a wave vector $k$...
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Are all collisions involving photons and electrons elastic?

In my textbook it asks me to calculate the energy gained by an electron that scatters an incoming x ray through a given angle. Using the Compton scattering equation you can work out the change in ...
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Can I consider electron scattering with grain boundaries in metal as a tunneling process?

I am reading about the Mayadas-Shatzkes model (MS model). when electrons are scattered with the grain boundary, there is a probability that it will be transmitted to the other side of the grain ...
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Elastic electron scattering

In an electron diffraction pattern, the elastically scattered electrons are distributed over resolutions in the pattern corresponding to resolutions considerably higher than 1 Å. What does this ...
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Why does the frequency of a wave does not change on reflection and on transmission? [duplicate]

I wanted to know why the frequency of a wave does not change even on reflection or transmission and does it only depends on the source only.
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How do you do partial wave analysis with spin?

The derivations of the partial wave expansion I've seen have assumed spinless particles. However, when spin is involved, $l$ (orbital angular momentum) is no longer a good quantum number. What are ...
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Thickness of a target bombarded with deuterium

I need to calculate de thickness of a sheet of Zinc that is being bombarded by deuterium nuclei. I'm given that the fraction of nuclei dispersed below $\theta=90º$ with $T=8MeV$ is $0.9999$ and the ...
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The relation between the electric field and magnetic field?

I was wondering under what condition the relationship between the electric and the magnetic field holds: $\overrightarrow{B} =−\frac{\overrightarrow{𝑘}}{𝜔}×\overrightarrow{𝐸_0}𝑒^{𝑖(𝑘⃗ ⋅𝑥⃗ −𝜔𝑡)...
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Where is the missing energy in the Debye-Waller effect?

X-ray/neutron scattering from crystals and liquids is well-described by the scattering theory to give the (dynamic) structure factor which is a function of momentum and energy: $$S(\mathbf{k},\omega)=...
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Does sky luminance really decrease in steps as the Sun goes deeper under the horizon?

Playing with some atmospheric scattering simulations, I've come across a fact that, as the Sun goes lower under the horizon, sky luminance (neglecting sources of light other than the Sun) appears to ...
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Why did recombination make the universe transparent?

It is commonly said that after the universe cooled enough for ionized Hydrogen to settle down into neutral Hydrogen, i.e. recombination, the universe became transparent. A reason I have heard for this ...
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If the probability that an alpha will deflect is $1/10000$, for $n$ layers, is the probability is only $1/10000n$?

I have attached a picture of an extract I read on Wikipedia (also in the AQA A-Level Physics specification and textbook). It says that 1/10000 alpha particles deflected in the alpha particle ...
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1D Potential Barrier Boundary Conditions (tunneling)

I'm trying to solve the boundary conditions of a 1D potential barrier for a free particle. The boundary conditions on the continuity of the wave function and its first derivatives leads to four ...
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Radiative Transport Equation scattering phase density probability term question

The development of Radiative Transport Equation has a contribution term called the scattering phase density probability function. It account to scattering events from photons from a different solid ...
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Reduced absorption coefficient question

I came across a paper that reads It is noteworthy that for a sample without lateral light propagation in the material, i.e. [reduced scattering] $\mu_s' = \infty$ and [absorption] $\mu_a=0$, ... ...
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Size of transversal momenta in Multi-Regge kinematics?

Considering a scattering process in which $2$ incoming particles annihilate and produce $n-2$ other particles, one can consider the particle momenta $p_i^\mu$ (with $i=1,2,3,...,n$) to be in so called ...
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$ e^+e^- \longrightarrow \mu^+\mu^-$ probability density function of $\theta$ strange trend

I'm considering the process: $$ e^+e^- \longrightarrow \mu^+\mu^-$$ The cross section in the center-of-mass frame: \begin{equation} \left( \frac{d \sigma}{d \Omega} \right)_{CoM}= \frac{\alpha^2}{4 s}...
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Why we don't need to normalize the scattering states?

I am new to QM, have find some wavefunction in different potentials, but there we need to normalize the wave function, for a reason that - particle should be found somewhere . So a wave-function, to ...
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What is the relationship between Mie scattering amplitudes, incident intensity and outgoing intensity?

Wikipedia's Mie scattering Mathematics discusses the scattering amplitudes $S_1(\theta), \ S_2(\theta)$ for each outgoing polarization of an incident EM plane wave on a uniform sphere. It defines the ...
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Why does the red light from Sun bend towards the moon during the total lunar eclipse?

During the total lunar eclipse the earth, moon and the sun are in perfect alignment so that the moon is within the umbral shadow of the earth. However, instead of turning invisible the moon actually ...
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Light in atmosphere versus space

The atmosphere appears bright because of scattering of light whereas space appears dark due no atmosphere to aid scattering. Is it possible to demonstrate it with such darkness in a huge vaccum ...
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Fourier transform of a scatering potential

The Fermi golden rules states $$ \Gamma(\vec{k},\vec{k}') = \frac{2\pi}{\hbar} \left| \left \langle \vec{k}|V|\vec{k}' \right \rangle \right|^2 \delta(E(\vec{k})-E(\vec{k}')) \, .$$ Many places (for ...
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Doppler shift in Acousto-Optic modulators

The interaction between a beam of light and an acoustic wave is commonly modelized as a photon-phonon scattering phenomenon. Applying the conservation of energy we have that $$ \hbar\nu_1=\hbar\nu_0\...
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Centre of mass collision

A proton with momentum 3 GeV in LAB frame of reference is difussed elastically by a stationary proton. The angle of diffusion of one of the protons, in the CM system is 10º, corresponding to a moment ...
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Rate of reaction of collision in relation to the geometric cross-section

I am reading "Particles and nuclei : an introduction to the physical concepts / Bogdan Povh" and on page 44 of the book there is a section about the geometric cross section in a idealised scattering ...
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Why are there no radiative corrections to the electron charge for (an on-shell interaction)?

