# Alpha, beta, and gamma radiation - why only these three
**URL:** https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998
**Category:** Factual Questions
**Created:** [June 24, 2019, 10:02pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998 "2019-06-24T22:02:22Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@zimaane](https://boards.straightdope.com/u/zimaane)
#### Post date: [June 24, 2019, 10:02pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/1 "2019-06-24T22:02:22Z")
In high school physics I learned that there are three types of radiation - alpha (2 protons and 2 neutrons), beta (one electron) and gamma (high energy photon). Why only these three? Why not 3 neutrons, or a proton/electron combo or something else?
---
### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [June 24, 2019, 11:00pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/2 "2019-06-24T23:00:23Z")
There are other types; those are just the most common. You can also have the reverse of beta radiation, emitting positrons (AKA anti-electrons), and neutron radiation. And fission can result in just about any sort of nucleus being emitted, though usually most of the energy goes into the lightest pieces like neutrons, so we don’t usually call the heavy daughter nuclei “radiation”.
As to why a nucleus with excess protons tends to emit helium nuclei, instead of individual protons or some other combination of protons and neutrons, what it mostly comes down to is that helium is really stable. There was [a recent thread](https://boards.straightdope.com/sdmb/showthread.php?t=875555) with more details.
---
### Author:  [@Andy\_L](https://boards.straightdope.com/u/Andy_L)
#### Post date: [June 25, 2019, 12:22am UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/3 "2019-06-25T00:22:27Z")
> [@Chronos](#):
>
> There are other types; those are just the most common. You can also have the reverse of beta radiation, emitting positrons (AKA anti-electrons), and neutron radiation. And fission can result in just about any sort of nucleus being emitted, though usually most of the energy goes into the lightest pieces like neutrons, so we don’t usually call the heavy daughter nuclei “radiation”.
>
> As to why a nucleus with excess protons tends to emit helium nuclei, instead of individual protons or some other combination of protons and neutrons, what it mostly comes down to is that helium is really stable. There was [a recent thread](https://boards.straightdope.com/sdmb/showthread.php?t=875555) with more details.
It’s worth noting that these three were named before we knew what they were. So we don’t call a high energy proton “delta (or epsilon, or whatever) radiation” - we just call it a high energy proton. But for historical reasons, alpha, beta and gamma are still used instead of “helium nuclei,” “electron” and very short wave light radiation.
---
### Author:  [@MikeS](https://boards.straightdope.com/u/MikeS)
#### Post date: [June 25, 2019, 11:27am UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/4 "2019-06-25T11:27:00Z")
Historically the terms [delta radiation](https://en.wikipedia.org/wiki/Delta_ray) and [epsilon radiation](https://en.wikipedia.org/wiki/Epsilon_radiation) were used as well, but those terms have fallen out of use. Also, delta and epislon radiation aren’t emitted directly from the nucleus; they basically consist of atomic electrons that have been knocked out of their orbits by alpha, beta, or gamma radiation.
---
### Author:  [@Andy\_L](https://boards.straightdope.com/u/Andy_L)
#### Post date: [June 25, 2019, 11:35am UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/5 "2019-06-25T11:35:05Z")
> [@MikeS](#):
>
> Historically the terms [delta radiation](https://en.wikipedia.org/wiki/Delta_ray) and [epsilon radiation](https://en.wikipedia.org/wiki/Epsilon_radiation) were used as well, but those terms have fallen out of use. Also, delta and epislon radiation aren’t emitted directly from the nucleus; they basically consist of atomic electrons that have been knocked out of their orbits by alpha, beta, or gamma radiation.
Thanks. I didn’t know that.
---
### Author:  [@jz78817](https://boards.straightdope.com/u/jz78817)
#### Post date: [June 25, 2019, 12:16pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/6 "2019-06-25T12:16:04Z")
> [@zimaane](#):
>
> In high school physics I learned that there are three types of radiation - alpha (2 protons and 2 neutrons), beta (one electron) and gamma (high energy photon). Why only these three? Why not 3 neutrons, or a proton/electron combo or something else?
Huh? What about radio, microwave, visible light, UV, x rays…?
---
### Author:  [@scr4](https://boards.straightdope.com/u/scr4)
#### Post date: [June 25, 2019, 12:52pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/7 "2019-06-25T12:52:08Z")
> [@zimaane](#):
>
> Why not 3 neutrons, or a proton/electron combo or something else?
3 neutrons would not bind together to form a stable particle.
A proton/electron combo would be a hydrogen atom. You normally wouldn’t see a high-energy beam of atoms because any process that would accelerate atoms would likely break them up. Stripping electrons from atoms (ionization) is much easier than breaking up a nucleus.
As others noted, there are many other types of high-energy particles. Neutron radiation from nuclear reactors & accidents can be quite dangerous.
---
### Author:  [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)
#### Post date: [June 25, 2019, 1:11pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/8 "2019-06-25T13:11:41Z")
It was only in the nineteenth century that it was discovered that there were kinds of radiation other than visible light, in the following order:
Infrared light 1800
Ultraviolet light 1801
Radio waves 1887
X-rays 1897
Alpha rays 1899
Beta rays 1899
Gamma rays 1900
> **[Radiation](https://en.wikipedia.org/wiki/Radiation)**
>
> In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:
> Radiation is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles. Ionizing radiation carries more than 10 eV, which is enough to ionize atoms and molecules and break chemical bonds. This is an important distinction due to the large difference in harmfulness to living organisms. A common so...
