Free neutrons are unstable: would a muon in say uranium be stable ?

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Discussion Overview

The discussion revolves around the stability of muons when bound in heavy nuclei, specifically uranium, and contrasts this with the stability of free neutrons and neutrons within a nucleus. Participants explore the implications of muon decay, the forces acting on muons in atomic orbits, and the potential for muons to influence nuclear processes.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants note that free neutrons are unstable with a half-life of about 15 minutes, while neutrons in certain nuclear configurations can be stable.
  • It is stated that muons have a half-life of approximately 4.4 milliseconds and that their decay can be affected by time dilation at near-light speeds.
  • One participant questions whether a muon in a heavy nucleus like uranium could be stable or have a longer half-life due to relativistic effects.
  • Another participant asserts that muons are not stable in any atomic orbit, including the 1S state of uranium.
  • There is a discussion about the different forces acting on neutrons and muons, with one participant explaining that the strong nuclear interaction stabilizes neutrons in a nucleus, while muons are primarily influenced by the Coulomb force.
  • One participant references the mean radius of muonic orbits being much smaller than electronic orbits, suggesting that muons would interact with nucleons within the nucleus.
  • Experimental work on muonic atoms has been mentioned, indicating that there is some research on the capture of muons in lighter nuclei.
  • Concerns are raised about the energy release in muon decay compared to nuclear energy differences, suggesting that muons would still decay even when bound in a Coulomb orbit.

Areas of Agreement / Disagreement

Participants express disagreement regarding the stability of muons in heavy nuclei, with some asserting they cannot be stable while others speculate on the possibility. The discussion remains unresolved with multiple competing views presented.

Contextual Notes

Participants reference various forces and interactions affecting muons and neutrons, but there are limitations in the discussion regarding the assumptions made about the stability of muons in heavy nuclei and the implications of relativistic effects.

bananan
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free neutrons are unstable: would a muon in say uranium be "stable"?

free neutrons are unstable: would a muon in say uranium be "stable"?

free neutrons decompose and have a half-life of about 15 minutes.
neutrons bound in a nucleus, especially in a magic shell configuration like helium-4 or iron, have an indefinite lifespan.

muons are unstable with 4.4 msec half-life.
muon decay can be lengthen near-light speeds due to special relativity time dilation

would a muon in an extremely heavy nucleous like uranium where 1S electrons have near-light speeds be stable, or have a long half-life?

such muons might serve as a basis for cold fusion.

remove 1 electron from a uranium atom (or other stable heavy isotope)

replace with muon.
 
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Muons are not stable, not even in an atom's 1S orbit, not even if the atom is uranium.
 
Astronuc said:
Muons are not stable, not even in an atom's 1S orbit, not even if the atom is uranium.

Has it ever been tested or does theory rule it out a priori?
 
You are acutally talking about two different kind of particle.

The neutron gets to be stable into the nucleus, mainly because of the strong nuclear interaction.

The muon, even into a 1S state, is mainly influence by the Coulomb force acting on it. That is one of the reasons why it does not become stable.
 
bananan said:
Has it ever been tested or does theory rule it out a priori?

You should check out the book by deBenedetti titled "Nuclear Interactions." There is a nice treatment of muonic atoms and weak interactions in nuclear physics contained within.

The funny thing about the muon in a 1S orbit of a large nucleus like uranium is that the mean radius of the muon will be inside the nucleus. The way to see this is as follows: the muon is about 200 times more massive than the electron. The bohr radius is inversely proportional to the mass. So the muonic orbits have 1/200 the radius of the electronic orbits. So... do you think the muon will interact with the nucleons in the nucleus at some point?

For your lighter nuclei, there has been experimental work done with the capture of muons. Do a google search on "muonic atoms" and you will turn up a lot of papers.
Here is one that does a nice (but technical) overview of muon-electron transitions in muonic atoms: http://arxiv.org/abs/hep-ph/9801218"

Hope this helps,
Norman
 
Last edited by a moderator:
bananan said:
free neutrons are unstable: would a muon in say uranium be "stable"?

free neutrons decompose and have a half-life of about 15 minutes.
neutrons bound in a nucleus, especially in a magic shell configuration like helium-4 or iron, have an indefinite lifespan.

muons are unstable with 4.4 msec half-life.
muon decay can be lengthen near-light speeds due to special relativity time dilation

would a muon in an extremely heavy nucleous like uranium where 1S electrons have near-light speeds be stable, or have a long half-life?

such muons might serve as a basis for cold fusion.

remove 1 electron from a uranium atom (or other stable heavy isotope)

replace with muon.
The neutron in He is stable because the energy release in neutron beta decay is less than the energy difference between He^4 and 3 p and 1 n.
The energy release in mu-->e decay is much greater than any nuclear energy differences, so mu's still decay when bound in a Coulomb orbit.
The relativistic effect in a muonic atom is small because of the muons large mass.
 

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