1s nuclear shell

[Rade]

I have an observation about the 1s nuclear shell. If we assume the "shell model" is a valid explanation of energy levels for isotopes, I find it very interesting (but I do not in any way understand) that only four isotopes find "stability" when nucleons (thus quarks) are packed into the first energy level, the 1s shell. I will use N=neutron, P=proton; thus the isotopes that find stability within the 1s shell are:

 

[P] = the proton

[NP] = deuteron

[PNP] = helium-3

[NPNP] = helium-4

 

And, the set of other possible nucleon arrangements for the 1s shell that are "unstable":

 

[N] = the neutron

[NN] = dineutron

[NNN] =trineutron

[NNNN] = tetraneutron

[NPN] = triton = hydrogen-3

[PP] = diproton

[PPP] = triproton

[PPPP] = tetraproton

[NPNN] = hydrogen-4

[PNPP] = lithium-4

 

Now, I look at the set of four stable isotopes, and I see a possible selection "fermion to boson" rule that would explain the building of stable light isotopes. It is:

 

1. Start with the stable proton [P] = fermion

2. Add an unstable neutron [N] = result is stable deuteron [PN] = boson

3. Add a second stable proton [P] = result is stable helium-3 [PNP] = fermion

4. Add a second unstable [N] = result is very stable helium-4 [PNPN] = boson

 

It thus seems to me, that stability in the 1s nuclear shell results from the formation of "clusters" of nucleons in a very specific order, from fermion to boson, starting with the very stable fermion [P], and ending with the very stable boson [PNPN] and not from the random placement of "individual" fermions [P & N] into separate proton and neutron energy potential wells within the 1s nuclear shell.

 

I would appreciate comments on the above from someone that studies nuclear shell structure. Thanks.