Talk:Bremsstrahlung

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new section on quantum mechanical description

I don't know that all of the information contained in this section is accurate. There are numerous theoretical reports that contradict the statement that "electrons whose kinetic energy is larger than the rest energy (511 keV) emit photons in forward direction while electrons with a small energy emit photons isotropically" (notably, L. Kissel, C. A. Quarles, and R. H. Pratt, At. Data Nucl. Data Tables 28, 381 (1983), on which the widely-used Monte Carlo code, PENELOPE, is based). Also, there are quite a few experimental reports that contradict the statement, as well (two examples off the top of my head: J. G. Chervenak and A. Liuzzi, Phys. Rev. A 12, 26 (1975) and D. Gonzales, B. Cavness, and S. Williams, Phys. Rev. A 84, 052726 (2011)). Maybe this section should be edited. 71.170.7.22 (talk) 21:28, 19 May 2013 (UTC)scott

Should the cross section per photon energy and angle by Köhn and Ebert be removed? I find it to be rather bulky, while equivalent equations exist in H. W. Koch, J. W. Motz, Bremsstrahlung Cross-Section Formulas and Related Data; Rev. Mod. Phys. 31, 920 and R. L. Gluckstern and M. H. Hull, Jr., Polarization Dependence of the Integrated Bremsstrahlung Cross Section; Phys. Rev. 90, 1030. The latter paper gives hints about how to solve the integrals from the Bethe-Heitler diferential cross section per frequency and photon and electron angles. Perhaps it is best to substitute Köhn and Ebert's equation for the simpler, older equation. — Preceding unsigned comment added by 83.165.101.201 (talk) 16:46, 25 September 2014 (UTC)

Braking radiation has a graphical representation in the graph of X-ray intensity versus wavelength. This illustration can be found at http://fisica.indivia.net/frespettro.gif. I find it more descriptive than the verbal explanations....

http://fisica.indivia.net/frespettro.gif seems to be a dead link. Is there another place to see the illustration? —Preceding unsigned comment added by 170.134.55.135 (talk) 16:33, 2 January 2010 (UTC)

Art Carlson, Nikola Tesla was the first scientist to study X-rays produced by Bremsstrahlung. He may not be the most important (others would have more precisely research this). He didn't name this ... but he DID identify this process for obtaining x-rays (this is how he got some of his radiographs). -Anon

reason for expending the deffinition

There was an inconsistency: The deffinition here coverd only breaking radiation, while the use in the article on gyrotrons was the more general one. David Ingham

plasma section

The plasma section seems a little sparse. The formulas fall from the sky, with no references or non-numerical expression. I looked up the calculation in Ichimaru's book "basic principles of plasma physics: a statistical approach", p. 228. I get a formula (with hbar's, c',s etc.) I'll add in a few moments to the main article. Numerically it's within 10% of the quoted numerical result. I guess this partly depends on how you average over velocity distribution and so on. Also, Ichimaru's calculation involves a maximum wavenumber cutoff, which has a different value based on whether the classical distance of closest approach or the deBroglie wavelength is longer (same issue occurs when finding the Coulomb logarithm). The formulas in this section use the quantum (deBroglie) cutoff, which is correct for most hot, fully-ionized plasmas. Dstrozzi 19:23, 18 December 2005 (UTC)

error

One of the formulas on the page comes up with some sort of failed to parse error. Someone might want to work on that...

• I tried to fix it but deleted everything by some accident. When I reverted, the problem went away. I am also having other problems, so maybe it was a Wikipedia software problem? David R. Ingham 18:37, 13 February 2006 (UTC)

The figure seems to have an error. E1 is greater than E2, so it should be h(nu) (or hf) = E1-E2. —Preceding unsigned comment added by 198.129.216.160 (talk) 19:15, 9 July 2008 (UTC)

The case where acceleration is parallel to velocity / Dipole radiation

I added this section but couldn't think of a shorter name for the section. The name is a bit long.Rotiro

Evgeny, may I ask what is "BS" about Griffith's treatment of bremsstrahlung? I'm pretty sure the difference between Griffiths' and Diver's angular power distributions is that Diver's is valid in the rest frame of the moving particle, whereas Griffiths gives the radiation that an observer would see when watching a particle move with speed v subject to acceleration a. The latter is arguably more useful, and is certainly not "BS" !! I would suggest reverting the edit, except the relativistic generalization is useful. I think some combination of the two versions of this section would be best. Rotiro (talk) 20:01, 11 February 2008 (UTC) I wish I had my texts with me, but I don't. Consider consulting Landau & Lifshitz; that's a fairly authoritative source. Rotiro (talk) 20:10, 11 February 2008 (UTC)

Actually, it is obvious that my initial hunch was correct, because Griffiths' expressions reduce to Diver's in the special case v = 0. I'm going to revert to the previously existing expressions since they were more general and useful, but I'll also include some new stuff you added. Rotiro (talk) 13:17, 12 February 2008 (UTC)
I'm going to make a few more improvements soon to show the similarity between the two expressions. Instead of the new notation beta dot, which is a proper time derivative, I'll use the already-introduced acceleration, for simplicity. This also pulls out a gamma squared factor, making clear that the two expressions are identical except for the a dot v term.

