Why are there only limited modes of radioactivity?

  • Thread starter Thread starter Dnphysicsuser
  • Start date Start date
  • Tags Tags
    Modes Radioactivity
Click For Summary

Discussion Overview

The discussion revolves around the limited modes of radioactivity, specifically questioning why only a few modes (alpha, beta, gamma, and others) are observed. Participants explore whether these modes are exhaustive or if there are theoretical frameworks that could predict additional modes, especially in the context of newly discovered isotopes.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants note that in addition to alpha, beta, and gamma decay, there are other modes such as positron emission, electron capture, spontaneous fission, and neutron radiation.
  • One participant suggests that the limited decay modes arise from the finite types of particles and forces available, likening it to having limited exits from a room.
  • There is mention of decay by proton emission, which is considered more theoretical due to the instability of isotopes that exhibit this mode.
  • Some participants discuss the potential for new discoveries in radioactivity if correlations between solar activity and decay rates are validated.
  • There are claims that heavy nuclei can decay by carbon nucleus emission and that exotic decay modes may occur at extreme energies in particle accelerators.
  • Questions are raised about whether the decay modes of heavy nuclei were predicted or discovered through observation, and whether all possible modes can be predicted based on the types of radioactive atoms present.
  • Participants express uncertainty about the completeness of the tabulation of natural decay modes and the possibility of discovering new stable superheavy elements that may decay differently.
  • There is a discussion about the theoretical underpinnings of observed decay modes, with references to quantum mechanics and conservation laws influencing allowed reactions.

Areas of Agreement / Disagreement

Participants generally agree that there are multiple modes of radioactivity beyond the commonly cited ones, but there is no consensus on whether all possible modes have been identified or predicted. The discussion remains unresolved regarding the theoretical explanations for the observed modes and the potential for new discoveries.

Contextual Notes

Some participants express uncertainty about the predictions versus observations of decay modes, and there are limitations in understanding the theoretical frameworks that govern these processes. The discussion also touches on the implications of new discoveries in radioactivity and the role of conservation laws in determining allowed decay modes.

Dnphysicsuser
Messages
3
Reaction score
0
Most texts on radioactivity starts by saying "there are three important modes of radioactivity-alpha, beta and gamma..." and goes on to describe their properties. But why are there only a few modes of radioactivity? Does that mean the modes observed so far, or, are there theories to describe the possible modes? Putting it other way, when a new radioactive isotope is ever discovered, will the mode of radioactivity be confined to alpha, beta, gamma or neutron emissions?
 
Engineering news on Phys.org
The radioactive decay mode of every radionuclide is known. In addition to the three you mentioned, there are positron emission and electron capture (variations of beta decay) and spontaneous fission.
 
There are limited decay modes because there are a limited amount of types of particles and forces. One can only exit a door a certain amount of ways!
 
There is also a neutron radiation (accompanies spontaneous fission).

Decay by proton emission is also possible, but it's more of theoretic interest: IIRC, all isotopes which exhibit it are very hard to produce, and very unstable.
 
mathman said:
The radioactive decay mode of every radionuclide is known. In addition to the three you mentioned, there are positron emission and electron capture (variations of beta decay) and spontaneous fission.

Electron capture per se is not a radiation, since captured electron is not radiated. But usually electron capture causes some gamma emission (because outer electrons fall into just-vacated inner orbital) and sometimes beta (auger electrons).

There is another rare "non-radiating" type of beta-decay, when newly born electron goes into an empty orbital. This requires empty orbital, usually inner one, IOW: requires atom to be highly ionized.
Interesting example is Dy-163: it is ordinarily stable, but when fully ionized (all 66 electrons stripped), it has half-life of only 47 days.
 
Some physicists have tentatively made a recent correlation between the suns activity and slight variances in the decay rate of radioactive substances. If it turns out to be a good observation there will have to be new discoveries regarding radioactivity.
http://physicsworld.com/cws/article/news/36108
 
seeyouaunty said:
Some physicists have tentatively made a recent correlation between the suns activity and slight variances in the decay rate of radioactive substances. If it turns out to be a good observation there will have to be new discoveries regarding radioactivity.
http://physicsworld.com/cws/article/news/36108

I wouldn't place any real trust in this yet.
 
Last edited by a moderator:
Dnphysicsuser said:
Most texts on radioactivity starts by saying "there are three important modes of radioactivity-alpha, beta and gamma..." and goes on to describe their properties. But why are there only a few modes of radioactivity? Does that mean the modes observed so far, or, are there theories to describe the possible modes? Putting it other way, when a new radioactive isotope is ever discovered, will the mode of radioactivity be confined to alpha, beta, gamma or neutron emissions?

There are other modes of decay at higher energies. Very heavy nucleus can decay by carbon nucleus emission. Also more exotic things can happen at extreme energies in particle accelerators involving mesons and muons and such.
 
QuantumPion said:
There are other modes of decay at higher energies. Very heavy nucleus can decay by carbon nucleus emission. Also more exotic things can happen at extreme energies in particle accelerators involving mesons and muons and such.

Hi QuantumPion, If you say heavy nucleus can decay by carbon emission, is that fact predicted, or is just a discovery after it has occurred. Given a mixture of fissile, fertile and other non-fissile non fertile naturally radioactive atoms, can we predict all possible modes of radioactivity?
 
  • #10
Dnphysicsuser said:
Hi QuantumPion, If you say heavy nucleus can decay by carbon emission, is that fact predicted, or is just a discovery after it has occurred. Given a mixture of fissile, fertile and other non-fissile non fertile naturally radioactive atoms, can we predict all possible modes of radioactivity?

I have no idea whether heavy decay modes were predicted or observed first.

I'm pretty sure all the normal natural decay modes have been tabulated by now, unless in the future we discover more stable superheavy elements which decay by other modes.
 
  • #11
QuantumPion said:
I have no idea whether heavy decay modes were predicted or observed first.

I'm pretty sure all the normal natural decay modes have been tabulated by now, unless in the future we discover more stable superheavy elements which decay by other modes.
I believe that the superheavy elements decay by spontaneous fission or alpha decay.

http://www.ornl.gov/sci/nsed/outreach/presentation/2011/Roberto.pptx (17.3 Mb, use 'save target as')

International team discovers element 117
http://www.ornl.gov/ornlhome/news_items/news_100407.shtml

ORNL's role included production of the berkelium-249 isotope necessary for the target, which was subjected to an extended, months-long run at the heavy ion accelerator facility at Dubna, Russia.

Other information on the production of superheavy elements can be found at www.webelements.com (click on each superheavy element)

http://www.webelements.com/nexus/chemistry/discovery-elements-atomic-number-114-and-116

http://www.gsi.de/forschung/kp/kp2/ship/index.html
 
Last edited by a moderator:
  • #12
All have tried to summarize all existing modes of radioactivity but the core of my doubt : is there any theory to explain the modes observed?
 
  • #13
Dnphysicsuser said:
All have tried to summarize all existing modes of radioactivity but the core of my doubt : is there any theory to explain the modes observed?

Quantum mechanics? I'm not really sure what you are asking.
 
  • #14
Quantum Mechanics/Particle Physics, some reactions and modes aren't allowed (conservation of parity, charge, mass etc). The other modes that are allowed have respective transition (decay rates) with certain process being favoured and being faster that others.
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
3K
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
4
Views
2K
  • · Replies 12 ·
Replies
12
Views
5K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 4 ·
Replies
4
Views
10K
  • · Replies 8 ·
Replies
8
Views
17K
  • · Replies 24 ·
Replies
24
Views
3K