Undergrad Static and dynamic excited states

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SUMMARY

The discussion clarifies the distinction between static and dynamic excited states in nuclear physics, specifically referencing Wong's nuclear physics book. The shell model describes static excitations where individual nucleons transition between energy levels, while the liquid drop model accounts for dynamic excitations involving collective behaviors like vibrations and rotations of the nucleus. These two models represent different perspectives on excitation levels, with individual nucleon transitions and collective deformations being fundamentally different phenomena. Experimental determination of excitation types, such as octupole deformations, depends on the specific experimental setup and energy conditions.

PREREQUISITES
  • Understanding of nuclear models, specifically the shell model and liquid drop model.
  • Familiarity with concepts of static and dynamic excitations in nuclear physics.
  • Knowledge of collective excitations and giant resonances in nuclei.
  • Basic principles of experimental nuclear physics and excitation measurement techniques.
NEXT STEPS
  • Research the differences between the shell model and liquid drop model in detail.
  • Explore the concept of collective excitations and their significance in nuclear reactions.
  • Study experimental techniques for identifying nuclear excitation types, including spectroscopy methods.
  • Investigate octupole deformations and their implications in nuclear structure and reactions.
USEFUL FOR

Nuclear physicists, students studying nuclear models, researchers in experimental nuclear physics, and anyone interested in the behavior of excited states in atomic nuclei.

kelly0303
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Hello! I am reading about excited levels in nuclei (I am mainly following Wong's nuclear physics book) and I am a bit confused about the nature of the excited states. In the one particle picture (mainly shell model) the excitation appears as static i.e. one nucleon moves from a certain orbital to another one and that's it. In the liquid drop model the excitation appears dynamic i.e. the energy leads to nucleus to vibrate or rotate. I am a bit confused if these 2 pictures are describing the same excitation levels, or they are two separate things? For example in molecules you have some "static" excitations (i.e. electronic excitations) and some "dynamic" ones (i.e. rotation and vibration). Is it the same here i.e. does the shell model describe static excitations and the liquid drop model describes dynamic ones, or they are the same ones just from 2 different perspectives? Basically when I see a diagram of a nucleus with energy levels (and spin and parity of each level), can any of these transitions (at least in principle) be described by both shell model and liquid drop model (of course one of them might be more adequate for a given nucleus), or each transition can be explain by only one of the two (I am aware that there are many other models out there, but I'd like to stick to these 2 for now). Thank you!
 
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They are different excitations. You can have individual nucleons reaching higher energy levels but you can also have the whole nucleus deform (collective excitations/giant resonances).
Note that - just like for orbitals - these deformations don't need to have a state that changes in time.
 
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mfb said:
They are different excitations. You can have individual nucleons reaching higher energy levels but you can also have the whole nucleus deform (collective excitations/giant resonances).
Note that - just like for orbitals - these deformations don't need to have a state that changes in time.
Thank you for your reply! So experimentally, how can one figure out the type of excitation? For example an excitation with ##\lambda = 3##, which is an octupole deformation, is it because a nucleon changed its orbital angular momentum value by 3, or because the nucleus as a whole was having octupole oscillations? Or it can be both depending on the energy?
 
That will depend on your experiment.
 

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