My question stems from the preliminary discussion of the electron vertex function found in section 6.2 of Peskin and Schroeder's Introduction to Quantum Field Theory. Specifically, they calculate the ...
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Adding helicities

The background: I am looking at Compton scattering in its most general form with $p+\gamma^*\rightarrow p'+\gamma'^*$ in the Breit-frame (which implies that in my case $\vec{p} = -\vec{p}'$). The ...
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Momentum of projectile in the centre of mass frame in a two body system

The COM frame is defined as the coordinate system in which the centre of mass of the system is at rest. In the case of a 2-body system the center of mass coordinate is: $$\vec{R_{CM}} = \frac{M_A \...
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Potential from scattering matrix [duplicate]

Given a scattering matrix, is there a procedure to find the potential from the scattering matrix? I think there should be a way as the scattering matrix holds the information of the boundary ...
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What are soft theorems in context of scalr fields

What are soft theorems ? I tried reading Weinberg’s paper but couldn’t understand it, are there any resources on this ? I am very interested in the case of scalars.
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Electrodynamics of inhomogeneous media

I'm interested in electromagnetic scattering and for that purpose I would like to write out Maxwell's equations for space-dependent permittivity (and permeability). Actually I only need them for ...
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$\psi\psi \longrightarrow \psi\psi$ scattering in Scalar Yukawa model

In David Tong's lecture notes, Equation 3.48 In line 2, how is $|0\rangle \langle 0|$ introduced between $\psi^{\dagger}(x_1)\psi^{\dagger}(x_2)\psi(x_1)\psi(x_2)?$ Why is $\langle p_2',p_1'|\psi^{\...
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Average differential cross section of neutron scattering on diatomic molecules

I am using Born Approximation to calculate this problem and I've already got the solutions to both of the problems. What confused me is the definition of the unpolarized differential cross section: $$\...
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Scattering of light in Quantum Vacuum

The quantum mechanical vacuum (i.e. the vacuum of a typical QFT) viewed as the zero-point state of the system has an energy (of course, here enters the Vacuum Catastrophe and all the mess that follows)...
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Why is intensity decreasing for higher orders of Bragg (x-ray)diffraction?

Bragg diffraction for x-rays by a crystal structure is governed by $$ n\lambda=2dsin\theta ,$$ where $n$ is an integer and the diffraction order, $\lambda$ is the x-ray wavelength, $d$ the lattice ...
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How does scattering of light happen in atmosphere?

I know that the scattering of light decreases as inversely proportional to the 4th power of wavelength. But what happens at the atomic level? Does the photon get absorbed and re-emitted? Does the ...
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Difference between Scattering and Reflection

I am confused: What exactly is the difference between optical scattering and optical reflection? To me, both terms are distinguished by where we place the observation plane. Reflection: Observation ...
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Second Order Correction to the Perturbative Approximation of the Transition Amplitudes in RQM

I am studying Relativistic Quantum Mechanics from my professor's notes. When calculating the second order perturbative correction to the transition coefficient $T_{fi}$* in a scattering process by a ...
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QFT Why do in and out states have a non-trivial overlap?

Im trying to follow chapter 4 about interacting fields in Peskin and Schröder. They define the S matrix by $_{out}<p_1 p_2 | k_a k_b>_{in} = <p_1 p_2 | S | k_a k_b>$, where $S = \lim_{T\...
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Universal curve of inelastic mean free path - why large at low energy?

I have seen the "universal" curve of inelastic mean free path (MFP) of electrons in many places (both experimental data, and just sketches of the curve) e.g. https://en.wikipedia.org/wiki/...
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Laser guns and scattering

I recently read an article that explained how the US Navy would like to use laser guns in the infrared region, with a high power - 500,000 W I guess. However, because of Rayleigh scattering that ...
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Radiative Transfer Equation: What's “multiple scattering”?

In the presence of multiple scattering, the radiative transfer equation cannot be solved analytically. But what's multiple scattering? Particularly if the RTE has the scatter coefficient, say, $\...
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Completeness of an electron-electron-scattering in the Feynman diagram

During an electron-electron-scattering in any case the electrons change their directions and by this undergo accelerations. Shouldn’t the electrons emit photons in this time, loosing a part of its ...
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Inelastic scattering and Mie theory

In most contexts in which I've come across Mie theory so far, authors do not even mention inelastic scattering but just seem to imply that all scattering is elastic. The only exception I've found is ...
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QFT cross section: missing information?

So I'm having a hard time understanding how the (QM) cross section fits into the general picture, of e.g. collider experiments. So we can calculate cross sections (for one reaction) exactly in QFT ...
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Rayleigh Scattering, Atmosphere-Dependant

I've come across the Wikipedia article on Rayleigh Scattering and it quotes that In detail, the intensity $I$ of light scattered by any one of the small spheres of diameter $d$ and refractive ...