Undergrad Gamma and beta radiation in accelerators?

[ZapperZ]

I think this description from Wikpedia sums it up best:

https://en.wikipedia.org/wiki/Gamma_ray

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.

 

[geoelectronics]

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.

"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."

We are not that far apart-

As I said in one of my very first post on this forum, there are X-Rays, there a Gamma Rays, and there are photons. At a distance they are indistinguishable from one another if they are of the same energy.

let me explain why I didn't answer your question:
1) You have never once answered any of my questions.
2) The question is badly worded and doesn't convey enough information.

If you had asked, "I have a photon of 74.96 keV, what is it?" My immediate answer would be, well, it could be a Ka X-Ray from the element Pb. (K shell, alpha level electron is the source) ...
and no one in science could say that's this is not 100% true. Notice I said COULD BE. It's a place to start.
So I would ask what else do you see, and you reply : " well I also see a 84.92 keV photon", my IMMEDIATE reply is wow, there is a high probability that you are seeing X-Rays from Pb, try looking lower!"

Then you say "wow I found a photon lurking down at 12.61 keV" STOP I say, you have Pb X-Rays, now let's examine why you have them by looking elsewhere. This can go on for pages at this point.

The Pb could be a stable lead block being activated by Cosmic nonRays, it could also be an excited lead atom being the daughter of some radioactive decay ( here the conversation shifts the the possible parents in a nuclear decay chain, there are numerous.) By the time we're finished we will know what lead iostope is present in a sample, and from that where it came from (in a geologic or elemental sense). If we wanted to know from where it came geographically we would walk it down the street to the NIST Archaeometr y Program lab for a quick mass spec.

https://www.murr.missouri.edu/
George Dowell

 

[Motore]

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.

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.
That's why I agree with Dr.AbeNikIanEdL and Wikipedia, that when discussing gamma rays and their origin it depeneds if you are talking to a nuclear physicist or an astrophysicist. If you just want to calculate things, then all you need is the energy and you can call Twinkies.

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... ?

And I agree with that, so as I said it depends on the context, or who you're talking to.
A nuclear physicis will look at you strangely if you were to say an two X-ray photon was emited when a Am-241 underwent a radioactive decay, but if you tell him one has an energy of 13.81keV and the other 13.76keV he will just remind you that ''the first is a gamma ray, the other an x-ray''. That is way a certain nomenclature is in place.

 

[geoelectronics]

"They are all called gama rays by the common definition. Common definition here meaning the byproduct of radioactive decay. 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."

Even by your definition (the spectrum chart) you would call them all X-Rays. They are not all, one is a Gamma Ray. If you don't know that please stop commenting on this, wait till someone who knows about high school atomic theory shows up I'm not calling anyone stupid, maybe you are TOO smart and educated, but you sure don;t communicate well with a 14 year old.

Common definition of Gamma Ray is actually "origination form a nucleus i.e. nuclear), which included radioactive decays.

Cosmic Rays are not rays, they are mostly physical particles (electron-proton plasma). Particles interact with particle (physical particles, some here want to call photons particles). When Cosmic Rays were named they thought they were rays. What they were detecting weren't rays, they weren't even cosmic.
What is detected at Earth's surface are secondary particles of matter from high altitude physical particle collisions. This was all cleared up later by a very brave scientist in a balloon, Victor Hess, but by then Robert Andrews Millikan had named them Cosmic Rays, so naturally nobody better correct the master.

Look up the definition of any of these terms in a respected dictionary (NOT Wiki).

George Dowell

 

[Motore]

Even by your definition (the spectrum chart) you would call them all X-Rays.

I edited the post while you were answering.

Common definition of Gamma Ray is actually "origination form a nucleus i.e. nuclear), which included radioactive decays.

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.

 

[Dr.AbeNikIanEdL]

Rather, the issue here is that "if you call this X, then it MUST only come from this process".

As I have tried to say before, I think you are the one who mistakes a change in label as a claim of actual physics here. This sentence in the current context is

“If you call photons from nuclear reactions Y, and all other photons X, then Y must only come from nuclear processes.”

Which obviously is true.

Common definition of Gamma Ray is actually "origination form a nucleus i.e. nuclear), which included radioactive decays.

Well, I think you should also acknowledge that this definition if of little use in other fields, where you either don’t precisely know or do not care what the source of radiation is, but just that it is around and has a certain energy. There is not one “common” definition in general, and neither of the definitions is really “better” in general. But insisting on a particular definition in the wrong context will not get you anywhere.

 

[geoelectronics]

I edited the post while you were answering.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.

I'm not expert in high energy particle collisions and don't claim to be.
But I can tell you that highly energetic photons come form all sorts of other particle interactions NOT within the nucleus. Each one has a specified name, and defined characteristics, but otherwise once away from the source they can't casually be identified as to what was that source, but under close measurement, probabilities can be assigned as to the possible source.

Please, and I'm sincere, show me the particle collision caused by Cosmic Rays and would like to make a stab at a comment.

