Wednesday, October 12, 2022

Neutron skin

Every now and again someone asks a question that hadn't occurred for me even to ask. Lead-208 is the heaviest stable isotope, at least since Bismuth's isotopes have all been spotted in decay. Here's how a nucleus looks inside. Absent metastability of course.

I'd assumed the 126 neutrons are all jumbled with the protons in a quantum-state. Turns out the neutrons assemble themselves on the outside so, shows what I know. The news goes more to measuring how thick is the neutron-"skin".

These incidentally used mathematics also used to simulate the possible spread of the coronavirus. We're not told to what degree those methods worked in practice.

Also the method can be extrapolated to other nuclei, like gold. Except that these are just means to get another model for each. Reproducible mathematics but, perhaps, not reproducible physics.

The real test would be astronomical measurements of neutron-stars especially if they are caught merging and emitting detectable elements. I'm more wondering how well it would work in finetuning nuclear reactors.

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