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Baroo
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How ,exactly, are gamma and beta radiations produced in electron accelerators? Is the process for gamma almost the same as X-ray in linear accelerators? What about beta?
Hello. May I ask a question concerning definitions (?), because clearly I am out of step with some on this forum. It is probably minor but is a big deal to me as a Nuclear Metrologist. We are trained to take measurements and MUST use certain terminology to describe those results. If this is not proper or I am in the wrong place, please give guidance.There are no beta rays produced by an Accelerator. Gamma rays are produced by interaction of electrons (bremsstrahlung).
What definitions are out of step ?
My definitions (the definitions imposed upon Gamma Spectrometry practitioners) are definitely out of step and quite different from those that PF instructors/mentors often (always?) use, and the one you just used. It would really be great if a Glossary would be posted (maybe it is and I can't find it?). I will be happy to move this to the appropriate forum if advised..
The main example is the use of the word Gamma Ray: "Gamma rays are produced by interaction of electrons (bremsstrahlung)"
let me explain-
In the scientific world I inhabit (nuclear metrology) Gamma Ray means simply, but strictly: "an electromagnetic photon produced within an a atomic nucleus", while on PF board it is used as a description of any photon within a certain segment of the electromagnetic spectrum.
In our lexicon, a photon produced in the atomic electron shell are X-Rays, and special cases like Bremsstrahlung are produced by charged particles during acceleration and/or decelleration. The list includes Annihilation Radiation from anti-particle annihilation, etc.
Here on PF I was ridiculed for some statement involving photons with the comment: "Are you CRAZY? Photons are PARTICLES". And another time "GRAVITY IS NOT A FORCE, it is a region in space-time".
Yes we need a glossary, but we also need respect between disciplines.
A lot of us are out here doing mundane room-temperature physics.
George Dowell
My definitions (the definitions imposed upon Gamma Spectrometry practitioners) are definitely out of step and quite different from those that PF instructors/mentors often (always?) use, and the one you just used. It would really be great if a Glossary would be posted (maybe it is and I can't find it?). I will be happy to move this to the appropriate forum if advised..
The main example is the use of the word Gamma Ray: "Gamma rays are produced by interaction of electrons (bremsstrahlung)"
let me explain-
In the scientific world I inhabit (nuclear metrology) Gamma Ray means simply, but strictly: "an electromagnetic photon produced within an a atomic nucleus", while on PF board it is used as a description of any photon within a certain segment of the electromagnetic spectrum.
In our lexicon, a photon produced in the atomic electron shell are X-Rays, and special cases like Bremsstrahlung are produced by charged particles during acceleration and/or decelleration. The list includes Annihilation Radiation from anti-particle annihilation, etc.
Here on PF I was ridiculed for some statement involving photons with the comment: "Are you CRAZY? Photons are PARTICLES". And another time "GRAVITY IS NOT A FORCE, it is a region in space-time".
Yes we need a glossary, but we also need respect between disciplines.
A lot of us are out here doing mundane room-temperature physics.
George Dowell
Would you mind very much telling me the definition you folks use for the word "Ray"?But you are using the definition restricted to within your profession, and thinking that that is the ONLY path to create gamma rays.
Gamma rays, first and foremost, is an electromagnetic wave! How and where it comes from is irrelevant in the general sense of its identity, as long as it falls within the frequency spectrum that we loosely define to be "gamma rays".
You may be familiar with nuclear processes that generate gamma rays, but it doesn't mean that this is the ONLY mechanism. In the context of this thread, i.e. particle accelerators, high energy electrons being stopped very quickly by either a beam-stop or something else can create high-frequency "braking radiation", i.e. bremsstrahlung.
I would not be surprised if, in a few years, advances in beam physics and insertion devices would have advanced enough that we will get gamma radiation (we already have hard x-rays) from FEL and synchrotron beamlines. Again, no nuclear processes there either!
Zz.
Would you mind very much telling me the definition you folks use for the word "Ray"?
Thank you.
George Dowell
But you are using the definition restricted to within your profession, and thinking that that is the ONLY path to create gamma rays.
Well, according to this definition it is the only path (as gamma radiation is defined to be radiation from a nucleus, in that sense the gamma and x-ray spectrum overlap). I have to agree that I find this to be a pretty standard definition, and if the question is "How is gamma radiation produced, in difference to X-rays" it is important to know what definition one uses for these words (in particular if beta radiation is in the mix, that also usually is reserved for electrons/positrons from nuclear decays).
