Quantum Mechanics: Nucleon Bound Energies

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Discussion Overview

The discussion revolves around the energy levels of nucleons within a finite square well, specifically addressing the comparison made in a quantum mechanics text regarding the spacing of these energy levels and the implications of the strong force at femto-meter scales.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants express confusion about the phrase comparing energy level spacing for nucleons to that of a finite square well, particularly regarding the order of MeV.
  • Visual aids are mentioned, with one participant noting the scale in femto-meters (fm) and questioning the meaning of the pink and blue graphs presented.
  • Another participant suggests that the blue line in the graph represents the potential well and the pink line indicates an energy level at 8 MeV.
  • There is a discussion about the nature of the strong force, with one participant explaining that it acts over a very short range, contrasting it with gravity's inverse square law behavior.
  • Some participants seek clarification on what is meant by a "very strong force" in the context of nucleon interactions.

Areas of Agreement / Disagreement

Participants generally express confusion and seek clarification on the concepts discussed, indicating that multiple interpretations and understandings of the strong force and energy levels exist. The discussion remains unresolved regarding the specific implications of the energy level spacing and the graphical representations.

Contextual Notes

Participants have not fully defined the assumptions regarding the strong force's range or the specific characteristics of the energy levels in question, leaving some aspects of the discussion open to interpretation.

evamaster
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I was reading my quantum mechanics text and I have a doubt. I have the energy levels well defined for the finite square well and the author suddenly compares (I believe) those levels with the levels of the nucleon with the following phrase: "is the spacing between levels on the order of MeV for a nucleon bound in a several-fm well?". So I have some troubles understanding the meaning of that particular pharse.

Thanks.
 
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evamaster said:
I was reading my quantum mechanics text and I have a doubt. I have the energy levels well defined for the finite square well and the author suddenly compares (I believe) those levels with the levels of the nucleon with the following phrase: "is the spacing between levels on the order of MeV for a nucleon bound in a several-fm well?". So I have some troubles understanding the meaning of that particular pharse.

Thanks.

Sometimes a visual can help, the scale along the bottom is in femto-meters (fm), the distance where the strong force is "very" strong.

nuclear_square_well.gif
 
edguy99 said:
Sometimes a visual can help, the scale along the bottom is in femto-meters (fm), the distance where the strong force is "very" strong.

nuclear_square_well.gif

Ok thanks but what does it mean the pink and blue graphs?
And what does it mean a very strong force?
 
It looks like the blue line represents the well and the pink line might be an energy level at 8Mev. The strong force is responsible for holding the nucleons together, but it only acts over a small distance. From the graph it looks like that distance is about 10 fm.
 
evamaster said:
... what does it mean a very strong force?

Unlike gravity where the force you feel from the Earth drops off slowly as you move away from Earth according to what is called the the inverse square law, the strong force (that holds neutrons and protons together) is very different. With the strong force, if you are within a few femto-meters of the other guy you feel a very large attraction. If you get out a little, say 20 femtometers away, you don't feel an attraction at all to the other neutrons and protons.
 

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