# Tag Info

## New answers tagged scattering

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Take a look at Collision theory by Goldberger&Watson (1964). Its an old classic book covering variety of topics in scattering theory within relativistic QM and QFT.

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what is the energy of a photon? how much has that energy changed after interacting with the electron? what is the formula for the kinetic ennergy of an electron? if the electron was not moving, and all of the change of the photon energy changed th eelectron's kinetic energy, then what is the speed of the electron? divide the answer from 4. by c.

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I think I've get a better idea of what you are looking for now, thanks. As background for others in the future: classic ion-solid interaction theory dates back to the 1960s and is commonly called LSS theory after Linhard, Scharff, and Schiott who first formulated the concepts. It splits the energy loss mechanisms of the ion into two components, electronic ...

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There is no theoretical upper limit. The question is whether the description has any practical use. Real-world objects will have some small deviations from the perfect sphere or cylinder shape, for which Mie theory applies. Look at the polar diagram of scattering of red light from a 10 micron water droplet. Figure 2 in ...

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At around the $1\mu$m particle size you're in the Mie scattering regime, and this makes life hard because there isn't a simple analytic formula for the cross section due to Mie scattering. However if you're prepared to consider particle sizes significantly smaller than the wavelength of light, say $0.1\mu$m and smaller, then it's easy to show there is an ...

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OK so it's not a question of normalization. My confusion arose because of naïvety. $$\tag{1} u^{(r)\dagger}u^{(s)} = 2E\delta_{rs}$$ $$\tag{2} {\bar{u}^{(s)}}u^{(s)} = 2m.$$ Since the normalization relations $(1)$ and $(2)$ applies to same momenta spinors i.e. $\bar{u}(p)[\cdots]u(p)$ and so on. If one is not as lazy as me, one can easily derive the ...

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(I assume this is a light or neutron scattering question.) In the Guinier regime, the intensity curve follows an exponential decay: $I(q)\propto \exp[-(qR_g)^2/3]$. If you plot the (natural) log of this vs. $q^2$, you can get the radius of gyration from the slope.

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This question has bothered me for a long time, asked some real EM/optics experts but never got a satisfying answer for it, so do not expect one from me. At best I heard that it was not a stupid but an interesting question. Despite what I was ever taught I for one believe that diffraction is a manifestation of irreversibility of EM. If you start with a hole ...

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We define entropy in the electromagnetic case the same way we define it everywhere else. Entropy is the cause that (in absence of other physical changes) heat flows from hot to cold. Consider two temperature baths of different temperature facing each other. The surfaces of both temperature baths are being treated as black body radiators. Using the ...

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Vacuum magnetic birefringence basically involves the same loop diagram as light-light elastic scattering except that two of the four photons come from a magnet. Detecting this effect is the aim of the PVLAS experiment in Ferrara, Italy. See arXiv:1406.6518 and references within. The experiment is running at the moment but the sensitivity is not good enough ...

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I don't know specifically what you're looking for, but I can give you the basic idea of the relation between the cross section and the differential cross section. Generally, the cross section $\sigma$ is defined as the integral of the differential cross section $\frac{d\sigma}{d\Omega}$ over the entire solid angle. Here, $d\Omega$ is the spherical surface ...

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Increasing the contrast on the projected object might help some, as well as changing the lens, but probably the best (easiest and cheapest) way to increase the contrast on the final image is to edit it after the fact, using some image/video manipulation software.

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