That figure shows the beryllium nucleus, with a nucleon which distance to the central 2He4 is 7fm. In the link they say about the beryllium nucleus:

“The surprise came with the beryllium. Unlike the other nuclei, it has two clusters of nucleons, each resembling a nucleus of an atom of helium-4.”

According to Quantum Ring Theory, all the nuclei with Z>2 have a structure with radius in order of 7fm.

Then why does Arrington says “unlike the other atoms”?
Why beryllium is an exception ?

Let’s see why.

According to QRT, the hexagonal floor begins with the isotopes of 3Li. In the link ahead we see the structure of 3Li6, shown in the page 230 of the book QRT:
http://hexfloor.blogspot.com.br/

3Li
The 3Li6 has a nuclear spin about the z-axis (vertically upward in the page 230). As the 3Li6 has an unpaired deuteron, it has a strong trepidation.
Then in Arrington’s experiment, due to such big vibration, the unpaired deuteron appears as a clould about the central 2He4 (the same happens with all the 3Li isotopes).

4Be
The next nucleus is the 4Be8.
Look at its structure in the page 230, shown beside the 3Li6.
The two nucleons 1H2 occupy two positins diametrally opposed regarding to the central 2He4, and so the three nucleons form a straight length 14fm.

Looking at the structure of 4Be8, we realize that it has no trepidation, because the masses of the two nucleons 1H2 are distributed symmetrically about the central 2He4 (that’swhy the 4Be8 has null electric quadrupole moment).
Therefore, when the two deuterons gyrate about the z-axis (because of the nuclear spin about the z-axis which crosses the central 2He4), they appears in the Arrington’s experiment as a straight line very well defined, 14fm long.

5B
The next nucleus is the 5B. It has one unpaired deuteron, and so it has a big trepidation. Due tothe nuclear spin, its image in the experiment appears as a cloud about the central 2He4

6C
The next nucleus is 6C. In the detail of page 231 we see the structure of 6C12. Its structre forms a cube with diagonal of about 14fm around the central 2He4. So, in spite the 6C12 has no trepidation, however due to the nuclear spin the four deuterons 1H2 appears in the images of the experiment as a cloud about the central 2He4.

7N
The next nucleus is the 7N. As it has one unpaired deuteron, its image shows in the experiments a cloud about the central 2He4.

80
The next nucleus is 8O.
The structure of 8O16 is shown in page 144 of the book QRT. The page is shown in the link previously posted.
The structure of 8O16 is not flat. Due to repulsion between the 6 nucleons 1H2, they oscillate about the central 2He4. This is shown in the Fig. 1.2 of the page 144.
So, in the image captured by the Arrington’s experiment, the 8O16 shows a cloud distributed about the central 2He4.

9F
After the nucleus 8O, a new hexagonal floor beggins, with the nucleus 9F. As it has an unpaired deuteron, its image shows a cloud about the central 2He4.

All the other nuclei exhibit a cloud about the central 2He4.
That’s why Arrington’s experiments showed the beryllium as a surprise. Only its image shows a straight line of length 14fm.

That’s why beryllium is an exception.