Guglinski's "second fact" on page 100 from the
2 pages from his book in this post is "from empirical fact, the physicists also concluded that all the nuclei have the same shell thickness "2b" = 2 * 0.55 F = 1.1 F".
The real problem is that he seems to be thinking that the
nuclear shell model has actual physical shells separated by a given thickness and that thickness is related to a proton radius,e.g. the protons are stuck on the shells somehow or orbit in circular orbits.
This is wrong. The shells in the
nuclear shell model are
allowable energy states of the nucleons in the nucleus. A higher energy means a different nuclear orbital and a higher probability of finding the nucleon further from the center of the nucleus.
There is no relationship with the size of protons. They do not fit snugly inbetween the shells.
The shell model is partially analogous to the atomic structure models (electrons in orbitals outside of the nucleus). The nuclear orbitals are labeled similarily (s, p, d, etc.).
If you were to (incorrectly!) take the analogy to be exact then nuclear orbitals would have similar shapes, e.g. spherical for the 1s orbital and dumb-bell shaped for the 1p orbital. This would mean that nucleons in a 1p orbital spend a small part of the time within the same space as nucleons in the 1s orbital.
Guglinski's ignorance of the basics of writing scientific literature (defining terms, giving citations) means that we have no idea what he means by "shell thickness" or from where he got the value of 1.1 F.