I do disagree about everyone knows Cosmic Rays are not rays. The discoverer's didn't- no student intuitively knows, and the science community should lobby to change/correct their name. Something like Cosmic Wind, while not scientific, gets the right idea across perfectly. Maybe Cosmic Plasma Wind is better.

George Dowell

 

[ZapperZ]

Huh? Would you call 100 MeV electrons "beta rays"? I can show you where that is in an accelerator.

Zz.

 

[ZapperZ]

Would you mind tell me if you actually understood the main point that I made regarding your restricted definition of gamma "ray" or "photons"?

Please tell me where exactly did I make such a restricted definition. In fact, I'm the one who was arguing against making the restriction that "gamma rays" must come only from specific processes.

And again, is 100 MeV electron considered as "beta rays"?

Zz.

 

[mfb]

@ZapperZ: There are two mutually incompatible ways to define x-rays vs. gamma rays. That's just how it is. You are more familiar with the classification by energy (which I prefer as well), but other fields use a classification by source.
Yes, that means you don't know if a 650 keV photon would be called x-ray or gamma ray if you classify by source. So what? You have the same e.g. for synchrotron radiation: You can't tell if a photon is synchrotron radiation or not just by looking at its energy.

 

[hutchphd]

Excuse my impertinence but what in heck is this discussion about? Perhaps an application of Feynman would help:

http://www.fotuva.org/feynman/what_is_science.html

 

[ZapperZ]

@ZapperZ: There are two mutually incompatible ways to define x-rays vs. gamma rays. That's just how it is. You are more familiar with the classification by energy (which I prefer as well), but other fields use a classification by source.
Yes, that means you don't know if a 650 keV photon would be called x-ray or gamma ray if you classify by source. So what? You have the same e.g. for synchrotron radiation: You can't tell if a photon is synchrotron radiation or not just by looking at its energy.

@mfb: please read what I have written. I never dismiss the fact that there can be different classification. It is the others who claim that ONLY radiation in that frequency coming from nuclear process can be called "gamma rays", and that if that same frequency did not come from nuclear radiation, then it can't be called as such!

I'm not the one being narrow and RIGID with the definition here!

Zz.

 

[mfb]

It is the others who claim that ONLY radiation in that frequency coming from nuclear process can be called "gamma rays", and that if that same frequency did not come from nuclear radiation, then it can't be called as such!

That's one of the two classification schemes. That statement is only true within that classification scheme, of course (and it is the definition in that scheme, so it is trivially true).

 

[ZapperZ]

That's one of the two classification schemes. That statement is only true within that classification scheme, of course (and it is the definition in that scheme, so it is trivially true).

Yes, but why are all these being addressed to me? Let me reemphasize that I wasn't the one being rigid with the definition. I was the one who couldn't care less if it was called a Twinkie!

Zz.

 

[mfb]

Yes, but why are all these being addressed to me?

Because your posts seemed to claim that this other definition doesn't exist, or must be wrong. At least that's the impression I got.

 

[ZapperZ]

Because your posts seemed to claim that this other definition doesn't exist, or must be wrong. At least that's the impression I got.

Where did I say that?

Zz.

 

[mfb]

In post 7, second paragraph, in post 11 and 14, and a few more.

 

[ZapperZ]

In post 7, second paragraph, in post 11 and 14, and a few more.

sorry, but I do not see it. Look closely. I was disputing the insistence that gamma rays was rigidly defined as being only from nuclear reactions. I repeatedly stated that THAT is not the only definition of it. I NEVER stated thatsuch usage was invalid.

zz

 

[vanhees71]

@ZapperZ: There are two mutually incompatible ways to define x-rays vs. gamma rays. That's just how it is. You are more familiar with the classification by energy (which I prefer as well), but other fields use a classification by source.
Yes, that means you don't know if a 650 keV photon would be called x-ray or gamma ray if you classify by source. So what? You have the same e.g. for synchrotron radiation: You can't tell if a photon is synchrotron radiation or not just by looking at its energy.

Hm, after all photons are bosons and thus indistinguishable. Just given a 650 keV photon you can't say, where it comes from. So if a distinction of photons by different names, it makes only sense to disinguish them by some intrinsic quantity of the photon, and in this case it's usually energy.

You may also ask whether "bremsstrahlung" is only right for emission of em. waves when a particle is decelerated, i.e., is it wrong to call "cyclotron radiation" (where the electron is accelerated) "bremsstrahlung" either? After all in physics both is due to acceration of charged particles. No matter whether the speed gets larger or smaller it's acceleration ;-)).

 

[Dr.AbeNikIanEdL]

Hm, after all photons are bosons and thus indistinguishable. Just given a 650 keV photon you can't say, where it comes from. So if a distinction of photons by different names, it makes only sense to disinguish them by some intrinsic quantity of the photon, and in this case it's usually energy.

Well, you can justify your preferred naming scheme as well as you want, that is not changing the real world fact that other naming schemes are in place and used by the some part of the community.