Evgeny, I'm sure others will appreciate it if you use some critical thought and check well-established citations before replacing perfectly good content, and especially if you exercise some restraint before calling something "BS" (though perhaps you were referring to "BremSstrahlung" ? ;) ) Anyway, there were some weaknesses with the previously-existing content, which I have tried to fix, while also including some good points you put in. However, I think this should be kept fairly simple ... the intended audience is neither physics PhD's nor MSc's. Rotiro (talk) 13:26, 12 February 2008 (UTC)

"perfectly good content"??? Hmm. In no specific order: (i) The content uses the relativistic notations without telling the reader it's about relativistic limit and/or making him/her think it's a relativistic effect only, (ii) weird use of ${\displaystyle \mu _{0}}$ instead of ${\displaystyle \epsilon _{0}}$ (they are connected, but what's the point?), (iii) lack of non-relativistic expressions (which are needed for e.g. understanding the next section), (iv) mix of three related values (v, beta, and gamma) instead of deciding on a single one, (v) obviously wrong statements like "integrating by parts", (vi) talking only about one specific case (a||v) and not mentioning the general one, (vii) making general conclusions (electrons vs. muons rates) based on this special case only (why?), (viii) no mention whatsoever that it's about dipole approximation only, etc. Add to it that for relativistic case, the actual results are strongly influenced by the QED corrections - see e.g. Landau&Lifshits&Pitaevski IVth book. Where do you see there the m^6 dependence? --Evgeny (talk) 18:16, 12 February 2008 (UTC)
Perfectly good, not "perfect" without qualifiers. :)
• (i) Sure, it should have mentioned it was relativistic. Now it does, and all the expressions are fully relativistic and correctly reduce in the non-relativistic limit.
• (ii) mu0 and epsilon0 are equally acceptable and I see no reason to prefer one over the other. I don't see what's "weird" about it, and I don't care which is used as long as only one is, since you don't need both. However, this way you don't get large powers of c.
• (iii) Better than giving the special case v=0, to which these expressions correctly reduce. If one is interested, one can follow the link to Lorentz factor and find that gamma ~= 1 + 1/2 beta^2. I'm not sure what the concern is since all relativistic expressions are also valid in non-relativistic situations.
• (iv) Of course, simplicity is desired, but I think this is probably unavoidable. If your other expressions were valid in an arbitrary frame of reference, they would have included v, then you also have acceleration a, beta and beta-dot (not the same as a and complicating things further due to proper vs. co-ordinate time).
• (v) What on earth is obviously wrong about integrating by parts? Indeed, you integrate over all angles, and by parts is perhaps the best way, and certainly a completely possible and utterly correct way, to do this integration.
• (vi) Yes, this was because the derivation in Griffiths was nice for this simplified case. But of course the derivation is not relevant here, and it's a bit weird to have the a||v restriction, so I am reconsidering.
• (vii) Because this is basically the simplest possible example of bremsstrahlung, and it illustrates an important, relevant and general property of muons without much complication. Of course I'm aware that gamma arises to different powers in different terms such as the a dot v term, but the intention is only to demonstrate that high powers of gamma have this general effect. I'll clarify this.
• (viii) Thanks, good point.
• (ix) Can you show me what's in this book? I am separated from all my books for some time. I think I know the effect you're referring to, by a different name. If I recall correctly(?), in the ultrarelativistic case, the *proportional* energy loss flattens to a plateau, becoming approximately constant. Anyway, mentioning QED corrections in this section with anything more than a little footnote would be a vast overcomplication. As I said, the point was to use the simplest possible example of bremsstrahlung to illustrate an important characteristic of muons. The exact power of gamma is not as important.
• Anyway, thanks for the criticisms. As I said, the section had some weaknesses which I have tried to address. Also, perhaps a general word of caution about this article (not directed at Evgeny). It is becoming a bit heavy on technical detail and formula. Some editor may request it to be toned down to a more general audience. I won't trim down any sections (but other editors might in order to improve the general readability), and regardless I strongly suggest having short simple examples and using them to illustrate a basic useful point. The guidelines are: cater to a general audience, keep readers first, and make technical articles accessible. Of course that doesn't mean we can't have a useful resource for physicists, but there must be balance! Rotiro (talk) 21:38, 15 February 2008 (UTC)