Would you mind tell me if you actually understood the main point that I made regarding your restricted definition of gamma "ray" or "photons"?
Zz.
But since WHEN did the SOURCE of EM radiation became part of the definition of what it is?
Yes I heard you, and I agree Gamma Rays are photons.
Gamma Rays as defined by Australian Government, Austaralian Radiation Protection and Nuclear Safety Department:
What are gamma rays?
"A gamma ray (g) is a packet of electromagnetic energy (photon) emitted by the nucleus of some radionuclides following radioactive decay. Gamma photons are the most energetic photons in the electromagnetic spectrum."
US NRC: "Radioactive decay
"The spontaneous transformation of one radioisotope into one or more different isotopes (known as “decay products” or “daughter products”), accompanied by a decrease in radioactivity (compared to the parent material)." This is the definition we (must) use. Merely emitting energy in the form of a gamma ray after the fact has a name too, IT= Isomeric Transition, note this is the daughter doing that not the parent.
Now what are you basic definitions.
And considering that I've shown where this definition is violated, who is at fault here?
Electromagnetic Spectrum
It has nothing to do with how or where it was created.
thinking that all EM radiation within this range can ONLY be generated via nuclear reaction is patently FALSE!
And considering that I've shown where this definition is violated, who is at fault here?
That is not the definition of gamma rays. That is the definition of radioactive decay.
It is EM radiation within a loosely defined range of frequency shown in the spectrum of EM radiation.
https://www2.lbl.gov/MicroWorlds/ALSTool/EMSpec/EMSpec2.html
It has nothing to do with how or where it was created.
In the end, what name you give it doesn't affect it one bit. However, the physics that is associated with it does matter, and erroneously thinking that all EM radiation within this range can ONLY be generated via nuclear reaction is patently FALSE!
Think about this: If I have a clump of electrons, and I jiggle it back and forth fast enough, I can generate EM radiation/photons at any frequency that I want, including gamma photons. This, naively, is what we do with those wigglers and undulators insertion devices in FELs and synchrotron centers all over the world. Nowhere in there do I require a radioactive decay.
Zz.
You just showed that two definitions of the word "gamma radiation" are incompatible.
So on the right edge of this picture there are "Hard X Rays" and "Gamma Rays" with the same wavelength/energy. What is then the difference between these two?
You seem to have this backwards. If you adopt the definition that gamma rays are the ones produced from nucleus, there is no reference to their energy. Only em radiation from nuclei is called gamma ray in this convention, this does not say that there is no other radiation in the same range where nuclear reactions typically are.
This is why I said that the "label", i.e. the name doesn't matter.
I'd call it a Twinkie, because I can.
All I care about is what it does, what property it has, and what it can do.
Oh look! NASA is misusing the name "gamma rays" in looking for the range of EM spectrum coming from "black holes and exploding stars"! None of those came from nuclear decay. Tsk, tsk. Someone should tell them that names and labels matter. They should rename that silly telescope because, obviously, even though they are looking for the same frequency range as gamma rays, these can't be given the same name!
I certainly agree with that. You just have to make sure to agree on what label to use for what. This is why I pointed out that there are two different definitions of gamma rays, with none better than the other (without any detail on the application), but which would give different answers to the question "How are gamma rays produced.".
Personally I don't care what definition is used, as long as you tell me which one.
But if you want to talk to someone about a Twinkie, you will have to tell him what exactly you mean by it.
But the question here was in particular how it is produced.
Sure, if you are handed photons and are asked to do something it makes more sense to label them according to their properties.
But if I am haded different sources of photons I might be more interested in how these sources work, what mechanism is responsible for photon production within them. I might not care particularly about the exact properties of the photons and "what they can do". In that case I will choose my labels rather according to the properties of the source.
Again, I am not advocating for any of these definitions, just pointing out that they exist and make some sense in particular circumstances.
No one is insisting that one of the two definitions is better. The two are just used in different physics communities.
