Talk:Synchrotron radiation

General comments

I am surprised you call linear acceleration synchrotron radiation; I would likely have picked "bremsstrahlung." The polarization (for a swarm of electrons with a power law spectrum) is polarized, but not perhaps "highly polarized" as was derived by Legg, M. P. C., & Westfold, K. C. 1968, ApJ, 154, 499.Pdn 16:36, 14 Jun 2005 (UTC)

"* Brilliance of about $10^{14}$."? $10^{14}$ in what units?

I need to comment here on the last part of the page. it is said:

Plasma physicist Hannes Alfvén suggested that ions travelling along a Birkeland current into a double layer, may be accelerated to relativistic velocities, which in an inhomengous magnetic field or pinches, accelerate ions to relativistic velocities through magnetic fields, producing synchrotron radiation.

However, there is absolutly no need for inhomogeneous magnetic fields. Charged particles will have, in general, a component of their velocity perpendicular to the local magnetic field, will thus gyrate and emit synchrotron emission. The whole end of this sentence does not make sense. Tusenfem

Removed for now. Be bold. Nonsuch 05:52, 1 March 2006 (UTC)

I've restored the deleted paragraph. There were TWO citations in the paragraph. Your job as editor is to clarify, not to remove stuff you don't understand. To find out what Alfvén meant, read the papers (the second paper is online in full (PDF)), asks other editors for clarification, and then rewrite it in words that you understand yourself. --Iantresman 10:15, 1 March 2006 (UTC)

I've removed POV-pusher Iantresman's attempt to circumvent consensus. Alfven's contribution is not worthy of contribution in this summary article. Just because you have a citation doesn't meant that it is editorally a wise idea to include the prose. --ScienceApologist 15:07, 1 March 2006 (UTC)

You really must get a handle on the meaning of Point of View. (1) I did not present MY point of view. (2) I did not present anyone else's point of view in a non-neutral manner. Unless you can find any SPECIFIC example in this example of where I contravened neutral point of view, I would be delighted to know.

That YOU'VE decided what is "worthy of contribution" IS a point of view. So tell me oh great one, what constitutes your worthiness? The fact that Alfvén was the first person to predict synchrotron radiation in space, based on his Nobel Prizing winning developement of magnetohydrodynamics isn't good enough for you? --Iantresman 16:10, 1 March 2006 (UTC)

There are two issues here. The first is that the sentence in question doesn't seem to make any sense. It's not even grammatically correct. It's a side issue to the subject of the article, so lets improve the article by removing this confusing paragraph. The other issue is the gratuitous portrait. In general, we don't stick a picture of everyone involved with a subject at the top of the subject article. Also, are you sure that the picture of Alfvén is fair use? The tag seems to indicate otherwise. Nonsuch 15:22, 1 March 2006 (UTC)

If the sentence doesn't make sense, we can improve it. Have a look at the citations, and propose an alternative wording. If you'd rather not, perhaps ScienceApologist can provide a dummed-down explanation of Alfvén's explanation. Do you think I should look through some of the other astronomy articles, and remove all the sentences that don't seem to make sense to me.

As for the image of Alfvén, I believe that ANY relevnant image in an article, especially in such a dry subject as this, is better than no image. Alfvén is not just vaguely related to the subject, but as mentioned earlier was the first person to predict synchrotron radiation in space. As for fair use, I don't know. --Iantresman 16:10, 1 March 2006 (UTC)

The postage stamp image shouldn't be in any of the articles it is (stamps are only fair use when illustrating the stamp itself), but Image:Hannes-alfven.jpg is okay. — Laura Scudder ☎ 17:16, 1 March 2006 (UTC)

The two mentions of "GeV-frequencies" should be "GHz-frequencies" surely? [The mention to "GeV-range" energies appears correct.] 203.109.242.80 07:11, 9 May 2006 (UTC)

I've restored the paragraph deleted by ScienceApologist on the grounds that (a) it provides a historical background to Alfvén's correct prediction of synchrotron radiation (b) it is factually accurate (c) supported by two citations.