In fact, the additional term due to a dot v in your expression gives a gamma^8 (!!!) dependance, which, along with the gamma^6 of the other term, only makes my point stronger. I have a strong preference for avoiding the complications of a discussion on proper vs. observer time, and not introducing additional notation, so do you mind if we change beta dot to (gamma a / c) ? And, do you have an expression for the relativistic angular power distribution for arbitrary a and v? I agree with you that there's not much point to consider only the case a||v. Rotiro (talk) 22:57, 15 February 2008 (UTC)

astro section

I added this section after being frustrated that every discussion on Bremsstrahlung radiation (BR) ignores its use in astrophysics, and specifically that BR has a broader application in the thermalized regime. The text is very simplistic, but is intended so to keep the reader from being bogged down in the specifics of calculations and physics details.

recent shortening of the article

somebody recently shortened the article cutting away a lot of text and the plot. Why? It is true that the previous incarnation was somewhat chaotic, but there was some valuable information that disappeared Gringo.ch 17:19, 9 November 2006 (UTC)

• I just noticed that also the categories physics, german loanword etc. disappeared... I will revert the page to the OCT 30 stand. Gringo.ch 17:24, 9 November 2006 (UTC)

How?

This article really needs an explanation of what causes bremsstrahlung. There's a definition of the term, but that's it. Maury 13:09, 21 November 2006 (UTC)

Beta decay

"the photon's energy comes from the electron/neutron pair"

Should this read "...from the electron/proton pair"? --67.69.5.166 21:19, 23 January 2007 (UTC)

Spelling

Shouldnt it be spelt Brehmsstrahlung? This spelling is supported by numerous website, and also the paper I am currently reading. —The preceding unsigned comment was added by RogueNinja (talkcontribs) 19:46, 2 February 2007 (UTC).

No, the spelling is correct (from german "bremsen", meaning to brake). 129.132.63.41 16:25, 1 March 2007 (UTC)

I came here to confirm I was spelling it correctly, as R. W. Bussard fairly consistently spelled it "bremmstrahlung", and I felt compelled to check after encountering that twice tonight. His spell-checker had no clue either way. The spelling in this article is consistent with every solid reference I've checked. Tomligon (talk) 03:08, 15 January 2009 (UTC)

defintely not "Brehmstrahlung", there's a german classic called "Brehms Thierleben", but that doesn't have anything to do with high energy fizzics =) ( cf. http://en.wikipedia.org/wiki/Alfred_Brehm, http://en.wikipedia.org/wiki/Brehms_Tierleben ) edit: wrong paste =)

I am from Germany, and it is Bremsstrahlung, without h and with one m. 137.226.140.178 (talk) 15:34, 26 November 2013 (UTC)

plural

Somebody added a plural form "Bremsstrahlungen". I removed it, since I do not believe this is used in english. The OED (second edition) does not report it. —The preceding unsigned comment was added by Gringo.ch (talkcontribs) 14:16, 2 April 2007 (UTC).

Correct. You can't have the plural of an innumerable noun. You can have "much Bremsstrahlung" but not "many Bremsstrahlungen". I get the same itchy feeling when people talk about "a large amount of people" instead of "a large number of people" : you can do it, but you have to mash them up first ... OrangUtanUK 17:30, 16 August 2007 (UTC)
: second that, "Bremsstrahlungen" doesn't make any sense, at least to a native speaker =)  —Preceding unsigned comment added by 87.79.148.234 (talk) 22:53, 24 November 2009 (UTC)

Questions

I've always wondered : Bremsstrahlung can occur when a particle enters a medium for which the speed of light is less that its actual speed. What happens when the speed of the particle has reduced to be equal to the speed of light - in terms of the dilation factor being infinite?

Also, is there any conceptual link between BS (no pun intended) and tachyons? OrangUtanUK 17:30, 16 August 2007 (UTC)

You may find the page on Cerenkov radiation helpful; this refers to light emitted when a charged particle moves faster than the speed of light inside a medium. When you refer to the "dilation factor", perhaps you mean the Lorentz factor ("gamma") that appears in special relativity? The speed of light "c" in the Lorentz factor is always the speed of light *in vacuum*, so nothing "mysterious" happens from the special-relativistic viewpoint when a particle moves at the speed of light *in a medium.*

I don't think there's any link between brems. and tachyons (with BS, perhaps), but I am not a high-energy physicist.

