Why are there only limited modes of radioactivity?

[Dnphysicsuser]

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?

 

[mathman]

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.

 

[Drakkith]

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!

 

[nikkkom]

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.

 

[nikkkom]

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.

 

[seeyouaunty]

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

 

[Drakkith]

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.

 

[QuantumPion]

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.

 

[Dnphysicsuser]

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?

 

[QuantumPion]

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.

 

[Astronuc]

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

 

[Dnphysicsuser]

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?

 

[Drakkith]

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.

 

[Yrrepy]

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.