Does tunneling affect the energy of a particle in a finite box?

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Discussion Overview

The discussion revolves around the effects of tunneling on the energy of a particle within a finite potential box, using alpha decay as a specific example. Participants explore the relationship between the energy of a particle inside a potential barrier and its energy after tunneling, considering both theoretical and practical implications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether tunneling affects the kinetic energy of a particle when it exits a finite box, suggesting that the tunneling probability formula does not provide information about the energy of the tunneled particle.
  • Another participant asserts that energy is conserved, but notes that the potential inside the box may not match the potential outside, implying that while energy is conserved, the kinetic energy may differ due to potential differences.
  • A follow-up question is raised regarding whether the emission of a gamma photon during the tunneling process would reduce the kinetic energy of the alpha particle, with a participant affirming that total energy conservation applies in this scenario.

Areas of Agreement / Disagreement

Participants generally agree that energy is conserved in the tunneling process, but there is uncertainty regarding how potential differences affect kinetic energy and whether the emission of other particles influences the energy of the tunneled particle.

Contextual Notes

Participants express varying interpretations of energy conservation in relation to potential differences, and there are unresolved questions about the definitions and implications of energy states inside and outside the potential barrier.

houlahound
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using alpha decay as a concrete example is the energy of the alpha inside and outside the nucleus the same. it appears so from what I can see but alphas do have a range of energies usually up to between 4 - 9Mev. which is the same range as inside the nucleus.

my question really is does tunnelling for say a particle in a finite box to out of the finite box change the kinetic energy of the particle in any situation, always or never?

the formula for tunnelling probability does not supply info on the energy of the tunnelled particle ie from hyperphysics (simple solution);

upload_2016-10-25_8-17-51.png


how would one calculate the energy/frequency of the wave function for the tunnelled particle?
 
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Energy is conserved, but the potential inside in general won't match the potential outside.

"The energy of the alpha nucleus inside the nucleus" is not really a well-defined concept. You can use this as heuristics, but there are not physically two protons and two neutrons together bouncing around.
 
thanks mfb, so if energy is conserved the particle does have the same energy on the outside implying there is no loss of energy passing through the barrier?

if as mostly does a gamma is also emitted will the gamma energy reduce the alpha particle kinetic energy?
 
houlahound said:
thanks mfb, so if energy is conserved the particle does have the same energy on the outside implying there is no loss of energy passing through the barrier?
Sure.
Its kinetic energy will be different if the potential is different, the total energy is conserved.
houlahound said:
if as mostly does a gamma is also emitted will the gamma energy reduce the alpha particle kinetic energy?
Sure. Same concept: total energy is conserved.
 

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