"Oh look! NASA is misusing the name "gamma rays" in looking for the range of EM spectrum coming from "black holes and exploding stars"! None of those came from nuclear decay. Tsk, tsk."Oh look! NASA is misusing the name "gamma rays" in looking for the range of EM spectrum coming from "black holes and exploding stars"! None of those came from nuclear decay. Tsk, tsk. Someone should tell them that names and labels matter. They should rename that silly telescope because, obviously, even though they are looking for the same frequency range as gamma rays, these can't be given the same name!
Zz.
I have zero issues with what you wrote here.
who was insisting that gamma rays must only come from nuclear reactions
and that to claim that a bremsstrahlung process can also generate similar EM radiation is a contradiction to the definition of "gamma rays"
I did not find that statement above. Can you point to the relevant post?
"Oh look! NASA is misusing the name "gamma rays" in looking for the range of EM spectrum coming from "black holes and exploding stars"! None of those came from nuclear decay. Tsk, tsk."
Of course these very much are Gamma Rays. Stars work by nuclear fusion, maybe some fission, lots of neutron activation- all nucleus related.
Definitely near the event horizon, nuclear disintegration. All clearly nuclear, all releasing the very powerful nuclear binding energy also known as mass deficit.
Were not that far apart really.
George Dowell
Post #6.
I don't find a statement about the energies of emissions from nuclear reactions or of bremsstrahlung there, in particular not that they would not overlap.
https://en.wikipedia.org/wiki/Gamma_rayWikipedia said:Gamma rays and X-rays are both electromagnetic radiation, and since they overlap in the electromagnetic spectrum, the terminology varies between scientific disciplines. In some fields of physics, they are distinguished by their origin: Gamma rays are created by nuclear decay, while in the case of X-rays, the origin is outside the nucleus. In astrophysics, gamma rays are conventionally defined as having photon energies above 100 keV and are the subject of gamma ray astronomy, while radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy. This convention stems from the early man-made X-rays, which had energies only up to 100 keV, whereas many gamma rays could go to higher energies. A large fraction of astronomical gamma rays are screened by Earth's atmosphere.
Wikipedia is a terrible citation for anything scientific.
"The only characteristics that DEFINE the 100 keV photon are its energy (which then defines its frequency and wavelength), its momentum (which then defines its direction), and its angular momentum quantum number. Nowhere in there is there an imprint or information on how it was created."The problem here has never been that "we call this range of EM spectrum as X" and then "we call this range of the EM spectrum as Y". As I've said, these are merely superficial labels, and those who care more about the physics than such labels really are using them only as a shortcut for communicating the frequency range.
Rather, the issue here is that "if you call this X, then it MUST only come from this process". That is what I have a problem with. As I've asked before, if I give you a 100 keV photon, are you able to tell me, using that alone, that it came from a nuclear reaction, a black hole, a synchrotron radiation center, etc... ?
The only characteristics that DEFINE the 100 keV photon are its energy (which then defines its frequency and wavelength), its momentum (which then defines its direction), and its angular momentum quantum number. Nowhere in there is there an imprint or information on how it was created.
That applies to the entire EM spectrum. Otherwise, when I switched from using 21.2 eV UV from the synchrotron radiation to the same UV from a He lamp, my photoemission result would change to reflect the different ways that UV was created.
Zz.
Those that come as a byproduct of nucleus decaying are called gama rays like 59keV photon, those that come from electron going from higher shell to a lower are X-rays by the common definition. But as I understood you, you think the gamma rays produced for example from cosmic rays interacting with the atmosphere should not be called gamma rays, as though that is only reserved for radioactive decays. That is clearly not the case.Those photons listed are a mix of X-Rays and Gamma Rays (by the common definition, not the ancient e-m spectrum charts). Can you say which is which? I can, it's what I do. Their energy tells me everything I need to know.
And I agree with that, so as I said it depends on the context, or who you're talking to.Rather, the issue here is that "if you call this X, then it MUST only come from this process". That is what I have a problem with. As I've asked before, if I give you a 100 keV photon, are you able to tell me, using that alone, that it came from a nuclear reaction, a black hole, a synchrotron radiation center, etc... ?
I edited the post while you were answering.Even by your definition (the spectrum chart) you would call them all X-Rays.
And I have no problem with that, as I have no problem calling gamma rays highly energetic photons that do not come from a radioactive decay. Like gamma rays created from an interaction of cosmic rays (which everbody knows are not really rays) with the atmosphere.Common definition of Gamma Ray is actually "origination form a nucleus i.e. nuclear), which included radioactive decays.