That other summaries omit the information is irrelevent; this is not most other summaries. --Iantresman 00:01, 22 May 2006 (UTC)

Prediction of synchrotron radiation and reason

As noted by the article, synchrotron radiation was first predicted by Hannes Alfvén and Nicolai Herlofson in 1950, and subsequently confirmed by Geoffrey R. Burbidge. The reason behind such a prediction, (indeed any notable prediction), would seem to be not only non-trivial, but consistent with the scientific method. Alfvén's reasoning then, is not just another theory, but the one which enabled him and Herlofson to successfully predict synchrotron radiation.

If "... there are a billion theories on the innumerable production methods of sync rad. in space .." why is one unverified theory left in the text? --Iantresman 11:26, 28 May 2006 (UTC)

That's not what I removed. I have no doubt he was the first to predict them existing. Its his theories in the 80's on ions in Birkeland currents and double layers that are not worth including and what I removed. Is it possible that's what's happening somewhere in the universe? yes, but its certainly not a major part of sync. radiation theory. its just a grasping attempt to validate the fringe "plasma universe" nonsense and doesn't belong here. The section which I removed in no way elucidates "Alfvén's reasoning ...which enabled him and Herlofson to successfully predict synchrotron radiation", it came decades after thier prediction which originally concerned electrons in a magnetic field, not ions in plasma currents. The first cited paper has exactly 2 (TWO!) citations since publication 20 years ago! The second has maybe a dozen and a half, the vast majority of which are plasma universe paper citations. Alfven was a fine scientist, not some all knowing god to be worshipped, stop this pov pushing. --Deglr6328 16:49, 28 May 2006 (UTC)--Deglr6328 16:49, 28 May 2006 (UTC)

Multiband image of M87's jet does not show only synchrotron radiation

And therefore it has been removed. --ScienceApologist 21:19, 28 May 2006 (UTC)

No-one said that the image of M87 shows only synchrotron radiation. But according to Geoffrey Burbidge, synchrotron radiation was first detected in M87. According to a Gemini Observatory Press Releases page, "Synchrotron Radiation, is the primary radiation that is emitted by galactic jets such as the prominent jet in M-87". The page has four images of M87 in different wavelengths. Why don't you choose the one that your feel best exemplifies M87 and the emission of synchrotron radiation. The caption I believe was both factually accurate, conforms to NPOV, and relates to M87 and synchrotron radiation. --Iantresman 22:04, 28 May 2006 (UTC)

Synchrotron radiation was indeed first detected in M87, but the four wavelength-band images are not all synchrotron radiation. The image is best left for discussion at galactic jets. Why not just include the standard image of Elliptical Galaxy M87? --ScienceApologist 23:07, 28 May 2006 (UTC)

I have revised the caption to direct attention to the blue jet emerging from the AGN core. Wwheaton (talk) 16:33, 21 December 2008 (UTC)

sales brochure?

The section "Synchrotron radiation from storage rings" reads like a sales brochure, or a research prospectus written by someone who's enthusiastic about applications of synchrotron radiation. The article is about the physical phenomenon in general, however. One could equally well have written this section from the point of view of a particle physicist, for whom synchrotron radiation is a nuisance. There's nothing wrong with talking about applications, but it should be clear that that's what's being talked about, and it shouldn't be incongruously prominent in the article.--76.81.164.27 02:53, 10 March 2007 (UTC)

What is the difference between brightness, intensity, and brilliance?

