Structure of the Excited Band in Mg24

I propose for the 18-39-MeV excited collective band in $^{24}\mathrm{Mg}$ an intrinsic cluster structure with tetragonal symmetry, point group $\overline{4}2m$, obtained by approximating edges of two $^{12}\mathrm{C}$ triangles to form a central bisphenoid. With the helion-helion distances in the $^{12}\mathrm{C}$ clusters assumed to retain their $^{12}\mathrm{C}$ value, 3.81 fm, the four lateral edges of the bisphenoid are found from the observed values of the levels to have length 4.15 fm. The agreement of this value with values for other nuclei supports the proposed structure.