Your comments triggered my BS detector regarding various misconceptions surrounding "the speed of light." In case you or others are not clear, as far as physics is currently known, there is no way to send information faster than c (speed of light in vacuum). Inside a medium, wave phenomena (such as light) have several "speeds", in particular a phase velocity and group velocity. Typically, information and energy travel at the group vel, which is always <= c, although the phase velocity can exceed c (this is the usual case in plasma physics). Dstrozzi 18:01, 18 August 2007 (UTC)

Contrasts

Could someone put in a section on contrasts with other raditions? Just wondering. J. D. Redding 21:40, 11 March 2008 (UTC)

Science Friction: An X-Ray Machine Energized by Adhesive Tape

Is this the same phenomena? http://www.sciam.com/article.cfm?id=x-ray-machine-adhesive-tape --82.181.201.182 (talk) 18:17, 28 October 2008 (UTC)

Yes. High energy electrons can be produced by many means, but whenever they hit a material, they produce x-rays by bremsstrahlung. --Art Carlson (talk) 20:22, 28 October 2008 (UTC)
Art, did you write this article? Whoever did, well done! At last, something with the fundamenal cause, instead of the usual, and mindless, "it happens because the electrons are hot". I've been looking for something like this for over a decade! Tomligon (talk) 03:03, 15 January 2009 (UTC)

Merge from Continuous x-ray

The article looks like it duplicates material from bremsstrahlung, along with a bit of material from either photon or electron volt. It doesn't seem to introduce any new information, and doesn't seem to be a detailed enough treatment to justify a separate article, so I've proposed the merge. Please comment as to whether or not a merge should occur. --Christopher Thomas (talk) 21:19, 8 October 2009 (UTC)

What's missing is the classic graph of the output of an X-ray tube, with the "continuous x-ray" background (due to bremsstrahlung) and then the sharp peaks (due to characteristic x-rays). [searching, searching...] Aha, here it is! File:TubeSpectrum.jpg Yes, this graph and a couple sentences within this article would do the job nicely! --Steve (talk) 22:55, 8 October 2009 (UTC)
To clarify, is this a "support merge" or "oppose merge and expand the separate article" vote? I've been a bit short on sleep this week, so I'm slow on the uptake. --Christopher Thomas (talk) 23:14, 8 October 2009 (UTC)
Support merge. There's really only a sentence or two to add to this article, along with that picture. No need for a separate article. --Steve (talk) 05:23, 9 October 2009 (UTC)

Done. I actually added a whole section, "Output of X-ray tube", explaining the concept, then turned continuous x-ray into a redirect. :-) --Steve (talk) 19:08, 20 February 2010 (UTC)

Finite at zero frequency

The article says

The bremsstrahlung power spectrum rapidly decreases from being infinite at ${\displaystyle \omega =0}$

but I'm sure the power spectrum is finite and constant at low frequencies (which is the origin of the infrared divergence). It's only the number of photons that diverges, not their power. --Michael C. Price talk 05:41, 20 February 2010 (UTC)

Capitalizing bremsstrahlung?

Should bremsstrahlung be capitalized or not? It looks like there is an arbitrary mix of capitalizing it and not on the page already... so is there some consistent and correct approach? —Preceding unsigned comment added by 98.155.93.196 (talk) 06:27, 11 May 2011 (UTC)

My personal style is to consider bremsstrahlung an English word now, and therefore not to be capitalized, even though it is capitalized in its language of origin. You would expect such a rule to be listed on Wikipedia:Manual of Style (capital letters), but it's not. I did find this on List of German expressions in English:
German common nouns adopted into English are in general not initially capitalised, and the ß is generally changed to ss.
On that basis, I would say that bremsstrahlung should be consistently de-capitalized. Art Carlson (talk) 07:37, 11 May 2011 (UTC)

I just noticed that the use of italics is similarly inconsistent. Art Carlson (talk) 07:47, 11 May 2011 (UTC)

As you mention, it all depends on whether it's an English word now or not; note that the Wiktionary entry is at Wikt:bremsstrahlung since December 2006. Following that, the remaining four capitalised occorrences, and the link to Wiktionary, should be changed. Further, it should not normally be italicised. -- Michael Bednarek (talk) 10:04, 11 May 2011 (UTC)

free-free absorption

'free-free absorption' appropriately redirects to this page, but it isn't mentioned once in the article. While emission is the more common and important thing to discuss, absorption definitely needs to be addressed as-well --- i think it warrants its own section. All Clues Key (talk) 18:48, 28 July 2012 (UTC)

Formulas are inconsistent with Larmor formula article??

Please read Talk:Larmor_formula#Inconsistent_with_Bremsstrahlung?? and discuss there. Thanks!! --Steve (talk) 14:21, 12 December 2012 (UTC)