The article lists as characteristics of synchrotron radiation:

1. High brightness and high intensity, many orders of magnitude more than with X-rays produced in conventional X-ray tubes
2. High brilliance, exceeding other natural and artificial light sources by many orders of magnitude

Can someone who understands the technical difference between brightness, intensity, and brilliance in this context make an attempt to translate each of these into a short phrase understandable to a layperson, as has been done here for other technical terms (e.g. high collimation, low emittance)? These three words are pretty much synonyms in ordinary daily English and even in many scientific contexts, but they are listed separately here as though they refer to three distinct characteristics. Piperh 20:20, 6 June 2007 (UTC)

This issue still needs addressing, though it is now moved somewhat to the companion synchrotron light source article. Probably a search through WikiP for articles on light, radiation transport, intensity (physics), photometry, etc should reveal careful definitions of these terms, but I have not yet done that. Wwheaton (talk) 16:51, 21 December 2008 (UTC)

Bremsstrahlung radiation

Skoch3 (talk) 06:09, 3 November 2008 (UTC):Shouldn't there be a brief mention of and link to the Bremsstrahlung_radiation article?

I think not, as it is entirely different in physical origin, though there are instances (in astronomy, say) when questions arise as to the nature of some particular radiation source. I would link as appropriate from the discussion of such cases, wherever they arise. Wwheaton (talk) 16:45, 21 December 2008 (UTC)

Merging Synchrotron radiation with Synchrotron light

 Done, with some name and scope changes as laid out below. Wwheaton (talk) 16:39, 21 December 2008 (UTC)

Someone added a merge header to the Synchrotron radiation and Synchrotron light articles, but didn't add a comment to the talk page suggesting why. I'll do the honors: "Synchrotron radiation" and "Synchrotron light" are the same thing. The only difference is that the latter could be considered a subset of the former, but the articles as written make (and need) no such distinction. The opening sections try to define the "Synchrotron light" article as being concerned with the applications of synchrotron radiation, while the "Synchrotron radiation" article is concerned with the production of synchrotron radiation, but that's a false bifurcation of a single topic. I strongly advocate merging the two articles. -- Dan Griscom (talk) 02:26, 12 November 2008 (UTC)

Strong Support The two are the same thing. (TimothyRias (talk) 11:06, 15 December 2008 (UTC))

I support the merge, but the Synchrotron light article seems to be largely about synchrotron light sources, the specialized electron accelerators use for x-ray and extreme UV materials research, etc. How about a general article focused on the physics of synchrotron radiation, and a general one on synchrotron light sources, with a link from Particle accelerators? Wwheaton (talk) 19:55, 20 December 2008 (UTC)

In fact, after looking around a bit more, I have moved the old Synchrotron light to Synchrotron light sources. I hope this is a step in the right direction. Wwheaton (talk) 20:08, 20 December 2008 (UTC)

And now the accelerator stuff in this article largely needs to be moved over to the Synchrotron light sources article, retaining the physics and astrophysics material here. Once that is done, the redirect from Synchrotron light to Synchrotron light sources probably needs to be switched to point here, to Synchrotron radiation. Wwheaton (talk) 20:20, 20 December 2008 (UTC)

Needs work

I have to stop now, but the article is still a bit of a mess. I hope it is at least a little better. In particular it almost totally lacks any real discussion of the emission physics, spectrum, and polarization, which I think should be the core material after the lead. Most of the section on storage rings needs to be moved to the Synchrotron light source article. I think there should be some mention of curvature radiation in the astrophysics section at least, but will have to go back to my textbooks before I can supply it. Wwheaton (talk) 02:48, 21 December 2008 (UTC)

I have done a little more, moving the "Storage rings" material to the synchrotron light source article, retaining a copy of a little of it that is relevant to the emission physics. I have basically not removed any material from either of the two articles except for what seemed obvious duplication. However all the references are now here, "Synchrotron light source" being completely unsourced. Nor have I added anything except smoothing connectives and explanation to ease the flow. Anyway, others should feel free to leap in. Wwheaton (talk) 19:16, 21 December 2008 (UTC)

Needs to have more information on how synchrotron radiation follows from the Lorentz force law. —Preceding unsigned comment added by Michael.r.sabino (talk • contribs) 03:05, 17 July 2010 (UTC)

