Liquid Drop Model of the Nucleus

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SUMMARY

The discussion centers on the liquid drop model of the nucleus and its relation to the semi-empirical formula for atomic mass, specifically regarding the stability of certain nuclei against beta and beta+ decay. The conversation highlights that nuclei like Copper-64 (Cu-64) can undergo multiple decay modes, including beta decay, positron emission, and k-shell electron capture. The stability and decay modes are influenced by binding energy and the symmetry term in the liquid drop model, with odd-odd nuclei such as Cu-64 and Vanadium-50 (V-50) being particularly noted for their decay behavior.

PREREQUISITES
  • Understanding of the liquid drop model of the nucleus
  • Familiarity with the semi-empirical formula for atomic mass
  • Knowledge of beta decay and positron emission processes
  • Concept of binding energy in nuclear physics
NEXT STEPS
  • Research the properties of odd-odd nuclei and their decay modes
  • Study the implications of binding energy on nuclear stability
  • Examine the symmetry term in the liquid drop model
  • Explore the decay pathways of Copper-64 and Vanadium-50 in detail
USEFUL FOR

Nuclear physicists, students studying nuclear chemistry, and researchers interested in nuclear decay processes and stability analysis.

venomxx
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Looking at the liquid drop model of the nucleus and the semi-empirical formula for the atomic mass of the nucleus.

I understand the formula but I'm trying to figure out why some nuclei are unstable against both beta- and beta+ decay. Any ideas? I assume it's something to do with the symmetry term?
 
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venomxx said:
Looking at the liquid drop model of the nucleus and the semi-empirical formula for the atomic mass of the nucleus.

I understand the formula but I'm trying to figure out why some nuclei are unstable against both beta- and beta+ decay. Any ideas? I assume it's something to do with the symmetry term?
Are you talking about stable nuclei, or those that decay only by k-shell electron capture?
 
Hi Bob,

Im talking about a nucleus that can undergoe either b+ or b- decay. There is a way of showing some can decay either way but i can't see it from the liquid drop model...the semi emperical formula can give mass and binding energy, the more i look into it the more i think that its the binding energy that will determine if it decays, but doesn't say whether it can decay by b+ or b-, or in my case both...

I hope that makes it a little clearer!
 
Here is what Wikipedia says about copper 64, an odd-odd nucleus that can decay by either electron (beta-) decay, positron (beta+) decay, or k-shell electron-capture. So Cu-64 decays 3 ways.

Wiki says
64Cu has a half-life of 12.701 ± 0.002 hours and decays by 17.86 (± 0.14)% by positron emission, 39.0 (± 0.3)% by beta decay, 43.075 (± 0.500)% by electron capture and 0.475 (± 0.010)% gamma radiation/internal conversion. These emissions are 0.5787 (± 0.0009) and 0.6531 (± 0.0002) MeV for positron and beta respectively and 1.35477 (± 0.00016) MeV for gamma.
 
Nuclei that can beta decay in either direction (Cu-64 is an example, as is V-50) will do so if it is energetically favorable to do so. This normally happens when the parent nucleus is doubly odd - high spin helps as well. This gives a large energy gap with respect to the daughters.
 
Cheers for the answers, helped me a lot!
 

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