---
### Author:  [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)
#### Post date: [June 25, 2019, 1:34pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/9 "2019-06-25T13:34:02Z")
Given that both sound and spokes of a wheel also radiate, the word radiation is perhaps a trifle misused in the modern world. Anything emanating from a point and describing a line is radiation.
---
### Author:  [@scr4](https://boards.straightdope.com/u/scr4)
#### Post date: [June 25, 2019, 1:34pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/10 "2019-06-25T13:34:36Z")
…N-rays in [1903](https://en.wikipedia.org/wiki/N_ray)… :smack:
---
### Author:  [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)
#### Post date: [June 25, 2019, 2:35pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/11 "2019-06-25T14:35:58Z")
The short answer is that when they were first starting to investigate natural radiation, they observed three different types of radiation with different properties, and no obvious explanation. It could well be that at first they expected all three types to be varieties of electromagnetic radiation (as gamma rays turned out to be), and it wasn’t clear that two of them would turn out to be particle beams (although they pretty quickly started displaying behavior inconsistent with light rays)
---
### Author:  [@zimaane](https://boards.straightdope.com/u/zimaane)
#### Post date: [June 25, 2019, 3:11pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/12 "2019-06-25T15:11:44Z")
> [@jz78817](#):
>
> Huh? What about radio, microwave, visible light, UV, x rays…?
sorry, I was using ‘radiation’ in the limited sense of ionizing particles or energy generated in the atomic nucleus.
---
### Author:  [@glowacks](https://boards.straightdope.com/u/glowacks)
#### Post date: [June 29, 2019, 3:23am UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/13 "2019-06-29T03:23:25Z")
> [@CalMeacham](#):
>
> The short answer is that when they were first starting to investigate natural radiation, they observed three different types of radiation with different properties, and no obvious explanation. It could well be that at first they expected all three types to be varieties of electromagnetic radiation (as gamma rays turned out to be), and it wasn’t clear that two of them would turn out to be particle beams (although they pretty quickly started displaying behavior inconsistent with light rays)
All three are both waves and particles in some way. We tend to think of photons more as the electromagnetic wave that “carries” them, and an electron as a point particle with an associated wave function, but other than the photon not having mass and having integer spin, while electrons have half-integer spin and do have mass, and thus their interactions with other things are quite different, there’s not really a difference between the two of them. In isolation they are both excitations of their underlying field, of which I am not too informed, but I’m told that’s how it works.
---
### Author:  [@sps49sd](https://boards.straightdope.com/u/sps49sd)
#### Post date: [June 29, 2019, 5:17am UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/14 "2019-06-29T05:17:16Z")
> [@Francis\_Vaughan](#):
>
> Given that both sound and spokes of a wheel also radiate, the word radiation is perhaps a trifle misused in the modern world. Anything emanating from a point and describing a line is radiation.
Can you get radioactive contamination from wheel spokes?
---
### Author:  [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)
#### Post date: [June 29, 2019, 6:46am UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/15 "2019-06-29T06:46:22Z")
> [@sps49sd](#):
>
> Can you get radioactive contamination from wheel spokes?
Herein of course is the nub of the problem of the word radiation. Radioactivity is only one very minor source of radiation. Alpha radiation is pretty much the exclusive domain of radioactivity on the earth. Coronal mass ejections probably account for most in our near vicinity. Until the advent of LCD and LED panel displays we all had sources of raw electrons (aka bets radiation) streaming away in our homes. The main sources of x-rays and gamma rays we have are still based on accelerating electrons and smacking them into a target. No radioactivity needed.
Radioactivity and contamination with radioactive materials is for now the result of messing with nuclear fission, or very specific elements. But somehow popular culture has confused radiation and radioactivity. The words have a similar root. The choice of “radioactivity” is an accident of history. There is little to no scientific reason to have chosen it other than the initial (flawed) observation that the emanations from the newly discovered weird minerals propagated in a straight line. Had an experiment been done with a magnet early on, the fact that the emanating stuff’s course could be bent, another’s name would probably have been more obvious. But the experiment came too late and we have “radioactivity” to confuse the public in a most unhelpful manner.
---
### Author:  [@DPRK](https://boards.straightdope.com/u/DPRK)
#### Post date: [June 29, 2019, 8:30am UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/16 "2019-06-29T08:30:52Z")
Radio activity
Is in the air for you and me
Radio activity
Discovered by Madame Curie
Radio activity
Tune into the melody
---
### Author:  [@The\_Librarian](https://boards.straightdope.com/u/The_Librarian)
#### Post date: [June 29, 2019, 11:27am UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/17 "2019-06-29T11:27:12Z")
> [@jz78817](#):
>
> Huh? What about radio, microwave, visible light, UV, x rays…?
Radio, microwave,visible light, UV, x-rays are essentially the same (all on the same spectrum) as are infrared and gamma.
Gamma is the part of the spectrum that damages tissue.
---
### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [June 29, 2019, 2:47pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/18 "2019-06-29T14:47:03Z")
You can’t contaminate anything with gamma rays, either, regardless of the source.
---
### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [June 29, 2019, 2:56pm UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/19 "2019-06-29T14:56:00Z")
You can’t contaminate anything with gamma rays, either, regardless of the source.
---
### Author:  [@Lumpy](https://boards.straightdope.com/u/Lumpy)
#### Post date: [June 30, 2019, 2:59am UTC](https://boards.straightdope.com/t/alpha-beta-and-gamma-radiation-why-only-these-three/835998/20 "2019-06-30T02:59:57Z")
Specifically, a beam of “alpha” radiation would be bent one way by a magnet, “beta” radiation would be bent the other way, and “gamma” radiation wouldn’t be bent at all.