Citation Image

This image http://en.wikipedia.org/wiki/File:Syncrotron_radiation_energy_flux.png seems to be a reproduction from D. H. Tomboulian and P. L. Hartman, Phys. Rev. 102 (1956) 1423. Shouldn't that be cited? 192.44.85.28 (talk) 12:07, 23 January 2014 (UTC)

Physical Meaning of the Critical Frequency

I think the physical meaning of the critical frequency as the frequency that divides the emitted power into equal halves (from: http://xdb.lbl.gov/Section2/Sec_2-1.html), should be added. Just giving out the equation without physical meaning is not helpful. سادىق سېتىنىياز (talk) 01:29, 2 December 2014 (UTC) — Preceding unsigned comment added by Sadik82 (talk • contribs) 01:22, 2 December 2014 (UTC)

Equation 8, and others

One of the equations has been recently changed by the user Special:Contributions/2001:DA8:D800:740:C19E:3912:33F4:CA84, as follows:

Integration over the whole solid angle yields the total power radiated by one electron

Old version:
$P={\frac {e^{2}}{6\pi \epsilon _{0}c}}\left|{\dot {\vec {\beta }}}\right|^{2}\gamma ^{4}={\frac {e^{2}c}{6\pi \epsilon _{0}}}{\frac {\gamma ^{4}}{\rho ^{2}}}={\frac {e^{4}}{6\pi \epsilon _{0}m^{4}c^{5}}}E^{2}B^{2},\qquad (8)$

New version, with a single $\beta ^{4}$ added:
$P={\frac {e^{2}}{6\pi \epsilon _{0}c}}\left|{\dot {\vec {\beta }}}\right|^{2}\gamma ^{4}={\frac {e^{2}c}{6\pi \epsilon _{0}}}{\frac {\beta ^{4}\gamma ^{4}}{\rho ^{2}}}={\frac {e^{4}}{6\pi \epsilon _{0}m^{4}c^{5}}}E^{2}B^{2},\qquad (8)$

I'd like someone knowledgeable to take a look at this equation to see which version is right. In fact, preferably someone should verify all the equations we have in the article -- it seems their accuracy is somewhat dubious. JudgeDeadd (talk) 11:05, 30 December 2014 (UTC)

You can derive the energy loss from [4.3] & [4.2] from https://slac.stanford.edu/pubs/slacreports/reports02/slac-r-121.pdf using:

$r_{\text{e}}={\frac {1}{4\pi \varepsilon _{0}}}{\frac {e^{2}}{m_{\text{e}}c^{2}}}$

and get:

$P_{\gamma }={\frac {e^{4}}{6\pi \epsilon _{0}m^{4}c^{5}}}E^{2}B^{2}$

or using the radius of curvature [4.4]:

$P_{\gamma }={\frac {e^{2}c\gamma ^{4}}{6\pi \epsilon _{0}\rho ^{2}}}$

first version seems ok for me. Jlpons (talk) 10:58, 24 November 2023 (UTC)

After more reflexion, the above formula are valid for a speed close to c $\beta \approx 1$. The radius of curvature is equal to:

$\rho ={\frac {\beta ^{2}c^{2}}{a}}$ where a is the acceleration (centripetal acceleration)

So the formula should be corrected with $\beta$

However in the formula the $\beta$ vector is confusing. Jlpons (talk) 07:50, 25 November 2023 (UTC)

'History of Detection' and Reber

The section states that SR "was first detected in a jet emitted by Messier 87 in 1956 by Geoffrey R. Burbidge". The article on Grote Reber notes (without citation) that his observations of significant low-energy radio signals did not support the (then-current) black-body radiation model. The Reber article then reads: "It was not until the 1950s that synchrotron radiation was offered as an explanation for these measurements."

