Hypernuclei: Understanding the Heaviest Atom & Stability Principles

[jerich1000]

What is the heaviest possible hypernucleus (atom), and why?

Are hypernuclei prone to exist with isotopes with more or fewer neutrons, and why?

What would it take for there to be a fully stable hypernucleus? I know there isn't any such thing--but I am trying to learn the principles involved.

Thank you for your help.

 

[K^2]

More neutrons, definitely. Protons are repulsive, and the higher the Z, the more energy it takes to add a proton. Adding a neutron only increases energy due to Pauli exclusion, which tends to require less energy in heavy nuclei.

It's apparent from trends too. Light nuclei have roughly the same number of protons and neutrons. That's due to Pauli exclusion. But the heavier you go, the more neutrons start to dominate. That's Coulomb repulsion.

As an extreme case, we can look at neutron stars. These are essentially hypernuclei held together by gravity. And I do think gravity is the only way to make it work. As mentioned above, energy of adding extra particles just keeps increasing. Without some form of long-range purely attractive force, you can't keep it together. And besides gravity, I can't think of anything.

 

[nismaratwork]

More neutrons, definitely. Protons are repulsive, and the higher the Z, the more energy it takes to add a proton. Adding a neutron only increases energy due to Pauli exclusion, which tends to require less energy in heavy nuclei.

It's apparent from trends too. Light nuclei have roughly the same number of protons and neutrons. That's due to Pauli exclusion. But the heavier you go, the more neutrons start to dominate. That's Coulomb repulsion.

As an extreme case, we can look at neutron stars. These are essentially hypernuclei held together by gravity. And I do think gravity is the only way to make it work. As mentioned above, energy of adding extra particles just keeps increasing. Without some form of long-range purely attractive force, you can't keep it together. And besides gravity, I can't think of anything.

That sounds about right, then you reach the point of absolute collapse, end of story. At high enough energies QCD isn't enough, so colour confinement is out of the picture. Gravity is it, or some kind of completely new physics.

 

[jerich1000]

Thank you for your responses!