Since Reber was essentially the world's only radio astronomer for a decade, doing much his work in the VHF range (GHz receivers being,erm, a bit crude in the 40s), it's quite possible that the 'detection' came before even Alfven and Herlofson. Alas, I don't have access to the Reber publications, but here's a bibliography of 91 of them (20 before 1950). Some attention to Reber seems appropriate here. Twang (talk) 07:34, 2 September 2015 (UTC)

Article needs an APPLICATIONS section

This article needs to have a section on the uses and applications of synchrotron radiation. The reader needs to be informed about X-ray crystallography, without which we would not know anything about protein-structures, and photoemission, which is essential for analysis of semiconductors and other technologically-important surfaces. HandsomeMrToad (talk) 03:49, 27 November 2016 (UTC)

Reevaluate article quality

This article is still marked as start-class quality, which I believe is inappropriate given that this article is now longer, has good graphics, and contains relevant physics equations. Would anyone be willing to reevaluate this article for quality? Mooseandbruce1 (talk) 07:29, 27 February 2017 (UTC)

Bremsstrahlung again

The connection with Bremsstrahlung has been discussed above and rejected on the grounds that it is of different physical origin. That contradicts the Bremsstrahlung article, which states this is simply a narrower definition of the same physical events. As I understand it, both are caused by the same underlying mechanism, the only difference between the definitions being that one is linear and the other perpendicular. Is there a difference in the underlying physical mechanism, or is the difference essentially source related? Maury Markowitz (talk) 12:53, 10 October 2017 (UTC)

I am retired, with most of my books in storage, and rapidly losing my memory..., so the likelihood of my adding anything useful is small, but I will try and think about it. However, I believe the answer to your question is "no". The meaning of "linear" and "perpendicular" depends on the velocity of the frame of reference, but of course the physical mechanism does not. By the way, it seems to have been agreed and settled in the Bremsstrahlung article talk page that the correct rendering of the noun in English is "bremsstrahlung", spelling correct, but lower case for the anglicized noun; but of course confused by the need for capitalization in the article title. Cheers, Wwheaton (talk) 19:53, 10 October 2017 (UTC)

@Wwheaton: I'm concerned about the "physical mechanism" part. That appears to be "acceleration" in both cases. This is the crux of my question. Maury Markowitz (talk) 20:41, 11 October 2017 (UTC)

Sorry so slow to respond, but yes, it is merely a matter of conventional usage. Any acceleration of a charged particle produces EM radiation. In the case of synchrotron radiation, this acceleration is produced by a magnetic field, while in the case of bremsstrahlung it is produced by the particle (usually electrons) bumping through matter at high speeds, in which case it is a chaotic mix of electric and magnetic fields that do the accelerating.

But notice that the distinction between B and E fields is not fundamental, and depends on the Lorentz frame of the observer — they are both part of the EM field, which is really a tensor object with components that transform in a complicated way with motion. In the rest frame of the charged particle, the magnetic component is zero, and the force is entirely electric. So, no synchrotron radiation from that rest frame point of view, in which "linear" and "perpendicular" have no meaning. Wwheaton (talk) 07:25, 3 December 2017 (UTC)

@Wwheaton: I just noticed that the lede already mentions this, sort of, in passing. I think that's good enough. Maury Markowitz (talk) 02:23, 8 December 2017 (UTC)

Density?

From the text of the article: "photoelectrons ... propagate secondary electrons from the pipe walls with increasing frequency and density up to 7×10^10." What are the units of the density being specified? Unless I am missing some concept by which density can be a unitless quantity, there should be units specified here. Dratman (talk) 02:06, 12 February 2019 (UTC)

Section "synchrotron radiation in astronomy" completely misleading

It all about bremmstralung and other emissions due to relativistic particle-particle collisions, but not about synchrotron radiation, which is due to interaction of particles with macroscopic magnetic field. Although SR emissions of discussed objects exists and very important, they are radio emissions, they not seen on images, and not mentioned in text.Lexey73 (talk) 10:47, 19 February 2023 (UTC)